Predictive and reactive grip force responses to rapid load increases in people with multiple sclerosis

Publication date: Available online 9 September 2016
Source:Archives of Physical Medicine and Rehabilitation
Author(s): Kathrin Allgöwer, Claudia Kern, Joachim Hermsdörfer
ObjectiveTo determine the effects of multiple sclerosis (MS) on predictive and reactive grip force control in a catching-task and on clinical tests of hand function.DesignCase-control study with matched-pairs control group.SettingKuratorium for Prevention and Rehabilitation at the Technical University of Munich e.V.ParticipantsFifteen people with MS (PwMS) and fifteen healthy controls, matched for sex, age and hand dominance.InterventionsNot applicable.Main Outcome MeasuresPerformance of the Expanded Disability Status Scale (EDSS), Nine Hole Peg Test (9-HPT), Jebsen Taylor Test (JTHFT) and two-point discrimination (2PD) was evaluated. To analyze grip force control, blindfolded subjects held a receptacle equipped with grip force and acceleration sensors in their hand. In a catching-task a weight was dropped (a) from the experimenter`s hand unexpectedly into the receptacle (reactive force control), respectively (b) from the subject`s opposite hand (predictive force control). Grip forces and time-lags were analyzed.ResultsPwMS (mean EDSS 4.2± 1.86) had impairments in the 9-HPT and JTHFT (p<.001). The 2PD did not differ significantly between PwMS and controls. During reactive force control (a) PwMS showed significantly higher grip forces immediately after impact (p<0.05) and a significant prolongation of the time from grip force increase until reaching the peak of grip force (p<.001). PwMS and controls did not differ during predictive force control (b) (p>0.1).ConclusionExaggerated grip force responses and alterations of timing after an unpredictable perturbation combined with preserved grip force control during predictable conditions is a characteristic pattern of fine motor control deficits in MS. Measures of reactive grip force responses may be used to complement neurologic assessments. Further studies exploring its usefulness should be performed in a broader community in PwMS.



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