Split Hand: characteristic neurological symptoms in ALS

Abstract

'Split hand' is dissociated hand muscle atrophy, characterized by preferential atrophies in the thenar and first dorsal interosseous muscles, with relative sparing of the hypothenar muscle. This symptom has been recognized as specific to amyotrophic lateral sclerosis (ALS), and distinct pathomechanisms are assumed to underlie this phenomenon. Recently, characteristic distributions of weakness and symptoms in ALS have been reported. Here, we describe characteristic symptoms of ALS, including split hand, split-hand plus sign, split elbow, split leg, relative preservation of finger flexion. Moreover, through these phenomena, potent mechanisms of motor neuron death in ALS are considered. Revealing the underlying pathophysiology of these symptoms may lead to the development of therapies for ALS.