Abstract

INTRODUCTION

The patient presenting with weakness and wasting of one limb, usually the arm, can be a considerable diagnostic challenge for the neurologist. While the spectre of the amyotrophic lateral sclerosis form of motor neuron disease (ALS/MND) is often in the clinician’s mind, there is also a significant differential diagnosis to be considered. While this article discusses a number of well-known conditions that should be in the differential diagnosis, I will focus particularly on a lesser known condition, Hirayama’s Disease (also known as Sobue Disease in North America), that is only rarely seen in European populations and may therefore be less familiar to neurologists outside Japan and India.

Monomelic amyotrophy or ‘juvenile non-progressive amyotrophy of the upper limb’ is rarely encountered in the general neurology clinics but it may be under diagnosed. Previously thought to be restricted to Japan and South Asia, it is now clear that this condition does