Split-elbow sign in the PRO-ACT and Southern Italy ALS cohorts: a potential marker of disease severity and lower motor neuron involvement?

Zoccolella, Stefano; Milella, Giammarco; Giugno, Alessia; Urso, Daniele; Tamburrino, Ludovica; Nigro, S. Ló; Gnoni, Valentina; Filardi, Marco; Logroscino, Giancarlo

doi:10.1007/s00415-023-11660-y

Cited by 4 publications

(3 citation statements)

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“…The dissociated wasting of the intrinsic hand, the elbow and the foot muscles represent typical manifestations of ALS, particularly in the initial stages when clinical signs are focal, especially for split-hand and split-leg signs ( 1 , 8 , 11 ). Conversely, the split-elbow remains actually poorly characterized ( 6 ).…”

Section: Discussionmentioning

confidence: 99%

“…This pattern aligns with the general Linear regression findings of the age distribution of the neurophysiological measures. understanding of the neuromuscular system, wherein a decrease in the nerve potential amplitude is expected with increasing age (6,21,22,(30)(31)(32)(33). These findings may be attributed to the effects of aging on nerve degeneration, including a reduction in the number and the size of axons as well as changes in the nerve fiber membrane (34).…”

Section: Discussionmentioning

confidence: 99%

“…In ALS, a phenomenon known as the “split-leg” (SL) sign is characterized by more pronounced wasting of the extensor digitorum brevis (EDB) in the lower limbs compared to the abductor hallucis (AH) ( 3 , 4 ). Finally, the biceps brachii muscles manifest more prominent weakness than the triceps brachii in ALS ( 5 , 6 ), and this is termed the “split-elbow” (SE) sign.…”

Section: Introductionmentioning

confidence: 99%

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Neurophysiological indices for split phenomena: correlation with age and sex and potential implications in amyotrophic lateral sclerosis

Zoccolella,

Milella,

Giugno

et al. 2024

Front. Neurol.

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BackgroundSplit phenomena (SP) are characterized by patterns of differential muscle wasting and atrophy, which are highly prevalent in amyotrophic lateral sclerosis (ALS) patients. Several neurophysiological indicators, including the split-hand index (SHI), split-leg index (SLI), and split-elbow index (SEI), have been proposed to assess SP. Nevertheless, their cutoff values and the impact of age and sex on these measures remain unclear.MethodsWe prospectively collected neurophysiological data from 300 healthy adult subjects. The following indices were measured from compound muscle action potentials (CMAPs): SHI [abductor pollicis brevis (APBcmap) x first dorsal interosseous (FDI)cmap/adductor digiti minimi (ADMcmap)], SEI (BICEPScmap/TRICEPScmap), SLI (extensor digit brevis (EDB)cmap/abductor Hallucis (AH)cmap), and the neurophysiological ratios APBcmap /ADMcmap and FDIcmap/ADMcmap. Multiple linear regression analysis was used to investigate the association between age, sex, CMAPs, and neurophysiological indicators.ResultsThe median SHI was 10.4, with a median APBcmap/ADMcmap ratio of 0.9 and a median FDIcmap/ADMcmap ratio of 1.2. The median SEI was 1.6 (IQR:1.1–2.4) and the median SLI was 0.7 (IQR:0.5–1.0). Negative associations were observed between age, most of the CMAPs, and all the neurophysiological indices, except for SLI. The male subjects exhibited significantly higher CMAP values for the first dorsal interosseous (FDI), biceps, and SHI compared to the female participants.ConclusionOur findings highlight the importance of age- and sex-adjusted normative data for SP indices, which could enhance their diagnostic accuracy and clinical utility in patients with ALS. The SL index appears to be the most reliable indicator, as it showed no significant association with age or sex.

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