Comparison of ketamine with midazolam versus ketamine with fentanyl for pediatric extracorporeal shock wave lithotripsy procedure: A randomized controlled study

Hakan Akelma, Ebru Tarikçi Kiliç, Fikret Salik, Ayhan Kaydu

Anesthesia: Essays and Researches 2018 12(2):459-464

Objectives: To compare the effects of ketamine-fentanyl (KF) and ketamine-midazolam (KM) combinations on hemodynamic parameters, recovery properties, pain, and side effects in pediatric patients undergoing extracorporeal shock wave lithotripsy (ESWL) procedure. Methodology: In this double-blinded, randomized trial, 60 pediatric patients aged between 1 and 13 years with American Society of Anesthesiologists physical status Classes I and II, who scheduled for ESWL procedure, were included in the study. Patients were randomly divided into two groups: Group KM received 0.1 mg/kg of midazolam +1–1.5 mg/kg of ketamine and Group KF received 1 μg/kg of fentanyl +1–1.5 mg/kg of ketamine intravenously. Results: There were similar demographic properties, recovery, and discharge times between groups. No statistically significant difference was found in peripheral oxygen saturation, mean and diastolic blood pressure, Ramsey sedation scores, modified Aldrete recovery scores, side effects, and recovery times (Group KM, 16.067 ± 1.2 min; Group KF, 19.46 ± 0.86 min) between groups (P > 0.05). Conclusion: KF combination offers better hemodynamic properties, less side effects with lower visual analog scores, and face, legs, activity, cry, and consolability scores than KM in the pediatric ESWL procedure.

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Geriatric patients with hip fracture: Frailty and other risk factors affecting the outcome

Bindu K Vasu, Kruthika P Ramamurthi, Sunil Rajan, Mathew George

Anesthesia: Essays and Researches 2018 12(2):546-551

Background: Hip fracture is a devastating health-care problem in a geriatric patient, leading to high mortality and morbidity. Preoperative risk assessment in the geriatric patient is often inexact because of the difficulty in measuring their poor physiologic reserves. Aims: The primary objective was to find the association of modified frailty index (MFI) with 90-day mortality in geriatric patients who received anesthesia for fractured hip. Secondary objectives were to assess the association of preoperative waiting time with the 90-day mortality and the correlation of preexisting medical conditions with poor functional outcome among the survivors. Settings and Designs: This prospective, observational study was conducted at a tertiary care institution. Subjects and Methods: In this prospective observational study, done over a period of 1 year, 60 geriatric patients aged ≥65 years who received anesthesia for fractured hip and fulfilled selection criteria were recruited. The association of MFI with 90-day mortality and the correlation of preexisting comorbidities with poor functional outcome among the survivors were assessed. Statistical Analysis Used: Independent sample t-test, Mann–Whitney test, and odds ratio were used as applicable. Results: Total 60 patients were available for analysis as two patients dropped off from final 62 on follow up, fifty three patients survived after 90 days. MFI and 90-day mortality showed a significant direct correlation with P < 0.0001. However, no association was found between the preoperative waiting time and 90-day mortality. Preexisting medical conditions showed a significant association of dementia with total dependence afterward with a P = 0.02. Conclusion: There is significant statistical correlation of MFI with the 90-day mortality in the geriatric hip-fractured patients undergoing surgery.

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Assessment of job satisfaction and quality of life among practicing Indian anesthesiologists

Akshaya N Shetti, Shivanand L Karigar, Rachita Govind Mustilwar

Anesthesia: Essays and Researches 2018 12(2):302-308

Introduction: Anesthesiologists are exposed to extreme level of stress from beginning of career. With evolution of super-specialty branches, level of stress faced has also raised. Prolonged working hours, poor hospital facilities and dependencies on surgeon are main contributing factors. Stress and unsatisfactory remuneration may lead to decrease in job satisfaction. One should have a good quality of life, but high level of stress may itself compromise quality of life. This study aims at assessment of stress, quality of life spent, job satisfaction, and health issues. Aim: The aim is to study stress level, job satisfaction, and quality of life of practicing Indian anesthesiologists. Setting and Design: This was an online survey, descriptive study. Subjects and Methods: An online survey consisting of 21 questions was sent to Indian anesthesiologists by E-mail using SurveyMonkey platform. The responses were collected and analyzed. Results: Out of 1219 anesthesiologists, 81% were satisfied being anesthesiologist, but 58% are unsatisfied with remuneration. More than one role was played by 47.7% of anesthesiologists. Nearly 83% of anesthesiologists agreed that the stress is highest among anesthesiologist compared to other medical professionals. Stress does reduce with the presence of another anesthesiologist while managing cases. Most anesthesiologists practiced various stress reduction methods of which spending time with the family was most popular method. Conclusion: This study divulges working pattern, job satisfaction, level of stress faced, methods to alleviate stress, and quality of life of anesthesiologists in India. A balanced family and professional life with proper utilization of leisure will reduce the stress.

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Epidural analgesia during labor: Attitudes among expectant mothers and their care providers

Garg Kamakshi, Grewal Anju, Singh Tania, Gupta Priyanka, Bansal Kamya, Pruthi Gegal, Chuttani Priyanka

Anesthesia: Essays and Researches 2018 12(2):501-505

Introduction: Varying levels of knowledge and attitudes among parturients and physicians toward epidural analgesia result in its low utilization. We aimed to assess the knowledge, attitude, and practice of parturients, obstetricians, and anesthesiologists regarding epidural labor analgesia. Methodology: We surveyed obstetricians, anesthesiologists, and parturients availing care and later delivered at our hospital from July 1, 2017, to December 31, 2017. Knowledge, attitude, and practice regarding epidural analgesia were collected using a semi-structured predesigned questionnaire. Data were described as frequencies and analyzed for association between parity and various beliefs and attitudes using Chi-square or Fisher's exact test. Results: About 33% of the parturients knew that delivery is possible without labor pains, but only 18% were satisfied with the procedure. Timely epidural anesthesia could not be availed by 83% of the parturients due to unavailability of service. Among the obstetricians, 64% preferred epidural analgesia and thought that epidural analgesia prolongs the duration of labor, and 55% thought that it would increase the incidence of lower uterine segment cesarean section (LUSCS). In our survey, 48% of all anesthesiologists thought that epidural analgesia would lead to an increase in the incidence of instrumental delivery, 52% required intravenous analgesics with epidural, and 63% thought that it would not increase the incidence of LUSCS. Fear of labor and delivery pain, knowledge status, unwillingness and demand for epidural analgesia, satisfaction level, and reasons for not undergoing the procedure were significantly associated with the gravid status. Conclusion: Wide gap between desire for labor analgesia and its availability exists. A collaborative approach between anesthesiologists and obstetricians is required to disseminate correct information regarding epidural analgesia.

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Clonidine as a sole epidural adjuvant in combined spinal-epidural: Clinical study

M Sathesha, RS Raghavendra Rao, Said Javid Hassan, K Sudheesh

Anesthesia: Essays and Researches 2018 12(2):309-312

Background and Aims: Clonidine has been used as an epidural adjuvant along with local anesthetics; however, its use as a sole epidural adjuvant in combined spinal-epidural (CSE) anesthesia has not been explored; thus, this study aimed to assess the effects of clonidine as a sole epidural adjuvant in CSE on sensory and motor characteristics of 0.5% hyperbaric bupivacaine given by subarachnoid route. Methodology: A total of 60 patients belonging to the American Society of Anesthesiologists Classes I and II aged 18–60 years were randomized in two groups; group G300 and group GNS. G300 group received 300 mg clonidine and GNS received normal saline through epidural route followed by 15 mg of 0.5% hyperbaric bupivacaine as subarachnoid block. Onset of sensory block (time to T10) and motor block (time to Bromage 3), level of sedation (using Modified Ramsay Sedation Score), and hemodynamic changes were recorded. Two-segment regression, duration of analgesia (time for 1st rescue analgesia), and motor block (time to Bromage 0) were recorded. Student's t-test (two-tailed, independent) and Chi-square/Fisher's exact probability test were used for statistical analysis. Results: The demographic data were comparable between the groups. The onset of sensory and motor block was significantly faster in G300 (sensory-71.63 ± 4.51 s, motor-55.63 ± 2.54 s) as compared to GNS (sensory-90.13 ± 4.88 s, motor-118.43 ± 9.50 s) (P < 0.001 and < 0.001, respectively). The two-segment regression was 199.33 ± 19.11 min and 79 ± 9.77 min in G300 and GNS, respectively, (P < 0.001). Duration of analgesia was 317.90 ± 15.32 min and 207 ± 20.66 min for G300 and GNS, respectively (P < 0.001), and duration of motor block was 409.9 ± 34.87 min and 204 ± 22.79 min for G300 and GNS, respectively (P < 0.001). The side effects such as hypotension and bradycardia were statistically and clinically not significant. Conclusion: Clonidine used as a sole epidural adjuvant in dose of 300 mg, for infraumbilical surgeries, has significantly faster onset of sensory and motor block with prolonged duration of analgesia and motor blockade and no significant side effects on a conventional subarachnoid block performed with 0.5% hyperbaric bupivacaine.

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A comparison of acute physiology and chronic health evaluation III and simplified acute physiology score II in predicting sepsis outcome in Intensive Care Unit

Parikshit Singh, Sharmishtha Pathak, Ram Murti Sharma

Anesthesia: Essays and Researches 2018 12(2):592-597

Context: Acute Physiology and Chronic Health Evaluation (APACHE) III and Simplified Acute Physiology Score (SAPS) II are frequently used to predict the outcome of Intensive Care Unit (ICU) patients of sepsis. Aim: The aim of the study was to compare the predictability of outcome with APACHE III and SAPS II score in ICU patients of sepsis, severe sepsis, and septic shock and the 28-day mortality. Settings and Design: This study was an observational, prospective cohort study. Materials and Methods: A total of 100 consecutive patients of sepsis were studied over 20 months. The worst physiological and biochemical parameters during the first 24 h were recorded for the scores and the patient's 28-day outcome followed up. Statistical Analysis Used: Continuous data were expressed as mean ± standard deviation or median. Receivers operating characteristic (ROC) curve was used to find the cutoff value, area under the curve, sensitivity and specificity of APACHE III score, and SAPS II score. Binary logistic regression with response variable as the outcome was utilized. P < 0.05 was considered statistically significant. Results: The mean APACHE III score in the survivor group was 66.49 ± 18.56 as opposed to 80.67 ± 19.03 for nonsurvivors. The mean SAPS II score for the survivor group was 43.32 ± 13.02 as against the nonsurvivor group at 51.92 ± 12.34. The area under the ROC curve for APACHE III was 0.711 with 95% confidence interval as against 0.686 for SAPS II. The best cutoff value obtained for mortality prediction using the ROC curve was 69 for APACHE III while that for SAPS II was 49. Conclusions: APACHE III was found to be a better predictor of mortality as compared to SAPS II though the margin of difference in mortality prediction was not high.

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The effect of single-dose intravenous dexamethasone on postoperative pain and postoperative nausea and vomiting in patients undergoing surgery under spinal anesthesia: A double-blind randomized clinical study

Prabha Parthasarathy, Kavitha Babu, RS Raghavendra Rao, Shreyavathi Raghuram

Anesthesia: Essays and Researches 2018 12(2):313-317

Background: The use of neuraxial anesthesia has dramatically increased. Acute postoperative pain is an undesirable outcome that can delay functional recovery for patients undergoing surgery. Nausea and vomiting in the postoperative period occurs in 20%–30% of the patients and together are the second-most common complaint reported (pain is the most common). Efficacy of glucocorticoids for reducing pain and inflammation after surgery is being explored. Glucocorticoids are strong anti-inflammatory agents, which can be used for a short-time postoperative pain control in various surgeries. Dexamethasone is a glucocorticoid with little mineralocorticoid effect commonly used perioperatively to reduce postoperative nausea and vomiting (PONV) and has a beneficial role in postoperative analgesia. Dexamethasone has also an antiemetic effect, in addition to its anti-inflammatory and analgesic effects. Aim: The main purpose of this study is to evaluate the effect of administration of single-dose intravenous (i.v.) dexamethasone on postoperative pain and PONV in patients undergoing surgery under spinal anesthesia. Settings and Design: A double-blind randomized clinical study was performed in our institute between November 2014 and October 2015 after obtaining clearance from the ethical committee. Materials and Methods: A double-blind randomized clinical study was performed on 60 patients posted for surgery under spinal anesthesia. Patients were randomly assigned into two groups: A (study: 2 ml [8 mg] dexamethasone) and B (control: 2 ml saline). In both the groups, variables such as mean arterial blood pressure (MAP), heart rate (HR), respiratory rate, severity of pain (based on visual analog scale), and other symptoms such as nausea and vomiting were recorded at different time points during the first 24 h after surgery. Statistical methods using Student t-test (two-tailed, independent) and Fischer's exact test were used for analyzing the data. Results: Between-group comparisons indicated significant differences in terms of severity of postoperative pain and PONV (P < 0.001), MAP (P = 0.063), and HR (P = 0.071), which in the study group were lower than the control group. Conclusion: i.v. dexamethasone is efficient in reducing postoperative pain, requirement of rescue analgesia on the first postoperative day, and incidence of PONV with no significant changes in vital signs.

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Would “suction above cuff” be a better option than the “standard” endotracheal tube for the prevention of ventilator-associated pneumonia: A randomized study in postoperative neurological patients

Gunjan , Ankesh , Saurav Shekhar, Akhileshwar , Priyesh Kumar

Anesthesia: Essays and Researches 2018 12(2):480-483

Context: Ventilator associated pneumonia is one the most common nosocomial infection encountered in the ICU patients. Despite of the implementation of the VAP prevention bundle, the incidence remains high. This can be attributed to the peritubal leak and the aspiration of the oropharyngeal secretions. The secretions further forms a nidus for the growth of organisms in the lower respiratory tract. In this study, a specialised tube, named 'suction above cuff endotracheal tube' is used, which has an additional suction port opening above the cuff. This is to facilitate timely aspiration of the secretion which pent-up above the cuff and gradually trickles down the trachea resulting in pneumonia. Aim: to compare the incidence of VAP with standard endotracheal tube (SETT) and suction above cuff endotracheal tube (SACETT) in neurological post-operative patients and its impact on clinical outcome. Settings and Design: 60 patients of post-operative neurological cases aged ≥ 18 years and requiring intubation and/or ventilation and anticipated to remain on ETT for ≥48 h were randomized to receive either SETT or SACETT. Results: In this study involving neurological population, there was no significant difference in incidence of clinical and microbiological VAP between SETT and SACETT group, when other strategies for VAP prevention were similar. Other outcomes were similar with use of either tube for intubation.

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Correlation between weight of the baby and the level of sensory blockade in spinal anaesthesia for caesarean section: An observational study

KS Sushma, Ashwini H Ramaswamy, Safiya I Shaikh

Anesthesia: Essays and Researches 2018 12(2):318-321

Background: The spread of local anaesthetics during spinal anaesthesia is affected by various factors and can be unpredictable especially in parturients undergoing caesarean section. Factors like abdominal girth, symphysis fundal height etc have to studied to know their impact on level of sensory blockade. We hypothesized a study to find any correlation between weight of the baby and the level of sensory blockade. Methods: 46 parturients posted for elective caesarean section belonging to American Society of Anaesthesiologists (ASA) physical status 1 and 2 were included in the study. Maternal height and weight were noted down before entering operation theatre. All patients were instituted subarachnoid block with 2 cc of 0.5% of hyperbaric bupivacaine in sitting position. Level of sensory blockade was assessed with pin prick along midline of the patient every min till 5th minute and 5 minutes till 15th minute. The birth weight of baby was recorded soon after delivery. Results: The weight of the baby and height of the mother were correlated with the sensory blockade of T4. The number of babies weighing more than 3.5 kgs were 3 in our study out of which 2 babies were associated with maximum sensory blockade at 15th minute. It amounts to 66.7% when compared with 14.7% in babies weighing 2.5 to 3.5 kgs which is suggestive of significance ('P' value of 0.093). Conclusion: There is no statistically significant correlation between weight of the baby and the level of sensory blockade.

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Prevention of emergence delirium in children – A randomized study comparing two different timings of administration of midazolam

Gerard Gonsalvez, Deepa Baskaran, Vasudeva Upadhyaya

Anesthesia: Essays and Researches 2018 12(2):522-527

Background: Emergence delirium (ED) is a distressing side effect of sevoflurane anesthesia in children. Midazolam is a widely studied drug for the prevention of ED with conflicting results. Aim, Settings and Design: We designed this prospective randomized double-blind study to compare the effect of 0.03 mg/kg midazolam administered at induction and the same dose administered 10 min before the end of surgery in the prevention of ED in children undergoing sevoflurane anesthesia and also the effect on the time to recovery in both groups. Materials and Methods: Eighty children between 2 and 8 years belonging to patient physical status American Society of Anesthesiologist Classes 1 and 2 undergoing infra-umbilical surgeries under general anesthesia were randomly allocated to receive 0.03 mg/kg midazolam at induction (Group A) and 10 min before the end of surgery (Group B). Caudal block was administered for analgesia after induction. The primary outcome, the incidence of ED was evaluated using the Paediatric Anaesthesia Emergence Delirium Scale from the time of extubation till 30 min postsurgery. The secondary outcome measured was the time to recovery (time from discontinuation of sevoflurane to the time of extubation) and the results were statistically analyzed. Results: The incidence of ED was comparable between the groups (30%, 10%, 5%, and 2.5% at 5, 10, 15, and 20 min, respectively in Group A and 25%, 10%, 5%, and 2.5% of children at 5, 10, 15, and 20 min, respectively in Group B). Recovery was significantly prolonged in Group B (42.5% of patients in Group A recovered within 6 min of discontinuation of sevoflurane in Group A compared to only 20% of patients in Group B). Conclusion: There is no difference in the reduction of incidence of ED following sevoflurane anesthesia when midazolam is administered at induction or the end of surgery. However, the time to recovery was longer when the drug was administered at the end of the surgery.

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Comparison of palonosetron, dexamethasone, and palonosetron plus dexamethasone as prophylactic antiemetic and antipruritic drug in patients receiving intrathecal morphine for lower segment cesarean section

Swastika Swaro, Daisy Karan, Anwesha Banerjee

Anesthesia: Essays and Researches 2018 12(2):322-327

Background: Intrathecal morphine is commonly used for postcesarean analgesia. Its use is frequently associated with opioid-induced nausea, vomiting, and pruritus. Palonosetron (0.075 mg) combined with dexamethasone (8 mg) is postulated to have an additive effect over each drug alone. The study, therefore, compared the effect of intravenous (i.v.) palonosetron, dexamethasone, and palonosetron with dexamethasone combination in preventing intrathecal morphine-induced postoperative vomiting and pruritus in lower segment cesarean section (LSCS) patients. Settings and Design: Randomized, prospective, double-blinded, observational clinical study. Methods: Ninety pregnant women, American Society of Anesthesiologists physical status class I undergoing LSCS were included in the study. They were randomly assigned to three groups – Group P received 0.075 mg palonosetron i.v., Group D received dexamethasone 8 mg i.v., and Group PD received palonosetron 0.075 mg along with dexamethasone 4 mg i.v., just after spinal anesthesia with bupivacaine 2.2 ml (12 mg) and 150 μg morphine. The incidence of pruritus, nausea, vomiting, and need for rescue drug were recorded for 24 h. Statistical Analysis: Statistical analysis was performed using Student's t-test for categorical variables and Chi-square test for noncategorical variables. Results: The incidence of nausea, vomiting was significantly more in Group D (40%) than Group P (27%) and Group PD (20%) in 24 h. The incidence of pruritus was significantly more in Group D (6%) than Group P and PD (3%). The need of rescue antiemetic was more in Group D (30%) than Group P (6%) and Group PD (3%). No difference in three groups requiring rescue antipruritic drug. Conclusion: Prevention of intrathecal morphine-induced vomiting and pruritus was more effective with palonosetron alone or with dexamethasone combination than dexamethasone alone. Combination of palonosetron and dexamethasone proved no better than palonosetron alone.

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Therapeutic efficacy of two different doses of dexmedetomidine on the hemodynamic response to intubation, the intubating conditions, and the effect on the induction dose of propofol: A randomized, double-blind, placebo-controlled study

Neha Sharma, Nandita Mehta

Anesthesia: Essays and Researches 2018 12(2):566-571

Context: The hemodynamic response associated with laryngoscopy and tracheal intubation is a common concern for the anesthesiologist, especially in high-risk patients. The use of dexmedetomidine has found favor in obtunding this response, in addition to providing better intubating conditions and reducing the dose of other anesthetic drugs. Most of the current literature states a loading dose of 1 μg/kg dexmedetomidine to be superior to lower doses in this regard. However, using a lower dose may be advantageous by reducing incidence of adverse effects such as hypotension and bradycardia which are likelier with the use of higher dose, in addition to being more cost-effective. Aims: The aim of the study was (1) to evaluate and compare the effect of loading doses of 1 μg/kg and 0.5 μg/kg dexmedetomidine on attenuation of hemodynamic response to laryngoscopy and intubation and (2) to evaluate the efficacy of dexmedetomidine in reducing the induction dose of propofol for achieving better intubating conditions. Materials and Methods: A randomized, double-blind, placebo-controlled study was planned on ninety American Society of Anesthesiologists I and II patients scheduled for elective surgery under general anesthesia. Patients were divided into three groups. Two groups received different loading doses of dexmedetomidine infusion before induction and the third group was a control group. The induction dose of propofol required to abolish the verbal response was noted and compared in all the three groups. All patients were assessed for the intubating conditions and hemodynamic response. Statistical Analysis: Nonparametric data were compared using the Chi-square test and parametric data were compared using Student's t-test using SPSS 16.0 software. Results: Both the loading doses of 1 μg/kg and 0.5 μg/kg dexmedetomidine were equally effective in reducing the induction dose of propofol, improving the intubating conditions and blunting the hemodynamic response to laryngoscopy and intubation. The incidence of adverse effects such as hypotension and bradycardia was lesser with the loading dose of 0.5 μg/kg. Conclusions: Dexmedetomidine when used as infusion in the loading dose of 0.5 μg/kg is therapeutically as effective as when used in the dose of 1.0 μg/kg not only in reducing the induction dose of propofol but also in providing good intubating conditions and blunting the hemodynamic response to intubation. A lower dose is associated with a lesser incidence of adverse effects such as hypotension and bradycardia.

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Intrathecal bupivacaine with neostigmine and bupivacaine with normal saline for postoperative analgesia: A cost-effective additive

Naga Seshu Kumari Vasantha, Ravi Madhusudhana

Anesthesia: Essays and Researches 2018 12(2):328-332

Context: In day-to-day practice, subarachnoid block remains the most common type of anesthesia. Bupivacaine is commonly used local anesthetic of neuraxial blockade, though earlier 5% xylocaine and now ropivacaine and levobupivacaine are also used. Additives such as opioids and α2agonists are also used. We are using neostigmine as an additive with bupivacaine to see the duration of postoperative analgesia. Aims: To compare the efficacy of intrathecal hyperbaric bupivacaine with neostigmine when compared to hyperbaric bupivacaine with normal saline with regard to time of onset and duration of sensory and motor blockade, time to two-segment regression. Settings and Design: Randomized, double-blinded study. Subjects and Methods: One hundred patients admitted for lower abdominal and lower limb surgeries done under spinal anesthesia (SA) during the period of February 2015–August 2016. Statistical Analysis Used: Data were entered into Microsoft excel data sheet and analyzed using SPSS 22 version. Categorical data were represented in the form of frequencies and proportions. Chi-square was used as a test of significance. Continuous data were represented as a mean and standard deviation. Independent t-test was used as a test of significance to identify the mean difference between two groups. Results: Mean onset of sensory blockade with neostigmine group was 174.1 ± 107.1 s and in normal saline group 171 ± 35.6 s. Mean onset of motor blockade with neostigmine group was 197.4 ± 111.6 s and in normal saline group was 219.4 ± 73.2 s. Mean two-segment regression with neostigmine group was 110.6 ± 22.7 s and in normal saline group was 71.5 ± 17.1 min. Duration of analgesia with neostigmine group was 336.3 ± 54.5 min and in normal saline group was 188.8 ± 18.4 min. Conclusions: Intrathecal neostigmine is associated with significantly prolonged sensory, motor blockade, and effective postoperative analgesia.

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Incident reporting of adverse drug reaction to intravenous ranitidine in an emergency department

Saurabh Sud, Deepak Dwivedi, Manish Paul, Sanasam Ushakiran Singh

Anesthesia: Essays and Researches 2018 12(2):605-606



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A comparative study of three vasopressors for maintenance of blood pressure during spinal anesthesia in lower abdominal surgeries

Dilpreet Kaur, Aamir Laique Khan, Amitesh Pathak

Anesthesia: Essays and Researches 2018 12(2):333-337

Introduction: Subarachnoid block, although being highly efficient with lesser drug doses, often has limitation such as hypotension, continues to be a matter of concern to the anesthetist. The present study was aimed to compare the use of phenylephrine, ephedrine, and mephentermine bolus for maintenance of blood pressure during spinal anesthesia in lower abdominal surgeries. Subjects and Methods: In a randomized, prospective study, 90 adult patients of either sex who developed hypotension during surgery under subarachnoid block were allocated into three groups to receive bolus phenylephrine, ephedrine, and mephentermine. The number of boluses and time taken to recover from hypotension was noted. Occurrence of adverse effects in the perioperative and postoperative period was also noted. Results: Results were analyzed by Student's paired t-test and Chi-square test. The ANOVA test was used to compare the group variances among the study groups. P < 0.05 was considered statistically significant. Thirty-four hypotensive events (average 1.03 events/patient) took place in mephentermine group. In phenylephrine group, a total of 53 hypotensive events took place. On an average, the group had a total of 1.61 hypotensive events per patient. No hypotensive event took place in ephedrine group after the first bolus of drug (average 1 event/patient). Mean heart rate in phenylephrine group was significantly lower as compared to the other two groups (P < 0.001). Conclusion: Mephentermine and ephedrine were similar in performance, offered a better hypotensive control, and had lower recurring events as compared to phenylephrine.

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Comparison of two doses of dexmedetomidine for supraclavicular brachial plexus block: A randomized controlled trial

Chandni Sinha, Amarjeet Kumar, Poonam Kumari, Akhilesh Kumar Singh, Shalini Sharma, Ajeet Kumar, Anup Kumar, Nishant Sahay

Anesthesia: Essays and Researches 2018 12(2):470-474

Background: Dexmedetomidine is commonly used as an additive in supraclavicular brachial plexus block (SBPB). Due to its adverse effects such as bradycardia and hypotension, finding the appropriate dose of dexmedetomidine is the question. Aims: We aimed to compare two commonly used doses of dexmedetomidine (1 μg/kg and 2 μg/kg) added to levobupivacaine in ultrasound-guided SBPB in terms of its effect on duration of analgesia, hemodynamics, and associated adverse effects. Settings and Design: This randomized, double-blinded prospective study was conducted over a period of 1.5 years in our tertiary care hospital. Materials and Methods: Clearance from the Institutional Ethical Committee and Clinical Trial Registry of India was taken. Ninety patients' physical status American Society of Anesthesiologists Classes I and II undergoing upper limb surgeries under SBPB were included in this study. Patients in Group I received 1 μg/kg dexmedetomidine, whereas patients in Group II received 2 μg/kg dexmedetomidine added to 20 cc levobupivacaine. The primary outcome measure was the duration of analgesia after administering the block. Secondary outcomes included effect on hemodynamics, duration of blockade, and adverse effects. Statistical Analysis: Statistical analysis was carried out using Stata Version 10. Unpaired t-test and Chi-square test were used. Results: The duration of analgesia and sensory and motor blockade were similar in both the groups. The heart rate (HR) and mean arterial pressure were statistically lower in Group II. The incidence of bradycardia and hypotension was more in Group II. Conclusions: Increasing the dose of dexmedetomidine does not prolong the duration of analgesia, but it is associated with lower HR and blood pressure. Incidence of hypotension and bradycardia is also more. Hence, a lower dose of 1 μg/kg dexmedetomidine added to 0.5% levobupivacaine is a good balance between safety and efficacy.

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Comparison of effect of airway nebulization with lignocaine 2% versus ropivacaine 0.25% on intubation and extubation response in patients undergoing surgery under general anesthesia: A randomized double-blind clinical trial

Ramyavel Thangavelu, Ranjan R Ventakesh, Kandasamy Ravichandran

Anesthesia: Essays and Researches 2018 12(2):338-343

Context: Both intubation and extubation are associated with pressor response. Aims: We aimed to evaluate if ropivacaine 0.25% nebulization would prevent hemodynamic and cough responses to intubation and extubation and compared it with lignocaine 2% and saline group. Settings and Design: This was a randomized double-blind clinical trial. Materials and Methods: A total of 75 patients classified as the American Society of Anaesthesiologists physical status Classes I and II belonging to 18–60 years were included in the randomized double-blind trial and divided into three groups; Group 1: received 5 ml of normal saline, Group 2: received 5 ml of 0.25% ropivacaine, Group 3: received 5 ml of 2% lignocaine through nebulization before the induction. Patients were then administered general anesthesia. Mean arterial pressure (MAP), heart rate (HR), and saturation were recorded at baseline (T1), at intubation (T2), upon anesthetic withdrawal (T3), upon eye opening (T4), upon extubation (T5), and 2 min after extubation (T6). Cough response was recorded at emergence and extubation. Statistical Analysis Used: Repeated measures analysis of variance were used to compare hemodynamic variables and Chi-square test to compare the grades of cough between the two groups. Results: The drug ropivacaine was found to be effective in reducing the hemodynamic responses to both intubation and extubation when compared to saline (P < 0.05). At extubation, though the mean values of HR and MAP were lower in ropivacaine compared to lignocaine group, the difference did not achieve statistical significance (P = 0.103 and 0.153 respectively). Only 40% of patients who received ropivacaine had cough at extubation (P < 0.001). Conclusion: Ropivacaine when used through nebulization preinduction effectively reduced both intubation and extubation responses when compared to saline. However, there was no significant difference between the ropivacaine and lignocaine on extubation response.

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The comparison of the efficacy and safety of midazolam, ketamine, and midazolam combined with ketamine administered nasally for premedication in children

Mehmet Erdem Akcay, Ebru Tarıkçı Kılıç, Mehmet Salim Akdemir

Anesthesia: Essays and Researches 2018 12(2):489-494

Background: In this prospective, randomized study, we evaluated the intranasal administration of Midazolam ketamine combination, midazolam, and ketamine in premedication for children. Material and Methods: We studied 60 American Society of Anesthesiology physical status Classes I and II children aged between 1 and 10 years undergoing ear nose throat operations. All cases were premedicated 15 min before operation with intranasal administration of 0.2 mg/kg midazolam in Group M, 5 mg/kg Ketamine in Group K, and 0.1 mg/kg Midazolam + 3 mg/kg ketamine in Group MK. Patients were evaluated for sedation, anxiety scores, respiratory, and hemodynamic effects before premedication, 5 min interval between induction and postoperative period. Results: There was no difference with respect to age, sex, weight, the duration of the operation, and for mask tolerance. Sedation scores were significantly higher in Group MK. There was no statistically difference between the groups for heart rate, oxygen saturation, and respiratory rate. Conclusion: We concluded that intranasal MK combination provides sufficient sedation, comfortable anesthesia induction with postoperative recovery for pediatric premedication.

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Inter scalene block: Revisiting old technique

Vinendra Nath Vaid, Aparna Shukla

Anesthesia: Essays and Researches 2018 12(2):344-348

Background and Aims: The technique of percutaneous brachial plexus block has persisted in many variations since first such block given by Hirsheli in 1911.[1] Both supraclavicular and infraclavicular approaches have been described. Consequent to perivascular technique (Winnie and Collins 1964), Winnie described interscalene block (ISB) in 1970.[2],[3] Winnie's was a single deposit block which relied upon volume for its success. It is nearly 50 years that ISB has stood the test of time and has evolved from single to multiple deposits Block. In mid-90s, ultrasound guidance was first explored by anesthetists for regional anesthesia in University of Vienna.[3] As ultrasound guidance is becoming popular and is increasingly available to budding anesthetist, popularity of old technique has started waning. In this study, old technique of ISB was revisited with a view to assess its success rate with established drugs and examine if in light of ultrasound guidance, this technique has become irrelevant for anesthetist today. Methods: A retrospective study, a survey with high response rate, was done on success rate of three variations of old technique of ISB in 100 patients. In variation-1, thirty patients received two deposits of local anesthetic in interscalene groove. In variation-2, thirty patients received four deposits of local anesthetic in interscalene groove. In variation-3, forty patients received six deposits of local anesthetic in interscalene groove along with infiltration of both scalene muscles. In none of the variations, paraesthesia was sought or peripheral nerve stimulator (PNS) or imaging gadget was used. Demographic data in three variations were compared statistically using Chi-square and one-way ANOVA test. Success rate among variations was analyzed by Fisher's exact test. Results: In variation-1, 17 out of 30, in variation-2, 23 out of 30, and in variation-3, 37 out of 40 blocks were successful. Conclusion: Success of ISB given without PNS or ultrasound guidance is directly proportional to the number of deposits of local anesthetic made in interscalene groove.

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Minimum alveolar concentration of desflurane for maintaining BIS below 50 in children and effect of caudal analgesia on it

Jeetinder Kaur Makkar, Deepak Dwivedi, Aswini Kuberan, Balbir Kumar, Indu Bala

Anesthesia: Essays and Researches 2018 12(2):512-516

Context: Neuraxial techniques have sedative properties secondary to decreased inputs from sensory and motor afferents. We hypothesized that caudal analgesia decreases the requirement of desflurane as measured by bispectral index (BIS). Aims: This study aims to determine the minimum alveolar concentration (MAC) of desflurane for maintaining BIS below 50 (MACBIS50) in children undergoing infraumbilical surgeries with laryngeal mask airway (LMA) and study the effect of caudal analgesia on the same. Settings and Design: This is prospective and observational study. Subjects and Methods: Thirty-nine American Society of Anesthesiologists physical status Classes I and II children in between 1 and 8 years of age undergoing elective infraumbilical surgery under general anesthesia were allocated randomly into two groups (Group C and Group D) after induction with sevoflurane and LMA insertion. In Group C, caudal block was performed with 0.75 mL/kg of 0.25% bupivacaine and BIS values were recorded after 10 min for 1 min at 10 s intervals. In Group D, BIS was recorded for desflurane for 1 min at 10 s intervals followed by a caudal block with the same dose. Statistical Analysis Used: Dixon up-down method with a step size of 0.5%, and probit analysis were used for analysis. Results: A total of 39 patients were enrolled. MAC of desflurane for maintaining MACBIS50was 5.57 (95% confidence interval [CI] 5.22–5.95) in Group D and 4.31 (95% CI 3.12–5.08) in Group C. The use of caudal anesthesia lowered the MAC of desflurane for maintaining MACBIS50 in children by 22.36% (P < 0.001). Conclusions: The use of caudal analgesia significantly reduced MAC of desflurane for maintaining MACBIS50in children undergoing infraumbilical surgeries using LMA.

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P129. Morphological changes of the vagus nerve are accompanied by changes of heart rat

Publication date: August 2018

Source: Clinical Neurophysiology, Volume 129, Issue 8

Author(s): D. Weise, J.O. Pelz, E. Belau

Background

The physiological regulation of the heart is determined by the interaction between the sympathetic and the parasympathetic nervous system. The parasympathetic efferent fibers originate from the nucleus ambiguous and the dorsal motor nucleus. Together with the afferent fibers from the spinal trigeminal nucleus and the solitary nucleus they form the vagus nerve (VN). The measurement of the heart rate variability (HRV) enables to assess the relative impact of the parasympathetic and sympathetic innervation on the heart with different impact of the right and left VN. Whether morphological changes of the right and left VN are accompanied by functional changes as indicated by altered HRV parameters is currently unknown.

Methods

Measurement of HRV was performed in 65 healthy subjects (38 women; mean age 52 years, range 23–76 years). RR intervals were measured on electrocardiograms at normal breathing for 10 min under resting and in supine position via the computer-based system ProSciCard (MedSet Medizintechnik GmbH, Hamburg, Germany). Besides heart rate at rest, several indices of the HRV were automatically computed: the standard deviation of RR-intervals (SDNN, higher index indicates higher variability), the root mean square of successive differences (RMSSD, estimate of short-term components of HRV), the number of all RR-intervals/maximal frequency (HRV index, higher index indicates higher variability). In addition, power spectral analyses in the low (ln(LF), 0.05–0.15 Hz) and in the high frequency spectrum (ln(HF), 0.15–0.5 Hz) were performed and the low frequency/high frequency ratio (ln(LF/HF) ratio) as a marker of sympatho-vagal interaction was calculated. In addition, the cross-sectional area (CSA) of the VN was sonographically measured at the level of the thyroid gland. Besides the lateralized assessment of the VN CSA, the ratio between the CSA of the right and left VN was calculated (VN-symmetry index).

Results

There was no correlation between the right or left VN CSA and heart rate at rest or any other HRV parameter in a correlation analyses adjusted for age and sex. However, we found a correlation between the VN-symmetry index and SDNN (0.30, p = 0.029), RMSSD (0.30, p = 0.027), HRV index (0.26, p = 0.055) and the ln(HF) (0.24, p = 0.085).

Conclusions

In a cohort of healthy subjects, morphological changes of both VN as represented by the VN-symmetry index are accompanied by functional changes mainly involving the parasympathetic nervous system. Further studies should examine whether this correlation is altered in (e.g.) neurodegenerative or inflammatory diseases involving the VN.

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P128. Can the extratemporal facial nerve been visualized by ultrasound?

Publication date: August 2018

Source: Clinical Neurophysiology, Volume 129, Issue 8

Author(s): G.F. Volk, J. Thielker, H. Wegscheider, O. Guntinas-Lichius, B. Moriggl

Introduction

Many peripheral nerves can be visualized by ultrasound for diagnostic and therapeutic interventions. The possibility of visualizing the facial nerve (FN) has been considered, but not jet proven scientifically. This study describes the first systematic evaluation of sonografic facial nerve vizualisation of the whole extratemporal facial nerv.

Methods

Eight cadaveric hemifaces were evaluated by means of high frequency ultrasound with two linear (13 MHz and 22 MHz) and a convex transducer (6.6 MHz), in order to detect the extratemporal course of the FN starting from its exit at the stylomastoid foramen: the main trunk, the parotid plexus between the two parts of the parotid gland (Image1), the distal branches terminating into the orbicularis oculi and the zygomatic major muscle. Ultrasound-guided color injections and FN dissection were performed to confirm the results (Image2).

Results

The main trunk of the FN, as it exits the stylomastoid foramen, was correctly stained in 75%, the parotid plexus in 100%. The branches innervating the orbicularis oculi muscle were stained in 100% and the branches innervating the zygomatic major muscle in 86% hemifaces, after 1 was withdrawn due to insufficient image quality.

Conclusions

Through our novel approach of high-resolution ultrasonography we could identify the various portions of the extratemporal FN, including its main trunk leaving the stylomastoid foramen, in an accurate and reproducible way. This might be a way to visualize and locate nerve damage.

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P127. Nerve ultrasound in children with ulnar neuropathy associated with supracondylar humerus fracture

Publication date: August 2018

Source: Clinical Neurophysiology, Volume 129, Issue 8

Author(s): A.K. Peyer Kauffmann, S. Mittas, A. Schiller, K. Otten, T. Schmitt-Mechelke, M. Calcagni, E. Wilder-Smith

Background

Assessing nerve traumas in children is challenging. Electrodiagnostic studies are often not tolerated. We tested if ultrasound examination in children with recent supracondylar humerus fracture and ulnar nerve pathology was well tolerated and whether it was helpful in assessing the nerve trauma.

Methods

This is a retrospective analysis of all pediatric cases with recent supracondylar humerus fracture and persistent ulnar deficits presenting to our neurology outpatients clinic from October 2016 to September 2017. All patients underwent clinical neurological examination. Additional examinations in the form of EMG and nerve ultrasound using a 18 MHz hockey stick probe were proposed as additional investigations.

Results

Patients were aged 3–10 years (mean age 6.3 years), 4 male and 2 female. All experienced severe extension type supracondylar humerus fractures (Type III and Type IV), treated with closed (3 patients) or open reduction (3 patients) and fixed with crossed pinning (2–4 pins). Ulnar nerve deficits in intrinsic hand muscles ranged from M0 to M3. 3 patients showed complete loss of ulnar sensory motor function. 3 were able to tolerate EMG. All 6 patients tolerated and were able to complete ultrasound examination. In 1 patient with complete loss of function, discontinuity of the nerve with formation of stump neuromas was detected in ultrasound. In the other 5 cases, nerve continuity could be demonstrated, but significant nerve swelling (sulcus to upper arm ratios 1.4–2.7; mean 1.97) was apparent in all. In the 2 most severe cases of nerve swelling, additional nerve compromise with scar tissue was detected. Ultrasound findings led to surgical intervention in 2 cases (in one additional EMG data was available): 1) nerve repair by a sural nerve graft for the case of neuronotmesis and 2) neurolysis followed by anterior displacement in one case with severe nerve swelling and compromising scar tissue.

Conclusions

Nerve ultrasound is well tolerated in children and proved to be useful and informative for management and counselling. Useful ultrasound indicators of neuronal damage included loss of nerve continuity, neuroma formation, compromising scar tissue and nerve swelling.

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P126. Identification by ultrasound of a cervical nerve root edema caused by vertebral artery loop

Publication date: August 2018

Source: Clinical Neurophysiology, Volume 129, Issue 8

Author(s): I. Aroyo, V. Prenosil, R. Kollmar

Abstract

Ultrasound is an excellent modality in imaging of peripheral nerves (Lawande et al., 2014, Suk et al., 2013). Although it is a well-established technique its use is not a first-line diagnostic tool in patients with brachialgias. In this case we report of a 44 years old male, who suffered for years from brachialgia of fluctuating intensity of the right arm. A lax humerus articulation of the same arm was diagnosed in the childhood and treated surgically. Actually the patient reported pain mainly in the C6 dermatome, but also shoulder area (C5). He associated these symptoms with a varicella zoster virus (VZV) affection of the shoulder some weeks ago. Cerebral spinal fluid (CSF) examination showed an altered cell count (11 cells/μL). Viral Plexus neuritis was suggested and antiviral therapy was started. Not congruent were the neurological status (Miller et al., 2000) and the electrophysiological examination of the periphery nerves, both within normal limits. The further results from the CSF suggested no acute viral infection and showed residual post infectious state with elevated IgG-Antibodies for VZV.

As part of the further differential diagnosis a sonography of the cervical roots and brachial plexus was realized. It showed an edema of the cervical root C6 and in less degree of C5 and C7. Furthermore the patient had a dominant right vertebral artery (V1 diameter 5,2 mm vs. 1,9 mm of the left side) with coiling in V2-segment next to the affected roots.

The MRI of the right plexus and MR-angiography confirmed the diagnosis and showed the elongated vertebral artery with a loop with contact to the affected roots.

We suggest that the edema is due to the pulsatile contact of the vertebral artery, concordant to a reported intermittent pulsatile pain of the shoulder and right thumb, combined with a chronic intrathecal irritation, which explains the elevated cell count in the CFS.

Conclusion

There are few case reports (Hoon Soo et al., 2010, Ahmed et al., 2014) describing a vertebral loop as origin of radiculopathy but we could not find reports of ultrasound of peripheral nerves for this diagnose. We postulate that routine ultrasound as preliminary evaluation of cervical roots and plexus of patients with brachialgias and diffuse arm pain symptoms could help to improve the diagnostic precision with this high definition and low cost methodology with no adverse events for the patients.

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P125. A look inside the nerve – morphology of nerve fascicles in healthy controls and patients with polyneuropathy

Publication date: August 2018

Source: Clinical Neurophysiology, Volume 129, Issue 8

Author(s): A. Grimm, N. Winter, H. Axer, M. Koch, E. Auffenberg

Objective

Polyneuropathies are increasingly analyzed by ultrasound. Summarizing, diffuse enlargement is typical in Charcot-Marie Tooth type 1 (CMT1a), regional enlargement occurs in inflammatory neuropathies. However, a distinction of subtypes is still challenging. Therefore, this study focused on fascicle size and pattern in controls and distinct neuropathies.

Methods

Cross-sectional area (CSA) of the median, ulnar and peroneal nerve (MN, UN, PN) was measured at predefined landmarks in 50 healthy controls, 15 CMT1a and 13 MMN patients. Additionally, largest fascicle size and number of visible fascicles was obtained at the mid-upper arm cross-section of the MN and UN and in the popliteal fossa cross-section of the PN.

Results

Cut-off normal values for fascicle size in the MN, UN and PN were defined (<4.8 mm², <2.8 mm² and <3.5 mm²). In CMT1a CSA and fascicle values are significantly enlarged in all nerves, while in MMN CSA and fascicles are regionally enlarged with predominance in the upper arm nerves. The ratio of enlarged fascicles and all fascicles was significantly increased in CMT1a (>50%) in all nerves (p < 0.0001), representing diffuse fascicle enlargement, and moderately increased in MMN (>20%), representing differential fascicle enlargement (enlarged and normal fascicles at the same location) sparing the peroneal nerve (regional fascicle enlargement). Based on these findings distinct fascicle patterns were defined.

Conclusion

Normal values for fascicle size could be evaluated; while CMT1a features diffuse fascicle enlargement, MMN shows regional and differential predominance with enlarged fascicles as single pathology.

Significance

Pattern analysis of fascicles might facilitate distinction of several otherwise similar neuropathies.

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P124. Evaluation of gait parameters in functional gait disorders

Publication date: August 2018

Source: Clinical Neurophysiology, Volume 129, Issue 8

Author(s): K. Breitkopf, J. Decker, M. Wuehr, F. Schenkel, T. Brandt, R. Schniepp

Objective

To identify thresholds for pathognomonic gait parameters in functional gait disorders.

Background

Characteristics of functional gait disorders are e.g. transient fluctuations in stance and gait, excessive slowness or hesitation that is not compatible with neurological disease, uneconomic postures with wastage of muscular energy, the 'walking on ice' gait pattern with typical small cautious steps with fixed ankle joints and sudden buckling of the knees that generally do not lead to falls (Lempert et al., 1991). Early diagnosis is important: Over half of the patients with psychogenic disorder of stance and gait remain unchanged after five and a half years. If the disorder is present no longer than four months complete remission can often be achieved (Brandt et al., 1994).

Methods

We used a pressure-sensitive GAITRite© carpet to assess gait analysis during eight gait conditions (three different walking speeds, two sensory and three cognitive tasks). Each of the 23 gait parameters was edited with custom software. A binary logistic regression, ROC (receiver operating characteristic) analysis and an inversed regression were performed to identify thresholds for pathological deviations from normal range.

Results

In the preferred speed condition, patients with functional gait disorder differed from healthy subjects in all gait parameters, particularly in velocity, spatial, and variability measures. In the cognitive dual task condition (i.e. dual task words), however, the gait parameters almost normalized, especially the variability parameters assimilate healthy subjects.

Conclusion

Characteristics of gait parameters of patients with functional gait disorder were similar to postural performance in patients with phobic postural vertigo (PPV; Wuehr et al., 2017): The dual-task effect in patients with functional gait disorder revealed that cognitive distraction led to a normalization in walking. This is typical for functional disorders and can also be observed in patients with PPV.

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P123. Ginkgo biloba extract EGb 761 improves vestibular compensation after unilateral labyrinthectomy in the rat and modulates hippocampal and cerebellar networks

Publication date: August 2018

Source: Clinical Neurophysiology, Volume 129, Issue 8

Author(s): A. Zwergal, M. Lindner, C. Branner, A. Krämer, L. Vomacka, A. Gosewisch, S. Ziegler, P. Bartenstein, M. Dieterich

Aim

Investigation of the efficacy and mode of action of the Ginkgo biloba extract EGb 761 in a rat model of unilateral labyrinthectomy (UL).

Methods

24 SD rats were included in the study and underwent a left-sided UL by transtympanic injection of bupivacaine/p-arsanilic acid. 8 rats each were randomized into groups receiving either control food only (Ctrl./Ctrl.); or control food prior to UL and EGb 761 supplemented food 15 after UL (Ctrl./EGb 761); or EGb 761 supplemented food 6 weeks prior and 15 days after UL (EGb 761/EGb 761). Vestibular behavioural testing including clinical scoring for nystagmus and postural imbalance as well as semi-automated analysis of locomotion in the open field was done on days 1, 2, 3, 5, 7, and 15 after UL. In addition, sequential whole-brain [18F]-FDG-μPET was performed before and on days 1, 3, 7, 15 after UL to measure cerebral glucose metabolism over time.

Results

After UL all animals exhibited severe signs of vestibular imbalance. A significantly stronger amelioration of nystagmus and postural imbalance scores was identified on days 1, 3, 5, 7 after UL in the EGb 761/EGb 761 group compared to the Ctrl./Ctrl. group (p < 0.05). Accordingly, locomotion speed in the open field was higher on day 7 in the EGb 761/EGb 761 group (p < 0.05). Improvement of symptoms was, to a lesser extent, also found when comparing the Ctrl./EGb 761 and Ctrl./Ctrl. group (reduced nystagmus score on days 1, 2, 5 and postural score at days 1, 5, 7 after UL). Measurements of the regional cerebral glucose metabolism (rCGM) by serial μPET revealed a gradual increase of rCGM in the hippocampal formation and decrease in the cerebellum in the EGb 761/EGb 761 > Ctrl./EGb 761 > Ctrl./Ctrl. group on days 1, 3, 15 after UL (p < 0.005).

Conclusion

EGb 761 improves central vestibular compensation in rats after unilateral inner ear damage compared to control treatment and modulates cerebral plasticity in hippocampal and cerebellar networks.

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P122. Multimodal probabilistic atlas of the human inner ear enables an automated and reliable segmentation of the endolymphatic space

Publication date: August 2018

Source: Clinical Neurophysiology, Volume 129, Issue 8

Author(s): F. Nejatbakhshesfahani, V. Kirsch, A. Berman, D. Keeser, A. Ahmadi, M. Dieterich, B. Ertl-Wagner

Introduction

Intravenous contrast agent enhanced magnet resonance imaging (ivMRI) of the endolymphatic space (ELS) of the inner ear permits the in vivo non-invasive verification of the endolymphatic hydrops (ELH). This might prove especially helpful in the at times complex clinical differentiation between Vestibular Migraine (VM) and Menières Disease (MD) (Nakada et al., 2014). However, current quantification methods of the ELS are cumbersome and experience-dependent (Gürkov et al., 2015). The aim of this study was (i) the development of a multimodal probabilistic atlas of the bony structures of the human inner ear, (ii) the establishment of an atlas-based segmentation of the ELS to then (iii) enable an automated and reproducible volume-based quantification of the ELS.

Methods

Twenty-four patients with vestibular migraine, but without ELH (12 females, aged 20 −76 years, mean age: 51.5 ± 3.9 years) underwent a delayed MRI of the ELS 4 h after the intravenous injection of gadobutrol was performed in a 3 T scanner (Nakada et al., 2014). Diagnostic work-up included neurologic & neuro-orthoptic assessment, VOG during caloric stimulation and head-impulse [HIT], audiometry. The preprocessing is performed by an affine and deformable fusion pipeline and the probabilistic multimodal atlas was created using a label-based approach (Brandt and Dieterich, 2017).

Results

The performance of the atlas was evaluated using three factors: population, number of control points and second Gaussian kernel. The optimum value of the factors for the used algorithm was recognized and atlas based segmentation was conducted. The accuracy of the segmentation was assessed using a dice score (right and left side mean dice score 89% and 86%). Right and left inner ear probabilistic atlas resulted in a 4.7% discrepancy.

Discussion

This novel multimodal probabilistic atlas of the human inner ear enables an automated and reliable segmentation of the endolymphatic space using a deformable registration pipeline, in which each newly generated template includes more comprehensive and plenary information. Applications include automated 3D segmentation and quantification of the inner ear and its different fluid-filled spaces, as well as of the vestibulocochlear nerve.

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P121. Multimodal assessment of the hippocampus in patients with bilateral vestibulopathy

Publication date: August 2018

Source: Clinical Neurophysiology, Volume 129, Issue 8

Author(s): V. Devulapally, V. Kirsch, M. Habs, D. Keeser, B. Ertl-Wagner, M. Dieterich

Introduction

Bilateral vestibular loss leads to anatomical and functional changes in the hippocampal formation, which are reflected in subjective and objective behavioural deficits in spatial navigation, learning and memory (Thomas et al., 2005, Kremmyda et al., 2016). The aim of our study was to specify the seen hippocampal volume changes within grey and white matter in BVP using a novel hippocampus subfield segmentation approach (Pipitone et al., 2014).

Methods

50 right handed subjects (25 healthy controls (HC): aged 58 years, range 31–86 years with physiological vestibular function [head impuls test (HT) gain at 60 ms right 0.9, left 1.0] and 25 patients with bilateral vestibulopathy (BVP) with residual vestibular function (calorics warm left: −2.6°/s; right 2.8°/s) aged 61 years, range 24–87 years] were measured in a 3 T MRI (Erlangen, Siemens, Verio.After hippocampal subfield segmentation (Pipitone et al., 2014) and intracranial volume correction, ANOVA was performed for both left and right hemispheres to evaluate the Bonferoni-corrected differences in the hippocampal subfield volumes between HC and BVP using FSL and R.

Results

Whole brain analysis did not reveal any areas of grey matter change for both contrasts (BVP > HC and HC > BVP).Within the hippocampus-subfield specific grey matter analysis volume decrease was most significant in the posterior part, more specifically in the right CA1 and subiculum (p < 0.001).Within the white matter left and right hippocampal regions were most significantly decreased in the anterior/middle part, more specifically in the CA2-CA3 (p < 0.001) and CA4-DG (p < 0.001) when compared to HC.

Discussion

Our findings are in line with previous human and animal studies that were able to link chronic bilateral vestibulopathy to hippocampal atrophies (Thomas et al., 2005, Kremmyda et al., 2016, Horii et al., 2004). More specifically white matter changes were laterality-unspecific and a little more localized to the anterior/middle part of the hippocampus, which is thought to represent inputs from the vestibular system (required for estimating direction during path integration). Whereas grey matter changes were right-sided and more localized to the middle/posterior part of the hippocampus, which is thought be involved in spatial navigation (Horii et al., 2004, Hüfner et al., 2011).

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P120. MRI of the inner ear enables differentiation of central and peripheral vestibular pathologies in a postoperative ELST patient

Publication date: August 2018

Source: Clinical Neurophysiology, Volume 129, Issue 8

Author(s): V. Kirsch, S. Becker-Bense, A. Berman, J. Gerb, B. Ertl-Wagner, M. Dieterich

Introduction

An endolymphatic sac tumour (ELST) is a rare form of a locally invasive very slowly growing papillary epithelial neoplasm originating from the endolymphatic sac and/or duct (Wick et al., 2015). This single case study exemplifies the usefulness of delayed intravenous gadolinium-enhanced magnetic resonance imaging (iMRI) of the inner ear for differentiation of divers vestibular pathologies in complex cases of dizziness (Nakada et al., 2014).

Case report & methods

A 48-year old, highly burdened right-handed female patient who had been operated on an ELST in the right petrosal bone presented with three different vestibular symptoms: (i) a persistent to-and-fro vertigo since 20 years, (ii) reproducible position-dependent short vertigo attacks accompanied by an inconsistent nystagmus when laying down on her side (R > L), and (iii) spontaneous rotational vertigo attacks for several hours associated by ear pressure, nausea, vomiting, and diarrhea. The diagnostic work-up included a careful neurootological and neuro-orthoptic assessment, videooculography during oculomotor examination (VOG), caloric stimulation (caloric) and head-impulse (HIT), audiometry, as well as an iMRI 4 h after injection of i.v. contrast agent (Nakada et al., 2014). Endolymphatic hydrops (ELH) was characterized by criteria previously described (Baráth et al., 2014). Volumetric assessment used manual segmentation in combination with machine learning and automated local thresholding algorithms (Gürkov et al., 2015).

Results

The structural MRI showed a focal defect zone in the right cerebellar hemisphere. In line, the neuro-orthoptic examination revealed a cerebellar syndrome with downbeat-nystagmus (DBN) that increased when lying down on her R > L side. Furthermore, a right-sided audio-vestibular peripheral deficit was disclosed (HIT_mean gain: R = 0.66, L = 0.98; calorics_mean[°/s]: R = 4, L = 11; audiometry_mean [dB]: R = 50, L = 15). The iMRI revealed a high-grade unilateral right-sided ELH (R = 87 mm3, R_cochlea(=c) = grade II-III, R_vestibule(=v) = grade III), whereas the left ear showed normal values (L = 32 mm3, Lc/v = grade 0).

Discussion

On the basis of these results the (i) ongoing vertigo with (ii) exacerbation when lying down on the side could be assigned to a DBN syndrome with central positional vertigo due to the cerebellar lesion. The spontaneous attacks (iii) were caused by a secondary right-sided ELH. The differentiation of aetiologies allowed a stepwise treatment with a combination of 4-aminopyridine (5 × 5 mg/d) to improve the DBN and betahistin (3 × 48 mg/d) to improve the ELH. Both medications lead to a considerable clinical benefit. Here, iMRI was crucial in assigning a complex symptomatology to different central and peripheral vestibular pathologies resulting in a successful treatment (Brandt and Dieterich).

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P119. Activity-dependent plasticity of the endolymphatic space in vestibular migraine – A single case study

Publication date: August 2018

Source: Clinical Neurophysiology, Volume 129, Issue 8

Author(s): V. Kirsch, S. Becker-Bense, A. Berman, E. Kierig, B. Ertl-Wagner, M. Dieterich

Introduction

A new reasonable and dependable distinguishing criterion in the difficult clinical differentiation between Vestibular Migraine (VM) and Menière's Disease (MD) might be the proof of an endolymphatic hydrops (ELH) via gadolinium-enhanced magnetic resonance imaging of the inner ear (iMRI) Lempert et al.. However, so far published studies are inconclusive and sparse. This single case study clinically documents the volume of the endolymphatic space (ELS) in a VM patient longitudinally over 12 months during an attack-free period (T1), shortly after an VM attack (T2), and three attack-free months later (T3).

Case report & methods

A 61-year old female patient with a 40-year history of recurrent attacks of spontaneous rotational vertigo lasting from a few hours to several days and occurring 1–4 times in 6 months was classified as definite VM. Additional symptoms during the attacks were unsteadiness, a feeling of bilateral head-fullness, bilateral aural pressure, intolerance of motion, photo- and phonophobia; no affection of hearing. Independent of these attacks, regular episodes of migraneous headache were reported. A bilateral vestibulopathy affecting the lower-frequency range had been detected earlier. Diagnostic work-up included neurootological and neuro-orthoptic assessment, VOG during caloric stimulation and head-impulse test [HIT], and audiometry. A delayed MRI of the ELS 4 h after the intravenous injection of gadobutrol was performed in a 3 T scanner (Nakada et al., 2014). ELH was characterized on published criteria (Baráth et al., 2014) whilst including an extra grade. Volumetric assessment of ELS used manual segmentation in combination with machine learning and automated local thresholding algorithms (Gürkov et al., 2015).

Results

Our study revealed an activity-dependent plasticity of the ELS with phases of ELH grade I-II within the left (L)- and right (R)- sided vestibule (v) or cochlea (c) (T1: R/Lv/c = grade 0; T2 R/Lv = grade II, R/Lc = grade I; T3: Rv = grade II, Rc = grade I; Lv = grade I, Lc = grade I) without relevant change in the other diagnostics (HITmean gain: R/LT1 = 0.8, R/LT2 = 0.9; R/LT3 = 0.8; caloricsmean [°/s]: R/LT1 = 2, R/LT2 = 4; R/LT3 = 5; audiometrymean [dB]: R/LT1 = 15, R/LT2 = 15; R/LT3 = 15). Longitudinal (T1–T3) depiction of detailed results revealed activity-dependent plasticity of the endolymphatic space (ELS) of the right inner ear showing an endolymphatic hydrops (ELH) without relevant changes in the ipsilateral diagnostics (HIT [gain], caloric [°/s], audiometry [dB]).

Discussion

This is the first time that plasticity of the ELS is described in VM dependent on the disease activity with an ELH during and after an attack. This raises further questions on the pathognomonic significance of the detection of an ELH within the cochlea and/or vestibule in Menière's Disease (MD) [2] and even more so in VM patients [4,5].

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P118. Speed- and phase-dependent suppression of downbeat nystagmus during locomotion

Publication date: August 2018

Source: Clinical Neurophysiology, Volume 129, Issue 8

Author(s): H. Dietrich, M. Wuehr, C. Pradhan, R. Schniepp

Introduction

Downbeat nystagmus (DBN) is the most common form of acquired fixation nystagmus. Patients typically suffer from oscillopsia and postural instability. Postural symptoms are known to improve during walking, in particular at fast speeds (Schniepp et al., 2014); however, it is unknown whether locomotion also influences ocular motor symptoms in these patients. We thus investigated the frequency and timing of DBN occurrence during standing and walking at different speeds in patients with DBN.

Methods

Eye movements of DBN patients with clear central-gaze nystagmus were recorded using video-oculography during standing as well as treadmill walking at individual slow, preferred and fast speeds. Subjects were instructed to fixate on a target straight in front of them at 2 m distance. We analyzed the frequency and timing of occurrence of compensatory quick-phases (downbeats) throughout the gait cycle as well as the angular and linear components of the vestibulo-ocular-reflex (VOR) to assess general gaze stabilization performance during walking in these patients. Results were compared to healthy controls.

Results

Compared to rest, slow walking significantly lowered the frequency of DBN occurrence in all patients. With increasing walking speed, DBN frequency was further reduced and in some subjects even fully suppressed during fast walking. In addition, DBN events predominantly occurred at the start of the swing phase, indicating that DBN occurrence is phase-coupled to distinct periods of the gait cycle. Whereas angular VOR gains of patients during walking were comparable to those of healthy subjects, linear VOR components were found to be significantly decreased.

Conclusion

DBN ocular-motor symptoms improve during walking, in particular at fast speeds, indicating a speed-dependent re-weighting of the involved vestibulo-cerebellar pathways during locomotion. In addition, compensatory quick-phase eye movements (downbeats) most frequently occur during distinct phases of the gait cycle, suggesting that a phase-coupled locomotor feedback such as spinal motor efference copies influences the brain networks associated with downbeat nystagmus. Notable deficits in compensating linear head motion during walking indicate impairments in pathways processing otolithic inputs, despite an intact integration of vestibular cues from the semicircular canals (Glasauer et al., 2004).

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P115. Painful mydriasis as the only clinical sign of an ipsilateral midbrain abscess

Publication date: August 2018

Source: Clinical Neurophysiology, Volume 129, Issue 8

Author(s): F. Thömke

History

A 39-year-old man noted increasing right frontal and right retroorbital pain. After 3 days, he also noted blurred vison in the right eye. On clinical examination, he had a mydriatic right pupil with diminished light reaction but otherwise normal findings including eye movements examination (and direct-current electro-oculography).

Findings

Masseter reflex testing disclosed an increased latency on the right side and was interpreted in favor of an ipsilateral mesencephalic lesion. MRI documented an abscess in the left ventral midbrain involving the region of the distal intra-mesencephalic segment of the 3rd nerve. Cerebrospinal fluid analysis revealed 185 leucocytes/μl, mildly elevated total protein (536 g/l), and normal glucose and lactate levels. There was no serological evidence for neuroborreliosis, neurolues, brucellosis, leptospirosis, echinococcosis, or fungal infections. Transesophageal echocardiography and dental and otolaryngological examinations were normal.

Treatment

He was treated with a combination of ceftriaxone (2 × 2 g/d) plus flucloxacillin (4 × 2 g/d) plus metronidazole (3 × 500 mg/d) for 6 weeks, and for another 6 weeks with cotrimoxazole (800 mg sulfamethoxazole + 160 mg trimethoprim twice daily). During the first 2 weeks antibiotic treatment was accompanied by dexamethasone (initial bolus of 40 mg i.v. followed by 4 × 8 mg/d, which was slowly tapered within 2 weeks).

Clinical course

Complete clinical recovery occurred within 2 weeks and CSF was normal after 15 days (4 leukoctes/μl, total protein: 228 g/l)

Conclusion

Painful unilateral mydriais may be the only clinical sign of an ipsilateral midbrain lesion.

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P113. Effects of theta-burst rTMS on cortical networks as probed with TMS-evoked potentials

Publication date: August 2018

Source: Clinical Neurophysiology, Volume 129, Issue 8

Author(s): S.M. Günther, C. Tscherpel, L. Hensel, C. Grefkes

Background

Intermittent theta burst stimulation (iTBS) as a specific protocol of repetitive transcranial magnet stimulation (rTMS) has been shown to induce changes in cortical excitability that last beyond stimulation. However, effects are subject to a high degree of intra- and inter-individual variability (Hamada et al., 2013 Cereb Cortex; Diekhoff-Krebs et al., 2017 Neuroimage Clin.). Combining transcranial magnet stimulation (TMS) with electroencephalography (EEG) allows investigating cortical responses with high spatiotemporal specificity and sensitivity. Here, TMS-evoked potentials (TEPs) can be used to test the reactivity and connectivity of cortical areas and thereby to examine the direct effects of iTBS on the cortex. Therefore, the study aims at furthering our insights into the individual neural underpinnings underlying iTBS-induced changes of cortical excitability.

Methods

A group of young (20–35 years), healthy subjects received three serially applied blocks of iTBS over the primary motor cortex (M1 stimulation) or over parieto-occipital vertex as control condition (Sham stimulation) in two stimulation sessions (washout period: at least 10 days). As behavioural parameters, motor performance was assessed using two different motor tasks, Purdue Pegboard Test (PPT) and maximum finger tapping. TMS-EEG was recorded online at baseline and after each application of iTBS using a TMS-compatible 64-channel EEG-System (BrainProducts). Neuronavigated TMS was applied as single pulses with 80% of resting motor threshold (RMT).

Results (preliminary)

iTBS over M1 increased MEP amplitudes compared with sham stimulation after each stimulation block. There was, however, considerable between-subject differences in the individual responses to iTBS. In addition, iTBS increased performance in the Purdue Pegboard Test but not in the maximum finger tapping task. At the neural level, we found differential changes in TEP components, with enhancement of the N100 component which is thought to reflect inhibitory mechanisms.

Conclusion

This is the first study investigating network effects of iTBS by means of TMS-EEG. Our preliminary results suggest that iTBS causes effects at the behavioural and local level (cortical excitability) as well as affecting specific components of TMS-evoked potentials.

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P112. Modulatory effects of anodal transcranial direct current stimulation on fronto-striatal gain control of the interplay between selective attention and perception

Publication date: August 2018

Source: Clinical Neurophysiology, Volume 129, Issue 8

Author(s): K. Gohil, S. Passow, N. Adelhöfer, C. Beste, S.C. Li

Carrying conversations in public spaces with a plethora of competing sensory inputs demands flexible interactions between attention and perception for selectively processing goal-relevant information. We postulate that the fronto-striatal network plays a key role in regulating this interaction. However, to date the underlying gain control mechanisms are not yet well understood. Neuronal gain control can be fine-tuned by membrane potential regulated changes in neuronal excitability. Anodal transcranial current stimulation (atDCS) has been shown to cause a depolarization of resting membrane potentials, which increases neuronal excitability. In the present study, we applied off-line atDCS over the right inferior frontal gyrus (IFG) in healthy young adults in a single-blinded sham-controlled study to investigate atDCS-induced effects on fronto-striatal gain control of auditory attention. We recorded high-density EEG recordings during a dichotic listening task in which both perceptual saliency and attentional focus were varied, creating conditions of low and high perceptual-attentional conflict. Compared to sham stimulation, pilot results suggest that atDCS enhanced auditory perception and attentional regulation: Specifically, atDCS increased discrimination ability of inter-aural intensity differences and enhanced performance in high conflict conditions. These behavioral effects were reflected by EEG correlates associated with attentional and perceptual processing.

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P111. Exploring the effects of transcranial direct current stimulation on cognitive control training

Publication date: August 2018

Source: Clinical Neurophysiology, Volume 129, Issue 8

Author(s): S. Weller, C. Plewnia

Introduction

The dorsolateral prefrontal cortex (dlPFC) is a brain structure responsible for working memory performance and cognitive control (CC). CC, critically underlying goal-directed behaviour, has been shown to be impaired in depression and to be associated with reduced activity of the dlPFC (Fitzgerald and Laird, 2008). Transcranial direct current stimulation (tDCS) of this brain area can modify the neuronal response and therefore CC, and has already shown potential for CC malleability: both amelioration as well as impairment ([Wolkenstein and Plewnia, 2013], [Plewnia et al., 2015a], [Plewnia et al., 2015b]). Within this study series we systematically investigate the effects of tDCS on a CC training in healthy participants by varying stimulation parameters regarding intensity, polarity and laterality.

Methods

Over the course of 8 sessions within 4 weeks and a follow-up session 3 months later participants perform a modified adaptive paced auditory serial addition task (PASAT) during which they hear a series of single digit numbers and are instructed to add the most recent digit to the third to last digit (n + n − 2). Digit presentation speed is adapted to performance with the goal to challenge CC by inducing stress and frustration during the experiment. TDCS is applied for 19 min during each training session. The first two test groups receive stimulation of the left dlPFC with 1 and 2 mA respectively, the third and fourth group are treated likewise except for stimulation being shifted to the right dlPFC. Each group is furthermore divided into subjects receiving either anodal, cathodal or sham tDCS.

Preliminary results and conclusion

Within the first study group, subjects who received anodal stimulation (1 mA) to the left dlPFC showed significant performance gains during PASAT training compared to cathodal (1 mA) and sham stimulation, suggesting that improvement was aided by plasticity enhancement of CC induced by tDCS.

Outlook

Data for the remaining three groups (2 mA, left dlPFC; 1 and 2 mA, right dlPFC) is currently being gathered. Collection will be finished by the end of the year, ensuing final analysis of the comprehensive data set by the beginning of 2018.

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P108. Effects of 10 Hz tACS on phonological language processing

Publication date: August 2018

Source: Clinical Neurophysiology, Volume 129, Issue 8

Author(s): T. Stenner, L. Sierau, M. Werchowski, S. Matern, C. Kaernbach, M. Siniatchkin, G. Hartwigsen, V. Moliadze

Introduction

A previous study (Hartwigsen et al., 2010) has shown that 10 Hz rTMS of the left or right posterior inferior frontal gyrus (IFG) impaired performance in a phonological decision-making task. However, it is unclear whether the neurodisruptive effect of 10 Hz-rTMS is caused by entrainment of alpha-oscillations. To address this issue, the present study investigated the following questions: (1) Are alpha-oscillations in the IFG functionally relevant for phonological processing? (2) Can we enhance alpha activity in the IFG using 10 Hz tACS? and (3) Does enhancement of alpha activity cause behavioral disruption?

Methods

24 right-handed, healthy participants (12 male, age range: 18–30 years, mean = 21.96, SD = 3.36) participated in the study. 9 mm² circular sponge electrodes were placed over the bilateral IFG. In three separate sessions, 1 mA tACS at 10 Hz or 16.18 Hz or sham stimulation were applied for 20 min. Before and after stimulation, 5 min of resting state EEG was recorded. The phonological task required the subjects to indicate via button press whether highly frequent German nouns like 'Zebra' consisted of two or three syllables. In a simple control task, participants had to indicate whether an arrow pointed left or right to control for unspecific effects.

Results

(1) Stimulation was a significant predictor for decision speed in the phonological task (p = .02). Specifically, participants responded faster after 10 Hz relative to sham stimulation, but not after 16.18 Hz. (2) This effect was task specific as tACS did not significantly affect the control task (p = 0.43). (3) Participants had an increase in resting state alpha power (p = .004), which wasn't modulated by stimulation (p = .70). (4) We found a significant event related desynchronization in the alpha band (p < .001), which wasn't modulated by stimulation (p = .79).

Conclusion

The results show an improvement in a phonological word task after applying 10 Hz tACS over the bilateral IFG but not in simple motoric control task. This might be explained by a paradoxical facilitation effect, resulting in an 'optimal' level of noise for task processing (Miniussi et al., 2013) or by inhibition of surrounding areas that might be competing for task resources. Since no specific effect on alpha oscillations could be found, further studies will therefore investigate effects of focal online stimulation.

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P107. Physiological mechanisms of cerebellar transcranial direct current stimulation in humans

Publication date: August 2018

Source: Clinical Neurophysiology, Volume 129, Issue 8

Author(s): G. Batsikadze, M. Nitsche, S. Herlitze, D. Timmann

Background

Recently, transcranial direct current stimulation (tDCS) became a popular method to non-invasively modulate cerebellar excitability and help us broaden our understanding of cerebellar functions and introduce new therapeutic applications. Despite its popularity, its parameters, such as current polarity, stimulation intensity and electrode positions to induce specific effects have not yet been standardized. We aimed (1) to test the effects of tDCS with different electrode montages (see below) on cerebellar-brain inhibition (CBI) and (2) to explore the effect of tDCS on specific cerebellar-brain connections measured by the CBI recruitment curve (CBI-RC).

Methods

15 and 14 young and healthy participants took part in Experiments 1 and 2, respectively. In all experiments, the target tDCS electrode was placed over the right cerebellar cortex. In Exp. 1, the return electrode over one of the following three positions: the right buccinator muscle, the left supraorbital area or the right deltoid muscle and in Exp. 2, it was positioned over the right buccinator muscle. CBI was measured by double-TMS protocol, with the conditioning stimulus (CS) over the right cerebellum with an intensity of 5% below the brainstem motor threshold (BMT) followed by the test pulse over the left primary motor cortex 5 ms later. For CBI-RC, five different CS intensities were used (−5%, −10%, −15%, −20%, −25% below BMT). The after-effects of 2 mA anodal or cathodal cerebellar tDCS on CBI or CBI-RC in Exp. 1 and 2, respectively, were measured before and for two hours after 15 min of tDCS.

Results

In Exp. 1, both tDCS polarities significantly decreased CBI for at least two hours compared to both sham and pre-stimulation values. No significant differences between different return electrode positions were observed. In Exp. 2, CBI was significantly increased after anodal and was decreased after cathodal tDCS with low CS intensities in a polarity-specific manner.

Conclusions

In accordance with the results reported by many studies, our results suggest that the return electrode positioning has no significant impact on the tDCS after-effects. The results of Exp. 2 show that the recruitment of the cerebellar-brain connections varies depending on tDCS polarity and CS intensity, suggesting that tDCS differently affects neurons in different layers of the cerebellar cortex. This polarity-specific dependence should be considered for tDCS applications and addressed in future studies.

Funded by Mercur Pr-2015-0010 and SFB1280 (TP A05 and A06).

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P106. Anodal tDCS over the left sensorimotor area improves motor symptoms and modulates corticocortical coherence in Parkinson’s disease

Publication date: August 2018

Source: Clinical Neurophysiology, Volume 129, Issue 8

Author(s): A. Schöllmann, M. Scholten, R. Krüger, C. Plewnia, D. Weiss

Network activity in the beta range is correlated with motor symptoms in Parkinson's disease (PD). Anodal transcranial direct current stimulation (atDCS) over the sensorimotor area modulates cortical excitability and may alleviate motor symptoms in PD. In this study, we aimed to explore the effect of atDCS over the left sensorimotor area on clinical motor outcome, right hand fine motor performance and cortical motor network connectivity.

In this double-blind randomized sham-controlled combined EEG and tDCS study, we investigated ten pharmacologically treated idiopathic PD patients after overnight withdrawal of dopaminergic medication and eleven healthy controls during an isometric precision grip task of the right hand before and after stimulation. Participants were studied and crossed-over in two sessions on different days with either 'verum' or 'sham' stimulation of atDCS (20 min; 1 mA; electrodes placed over left 'C3' (anode) and right 'Fp2' (cathode)). Cortical connectivity was expressed as corticocortical imaginary coherence in the high beta band (22–27 Hz) between 'C3' and all other EEG-channels; the topographic distribution was obtained from 25 cortical EEG channels placed according to the 10–20 system. Fine motor performance was expressed as accuracy error during the precision grip task with lower accuracy error indicating higher motor precision. Clinical motor outcome was measured using the UPDRS III motor score.

PD patients with 'verum' stimulation showed an increase of corticocortical imaginary coherence in the high beta band from 'C3' to the right motor area 30 min after stimulation. This was paralleled by a significant decrease in the UPDRS III motor score. There was no similar modulation in PD 'sham' stimulation and in healthy controls in both 'verum' and 'sham' conditions. However, interestingly, HC showed beta band coupling prior to stimulation directed from 'C3' to the right hemisphere. Both groups showed no significant change regarding the accuracy error after stimulation.

AtDCS of 'C3' entrains beta band coupling between 'C3' and the right sensorimotor area with 'C3' leading right hemispheric beta band oscillations in the temporal domain. We speculate that this could represent a mechanism to tone down inhibitory influences of the right hemisphere ipsilateral to the right hand, given that increased beta synchrony is associated with increasing motor inhibition in previous studies.

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P105. Does transcranial alternating current stimulation entrain posterior alpha rhythm?

Publication date: August 2018

Source: Clinical Neurophysiology, Volume 129, Issue 8

Author(s): G. Hermann, I. Rothkirch, H. Laufs, K. Witt

Background

Previous studies described long term effects of transcranial alternating current stimulation (tACS) on alpha (α) frequency (Helfrich et al., 2014; Müller et al., 2015; Varlet et al., 2017).tACS was hence proposed as a tool to synchronize and modulate regional biological neuronal oscillations.

Objective

Our objective was to validate tACS as a suitable method effecting neuronal oscillations over a stimulated areal.This study is part of a project that investigates the clinical relevance of the stimulation as a treatment option for impulse control disorders.

Methods

We applied tACS over the occipital cortex with an α frequency of 10 Hz as well as an appropriate sham stimulation.We studied 17 participants (18–30 yrs) in two separate sessions using the neuroConn DC-stimulator plus.Before and after the stimulation three minute EEG-intervals were analysed with respect to their α peak frequency and power spectral density.We segmented these intervals in 1 s epochs and applied an FFT followed by averaging using BrainVision Analyzer and MatLab.With R statistics we computed the individual α peak frequency and the corresponding power spectral density of every EEG-channel before and after stimulation.For comparison of pre and post stimulation differences we used the Wilcoxon signed-rank test as we cannot assume our data do be normally distributed.

Results

Concerning all EEG-channels, we found a significant α peak frequency shift towards the stimulated frequency in the post compared to the pre stimulation condition (Wilcoxon signed-rank test W = 18436, p = .002).When focusing on the electrodes in vicinity of the occipital stimulation we found that the averaged individual α peak frequencies (Electrode O1) over all participants slightly approximated the stimulation frequency.Comparing the segments before and after stimulation, peak frequency changed from 9.7 ± .8 Hz pre-stim to 10.1 ± 1.1 Hz post-stim.When analysing the individual frequency shifts to the stimulation frequency of 10 Hz with the Wilcoxon signed-rank test, we did not find any significant effect induced by tACS (W = 20.5, p = 0.859) (Fig.1).Even analyzing α peak frequency shifts direction, no trend could be detected – out of 17 subjects only four had the expected α peak frequency drift towards the stimulation frequency (Table1).

Conclusions

In contrast to previous work, the results of this study show a tACS-induced effect on individual α peak frequency only across all electrode positions, but we did not find any significant effect on an individual electrode near the stimulation site. This challenges the robustness of tAC stimulation effects on neuronal oscillations. In a next step, we will evaluate how tACS effects depend on the brain state (e.g. wakefulness).

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3D Printed Electrodes for Improved Gas Reactant Transport for Electrochemical Reactions

3D Printing and Additive Manufacturing, Ahead of Print.


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P13. Semi-automatic, machine-learning based segmentation of peripheral nerves for quantitative morphometry: Comparison of low- and high-resolution MR neurography

Current state-of-the-art to diagnose peripheral neuropathy are neurological examination and electrodiagnostic studies. However, deeply situated nerves and plexus remain difficult to assess using these techniques, hence magnetic resonance neurography (MRN) emerged as a complementary method. MRN remains a qualitative approach and quantification, in terms of extraction of imaging biomarkers is needed to facilitate diagnosis and for follow-up examinations. Towards a multi-parametric quantitative imaging approach, accurate nerve segmentation needs to be performed first.

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P73. A new cognitive diagnostic marker to distinguish between Subjective Cognitive Decline, mild cognitive impairment and healthy adults?

Patients with Subjective Cognitive Decline (SCD) have an increased risk of Alzheimer's diseases (AD) pathology while their performance in usual cognitive tests is normal. The goal of the present study was to assess whether another cognitive test, late verbal recall, can distinguish between SCD, mild cognitive impairment (MCI) and no cognitive impairment (healthy controls, HC).We used a late recall method which has so far only been applied in epilepsy patients (Witt et al., 2012). After being screened with the CERAD test battery (Morris et al., 1989; Mirra et al., 1991) patients from our memory clinic were called 24 h later and asked whether they still remembered words of the list they had to learn the day before.

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