Compound Muscle Action Potential Amplitude Research Articles

Botulinum toxin modulates the blink reflex via the trigeminal afferent system in hemifacial spasm: an early and late-term effect.

There is growing evidence that botulinum neurotoxin (BoNT) can mediate changes at the central level through peripheral mechanisms, leading to alterations in central sensorimotor integration. However, the effect of BoNT on brainstem excitability in patients with hemifacial spasm(HFS) is not yet fully understood, and its long-term effects remain unknown. This study aims to investigate the impact of BoNT on the excitability of the facial nucleus in patients with idiopathic HFS. In order to evaluate the peripheral effect of the toxin, the amplitude of compound muscle action potential (CMAP) of orbicularis oculi (OOc) muscles was evaluated. To investigate the effects of locally injected BoNT on the brainstem, particularly the facial motor nucleus, we evaluated the amplitude and latency of the blink reflex (BR), the synkinetic responses (SR) and the ratio of contralateral R2 (cR2) amplitude of BR/CMAP amplitude in 16 patients with HFS. These measurements were performed before and after the 1 and 4month BoNT injection. Following BoNT therapy there was a significant amplitude reduction and latency prolongation of R1, iR2, cR2 and SR elicited by the stimulation of the side of BoNT injection. The mean CMAP amplitude of OOc muscle was significantly lower after BoNT injection. The ratio of cR2 amplitude/CMAP amplitude of OOc showed a significant decline after BoNT therapy. Our study demonstrated that BoNT suppresses the excitability of facial motor neurons in idiopathic HFS via the trigeminal afferent mechanism. These effects persisted during the fourth month, despite BoNT's diminished activity.

Reliability of MScanFit Motor Unit Number Estimation in the Trapezius Muscle.

MScanFit motor unit number estimation (MUNE) is the most recent MUNE method which has shown promising results in extremity muscles, but it has not been applied to bulbar muscles. Bulbar muscles are particularly important in the diagnosis of amyotrophic lateral sclerosis (ALS). This study aimed to investigate the feasibility and reliability of MScanFit MUNE in the accessory nerve and trapezius muscles. A total of twenty healthy participants were examined twice within 1-2 weeks. We extracted the MScanFit MUNE and size parameter, and compound muscle action potential (CMAP) amplitude values. The reliability of these parameters was assessed using the intra-rater coefficient of variation (CoV), intraclass correlation coefficient (ICC), and Bland-Altman plots. We also correlated MUNE values with CMAP amplitudes using correlation coefficients. Mean MUNE values (Day 1 = 132.1 and Day 2 = 137.4), CMAP amplitudes (Day 1 = 9.71 mV and Day 2 = 10.10 mV) and size parameters did not differ between the two sessions (p > 0.05). CoV showed excellent reliability for MUNE values, size parameters, and CMAP amplitudes (CoV < 7%) whereas ICCs showed moderate reliability for MUNE values (ICC = 0.619), poor to moderate reliability for size parameters (between 0.393 and 0.689), and good reliability for CMAP amplitude (ICC = 0.864) There was no correlation between MUNE values and CMAP amplitudes. MScanFit MUNE is applicable and mostly reliable in the trapezius muscle. Further studies in patients are needed to investigate the sensitivity of MScanFit in this muscle in detecting motor unit loss, particularly in ALS.

Paraneoplastic Cerebellar Degeneration and Symptomless Lambert–Eaton Myasthenic Syndrome With SOX‐1 Antibodies

ABSTRACTA 62‐year‐old man was diagnosed with paraneoplastic cerebellar degeneration (PCD) at a previous hospital due to cerebellar ataxia, positive serum SOX‐1 antibodies, and small cell lung cancer. Although the tumor has shrunk by chemotherapy, the cerebellar ataxia progressed and left him unable to walk. Lambert–Eaton myasthenic syndrome (LEMS) was suspected, because nerve conduction studies showed that reduced compound muscle action potential amplitudes disproportionate to muscle weakness. PCD‐LEMS with SOX‐1 antibodies was diagnosed on the basis of waxing by high‐frequency repetitive nerve stimulation test and high P/Q‐type voltage‐gated calcium channel antibody levels. Immunoglobulin therapy and 3,4‐diaminopyridine contributed to improved activities of daily living by improving muscle weakness masked by cerebellar symptoms. In patients with SOX‐1 antibodies, investigating for tumors and LEMS is necessary, even if muscle weakness is not noticeable.

Early and Late Intrinsic Hand Muscle Reinnervation After End-to-Side AIN to Ulnar Motor Nerve Transfer.

The "supercharge" end-to-side (SETS) anterior-interosseous-nerve (AIN) to ulnar-motor nerve transfer is used to improve intrinsic muscle recovery in cases of severe ulnar nerve compression or proximal axonotmetic injuries. Previous work has found differing intrinsic muscle recovery after this transfer. The objectives of this study were to examine the patterns of recovery in first dorsal interossei (FDI) and abductor digiti minimi (ADM) and the impact of AIN transfer to a specific fascicular location on the ulnar-motor nerve. A retrospective review of one fellowship-trained surgeon's consecutive patients at a single center from December 2019 to September 2021 was conducted. Patients who had an AIN to ulnar-motor nerve transfer for any indication were included and were excluded if they had less than 9 months follow-up. Seventeen patients were included (88% male, mean age 55 ± 14 years). At early follow-up, compound muscle action potential amplitudes for ADM and FDI did not increase. Compound muscle action potential amplitude for ADM significantly increased at late follow-up (P < .01). Average British Medical Research Council (BMRC) strength increased at early follow-up for FDI (P < .05), but not ADM. The proportion of patients with BMRC ≥ 3 increased for FDI (P < .01) and ADM (P < .05) at late follow-up. Volar-ulnar AIN insertion position did not have a clear effect on outcomes. The SETS AIN to ulnar-motor nerve transfer demonstrates clinical and electrophysiologic evidence of intrinsic muscle recovery and reinnervation, with differing recovery of outcomes. The role of specific fascicular targeting is still unclear and required further examination as does the mechanism behind differing intrinsic recovering.

Clinical Features of Conduction Block in Ulnar Neuropathy at the Elbow: The Surgery of the Ulnar Nerve (SUN) Multicenter Clinical Trial.

In ulnar neuropathy at the elbow, weakness is classically a sign of severe disease. Weakness is associated with motor axonal loss as measured by decreased distal compound muscle action potential (CMAP) amplitude. Conduction block, a demyelinating phenomenon that recovers readily, can also cause weakness, creating ambiguity for the treating clinician. This cross-sectional study evaluated baseline blinded data collected from 2020-2023 from the Surgery of the Ulnar Nerve randomized controlled trial comparing in-situ decompression versus transposition procedures. Adult patients underwent electrodiagnostic testing, clinical motor and sensory testing, and completed the Michigan Hand Questionnaire and Carpal Tunnel Questionnaire. 177 patients were categorized into 3 distinct groups based on normal distal CMAP amplitudes (77 patients), presence of conduction block with or without distal CMAP amplitude loss (37 patients), or pure axonal loss with distal CMAP amplitude loss in the absence of conduction block (63 patients). Compared to the normal group, patients with conduction block had significantly decreased pinch strength and worse function domain scores on the Michigan Hand Questionnaire and Carpal Tunnel Questionnaire, but shorter duration of disease. Patients with pure axonal loss had decreased pinch strength, worse 2-point discrimination, and worse overall, function and aesthetics domain scores on the Michigan Hand Questionnaire. There was a significant interaction between the effects of conduction block and distal CMAP amplitude on pinch strength, indicating that higher degrees of conduction block resulted in more pronounced loss of pinch strength in patients with relatively preserved distal CMAP amplitude. Our findings support the paradigm that ulnar neuropathy at the elbow presenting with conduction block represents a distinct and intermediate pathophysiology, distinguished by quicker onset with less advanced neurological deficits. Prognostic Level II.

Hydroxychloroquine Mitigates Cytokine Storm and Prevents Critical Illness Neuromyopathy in a Rat Sepsis Model.

Background and Objectives: It is known that critical illness and associated neuromuscular problems begin to appear in patients hospitalized in the intensive care unit (ICU) for more than a week. The goal of this study was to research the role of hydroxychloroquine (HCQ) in the treatment of cytokine storm and critical illness neuromyopathy (CINM) in a rat sepsis model. Materials and Methods: Rats were assigned into three groups, and a feces intraperitoneal-injection group (FIP) procedure was carried out on 30 rats to induce a model of sepsis for critical illness polyneuromyopathy (CINM). The study groups were as follows: Group 1: control (nonoperative and orally fed control, n = 10), Group 2: FIP with 0.9% NaCl saline was given as 1 mL/kg/day by oral gavage (n = 10), and Group 3: FIP with 10 mg/kg/day of hydroxychloroquine (Plaquenil 200 mg) administered by oral gavage (n = 10). Electrophysiological recordings (EMG) were conducted six days after surgery. EMG was carried out three times on the right sciatic nerve, which was stimulated with supramaximal intensity utilizing a bipolar needle electrode at the sciatic notch. Tumor necrosis factor-alpha (TNF-α), malondialdehyde (MDA), lactic acid levels, and interleukin-6 (IL-6) were evaluated. Results: In terms of TNF-α, MDA, lactic acid levels, and IL-6, there was a statistically significant decrease in the CINM + 10 mg/kg HCQ group compared to the CINM and saline group (p < 0.0001, p < 0.05, p < 0.05, and p < 0.05, respectively). Compound muscle action potentials (CMAPs) latency and duration were decreased in the CINM + 10 mg/kg HCQ group compared to other groups (p < 0.01 and p < 0.001). However, CMAP amplitude was significantly higher in the CINM + 10 mg/kg HCQ group unlike the CINM and saline group (p < 0.001). Conclusions: This is the first study to demonstrate the effects of HCQ on CINM in a rat model of sepsis. The findings of our research suggest that hydroxychloroquine may be used as a potential therapeutic agent in the treatment of sepsis. Hydroxychloroquine may have an important effect in the pathogenesis of sepsis-associated CINM by reducing cytokine production and oxidative stress.

Ultrasound as a Complementary Tool to Electrodiagnostics in the Evaluation of Compressive Neuropathy of the Common Fibular Nerve

Background: Compressive neuropathy of the common fibular nerve (CFN) is increasingly recognized as an etiology for foot drop and falls. Electrodiagnostic (EDX) studies are widely used to evaluate this condition, but such tests are invasive and costly. As with carpal and cubital tunnel syndromes, there may be patients with characteristic symptoms of CFN compressive neuropathy but normal EDX studies in which ultrasound may aid in decision-making. Purpose: We sought to examine the association between ultrasound and nerve conduction studies (NCS) and electromyography (EMG) in the diagnosis of compressive neuropathy of the CFN. Methods: We performed a retrospective review identifying 104 patients who underwent CFN decompression from January 1, 2015, to June 30, 2023. Patients were included if they had both ultrasound and NCS/EMG prior to CFN decompression for compressive neuropathy and if they were older than 18 years at time of surgery. Patients were excluded if they had entrapment secondary to trauma, iatrogenic injury, or if they had had superficial fibular decompression alone without CFN decompression. After applying exclusion criteria, 17 patients remained in the cohort. Results: Mean ultrasound cross-sectional area and side-to-side (STS) ratios were significantly higher in those with abnormal compound muscle action potential (CMAP) amplitudes versus those with normal CMAP amplitudes. The probability of having an abnormal CMAP amplitude when STS ratio was abnormal was 18 times greater compared with those with normal STS ratio. With each unit increase in STS ratio, CMAP amplitude was reduced by 2.79 mV. Conclusions: This retrospective review found that ultrasound may provide complementary diagnostic information to EMG/NCS for compressive neuropathy of the CFN. Further study is needed to examine the relationship between ultrasound findings for CFN compressive neuropathy and results of surgical decompression.

Bioactive MXene hydrogel promotes structural and functional regeneration of skeletal muscle through improving autophagy and muscle innervation

Complete skeletal muscle regeneration after traumatic injuries remains a challenge due to impaired regenerative capability and dysregulated microenvironments. Autophagy plays a crucial role in the muscle regeneration process by regulating myogenic and non-myogenic cells. Herein, we report a bioactive MXene hydrogel (FPGM) capable of upregulating autophagy and increasing muscle innervation to restore skeletal muscle structure and function. FPGM possessed excellent electrical conductivity, tissue adhesive ability and antioxidation, which could eliminate excess reactive oxygen species to reduce oxidative stress and decrease the secretion of pro-inflammatory cytokine. FPGM upregulated the autophagy level of myoblasts and promoted the migration and tube formation of endothelial cells as well as myogenic differentiation with negligible toxicity. FPGM accelerated muscle fiber formation and skeletal muscle regeneration by improving autophagy, which could regulate microenvironment through raising M2 macrophages to alleviate excessive inflammation, facilitating angiogenesis and decreasing fibrous scar tissue formation in vivo. Importantly, FPGM could efficiently restore muscle function by improving muscle innervation, tibialis anterior compound muscle action potential amplitude and neuromuscular conduction. This work demonstrates that bioactive MXene hydrogel should be a promising candidate for complete skeletal muscle regeneration.

Neurofilament light chain as a biomarker for hereditary ATTR amyloidosis − correlation between neurofilament light chain and nerve conduction study

Background Neurofilament light chain (NfL) is a biomarker of neuronal injury in hereditary ATTR (ATTRv) amyloidosis. However, the correlation between NfL and nerve conduction study (NCS), the standard test for ATTRv neuropathy, has not been investigated. Objective Elucidate the correlation between NfL and NCS parameters. Methods 227 serum NfL measurements were performed in 45 ATTRv patients, 5 asymptomatic carriers, and 12 controls. Among them, 177 simultaneous analyses of NCS and NfL were conducted in 45 ATTRv patients. Results NfL levels of symptomatic patients were significantly higher than those of asymptomatic carriers and controls. Serum NfL levels were correlated with NCS parameters, especially compound muscle action potential (CMAP) and sensory nerve action potential (SNAP) amplitudes, indicators of axonal damage. CMAP and/or SNAP amplitudes were undetectable in 9 patients (no-amplitude group) due to advanced neuropathy. NfL levels in the no-amplitude group were significantly higher than those in patients with detectable CMAP/SNAP. NfL levels significantly decreased with patisiran, although no significant changes were observed in CMAP and SNAP. Conclusions NfL levels are found to be correlated with CMAP/SNAP amplitudes. Compared with NCS, NfL can be a more sensitive biomarker for detecting treatment response and active nerve damage even in patients with advanced neuropathy.

Structural and Functional Alterations of the Deltoid Muscle After Arthroscopic Rotator Cuff Repair: A 2-Year Longitudinal Observation Study.

Deltoid muscle detachment and atrophy have been reported to occur after shoulder surgery. To investigate the 2-year changes in deltoid muscle structure and function after arthroscopic rotator cuff repair (ARCR) using magnetic resonance imaging (MRI) and electrophysical examination. Case series; Level of evidence, 4. A total of 72 patients (72 shoulders) who underwent ARCR between 2015 and 2020 were enrolled. Whole deltoid muscle volume and regional (anterior, lateral, and posterior) muscle thicknesses were determined on T2-weighted MRI scans of both shoulders taken preoperatively and at 1, 3, 6, 12, and 24 months postoperatively, and their correlations with compound muscle action potentials (CMAPs), shoulder abduction muscle strength, and Constant scores were investigated. Comparison between groups was performed using paired or Student t tests, and the relationship between deltoid muscle volume and various factors was determined using Pearson correlation analysis. The volume of the deltoid muscle on the affected side decreased from 44,369 ± 12,371 mm3 preoperatively to 38,139 ± 10,615 mm3 at 1 month postoperatively (P < .05), representing a 14% decrease. The deltoid muscle volume of the contralateral side also significantly decreased during the same time frame, from 43,278 ± 12,248 to 40,273 ± 11,464 mm3 (P < .05), representing a 7% decrease at 1 month postoperatively. Subsequently, the deltoid muscle volume on both sides recovered to preoperative levels at 12 months and was maintained at 24 months. Only the thickness of the anterior part of the deltoid was markedly decreased, from 13.9 ± 3.7 mm preoperatively to 12.0 ± 3.2 mm at 1 month postoperatively (P < .05), representing a 14% reduction. The CMAP amplitude showed a significant decrease at 1 month postoperatively; however, no significant difference was observed after 12 months when compared with the preoperative values or the values on the contralateral side. Positive correlations were found between deltoid muscle volume and CMAP amplitude at 24 months as well as between deltoid muscle volume and shoulder abduction muscle strength (R 2 = 0.698; P < .05) and Constant score (R 2 = 0.133; P < .05). Our study demonstrated that the early structural and functional decline of the deltoid muscle after ARCR was fully recovered within 1 year, confirming that this procedure does not negatively affect the deltoid muscle.

Diosmin and Hesperidin Have a Protective Effect in Diabetic Neuropathy via the FGF21 and Galectin-3 Pathway.

Background and Objectives: This study aimed to investigate the protective effect of diosmin and hesperidin in diabetic neuropathy using a rat model, focusing on their impact on nerve regeneration through the fibroblast growth factor 21 (FGF21) and galectin-3 (gal3) pathway. Materials and Methods: Forty adult male Wistar rats were used in this study. Diabetes was induced using streptozotocin (STZ), and the rats were divided into control, diabetes and saline-treated, diabetes and diosmin + hesperidin (150 mg/kg) treated, and diabetes and diosmin + hesperidin (300 mg/kg) treated groups. Electromyography (EMG) and inclined plane testing were performed to assess nerve function and motor performance. Sciatic nerve sections were examined histopathologically. Plasma levels of FGF21, galectin-3, and malondialdehyde (MDA) were measured as markers of oxidative stress and inflammation. Results: Diabetic rats treated with saline displayed reduced nerve conduction parameters and impaired motor performance compared to controls. Treatment with diosmin and hesperidin significantly improved compound muscle action potential (CMAP) amplitude, distal latency, and motor performance in a dose-dependent manner. Histopathological examination revealed decreased perineural thickness in treated groups. Additionally, treatment with diosmin and hesperidin resulted in increased plasma FGF21 levels and reduced plasma levels of galectin-3 and MDA, indicating decreased oxidative stress and inflammation. Conclusions: Diosmin and hesperidin exhibited protective effects in diabetic neuropathy by promoting nerve regeneration, enhancing nerve conduction, and improving motor performance. These effects were associated with modulation of the FGF21 and galectin-3 pathway. These findings suggest that diosmin and hesperidin may hold potential as adjunctive therapies for diabetic neuropathy.

Inhibition of KIF5b-mediated Nav1.8 transport by ropivacaine contributes to axonal regeneration following sciatic nerve injury in rats

Peripheral nerve injury (PNI), typically caused by traumatic accidents or medical events, is currently one of the most common diseases that leads to limb disability. After PNI, tetrodotoxin-resistant voltage-gated sodium channel Nav1.8 is upregulated at the lesion site. Our earlier study suggested that ropivacaine promotes axon regrowth by regulating Nav1.8-mediated macrophage signaling. Nevertheless, the mechanism of ropivacaine in regulation of Nav1.8 expression remains incompletely understood. Kinesin family 5b (KIF5b) was reported to mediate the Nav1.8 axonal transport from dorsal root ganglia (DRGs) to lesion site. Herein, we investigated whether ropivacaine promotes axon regeneration through inhibition of KIF5b-mediated Nav1.8 transport. Reduced levels of KIF5b and Nav1.8 in DRGs coincide with their increase at the lesion site. Nav1.8 mRNA was significantly increased at the lesion site but not in DRGs. Surprisingly, ropivacaine reversed the alterations of Nav1.8 and KIF5b protein expression without affecting Nav1.8 mRNA level. Due to KIF5b overexpression in DRGs, Nav1.8 protein level was significantly decreased in DRGs and increased at the lesion site. We also found KIF5b overexpression significantly impaired behavioral functions, reduced the recovery index of compound muscle action potential (CMAP) amplitude, inhibited axonal regrowth, slowed M1 macrophage infiltration and shift to M2 phenotype, and delayed myelin debris clearance. Notably, all aforementioned results caused by KIF5b overexpression were alleviated by ropivacaine. Furthermore, we demonstrated that inhibition of Nav1.8 transport by A-803467 produced mitigating effects on the impairment of regenerative capacity induced by KIF5b overexpression similar to ropivacaine. These results suggest that ropivacaine promotes axonal regeneration at least partially by inhibiting KIF5b-mediated Nav1.8 forward transport.

Fluorescein Angiography for Monitoring Neural Blood Flow in Chronic Nerve Compression Neuropathy: Experimental Animal Models and Preliminary Clinical Observations.

Pathologies associated with neural blood disturbance have been reported in patients with chronic nerve compression (CNC) neuropathy. Fluorescein angiography (FAG) and laser Doppler flowmetry (LDF) are effective for real-time peripheral nerve blood flow assessment. However, their reliability in severe neuropathy models in large animals or clinical conditions remains unclear. Initially, we aim to apply FAG to two different CNC animal models and evaluate their characteristics in comparison with those of LDF. In FAG, we quantified the peak luminance at the compression site following fluorescein injection. Then, we positioned the LDF probe at the center of the compression site and recorded the blood flow. Subsequently, we analyzed whether the FAG characteristics obtained in this animal experiment were consistent with those of clinical studies in patients with severe carpal tunnel syndrome (CTS). In the CNC rat model, FAG and LDF effectively monitored reduced neural blood flow over time. We observed significant blood flow reduction using both techniques in a newly developed severe CNC rabbit model. Notably, FAG correlated strongly with the compound muscle action potential (CMAP) amplitude in electrodiagnostic findings, unlike LDF. As a next step, we performed FAG after open carpal tunnel release in clinical cases of CTS. FAG correlated significantly with preoperative CMAP amplitude. This indicates FAG's importance for assessing nerve blood flow during surgery, potentially improving diagnostic accuracy and surgical outcomes.

Long-term impact of nusinersen on motor and electrophysiological outcomes in adolescent and adult spinal muscular atrophy: insights from a multicenter retrospective study.

5q spinal muscular atrophy (SMA) is a progressive autosomal recessive motor neuron disease. We aimed to assess the effects of nusinersen on motor function and electrophysiological parameters in adolescent and adult patients with 5q SMA. Patients with genetically confirmed 5q SMA were eligible for inclusion, and clinical data were collected at baseline (V1), 63days (V4), 180days (V5), and 300days (V6). The efficacy of nusinersen was monitored by encompassing clinical assessments, including the Revised Upper Limb Module (RULM), Hammersmith Functional Motor Scale Expanded (HFMSE), 6-Minute Walk Test (6MWT), and percent-predicted Forced Vital Capacity in sitting position (FVC%) and Compound Muscle Action Potential (CMAP) amplitude. The patients were divided into "sitter" and "walker" subgroups according to motor function status. 54 patients were screened, divided into "sitter" (N = 22) and "walker" (N = 32), with the mean age at baseline of 27.03years (range 13-53years). The HFMSE in the walker subgroup increased significantly from baseline to V4 (mean change +2.32-point, P = 0.004), V5 (+3.09, P = 0.004) and V6 (+4.21, P = 0.005). The patients in both the sitter and walker subgroup had no significant changes in mean RULM between V1 and the following time points. Significant increases in CMAP amplitudes were observed in both upper and lower limbs after treatment. Also, patients with RULM ≥ 36 points showed significant CMAP improvements. Our analysis predicted that patients with CMAP amplitudes of trapezius ≥ 1.76mV were more likely to achieve significant motor function improvements. Nusinersen effectively improves motor function and electrophysiological data in adolescent and adult patients with SMA. This is the first report on the CMAP amplitude changes in the trapezius after treatment in patients with SMA. The CMAP values effectively compensate for the ceiling effect observed in the RULM, suggesting that CMAP could serve as an additional biomarker for evaluating treatment efficacy.

Motor unit number index in Bell's palsy: A potential electrophysiological biomarker for early evaluation.

Reliable, noninvasive early diagnostics of neuromuscular function in Bell's palsy, which causes facial paralysis and reduced quality of life, remain to be established. Here, we aimed to evaluate the utility of the motor unit number index (MUNIX) for the quantitative electrophysiological assessment of early-stage Bell's palsy, its correlation with clinical assessments, changes following treatment, and association with clinical prognosis. MUNIX measures were recorded from the bilateral zygomaticus, orbicularis oculi, and orbicularis oris muscles of 10 healthy individuals and 64 patients with Bell's palsy. The patients were assessed by two specialist neurologists using the House-Brackmann and Sunnybrook Facial Grading Systems. Repeat assessments were performed on 20 patients with Bell's palsy who received treatment. Additionally, the 64 patients were reassessed using clinical scales after a 1-month interval. The MUNIX values of the main affected muscles on the affected side were lower than those on the healthy side in patients with Bell's palsy (p<.05). The MUNIX measurements significantly correlated with the clinical facial nerve palsy scale scores (p<.05). Significant improvements were observed in the MUNIX values on repeat testing following treatment (p<.05). The baseline motor unit size index (the compound muscle action potential amplitude divided by MUNIX) was positively associated with improved clinical presentation after 1 month (p<.05). MUNIX can be used as an electrophysiological biomarker for the quantitative assessment of facial nerve palsy and treatment response, and as a prognostic biomarker, in patients with early Bell's palsy, and is recommended as a complement to conventional neurophysiological examinations.

Long-chain n-3 polyunsaturated fatty acid supplementation and neuromuscular function in older adults.

This review aims to explore the latest research investigating the effects of marine-derived long-chain n -3 polyunsaturated fatty acid (LC n -3 PUFA) supplementation on neuromuscular function in older adults. Ageing results in a decline in skeletal muscle strength and mass. There is growing evidence that LC n -3 PUFA supplementation increases muscle strength and mass in healthy older adults, yet the mechanisms underlying these effects remain elusive. Recent studies investigating LC n -3 PUFA supplementation have demonstrated effects on neuromuscular function such as increases in the compound muscle action potential (M-wave) amplitude and surface electromyography alongside increases in muscular strength. Therefore, evidence suggests that LC n -3 PUFA may elicit a beneficial effect at the neuromuscular junction and possess neuroprotective properties in older adults. LC n -3 PUFA supplementation may increase or maintain neuromuscular function throughout the ageing process. Further research is warranted to investigate the long-term effects LC n -3 PUFA supplementation on neuromuscular outcomes such as single motor unit properties and cortical/supraspinal networks, utilizing state-of-the-art techniques in neuromuscular physiology.

The Spectrum of Childhood-Onset Lower Motor Neuron Disease of Spinal Muscular Atrophy Phenotype Associated with Survival Motor Neuron-2 Gene Deletion

AbstractPediatric lower motor neuron disease is clinically and genetically heterogeneous. We characterized disease progression among children with the spinal muscular atrophy (SMA) phenotype having 2:0 (group A) and 2:1 (group B) of the survival motor neuron 1/2 (SMN1:SMN2) genotype over 1 year. We included children aged 0 to 12 with the SMA phenotype between January 2018 and December 2021. Their demographic, clinical (Children's Hospital of Philadelphia Infant Test of Neuromuscular Disorders [CHOP-INTEND] scores), electrophysiological, radiological, and genetic data were collected from past medical records. The sequential CHOP-INTEND scores and the compound muscle action potential (CMAP) amplitudes were compared using an analysis of covariance test, controlling for age and sex. A linear regression was run to determine the association between the ages of the patients and the CHOP-INTEND scores. Among nine children in group A and six in group B, the decline of the mean (standard deviation) CHOP-INTEND score from the initial value to the 12th-month follow-up value was significant only in group A. CHOP-INTEND scores did not significantly differ between the two groups at the first admission but were significantly lower in group A at the subsequent visits. Group A patients had significantly lower CMAP amplitudes than patients in group B. There was a moderate, negative association between the age of patients and the CHOP-INTEND scores in group A. Group A patients had a significantly higher age-dependent decline in CHOP-INTEND scores and CMAP values than group B, although their age and the severity of weakness did not significantly differ at presentation.

Analysis of the characteristics of patients with amyotrophic lateral sclerosis with neuromuscular junction dysfunction prior to motor neuron degeneration

Objective: To investigate the clinical and electrophysiological characteristics of patients with amyotrophic lateral sclerosis (ALS) with positive repetitive nerve stimulation (RNS) test results on the accessory nerve and negative needle electromyography (EMG) test results on the sternocleidomastoid with the goal to enrich the knowledge of disease progression in patients with ALS. Methods: The clinical data of 612 patients diagnosed with ALS at the Neurology Department of the First Medical Center, Chinese PLA General Hospital from June 2016 to August 2022 were collected. In total, 267 cases had undergone EMG tests on the sternocleidomastoid following a positive 3 Hz RNS test result on the accessory nerve, who were selected as the study subjects. The differences in clinical indicators were compared between RNS (+)/EMG (-) group and RNS (+)/EMG (+) group. A binomial distribution model with multiple variables was built to quantitatively analyze the major factors and their effects. Results: At the initial visit, 15.8% of patients with ALS were 3 Hz RNS (+) on the accessory nerve and EMG (-) on the ipsilateral sternocleidomastoid, accounting for 36.3% of RNS (+) patients. The decremental range of the 3 Hz RNS test delivered to the accessory nerve in these patients [-14% (-19%, -12%)] was lower than that in patients with RNS (+)/EMG (+) [-17% (-23%, -13%)] (P<0.05), while the ratio of upper limb onset (64.9%) and non-definite diagnosis (28.9%) were higher [54.7% and 13.5% for patients with RNS (+)/EMG (+), P<0.05]. Furthermore, the Revised Amyotrophic Lateral Sclerosis Functional Rating Scale (ALSFRS-R) score [40 (37, 42)], body mass index (BMI) [23.8 (22.0, 25.4) kg/m2] and forced vital capacity (FVC) [92.8% (76.6%, 103.8%)] were higher in patients with RNS(+)/EMG(+) (P<0.05). The multivariate model suggested that, in patients with RNS (+)/EMG (-), the ratio of upper limb onset to lower limb onset was 1.04, while that of upper limb onset to bulbar onset was 2.02, and that of lower limb onset to bulbar onset was 1.94. The ratio of non-definite ALS to definite ALS was 1.13. The ALSFRS-R score, BMI, and FVC had a protective contribution to the electrophysiological function of the motor neurons. The ratio of the effect size of the ALSFRS-R or BMI to that of FVC was 3.37 and 1.14, respectively. Conclusions: Patients with ALS that were 3 Hz RNS (+) on the accessory nerve and EMG (-) on the ipsilateral sternocleidomastoid had a smaller decremental range of the compound muscle action potential amplitude, and a higher proportion of upper limb onset and non-definite ALS. A higher ALSFRS-R score, BMI, and FVC have a protective effect to the electrophysiological function of motor neurons. The effect size of the ALSFRS-R score is the largest, followed by BMI and FVC.

Fu's subcutaneous needling promotes axonal regeneration and remyelination by inhibiting inflammation and endoplasmic reticulum stress

Fu's subcutaneous needling (FSN) is a traditional Chinese acupuncture procedure used to treat pain-related neurological disorders. Moreover, the regulation of inflammatory cytokines may provide a favorable environment for peripheral nerve regeneration. In light of this, FSN may be an important novel therapeutic strategy to alleviate pain associated with peripheral neuropathy; however, the underlying molecular mechanisms remain unclear. This study revealed that patients who had osteoarthritis with peripheral neuropathic pain significantly recovered after 1 to 2 weeks of FSN treatment according to the visual analog scale, Western Ontario and McMaster Universities Osteoarthritis Index, Lequesne index, walking speed, and passive range of motion. Similarly, we demonstrated that FSN treatment in an animal model of chronic constriction injury (CCI) significantly improved sciatic nerve pain using paw withdrawal thresholds, sciatic functional index scores, and compound muscle action potential amplitude tests. In addition, transmission electron microscopy images of sciatic nerve tissue showed that FSN effectively reduced axonal swelling, abnormal myelin sheaths, and the number of organelle vacuoles in CCI-induced animals. Mechanistically, RNA sequencing and gene set enrichment analysis revealed significantly reduced inflammatory pathways, neurotransmitters, and endoplasmic reticulum stress pathways and increased nerve regeneration factors in the FSN+CCI group, compared with that in the CCI group. Finally, immunohistochemistry, immunoblotting and enzyme-linked immunosorbent assay showed similar results in the dorsal root ganglia and sciatic nerve. Our findings suggest that FSN can effectively ameliorate peripheral neuropathic pain by regulate inflammation and endoplasmic reticulum stress, thereby determine its beneficial application in patients with peripheral nerve injuries.

CLINICAL AND INSTRUMENTAL PREDICTORS OF THE EFFICIENCY OF CONSERVATIVE AND OPERATIVE TREATMENT OF MEDIAN NERVE NEUROPATHY IN THE CARPAL TUNNEL

Introduction. Clinical and instrumental predictors of the efficiency of conservative and surgical treatment of median nerve neuropathy in the carpal tunnel still remain a topical issue. Aim. To identify clinical and instrumental predictors of clinical outcomes and patients’ satisfaction after conservative and surgical treatment of carpal tunnel syndrome. Materials and methods. Analysis of clinical outcomes and patients’ satisfaction in 93 cases with carpal tunnel syndrome: the first group included 49 patients (68 wrists) after conservative and the second group included 44 patients (50 wrists) after surgical treatment. To identify predictors of the efficiency of treatment, analyzed the following clinical-instrumental values: patients’ age, duration of the disease, discriminative sensation, pain intensity according to VAS, values of DASH, BCTQ, CTS scales, clinical stage by Hi-Ob scale, electromyography severity grade according to Bland J.D., nerve conduction study and sonography results. Results. The nerve conduction study and clinical examinations data (discriminative sensation, clinical stage, duration of the disease, BCTQ and DASH values) show reliable effects on clinical outcomes and patients’ satisfaction after conservative treatment. The sensory nerve action potential amplitude and electromyography severity grade have the highest prognostic accuracy (91.4% and 84.5% respectively) for poor (unsatisfactory) result. For surgical treatment, identified results of nerve conduction study, sonography, and patients' age show reliable effects on clinical outcomes and patients’ satisfaction. The values of the highest prognostic accuracy for poor (unsatisfactory) result were nerve deformity index established by sonography (77.8%) and thenar compound muscle action potential amplitude – by nerve conduction study (78.7%). Conclusions. We identified clinical-instrumental predictors of clinical outcomes and patients’ satisfaction after conservative and surgical treatment of carpal tunnel syndrome. Specific results of instrumental examination demonstrated excellent diagnostic quality and the highest prognostic accuracy.