Dissociated leg muscle atrophy in amyotrophic lateral sclerosis/motor neuron disease: the 'split-leg' sign.

ABSTRACT: Disproportionate muscle atrophy is a distinct phenomenon in amyotrophic lateral sclerosis (ALS); however, preferentially affected leg muscles remain unknown. We aimed to identify this split-leg phenomenon in ALS and determine its pathophysiology. Patients with ALS (n?=?143), progressive muscular atrophy (PMA, n?=?36), and age-matched healthy controls (HC, n?=?53) were retrospectively identified from our motor neuron disease registry. We analyzed their disease duration, onset region, ALS Functional Rating Scale-Revised Scores, and results of neurological examination. Compound muscle action potential (CMAP) of the extensor digitorum brevis (EDB), abductor hallucis (AH), and tibialis anterior (TA) were reviewed. Defined by CMAP_EDB/CMAP_AH (SI_EDB) and CMAP_TA/CMAP_AH (SI_TA), respectively, the values of split-leg indices (SI) were compared between these groups. SI_EDB was significantly reduced in ALS (p?TA reduction was more prominent in PMA (p?EDB), while was rather increased with clinical upper motor neuron signs (SI_TA). Compared to the AH, TA and EDB are more severely affected in ALS and PMA patients. Our findings help to elucidate the pathophysiology of split-leg phenomenon.

SUBMITTER: Min YG 

PROVIDER: S-EPMC7518279 | biostudies-literature | 2020 Sep

REPOSITORIES: biostudies-literature