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Objective: To determine the practical diagnostic utility of split-hand index (SI) values calculated from F-wave persistence (SI FP ) and the F/M amplitude ratio (SI F/M ) for differentiating patients with amyotrophic lateral sclerosis (ALS) from other conditions. Methods : This prospective study recruited consecutive patients from Peking Union Medical College Hospital, China, between June 2019 and December 2019. Patients 18-80 years old who had clinical neuromuscular symptoms affecting the upper limbs and required electrophysiological examinations to aid diagnosis were eligible. Compound muscle action potentials (CMAPs) and F-waves recorded from the abductor pollicis brevis (APB), first dorsal interosseous muscle (FDI), and abductor digiti minimi (ADM) were examined. SI FP and SI F/M were calculated as: SI = (APB × FDI)/ADM. The sensitivity and specificity of SI FP and SI F/M in differentiating ALS from non-ALS conditions were derived using receiver operating characteristic (ROC) curves. Results: A total of 309 participants, comprising 91 (29.4%) with ALS and 218 (70.6%) with other neuromuscular disorders, were enrolled after 54 were excluded. SI FP was significantly reduced and SI F/M increased in the ALS group compared with the non-ALS group ( p  < 0.001). By ROC curve analysis, an SI FP cutoff of 73.3 showed 85.7% sensitivity and 80.7% specificity for differentiating ALS from non-ALS. SI F/M and SI CMAP showed lower sensitivity (67% and 75.8%, respectively, p  < 0.001) than SI FP for ALS diagnosis. SI FP and SI F/M combined did not outperform SI FP alone. Conclusion : SI FP could be a sensitive, noninvasive neurophysiological diagnostic marker for ALS patients with affected upper limbs. In particular, an SI FP value of 73.3 might be the optimal cutoff for diagnosing ALS.

Objective: Split-hand sign is a useful clinical and electrophysiological feature in the diagnosis of amyotrophic lateral sclerosis (ALS). We proposed a novel split-hand index (SI) using F-wave persistence (FP) and assessed its diagnostic utility in ALS. Methods: Eighty-three consecutive ALS patients were recruited, and 50 healthy, age-, and height-matched volunteers were used as a control group. Compound muscle action potentials (CMAP) and FP were recorded from the abductor pollicis brevis (APB), first dorsal interosseous (FDI), and the abductor digiti minimi (ADM) muscles. The SI derived from FP was calculated using the following formula: SI FP = (FP APB ×FP FDI )/FP ADM . The sensitivity and specificity of SI FP and SI CMAP in differentiating ALS from healthy controls (HCs) were derived from receiver-operating characteristic (ROC) curve analysis. Results: Both SI FP and SI CMAP were significantly reduced in ALS patients. The ROC curve analysis indicated that both SI FP and SI CMAP reliably differentiated ALS from HCs [0.92 (95% CI: 0.88-0.95); 0.86 (95% CI: 0.82-0.91)], but SI FP showed better diagnostic accuracy than SI CMAP ( p  = 0.04), with a high sensitivity (81.2%) and specificity (97%). In subgroup analyses, SI FP appeared to be a better variable than SI CMAP for differentiation of ALS patients with normal CMAP from HCs, with an area under the curve of 0.87 (95% CI: 0.80-0.93), sensitivity of 69.4%, and specificity of 94%. Conclusion: The SI FP reliably distinguished ALS patients from HCs and may be more sensitive for determining the split-hand pattern of ALS than SI CMAP , particularly in the early stage of the disease.

Background: Ongoing efforts have been made to identify new neuroimaging markers to track amyotrophic lateral sclerosis (ALS) progression. This study aimed to explore the monitoring value of multimodal magnetic resonance imaging (MRI) in the disease progression of ALS., Methods: From September 2015 to March 2017, ten patients diagnosed with ALS in Peking Union Medical College Hospital completed head MRI scans at baseline and during follow-up. Multimodal MRI analyses, including gray matter (GM) volume measured by voxel-based morphometry; cerebral blood flow (CBF) evaluated by arterial spin labeling; functional connectivity, including low-frequency fluctuation (fALFF) and regional homogeneity (ReHo), measured by resting-state functional MRI; and integrity of white-matter (WM) fiber tracts evaluated by diffusion tensor imaging, were performed in these patients. Comparisons of imaging metrics were made between baseline and follow-up using paired t-test., Results: In the longitudinal comparisons, the brain structure (GM volume of the right precentral gyri, left postcentral gyri, and right thalami) and perfusion (CBF of the bilateral temporal poles, left precentral gyri, postcentral gyri, and right middle temporal gyri) in both motor and extramotor areas at follow-up were impaired to different extents when compared with those at baseline (all P < 0.05, false discovery rate adjusted). Functional connectivity was increased in the motor areas (fALFF of the right precentral gyri and superior frontal gyri, and ReHo of right precentral gyri) and decreased in the extramotor areas (fALFF of the bilateral middle frontal gyri and ReHo of the right precuneus and cingulate gyri) (all P < 0.001, unadjusted). No significant changes were detected in terms of brain WM measures., Conclusion: Multimodal MRI could be used to monitor short-term brain changes in ALS patients., Competing Interests: There are no conflicts of interest.

Background: The muscle patterns involved in the "split-leg" syndrome of amyotrophic lateral sclerosis (ALS) remains controversial. We sought to evaluate and reassess the pattern of the extensor digitorum brevis (EDB) and the abductor hallucis (AH) muscles' involvement in split-leg syndrome in ALS. Methods: We recruited 60 consecutive patients with ALS and 25 healthy controls (HCs). Compound muscle action potentials (CMAPs) and F-waves were recorded over the EDB and AH muscles in all subjects. For comparison, we classified patients into two categories based on the presence or absence of lower limbs symptoms. Results: The EDB/AH CMAP amplitude ratio was significantly reduced in patients with affected legs (0.33 ± 0.21, P = 0.007), whereas patients with unaffected legs had a ratio similar to that of the HCs. The EDB/AH ratios for the F-wave latencies, mean F-wave amplitude, mean F/M amplitude ratio, and the persistence of the total repeater F-wave shapes (index Freps) of the EDB-AH, were significantly increased in the affected leg group, whereas the EDB/AH ratio for F-wave persistence was significantly reduced. These findings indicated a greater loss of lower motor neurons (LMNs) innervating the EDB and dysfunction of spinal motoneurons innervating the EDB. In the unaffected leg group, the EDB, but not the AH, F-wave latencies, mean and maximal F/M amplitude ratios, and index Freps were significantly altered. Receiver operating characteristic curve analysis suggested that the EDB F-wave latencies, mean F/M amplitude ratios, and index Freqs (area under the curve [AUC] > 0.8) more strongly differentiated patients with ALS from the HCs compared to the EDB/AH CMAP amplitude ratio (AUC = 0.61). Notably, the EDB maximal F-wave latency and index Freqs reliably differentiated patients with unaffected legs (HCs), with AUCs of 0.83 (95% CI 0.76–0.91) and 0.81 (95% CI 0.72–0.89), sensitivities of 76 and 78%, and specificities of 76 and 78%, respectively. Conclusions: These results suggest preferential EDB compared to AH involvement in the split-leg syndrome of ALS. The EDB maximal F-wave latency and index Freqs robustly differentiated patients with ALS from HCs, which might facilitate an earlier identification of ALS. [ABSTRACT FROM AUTHOR]

The F-wave test allows for the non-invasive assessment of spinal motoneuron excitability. We investigated the difference in spinal motoneuron dysfunction between the first dorsal interosseous (FDI) and abductor digit minimi (ADM) muscles by investigating F-waves and to assess the contribution of spinal mechanisms to split-hand syndrome in patients with amyotrophic lateral sclerosis (ALS). Sixty-five consecutive ALS patients and twenty age- and gender-matched healthy controls (HCs) were enrolled. Motor nerve conduction studies and F-waves were performed bilaterally on median and ulnar nerves in all subjects. HCs revealed prominently longer F-wave latencies, lower chronodispersion, mean F-wave amplitude, and mean and maximal F/M amplitude ratio (P < 0.001) in the FDI compared to the ADM. However, no significant differences in almost all F-wave parameters between the FDI and ADM were observed in ALS patients with affected hands except the minimal and mean F-wave latency. These data suggest that excitability is greatly changed in the spinal motoneurons innervating the FDI. Furthermore, the mean F-wave amplitude (r = 0.454, P = 0.002) of the FDI was significantly correlated with the FDI/ADM CMAP amplitude ratio in ALS patients with affected hands but not of the ADM. Our findings suggested that the dysfunction of spinal motoneurons between the FDI and ADM was different in ALS, and spinal motoneuron dysfunction was associated with development of the split-hand phenomenon. [ABSTRACT FROM AUTHOR]