Dynamometry of intrinsic hand muscles in patients with Charcot-Marie-Tooth disease.

BACKGROUND Several problems are associated with manual muscle testing and dynamometry in the hands of patients with Charcot-Marie-Tooth (CMT) disease. OBJECTIVE To evaluate the efficacy of the Rotterdam Intrinsic Hand Myometer (RIHM) to directly measure intrinsic hand muscle strength in CMT disease. METHODS We measured hand muscle strength and hand function in 41 patients with CMT disease. RESULTS RIHM measurement of intrinsic strength had excellent reliability. We found overlapping RIHM strength values in Medical Research Council grades 3 to 5. High grip and pinch strength could be found in patients with severe intrinsic muscle weakness. RIHM measurements were more strongly correlated with fine motor skills of the hand than grip and pinch strength. CONCLUSIONS The Rotterdam Intrinsic Hand Myometer is a reliable instrument to measure intrinsic hand muscles strength in patients with Charcot-Marie-Tooth disease, providing more detailed information than manual muscle testing and a more direct assessment of intrinsic muscle loss than grip and pinch dynamometers.