Hirayama's Disease: A Rare Clinical Variant of Amyotrophic Lateral Sclerosis.

Hirayama's disease is a rare clinical variant of amyotrophic lateral sclerosis where distal muscles are involved more compared to proximal muscles and vice-versa occurs only in 10% cases and so it is differentiated from O'Sullivan McLeod syndrome which involves only small muscles of single limb. Here, we present a case of Hirayama's disease where disease achieved a plateau after 3 years with no further progression. His electrophysiological studies, and clinical picture, and magnetic resonance imaging findings were consistent with a diagnosis of Hirayama's disease.