Objective The objective of this study was to investigate the usefulness of muscle ultrasound in evaluating dissociated small hand muscle atrophy, termed ‘split hand’, and its feasibility in the diagnosis of amyotrophic lateral sclerosis (ALS).
Methods Forty-four patients with ALS, 18 normal subjects and 9 patients with other neuromuscular disorders were included in this study. The hand muscles were divided into three regions, the median-innervated lateral hand muscle group (ML), the ulnar-innervated lateral hand muscle (UL) and the ulnar-innervated medial hand muscle (UM), and the muscle echo intensity (EI) and compound muscle action potential (CMAP) were measured. We calculated the split hand index (SHI) using muscle EI (SHImEI) and CMAP (SHICMAP) for comparison among groups. The SHI was derived by dividing muscle EI (or CMAP) measured at the ML and UL by that measured at the UM.
Results The SHImEI was significantly higher in patients with ALS (51.7±28.3) than in normal controls (29.7±9.9) and disease controls with other neuromuscular disorders (36.5±7.3; P<0.001), particularly in upper limb-onset ALS (66.5±34.0; P<0.001). Receiver operating characteristic curve analysis indicated that the SHImEI had significantly better diagnostic accuracy than the SHICMAP.
Conclusions The SHImEI was more sensitive in evaluating dissociated small hand muscle atrophy compared with the SHICMAP and may be a reliable diagnostic marker for differentiating ALS from other neuromuscular disorders and healthy controls.
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HYS and JP contributed equally.
SHK and B-JK contributed equally.
Contributors B-JK and SHK conceived and designed the research. HYS performed the experiments. HYS, JP, YHK, K-WO and B-JK analysed the data. HYS, B-JK and SHK drafted the manuscript.
Funding This article was supported by grants from the Technology Innovation Program, which is funded by the Ministry of Trade, Industry and Energy (MI, Korea) (grant no 100499743, ‘Establishing a medical device development open platform, as a hub for accelerating close firm-hospital communication’), and from the KDA and the Korean Health Technology R&D Project, Ministry of Health, Welfare and Family Affairs, Republic of Korea (grant no HI16C2131).
Competing interests None declared.
Patient consent Obtained.
Ethics approval The institutional review board of the participating centres approved this study (#HYI-10-01e3 and #AN15198-004).
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement The data used and/or analysed during the current study are available from the corresponding author on reasonable request.
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