title: Reverse split hand syndrome: Dissociated intrinsic hand muscle atrophy pattern in Hirayama disease/brachial monomelic amyotrophy.
abstract: Preferential involvement of C7, C8, T1 level anterior horn cells is a typical feature in Hirayama disease/brachial monomelic amyotrophy (BMMA). There are no clinico-electrophysiological studies to substantiate the peculiar pattern of muscle involvement. Thirty subjects, 10 in each group of BMMA, amyotrophic lateral sclerosis (ALS) and age-matched normal healthy subjects underwent detailed clinical and electrophysiological testing. Results showed that the mean age at evaluation for BMMA and ALS patients was 25.8 ± 3.8 and 51.8 ± 9.5 years, respectively; illness duration was 8.1 ± 5.7 years and 11.14 ± 2.85 months, respectively. Clinically, all BMMA patients had reverse of split hand (RSH) syndrome [abductor digiti minimi (ADM) affected more than abductor pollicis brevis (APB)], while 7/10 ALS patients had classical split hand syndrome (APB affected more than ADM). In BMMA, the compound muscle action potential (CMAP) of APB was preserved but reduced/absent in ADM compared to the ALS group which demonstrated reverse findings. APB/ADM ratio was >0.8 in the BMMA group (>1.4 in 80%), around 1.0 in normal controls (none had >1.4) and <0.8 in ALS (70% having values <0.6). In conclusion, RSH syndrome may provide valuable diagnostic clues to differentiate this relatively self-restricted disease from progressive degenerative disease like ALS.
authors: a Department of Neurology , National Institute of Mental Health and Neurosciences , Bengaluru , India.
authors: Ravinder-Jeet
authors: RJ
authors: Singh
authors: b Department of Clinical Neurosciences , National Institute of Mental Health and Neurosciences , Bengaluru , India , and.
authors: Veeramani
authors: V
authors: Preethish-Kumar
authors: b Department of Clinical Neurosciences , National Institute of Mental Health and Neurosciences , Bengaluru , India , and.
authors: Kiran
authors: K
authors: Polavarapu
authors: a Department of Neurology , National Institute of Mental Health and Neurosciences , Bengaluru , India.
authors: Seena
authors: S
authors: Vengalil
authors: c Department of Neuroimaging and Interventional Radiology , National Institute of Mental Health and Neurosciences , Bengaluru , India.
authors: Chandrajit
authors: C
authors: Prasad
authors: a Department of Neurology , National Institute of Mental Health and Neurosciences , Bengaluru , India.
authors: Atchayaram
authors: A
authors: Nalini
mesh_terms: D000328:Adult; D000368:Aged; D000690:Amyotrophic Lateral Sclerosis / Q000150:complications; D004558:Electric Stimulation; D019054:Evoked Potentials, Motor / Q000502:physiology; D005260:Female; D006225:Hand / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000503:physiopathology*; D009133:Muscular Atrophy / Q000209:etiology* / Q000473:pathology*; D012372:ROC Curve; D014897:Spinal Muscular Atrophies of Childhood / Q000150:complications*; D018709:Statistics, Nonparametric; D013577:Syndrome; D055815:Young Adult
keywords: Anterior horn cell disease; Hirayama disease (HD); brachial monomelic amyotrophy (BMMA); reverse split hand syndrome; split hand syndrome