Atypical Form of Motor Neuron Disease: Brachial Amyotrophic Diplegia

ABSTRACT

Brachial amyotrophic diplegia is a rare disease presenting with severe weakness that is completely confined to the upper limbs over time without upper motor neuron sign. It might be a stable and relatively benign variant of motor neuron disease and should be differentiated from other motor neuropathies. A 60-year-old man presented with a two year history of symmetrical muscle wasting and weakness in his arm and shoulder girdle. Bulbar and leg muscle were not affected and he was independent in ambulation. Nerve conduction studies revealed normal except the low amplitude of median and ulnar compound muscle action potential with no evidence of conduction block. Needle electromyography showed denervation potential and neuropathic motor unit action potential throughout the upper limb. We report this case with a brief review of related literatures.