The Effect of Symptoms of Carpal Tunnel Syndrome on Ultrasonographic Median Nerve Measures Before and After Wheelchair Propulsion

ObjectiveTo quantify median nerve characteristics before and after strenuous wheelchair propulsion and relate them to symptoms of carpal tunnel syndrome (CTS). We hypothesized that persons with and without symptoms of CTS would have significantly different nerve characteristics at baseline and after propulsion.DesignA repeated-measures design was used to obtain ultrasound images of the median nerve at 3 levels of the wrist (radius, pisiform, and hamate) before and after wheelchair propulsion. Investigators were blinded to subject history related to CTS.SettingThe 2007 and 2008 National Veterans Wheelchair Games and the Human Engineering Research Laboratories.ParticipantsFifty-four participants between the ages of 18 and 65 years with a nonprogressive disability who used a manual wheelchair as their primary means of mobility completed this study.MethodsParticipants completed questionnaires regarding demographics and the presence and severity of symptoms of CTS. Ultrasound images of the median nerve were obtained before and after a 15-minute strenuous wheelchair-propulsion task.Main Outcome MeasurementsBaseline values and post-propulsion changes were determined for median nerve cross-sectional area, flattening ratio, and swelling ratio. Differences in median nerve variables between symptomatic and asymptomatic groups were assessed.ResultsNo significant differences between symptom groups were identified at baseline; however, persons with symptoms of CTS showed a significantly different percent change from baseline compared with the asymptomatic participants for cross-sectional area at pisiform (P = .014) and flattening ratio at hamate (P = .022), and they showed a strong trend toward a difference in swelling ratio (P = .0502). For each of these variables, the change in the symptomatic group was in the opposite direction of the change in the asymptomatic group.ConclusionsWe found several median nerve responses to wheelchair propulsion associated with symptoms of CTS. These responses occurred even though no baseline ultrasound difference was found based on symptoms. Future research is necessary to determine how propulsion characteristics (ie, force, repetition, and posture) affect the median nerve response.