Overwork weakness in Charcot-Marie-Tooth disease

Objective: To determine the incidence of overwork weakness in Charcot-Marie-Tooth disease (CMT). Design: Prospective survey. Setting: Rehabilitation department for CMT in an Italian tertiary care hospital. Participants: A total of 106 outpatients with CMT, selected for absence of other causes of weakness (age range, 11-69y), and 48 healthy volunteers (controls). Interventions: The strength of 2 intrinsic hand muscles (abductor pollicis brevis [APB], first dorsal interosseous) in the dominant and nondominant hands was graded by using manual muscle testing and a modified Medical Research Council (MRC) Scale. Main Outcome Measures: The side of the stronger muscle and the difference in strength between the nondominant and dominant muscles. Results: Muscles were stronger on the nondominant side in 65.57% of patients versus 1.04% of controls, and on the dominant side in .94% of patients versus 84.38% controls. T e difference in strength for first dorsal interosseous was .51 in patients and -.32 in controls (P>.01). The difference in strength for APB was .65 in patients and -.35 in controls (P>.01). Conclusions: CMT muscles in the dominant hand are weaker than in the nondominant hand. This may be the result of overwork weakness. (C) 2003 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation.