Review articleSplit hand in amyotrophic lateral sclerosis: A systematic review and meta-analysis
Introduction
Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by relentlessly progressive skeletal muscle paralysis [1]. The incidence of ALS was between 0.6 and 3.8 per 100 000 person-years, and continuously increased in the past few years [2]. The survival duration from symptoms onset to death or invasive respiratory support was between 24 and 50 months [3], [4]. Although several diagnostic criteria have been suggested by WFN (the World Federation of Neurology) and IFCN (International Federation of Clinical Neurophysiology) [5], more reliable biomarkers are still needed.
Split hand is a specific pattern of dissociated hand muscle atrophy, characterized by preferential weakness and wasting of the abductor pollicis brevis (APB) and first dorsal interosseous (FDI) muscles with relative sparing of the abductor digiti minimi muscle (ADM) [6]. Since first reported by Wilbourn et al. in the 1994 [7], split hand has been believed to be a characteristic sign in ALS and helpful to diagnose ALS. However, data of the frequency of split hand in ALS patients are currently scarce [8]. Increasingly studies have been done to explore the diagnostic accuracy of indices regarding split hand including APB/ADM ratio (AA) and split-hand index (SI) using compound muscle action potentials (CMAP) while no consensus has been reached. Other types of split signs were also reported to be potential biomarkers for the diagnosis of ALS [9], [10], which might even show higher sensitivity and specificity.
Therefore, the aim of this study is to summarize the frequency of split hand in patients with ALS and compare the AA and SI using CMAP (AACMAP and SICMAP) between patients with ALS and controls. We also explored the diagnostic accuracy of SICMAP though receiver operating characteristic (ROC) analysis. Our results might provide the new and comprehensive evidence of the application of SI in clinical practice.
Section snippets
Methods
This work was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) [11] and the Cochrane Handbook for Systematic Reviews of Diagnostic Test Accuracy [12].
Literature selection
A total of 630 studies were included in our study, including the results of keywords search (n = 628) and additional records identified from reference lists (n = 2). After the detailed reading of full texts, seventeen articles [8], [14], [15], [16], [17], [18], [19], [20], [21], [22], [23], [24], [25], [26], [27], [28], [29] were potentially eligible for meta-analysis (Fig. 1). Five studies [16], [19], [25], [26], [29] reported the frequency of split hand in patients with ALS, three studies [21]
Discussion
In the present systematic review and meta-analysis, we summarized available results to show the frequency of split hand in ALS patients, the differences of APB/ADMCMAP and SICMAP between patients with ALS and control population. Totally seventeen studies including 974 ALS patients and 973 controls were included in our analysis. The diagnostic accuracy of SICMAP was also detected using AUC in combination with sensitivity and specificity (Fig. 3.).
Conclusions
Our results suggested half of patients with ALS might show split hand. APB/ADMCMAP of ALS patients was significantly lower than healthy controls. SICMAP in ALS patients was considerably lower than both healthy population and other neuromuscular diseases. SICMAP showed good performance in diagnosis of ALS. Our study provided new and comprehensive evidence on the diagnostic accuracy of biomarkers regarding split hand, which might aid in the clinical diagnosis of ALS and reducing the heavy social
Ethical approval and consent to participate
Ethical approval and consent to participate were not necessary for this systematic review.
Availability of data and materials
All data analyzed during this study are included in published articles
Authors' contributions
Nan Hu: design of the work and writing of the main manuscript; Jingyi Wang: data extraction; Mingsheng Liu: design of the work and revision of the main manuscript. All authors have read and approved the manuscript.
Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgments
Authors would like to thank all the authors of the original articles.
Funding
No applicable.
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