Widespread electromyographic abnormalities in patients with monomelic amyotrophy: a detailed EMG study.

Objective: To evaluate subclinical electromyogruphic changes in unaffected muscles of the patients with monomelic amyotrophy (MMA). Patients and methods: 35 patients of MMA with single limb atrophy (30 patients with upper limb involvement and 5 patients with lower limb involvement) were studied at All India Institute of Medical Sciences, New Delhi, from September 2000 to September 2002. All the patients were evaluated clinically, by detailed three limb electromyography (EMG) and by MRI scan of the spine to rule out other disorders. Results: The mean age of 35 male patients was 24.17 (′ 6.8) years and the mean duration of illness was 3.64 (′2.7) years. Patients with upper limb involvement had segmental pattern of atrophy, predominantly distal or proximal. EMG revealed evidence of subclinical diffuse chronic reinnervative changes. All the patients (100%) had bilateral chronic reinnervative changes and 50% had chronic reinnervative changes in three limbs. Conclusions: Patients with clinically single limb MMA were found to have evidence of widespread chronic reinnervative changes on EMG.