Split hand sign

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The split hand sign is a clinical sign classically seen in amyotrophic lateral sclerosis (ALS) and refers to loss of pincer grasp due to preferential wasting of the thenar eminence (abductor pollicis brevis and first dorsal interosseous muscle) with relative preservation of the hypothenar eminence (abductor digiti minimi) . When the flexor pollicis longus is also noted to be relatively preserved, this is termed the split hand plus sign .

In addition to being encountered in the setting of amyotrophic lateral sclerosis (ALS) it is also seen other neuromuscular diseases such as autosomal dominant spinal muscular atrophy, juvenile muscular atrophy and spinocerebellar ataxia type 3 (SCA3) .

History and etymology

Split hand sign was first described by Dr Asa Wilbourn in 1996 .