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Introduction/Aims: While amyotrophic lateral sclerosis (ALS) is primarily characterized as a motor system disorder, there is a growing body of evidence indicating sensory involvement. This study aimed to examine the hypothesis that somatosensory processing is impaired in ALS. Methods: Study participants were ALS patients followed at the Neuromuscular Outpatient Unit, as well as healthy volunteers, from March 2021 to July 2023. The Medical Research Council (MRC) sum score was calculated for nine muscle groups bilaterally. The clinical status of patients was evaluated with the ALS Functional Rating Scale‐Revised (ALSFRS‐R) and the Penn Upper Motor Neuron core. Somatosensory temporal discrimination thresholds (STDTs) were recorded on the medial and lateral parts of both hands. Somatosensory cortex excitability was investigated with the paired somatosensory evoked potentials (SEP) paradigm in a subgroup. Results: Increased STD values were detected in ALS patients compared to controls in both medial (107.66 ± 35 ms vs. 82.7 ± 32.5 ms, p =.001) and lateral (106.5 ± 34.5 ms vs. 82.9 ± 31.3 ms, p =.002) hands. There were no significant differences in STDTs among ALS patients across four regions (medial and lateral parts of the right and left hands). Amplitude ratios obtained from the paired‐pulse SEP paradigm were approximately 1 for all interstimulus intervals (ISIs). STDTs did not show any correlations with motor findings or scales. Discussion: Somatosensory processing appears to be compromised among ALS patients. The lack of correlation between impaired STDT and motor findings implies that it is a purely sensory deficit in ALS. [ABSTRACT FROM AUTHOR]

Introduction/Aims: MScanFit motor unit number estimation (MUNE) is a promising method for motor unit estimation and is reported to have good reliability in distal and small muscles. In this study, we investigated the reliability of MScanFit MUNE in a proximal forearm muscle, the flexor carpi ulnaris. Methods: Twenty healthy volunteers were included in this study, and 15 participants were re‐evaluated in a second session. The ulnar nerve was stimulated at the elbow and a compound muscle action potential (CMAP) scan from the flexor carpi ulnaris (FCU) muscle was recorded from each arm. CMAP, MUNE, and other motor unit parameters were obtained. Reproducibility was evaluated using intraclass correlation coefficients (ICCs). Results: The average MUNE from 40 FCU muscles was 90.9 (standard deviation: 16.4). MScanFit MUNE and CMAP were not significantly different between the dominant and non‐dominant sides. The ICC indicated good reliability between sessions for each side (0.81 and 0.8, respectively). Discussion: Our results indicate that MScanFit MUNE is a feasible method with good reproducibility for MUNE of the FCU muscle. [ABSTRACT FROM AUTHOR]

Introduction: Although motor imagery (MI) has been reported to increase motor cortical excitability, its effect on central motor conduction time (CMCT), a widely used neurophysiological diagnostic method, has not been investigated. In this study, we sought to determine the effect of MI on CMCT., Methods: In this cross-sectional study, 21 healthy volunteers (11 females, 10 males) aged 24 to 67 years (mean age: 38.8 years) were recruited between April 2022 and June 2023. CMCT was calculated during MI from the abductor digiti minimi (ADM) and tibialis anterior (TA) muscles. Measurements were also performed with conventional measurement methods, such as resting and voluntary contraction, to compare the effect of MI on CMCT., Results: The ANOVA test revealed that the CMCT session (rest, MI, and voluntary contraction) was a significant factor (p < 0.05). In both muscles, CMCT was shorter in the imagery state than in the resting state but longer than in the voluntary contraction state (p < 0.05). Similarly, motor-evoked potential (MEP) latencies obtained during imagery were shorter for both muscles than the resting state but longer for the voluntary contraction state., Conclusion: The study's findings suggest that MI is a mental activity that modulates CMCT measurement. MI shows a voluntary contraction-like effect on CMCT and MEP latency, although the effect is more uncertain., Competing Interests: Human subjects: Consent was obtained or waived by all participants in this study. Local Ethics Committee of Gazi University issued approval 25-672. The Local Ethics Committee of Gazi University approved the study. Animal subjects: All authors have confirmed that this study did not involve animal subjects or tissue. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work., (Copyright © 2024, Boran et al.)

Objective: MScanFit motor unit number estimation (MUNE) is a sensitive method for detecting motor unit loss and has demonstrated high reproducibility in various settings. In this study, our aim was to assess the outputs of this method when the nerve conduction distance is increased., Methods: MScanFit recordings were obtained from the abductor digiti minimi muscle of 20 healthy volunteers. To evaluate the effect of nerve conduction distance, the ulnar nerve was stimulated from the wrist and elbow respectively. Reproducibility of MUNE, compound muscle action potential (CMAP), and other motor unit parameters were assessed using intraclass correlation coefficients (ICCs)., Results: Motor unit numbers obtained from stimulation at the wrist and elbow did not significantly differ and exhibited strong consistency in the ICC test (120.3 ± 23.7 vs. 118.5 ± 27.9, p > 0.05, ICC: 0.88). Similar repeatability values were noted for other parameters. However, the Largest Unit (%) displayed notable variability between the two regions and exhibited a negative correlation with nerve conduction distance., Conclusion: Our findings indicate that MScanFit can consistently calculate motor unit numbers and most of its outputs without substantial influence from nerve conduction distance. Exploring MScanFit's capabilities in various settings could enhance our understanding of its strengths and limitations for extensive use in clinical practice., Competing Interests: Declaration competing of interest None., (Copyright © 2024 Elsevier Masson SAS. All rights reserved.)