Sudomotor dysfunction is frequent and correlates with disability in Friedreich ataxia

Publication date: Available online 31 August 2018

Source: Clinical Neurophysiology

Author(s): Karen A.G. Takazaki, Thiago Junqueira R. Rezende, Alberto R.M. Martinez, Carelis González, Anamarli Nucci, Iscia Lopes-Cendes, Marcondes C. França

Abstract

Objectives

To evaluate autonomic symptoms and function in Friedreich's Ataxia (FRDA).

Methods

Twenty-eight FRDA patients and 24 controls underwent clinical/electrophysiological testing. We employed the Friedreich's Ataxia Rating Scale (FARS) and the Scales for Outcomes in Parkinson's Disease: Autonomic Questionnaire-SCOPA-AUT to estimate the intensity of ataxia and autonomic complaints, respectively. Cardiovagal tests and the quantitative sudomotor axonal reflex, Q-SART were then assessed in both groups. Results

In the patient group, there were 11 men with mean age of 31.5±11.1 years. Mean SCOPA-AUT score was 15.1±8.1. Minimum RR interval at rest was shorter in the FRDA group (Median 831.3 x 724.0ms, p<0.001). The 30:15 ratio, Valsalva index, E:I ratio, low and high frequency power presented no differences between patients and controls (p>0.05). Sweat responses were significantly reduced in patients for all sites tested (forearm 0.389 x1.309 µL; proximal leg 0.406 x1.107 µL; distal leg 0.491 x 1.232 µL; foot 0.265 x 0.708µL; p value<0.05). Sweat volumes correlated with FARS scores. Conclusions

We found abnormal sudomotor but normal heart rate variability in FRDA. Small cholinergic post-ganglionic fibers are affected in the disease.

Significance

Quantification of sudomotor function might be a biomarker for FRDA.

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