Chapter 11 Monomelic amyotrophy of upper or lower limbs

Abstract

Publisher Summary Monomelic amyotrophy (MMA)—in which neurogenic atrophy is restricted to one limb—is a heterogeneous disorder, involving one upper or lower limb. Insidious onset of atrophy and weakness, presumed to be due to anterior horn cell involvement, starting in the second or third decade with male preponderance and sporadic occurrence are the characteristic features. Progression is slow and followed by stabilization within a few years, resulting in a benign outcome. The age of onset in the majority (90%) varies from 15 to 35 years with a median age of 20 years in MMA of the upper limb and slightly older in MMA of the lower limb with a median age of 25 years. In MMA of the upper limb, the common initial symptoms are weakness and atrophy in the majority, followed by tremulousnesss of the fingers. In various cases involving MMA of the lower limb, atrophy of the limb was noted by the patient due to pain while walking, and in nearly a third of the patients it was incidentally observed by a family member, friend, or physician during consultation for unrelated illness.