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) 1. When the flexor pollicis longus is also noted to be relatively preserved, this is termed the split hand plus sign 3.
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) 1.
History and etymology
Split hand sign was first described by Dr Asa Wilbourn in 1996 2.
- 1. Benny R, Shetty K. The split hand sign. (2012) Annals of Indian Academy of Neurology. 15 (3): 175-6. doi:10.4103/0972-2327.99700 - Pubmed
- 2. Wilbourn AJ. Electrodiagnostic evaluation of the patient with possible ALS. In: Belsh JM, Schiffman PL, editors. Amyotrophic lateral sclerosis. Armonk, NY: Futura Books; 1996. p. 183.
- 3. Menon P, Bae JS, Mioshi E, Kiernan MC, Vucic S. Split-hand plus sign in ALS: differential involvement of the flexor pollicis longus and intrinsic hand muscles. (2013) Amyotrophic lateral sclerosis & frontotemporal degeneration. 14 (4): 315-8. doi:10.3109/21678421.2012.734521 - Pubmed