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The Small Intestine (SI)
Published in Narda G. Robinson, Interactive Medical Acupuncture Anatomy, 2016
Clinical Relevance: Patients with amyotrophic lateral sclerosis (ALS) experience hand muscle wasting that usually affects the thenar muscles and spares, to some degree, the hypothenar muscles such as the abductor digiti minimi.2 Although the ulnar nerve supplies both the first dorsal interosseous muscle and the abductor digiti minimi, the former undergoes atrophy in ALS while the latter less so. Whether the underlying mechanism relates to ion channel differences, cortical influences, or differential oxidative stress, this phenomenon called the “split hand syndrome” is considered a useful diagnostic sign in early cases of ALS, with a high degree of specificity. If a patient complains of having problems with a pincer or precision grip, consider ALS within the differential. Although acupuncture and related techniques may assist in preserving hand function, these treatments should not delay appropriate referral and diagnostics.
A prospective study on split-hand index as a biomarker for the diagnosis of amyotrophic lateral sclerosis
Published in Amyotrophic Lateral Sclerosis and Frontotemporal Degeneration, 2020
Zhi-Li Wang, Mingsheng Liu, Zhengyi Cai, Qingyun Ding, Youfang Hu, Liying Cui
SICMAP was found to be a diagnostic biomarker for ALS (5). A previous study reported that SICMAP achieved sensitivity of 74% in differentiating ALS patients from patients with ALS-mimic disorders, an improvement over the 52% sensitivity achieved in a multicenter Japanese study using an APB/ADM CMAP amplitude ratio <0.6 or an FDI/ADM CMAP ratio <0.9 as the electrophysiological criterion for the split-hand phenomenon (3–5). Studies have shown that low F-wave persistence indicates loss of functional LMN and decreased excitability of the motor neuron pool (7). In this study, the diagnostic efficiency of reduced SIFP, especially the sensitivity, was significantly higher than that of SICMAP, even early in the disease process. These results are consistent with the higher sensitivity of F-wave compared with CMAP for assessing the loss of LMNs (8). Our results presumably reflect LMN involvement in ALS following a split-hand distribution and contributing to development of split-hand syndrome. In addition, when SI calculated from F-wave persistence and amplitude were compared between riluzole use and no-riluzole use groups, no difference was found. This finding supports that riluzole not effecting LMN excitability (15) or the parameters of SIFP and SIF/M. Moreover, the diagnostic efficiency of SIFP and SIF/M calculated by F-waves from 100 stimuli was significantly greater than that of SIFP and SIF/M from 10 stimuli, demonstrating that a sample size of 100 could ensure a better and more adequate exploration of LMNs changes (12,16).
The split hand in amyotrophic lateral sclerosis: a possible role for the neuromuscular junction
Published in Amyotrophic Lateral Sclerosis and Frontotemporal Degeneration, 2019
Mamede de Carvalho, Michael Swash
The results we describe are consistent with a peripheral component to split hand syndrome in ALS, and also with the uncommon finding of a split hand distribution of muscle atrophy in other lower motor neuron disorders (2). We therefore suggest that physiological differences in the function of end-plate in hand muscles can be important as a susceptibility factor for predominant early involvement in ALS, mirroring as split-hand phenomenon. The finding of “reversed split hand” atrophy in SMA suggests that studies of other motor neuron degenerations, and of motor neuropathies, should be undertaken to further investigate these phenomena, which may have relevance in understanding susceptibility to denervation in other motor disorders.
Split-hand index in amyotrophic lateral sclerosis: an F-wave study
Published in Amyotrophic Lateral Sclerosis and Frontotemporal Degeneration, 2019
Zhi-Li Wang, Mingsheng Liu, Qingyun Ding, Youfang Hu, Liying Cui
One possibility regarding split-hand syndrome in ALS is that more frequent use of the thenar muscles (APB and FDI) renders these muscles and their motor neurons more susceptible to oxidative stress or increased metabolic demand, leaving the motor neurons of these muscles more vulnerable to degeneration processes (4,18). Another possibility is that corticomotoneuronal hyperexcitability causes the thenar spinal anterior horn cells to preferentially degenerate through anterograde glutamate-induced excitotoxicity (19,20). Thus, abnormalities of the spinal motor neurons appear to play an important role in split-hand syndrome. In addition, previous electrophysiological studies have suggested that increased F-wave amplitudes combined with low persistence can be considered a particular pattern of F-wave changes in ALS, and that reduced FP indicates a loss of functional LMNs and decreased excitability of the motoneuron pool (7). Therefore, comparison of the FP between the APB, FDI, and ADM may provide a useful method for investigating the dissociated alterations spinal motor neurons in ALS. Our recent study investigated differences in spinal motoneuron dysfunction between the FDI and ADM muscles (innervated by the same ulnar nerve) by investigating F-waves, and assessed the contribution of spinal mechanisms to split-hand syndrome in patients with ALS (12). We found that the dysfunction of spinal motor neurons between the FDI and ADM was different in patients with ALS and spinal motoneuron dysfunction was likely to be associated with development of the split-hand phenomenon (12). Interestingly, in our previous study we also observed an early decline in FP in patients with unaffected hands, suggesting early dysfunction of spinal motor neurons in ALS, and indicating that subtle subclinical alterations may be reliably assessed using the F-wave test. In the present study, ALS patients exhibited markedly low SIFP, which is compatible with the split-hand phenomenon and also suggests preferential involvement of the spinal motor neurons of the APB and FDI but not the ADM in ALS. The present findings appear to support the notion that spinal processes contribute to the developmentnt of the split-hand sign in ALS.