Conduction and morphological changes in wrist nerves immediately after bilateral sanding exercises in hemiparetic subjects

Abstract

Objective: To investigate the immediate effects of bilateral upper-extremity sanding exercises on conduction and morphologic characteristics of the median and ulnar nerves at the wrist in hemiparetic subjects and control subjects.

Design: Case control study using a pretest-post-test design.

Setting: Inpatient rehabilitation department affiliated with a teaching hospital.

Patients (or participants): Thirty hemiparetic subjects and 21 matched control subjects who met our inclusion criteria and had no history of diseases that may have predisposed them to peripheral neuropathies were recruited for this study.

Methods: Bilateral nerve conduction tests and ultrasonographic evaluations were performed on each subject before and immediately after a 30-minute bilateral sanding exercise with a frequency of 5 repetitions per minute.

Main outcome measurements: The effects of exercises on bilateral median and ulnar wrist nerves were assessed with the use of sensory and motor nerve conduction velocity tests and by width/thickness ratios in ultrasonographic evaluations.

Results: In the hemiparesis group, the pre-exercise amplitude of the motor component for the median and ulnar nerves were respectively lower than the corresponding values in the control group (P < .05), whereas the pre-exercise amplitude and velocity of the sensory component were lower than the corresponding values in the control group (P < .01). After the exercise, the assessments for the affected side showed reductions in the conduction velocity of the sensory component and an increase in the width/thickness ratio for the median nerve (P < .05).

Conclusions: The median and ulnar nerves at the wrist in hemiparetic subjects before sanding exercises showed different conduction characteristics compared with control subjects. Their affected side also demonstrated significant conduction and morphologic changes after the exercises. These subclinical findings may be attributed to different mechanisms such as overuse, spasticity, and demyelinating changes. Prevention of these subclinical changes is recommended to enhance exercise safety in hemiparetic patients.