Reference values for nerve conduction studies of the peroneal, tibial, and sural nerve derived from a large population-based cohort: Associations with demographic and anthropometric characteristics-The Maastricht study

INTRODUCTION/AIMS

Nerve conduction studies (NCSs) are widely used to support the clinical diagnosis of neuromuscular disorders. The aims of this study were to obtain reference values for peroneal, tibial, and sural NCSs and to examine the associations with demographic and anthropometric factors.

METHODS

In 5099 participants (aged 40-79 years) without type 2 diabetes of The Maastricht Study, NCSs of peroneal, tibial, and sural nerves were performed. Values for compound muscle action potential (CMAP) and sensory nerve action potential amplitude, nerve conduction velocity (NCV), and distal latency were acquired. The association of age, sex, body mass index (BMI), and height with NCS values was determined using uni- and multivariate linear regression analyses.

RESULTS

Detailed reference values are reported per decade for men and women. Significantly lower NCVs and longer distal latencies were observed in all nerves in older and taller individuals as well as in men. In these groups, amplitudes of the tibial and sural nerves were significantly lower, whereas a lower peroneal nerve CMAP was only significantly associated with age. BMI showed a multidirectional association. After correction for anthropometric factors in the multivariate analysis, the association between sex and NCS values was less straightforward.

DISCUSSION

These values from a population-based dataset could be used as a reference for generating normative values. Our findings show the association of NCS values with anthropometric factors. In clinical practice, these factors can be considered when interpreting NCS values.

Early Neurophysiological Abnormalities in Suspected Acute Canine Polyradiculoneuropathy

Acute canine polyradiculoneuritis (ACP) is a common peripheral neuropathy in dogs, and is generally self-limiting and benign. Electrodiagnostic (EDX) tests are typically performed after 7-10 days. Delaying the definitive diagnosis may hamper the treatment of other causes of acute weakness, which may require specific treatments and may carry different prognoses. This retrospective multicenter study aims to assess whether EDX performed within the first 6 days of clinical signs onset can detect alterations indicative of ACP, and aims to characterize the most prevalent alterations. A total of 71 dogs with suspected ACP were retrospectively analyzed and classified into two groups based on EDX timing: early group (EG, 1-6 days after symptom onset) and late group (LG, 7-15 days after symptom onset). In our study, no significant differences were found between the two groups in motor nerve conduction studies (MNCSs) and F-wave analysis, indicating that EDX is able to demonstrate abnormalities even in the first 6 days from onset. Although the LG showed significantly greater degrees of electromyographic (EMG) alterations compared to the EG, frequent muscle alterations were still observed in the EG group. These findings support the use of EDX in patients with suspected ACP within the first 6 days from the clinical onset. Prompt neurophysiological examinations for suspected ACP patients can be performed effectively and can help allow for early diagnosis and facilitate appropriate treatment.

Visual evoked potential in generalized joint hypermobility: A case-control study

INTRODUCTION

Generalized joint hypermobility (GJH) can be the result of several hereditary connective tissue disorders, especially Ehlers-Danlos syndrome. Cerebrovascular manifestations are among the most common complications in this disorder, and understanding their extent can help better diagnosis and prevention of hazardous events. We investigated visual evoked potential (VEP) changes in patients with GJH and compared them with healthy individuals.

METHODS

Our case-control study included 90 patients who fulfilled the Beighton score (B score) for joint hypermobility and other 90 healthy participants. All of them went under VEP study, and the amplitude and latency of the evoked potential (P100) were compared to each other.

RESULTS

The Case group had significantly higher B score (7.18 ± 0.967 vs. 1.18 ± 0.712), P100 latency (110.23 ± 6.64 ms vs. 100.18 ± 4.273 ms), and amplitude (6.54 ± 1.26 mv vs. 6.50 ± 1.29 mv) compared with the Control group, but the difference was only significant regarding B score, and P100 latency (p-value <.0001). Moreover, both latency and amplitude of P100 had significantly positive correlations with the B score in the Case group (p-value <.0001), but such correlations were not found in the Control group (p-value = .059).

CONCLUSION

Our study could reveal VEP changes, especially significant P100 latency in GJH patients without previous neurologic or musculoskeletal disorders. Whether these changes are due to GJH itself or are predictive of inevitable neurologic disease or visual pathway involvement, particularly Multiple Sclerosis needs further investigation with longer follow-up periods.

Serum SARM1 Levels and Diabetic Peripheral Neuropathy in Type 2 Diabetes: Correlation with Clinical Neuropathy Scales and Nerve Conduction Studies and Impact of COVID-19 vaccination

Patients with peripheral neuropathy with type 2 diabetes mellitus (T2DM) are more likely to have functional impairments. Recently, the gene for serum sterile alpha and toll/interleukin receptor motif-containing protein 1 (SARM1), which may contribute to the pathogenesis of Wallerian degeneration, was discovered in mice models of peripheral neuropathy. We set out to assess serum SARM1's activity as a potential biomarker for the early identification of diabetic peripheral neuropathy in T2DM patients while also examining the impact of the COVID-19 vaccine on SARM1 levels. We assessed the cross-sectional relationships between the SARM1 biomarker, clinical neuropathy scales, and nerve conduction parameters in 80 participants aged between 30 years and 60 years. The analysis was carried out after the patients were split into two groups since we discovered a significant increase in SARM1 levels following the second dose of the COVID-19 vaccination, where group A received one dose of the COVID-19 vaccine inoculation, and group B received two doses of the COVID-19 vaccine. SARM1 was correlated significantly (p < 0.05) with MNSIe and NSS in group A and showed a consistent positive correlation with the other neuropathy clinical scales in group A and group B without reaching statistical significance. Additionally, SARM1 was negatively correlated significantly (p < 0.05) with the median sensory amplitude in group A and showed a consistent negative correlation with the six other sensory and motor nerves' potential amplitude in group A and group B without reaching statistical significance. In conclusion, SARM1 showed a consistent correlation with clinical neuropathy scales and nerve conduction parameters after accounting for the influence of COVID-19 vaccination doses.

Efficacy of focused shockwave therapy in patients with moderate-to-severe carpal tunnel syndrome: a preliminary study

OBJECTIVE

To evaluate the efficacy of focused extracorporeal shockwave therapy for symptoms and function in patients with moderate-to-severe carpal tunnel syndrome.

DESIGN

A single-blind randomized controlled trial.

SUBJECTS

Twenty-four outpatients with moderate-to-severe carpal tunnel syndrome.

METHODS

Patients were randomly allocated into 2 groups: a focused extracorporeal shockwave therapy group and a control group. The focused extracorporeal shockwave therapy group received conservative treatment in addition to focused extracorporeal shockwave therapy with an energy flux density ranging from 0.01 to 0.15 mJ/mm2, a frequency of 4-5 Hz, and 1500 pulses per session once a week for a total of 3 sessions. The control group received only conservative treatment, which comprised gliding exercises for carpal tunnel syndrome, a night wrist splint, and lifestyle modification. The Thai version of the Boston Carpal Tunnel Questionnaire (T-BCTQ), a nerve conduction study, and ultrasonography of the median nerve cross-sectional area were performed before treatment and at 3 and 6 weeks after baseline.

RESULTS

The T-BCTQ symptom and function scores had significantly decreased in both groups, favouring focused extracorporeal shockwave therapy at all time-points. In addition, distal sensory and motor latency were significantly different between the groups at 3 weeks from baseline.

CONCLUSION

Focused extracorporeal shockwave therapy plus conservative treatment effectively provided short-term improvement in symptoms, hand function, and nerve conduction in patients with moderate-to-severe carpal tunnel syndrome compared with conservative treatment alone.

Provocative changes in nerve conductions: Fact or fiction?

At times electrodiagnostic medical consultants (EMCs) are asked to perform studies in both a neutral position, and then again after the patient is in a provocative position that exacerbates symptoms, to assess for measurable electrophysiologic changes. While this approach might seem initially appealing, particularly when standard studies are not effective at diagnosis, empiric studies in several conditions have been unimpressive. Studies in median neuropathy at the wrist, thoracic outlet syndrome, piriformis syndrome, and radial tunnel syndrome have failed to demonstrate reproducible changes in nerve conduction studies in positions that exacerbate symptoms. Furthermore, there is lack of a plausible pathophysiologic mechanism for producing both measurable and rapidly reversible electrophysiologic changes after just a few minutes, or less, of compression. Axon loss and demyelination would not be rapidly reversible, and positional changes of 2 min or less (the durations generally studied) would be insufficient to produce measurable nerve ischemia. Last, we have gained a greater appreciation for how much nerves move within limbs with changes in joint position; this movement can lead to misleading changes in nerve conduction studies. It is thus appropriate to conclude that testing nerve conduction in provocative or symptomatic positions adds no value to electrodiagnostic testing.

Occupational and non-occupational risk factors correlating with the severity of clinical manifestations of carpal tunnel syndrome and related work disability among workers who work with a computer

The contribution of certain occupational and personal factors to the development of carpal tunnel syndrome (CTS) is still uncertain. We investigated which specific occupational and non-occupational factors correlate with the level of clinical manifestations and work disability related to CTS. The study included 190 workers who work with a computer and have diagnosed CTS (100 men, 90 women, aged 20-65 years). Subjective experience of CTS-related impairments was assessed with the Symptom Severity Scale (SSS) and the Functional Status Scale (FSS) of the Boston Carpal Tunnel Syndrome Questionnaire (BCTQ). The objective, neural impairments were tested with electrodiagnostics (EDX), whereas CTS-related work disability data were collected from medical records. We found a high inter-correlation between BCTQ, EDX, and work disability data. These also showed high correlations with certain occupational factors (duration of computer-working in months and hours spent daily in computer-working, certain ergonomic, microclimatic, and other occupational conditions) and non-occupational factors (demographic and lifestyle factors: nutritional status, diet, smoking, alcohol consumption, and physical activity). Despite its limitations, our study has identified occupational and non-occupational risk factors that can aggravate CTS and work disability, but which can also be improved with workplace and lifestyle preventive and corrective measures. More research is needed, though, to establish the possible causal relationships and the independent influence of each of those risk factors.

Protective vs. Therapeutic Effects of Mitochondria-Targeted Antioxidant MitoTEMPO on Rat Sciatic Nerve Crush Injury: A Comprehensive Electrophysiological Analysis

Protective vs. Therapeutic Effects of Mitochondria-Targeted Antioxidant MitoTEMPO on Rat Sciatic Nerve Crush Injury: A Comprehensive Electrophysiological Analysis. Peripheral nerve injuries often result in long-lasting functional deficits, prompting the need for effective interventions. MitoTEMPO (2-(2,2,6,6-tetramethylpiperidin-1-oxyl-4-ylamino)-2-oxoethyl) triphenylphosphonium chloride) is a mitochondria-targeted antioxidant that has shown protective and therapeutic effects against pathologies associated with reactive oxygen species. This study explores the utilization of MitoTEMPO as a therapeutic and protective agent for sciatic nerve crush injuries. By employing advanced mathematical approaches, the study seeks to comprehensively analyze nerve conduction parameters, nerve excitability, and the distribution of nerve conduction velocities to gauge the potential. Forty Wistar-Albino rats were randomly divided into following groups: (I) SHAM-animals subjected to sham operation and treated intraperitoneally (i.p.) with vehicle (bidistilled water) for 14 days; (II) CI (crush injury)-animals subjected to CI and treated with vehicle 14 days; (III) MiP-animals subjected to 7 days i.p. MitoTEMPO treatment before CI (0.7 mg/kg/day dissolved in vehicle) and, only vehicle for 7 days after CI, protective MitoTEMPO; and (IV) MiT-animals i.p. treated with only vehicle for 7 days before CI and 7 days with MitoTEMPO (0.7 mg/kg/day dissolved in vehicle) after CI, therapeutic MitoTEMPO. Nerve excitability parameters were measured, including rheobase and chronaxie, along with compound action potential (CAP) recordings. Advanced mathematical analyses were applied to CAP recordings to determine nerve conduction velocities and distribution patterns. The study revealed significant differences in nerve excitability parameters between groups. Nerve conduction velocity was notably reduced in the MiP and CI groups, whereas CAP area values were diminished in the MiP and CI groups compared to the MiT group. Furthermore, CAP velocity was lower in the MiP and CI groups, and maximum depolarization values were markedly lower in the MiP and CI groups compared to the SHAM group. The distribution of nerve conduction velocities indicated alterations in the composition of nerve fiber groups following crush injuries. In conclusion, postoperative MitoTEMPO administration demonstrated promising results in mitigating the detrimental effects of nerve crush injuries.

Evaluation of the serum level of estrogen, progesterone, prolactin, and testosterone in patients with trigeminal neuralgia compared to a healthy population

OBJECTIVES

The goal of this study is to measure and compare the hormonal serum levels (estrogen, progesterone, testosterone, prolactin, dihydrotestosterone [DHT]) in trigeminal neuroglia (TN) menopausal women and healthy women.

MATERIALS AND METHODS

This cross-sectional and case-control study was performed in 2018 and 2019. For this study, menopausal women with confirmed TN were enrolled. Twenty-two healthy women in the control group and 19 in the case group participated. Blood samples were taken from participants for assessment of hormonal serum levels (estrogen, progesterone, testosterone, prolactin, DHT). Data were analyzed by SPSS version 18. Mann-Whitney, T-test, kormography test, nonmetric, χ2  test, and odds ratios have been used.

RESULTS

In patients with TN, the serum level of testosterone was significantly higher (p = .036), and the serum level of prolactin (p = .016) was significantly lower. Other evaluated hormones' serum level was identical in the two groups. Patients with abnormal estrogen levels were more in the TN group in comparison with the healthy group. The abnormality of progesterone in TN patients was more in comparison to the healthy control group.

CONCLUSIONS

Estrogen and progesterone serum levels in TN patients are higher in comparison with the healthy group, while prolactin and testosterone serum levels are lower in the control group. Moreover, the DHE serum level is similar in both groups.

Broad-spectrum neuroprotection exerted by DDD-028 in a mouse model of chemotherapy-induced neuropathy

ABSTRACT

Neurotoxicity of chemotherapeutics involves peculiar alterations in the structure and function, including abnormal nerve signal transmission, of both the peripheral and central nervous system. The lack of effective pharmacological approaches to prevent chemotherapy-induced neurotoxicity necessitates the identification of innovative therapies. Recent evidence suggests that repeated treatment with the pentacyclic pyridoindole derivative DDD-028 can exert both pain-relieving and glial modulatory effects in mice with paclitaxel-induced neuropathy. This work is aimed at assessing whether DDD-028 is a disease-modifying agent by protecting the peripheral nervous tissues from chemotherapy-induced damage. Neuropathy was induced in animals by paclitaxel injection (2.0 mg kg -1 i.p). DDD-028 (10 mg kg -1 ) and the reference drug, pregabalin (30 mg kg -1 ), were administered per os daily starting concomitantly with the first injection of paclitaxel and continuing 10 days after the end of paclitaxel treatment. The behavioural tests confirmed the antihyperalgesic efficacy of DDD-028 on paclitaxel-induced neuropathic pain. Furthermore, the electrophysiological analysis revealed the capacity of DDD-028 to restore near-normal sensory nerve conduction in paclitaxel-treated animals. Histopathology evidence indicated that DDD-028 was able to counteract effectively paclitaxel-induced peripheral neurotoxicity by protecting against the loss of intraepidermal nerve fibers, restoring physiological levels of neurofilament in nerve tissue and plasma, and preventing morphological alterations occurring in the sciatic nerves and dorsal root ganglia. Overall, DDD-028 is more effective than pregabalin in preventing chemotherapy-induced neurotoxicity. Thus, based on its potent antihyperalgesic and neuroprotective efficacy, DDD-028 seems to be a viable prophylactic medication to limit the development of neuropathies consequent to chemotherapy.

Mouse models of human CNTNAP1-associated congenital hypomyelinating neuropathy and genetic restoration of murine neurological deficits

The Contactin-associated protein 1 (Cntnap1) mouse mutants fail to establish proper axonal domains in myelinated axons. Human CNTNAP1 mutations are linked to hypomyelinating neuropathy-3, which causes severe neurological deficits. To understand the human neuropathology and to model human CNTNAP1C323R and CNTNAP1R764C mutations, we generated Cntnap1C324R and Cntnap1R765C mouse mutants, respectively. Both Cntnap1 mutants show weight loss, reduced nerve conduction, and progressive motor dysfunction. The paranodal ultrastructure shows everted myelin loops and the absence of axo-glial junctions. Biochemical analysis reveals that these Cntnap1 mutant proteins are nearly undetectable in the paranodes, have reduced surface expression and stability, and are retained in the neuronal soma. Postnatal transgenic expression of Cntnap1 in the mutant backgrounds rescues the phenotypes and restores the organization of axonal domains with improved motor function. This study uncovers the mechanistic impact of two human CNTNAP1 mutations in a mouse model and provides proof of concept for gene therapy for CNTNAP1 patients.

Neuropathy in multiple sclerosis patients treated with teriflunomide

OBJECTIVE

Teriflunomide is an oral medication approved for the treatment of patients with multiple sclerosis. The primary effect of teriflunomide is to reduce de novo pyrimidine synthesis by inhibiting mitochondrial dihydroorotate dehydrogenase, thereby causing cell-cycle arrest. We aimed to investigate the occurrence of peripheral neuropathy, a rare side effect of teriflunomide, in patients receiving teriflunomide.

METHODS

Multiple sclerosis patients receiving teriflunomide (n=42) or other disease modifying therapies (n=18) and healthy controls (n=25) were enrolled in this cross-sectional study between January 2020 and 2021. The mean duration of teriflunomide treatment was 26 months (ranging from 6 to 54 months). All participants underwent neurological examination and nerve conduction studies of tibial, peroneal, sural, superficial peroneal, median, and ulnar nerves by using surface recording bar and bipolar stimulating electrodes.

RESULTS

The mean superficial peroneal nerve distal latency and conduction velocity were significantly slower, and the mean superficial peroneal nerve action potential amplitude was lower in patients using teriflunomide (2.50 ms, p<0.001; 47.35 m/s, p=0.030; and 11.05 μV, p<0.001, respectively). The mean peroneal motor nerve distal latency was significantly longer and amplitude was lower in teriflunomide patients (3.68 ms, p<0.001, and 5.25 mV, p=0.009, respectively). During the study period, treatment switching to another disease-modifying therapy was planned in 10 patients, and all neuropathic complaints were reversed after switching.

CONCLUSION

Teriflunomide has the potential to cause peripheral neuropathy. The awareness of peripheral neuropathy, questioning the symptoms, and if suspected, evaluation with electromyography and switching the therapy in patients under teriflunomide treatment are crucial.

Immune-mediated polyneuropathy in cats: Clinical description, electrodiagnostic assessment, and treatment

BACKGROUND

Suspected immune-mediated polyneuropathy has been increasingly reported in cats, especially in the last decade, but the condition remains poorly understood.

OBJECTIVES

Refine the clinical description and review the classification of this condition based on electrodiagnostic investigation and evaluate the benefit of corticosteroid treatment and L-carnitine supplementation.

ANIMALS

Fifty-five cats presented with signs of muscular weakness and electrodiagnostic findings consistent with polyneuropathy of unknown origin.

METHODS

Retrospective, multicenter study. Data from the medical records were reviewed. The owners were contacted by phone for follow-up at the time of the study.

RESULTS

The male-to-female ratio was 2.2. The median age of onset was 10 months, with 91% of affected cats being <3 years of age. Fourteen breeds were represented in the study. The electrodiagnostic findings supported purely motor axonal polyneuropathy. Histological findings from nerve biopsies were consistent with immune-mediated neuropathy in 87% of the tested cats. The overall prognosis for recovery was good to excellent, as all but 1 cat achieved clinical recovery, with 12% having mild sequelae and 28% having multiple episodes during their lifetime. The outcome was similar in cats with no treatment when compared with cats receiving corticosteroids or L-carnitine supplementation.

CONCLUSIONS AND CLINICAL IMPORTANCE

Immune-mediated motor axonal polyneuropathy should be considered in young cats with muscle weakness. This condition may be similar to acute motor axonal neuropathy in Guillain-Barré syndrome patients. Based on our results, diagnostic criteria have been proposed.

Role of Nerve Conduction Studies in Hansen's Disease

Background and Objective

To report the role of nerve conduction study (NCS) in diagnosis, monitoring, and prognosis of Hansen's disease (HD).

Materials and Methods

In a hospital-based prospecive observational study, the patients with HD as per World Health Organization (WHO) criteria were included; muscle wasting power, reflexes, and sensations were recorded. Motor NCS of median, ulnar, and peroneal nerves and sensory NCS of ulnar, median, and sural nerves were recorded. Disability was graded using WHO grading scale. The outcome was assessed after 6 months using modified Rankin scale.

Results

In the present study, 38 patients with a median age of 40 (15-80) years and five females were included. The diagnosis was tuberculoid in seven, borderline tuberculoid in 23, borderline lepromatous in two, and borderline in six patients. The disability was grade 1 and 2 in 19 patients each. Out of 480 nerves studied, NCS was normal in 139 sensory (57.4%) and 160 (67.2%) motor nerves. NCSs were axonal in seven sensory and eight motor nerves, demyelinating in three nerves, and mixed in one in seven patients who had lepra reaction. NCS findings did not correlate with disability (p = 1.0) or outcome (0.304) and provided additional information in 11 nerves (seven patients). Peripheral nerves were enlarged in 79. NCSs were normal in 32 (29.90%) in thickened nerves.

Conclusion

In HD, NCS abnormalities correlated with respective sensory or motor abnormality but related with neither disability nor the outcome.

The Effects of a 10-Week Aerobic and Unilateral Lower Extremity Resistance Training Program on Amplitude and Nerve Conduction Velocity of Sensory and Motor Nerves in Diabetic Patients with Neuropathy

This study aimed to investigate the effects of 10-week aerobic and unilateral lower extremity resistance training on nerve conduction velocity and amplitude of sensory and motor nerves in diabetic patients with neuropathy. This clinical trial was conducted on twenty women and men (aged 30-60 years old) with diabetic neuropathy. Participants were randomly assigned to one of the two groups: an exercise group (EG; n = 10) and a control group (CG; n = 10). The EG performed a 10-week programme with one session of aerobic exercises (40% to 70% of HR reserve), supplemented with one session of specific lower extremity resistance exercises (60-90 min/day) on the same day for four days per week. The CG subjects performed their regular daily activities. The nerve conduction velocity, amplitude of sensory and motor nerves and glycosylated haemoglobin A1c were measured before and after the intervention. The repeated-measures ANOVA showed a significant increase in the conduction velocity of the sural sensory nerve as well as the peroneal motor nerve (p < 0.01, p < 0.01). The changes in the conduction velocity of the tibial nerve were similar when compared to the control group (p > 0.05). A significantly greater decrease in glycosylated haemoglobin was also observed in the EG group (p < 0.01). Performing 10 weeks of aerobic and specific unilateral lower extremity exercises can improve the function of sensory and motor nerves and improve symptoms in diabetic patients with neuropathy. Given the limited studies in this area, the exact mechanisms of this performance improvement need further examination.

Shear-wave elastography evaluation of thenar muscle in carpal tunnel syndrome

PURPOSE

We aim to evaluate the shear wave velocity (SWV) of the thenar muscle as an adjunct diagnostic tool for carpal tunnel syndrome (CTS).

METHODS

Ninety-two wrists with CTS and 30 control wrists without CTS underwent ultrasonographic evaluation of thenar muscle and median nerve including shear-wave elastography. Cross sectional area (CSA) of medial nerve and SWV of thenar muscle and median nerve were evaluated. CTS patients were assessed for Boston CTS, Padua CTS, modified Hirani grading scores, and nerve conduction study (NCS). SWVs, CSA, and NCS parameters were compared between two groups.

RESULTS

The SWVs of thenar muscle and median nerve (p < 0.001, respectively), and CSA of median nerve (p < 0.001) were more significantly greater in patients with CTS than in controls. The SWV of median nerve was moderately correlated with CSA of median nerve (r = 0.35, p < 0.001) and modified Hirani CTS score (r = 0.35, p < 0.001). The SWV of thenar muscle was inversely correlated with modified Hirani CTS score (r = -0.21, p = 0.04).

CONCLUSION

The SWV of thenar muscle and median nerve of CTS were significantly increased compared to that of control, and significantly negatively correlated with NCS parameters (modified Hirani CTS score). SWVs may be used as an adjunct diagnostic tool for CTS.

Correlation between nerve conduction changes and BETA-2 microglobulin concentration in chronic kidney disease patients on hemodialysis combined with hemodiafiltration online

This study aimed to investigate the correlation between beta-2 microglobulin (B2M) concentration and some nerve conduction indices and evaluate the changes in some nerve conduction indices after treatment with hemodialysis (HD) combined with hemodiafiltration online in end-stage renal disease patients. From July 2021 to July 2022, a cross-sectional study was conducted on 80 end-stage renal disease patients on HD at Can Tho General Hospital, Viet Nam. All the patients had B2M testing and nerve conduction measurements. Patients with nerve conduction disorders were treated and remeasured after 6 months to evaluate the treatment results. At baseline, there was a moderate negative correlation between B2M and the tibial nerve and motor branch of the ulnar conduction velocity (V) (r = -0.305 and -0.315, P < .05). There was a moderate positive correlation between B2M and motor latency of the tibial and peroneal nerve (r = 0.434 and 0.440, P < .05). After 6 months of using the combination of HD and hemodiafiltration online, the V (31.3 ± 7.96 up to 44.88 ± 9.67 m/s) and the amplitude (A) (1.71 ± 1.16 up to 2.61 ± 1.51 mV) of the peroneal nerve increased, the motor latency decreased (8.21 ± 2.65 down to 5.23 ± 3.58 ms). With the tibial nerve, motor conduction V increased from 30.53 ± 8.05 m/s to 43.56 ± 8.99 m/s and the A increased from 5.04 ± 3.16 mV to 7.75 ± 4.45 mV. With the ulnar nerve, the A increased, and motor latency decreased after 6 months. The nerve conduction indices also improved significantly in the median nerve.

Assessment of Nerve Conduction in Patients With Lower Motor Neuron Facial Paralysis

Introduction Bell's palsy (BP), a lower motor neuron facial paralysis, commonly causes dysfunction of muscles of facial expression. Nerve conduction electrodiagnostic studies differentiate early-stage minor conduction blocks from later-stage Wallerian degeneration. Nerve conduction studies (NCSs) assess facial nerve function by delivering supramaximal electrical stimulus at the stylomastoid foramen. The amplitude loss percentage of the affected side is calculated with reference to the normal side. Aim The study's aim was to characterize the ncs in BP cases and to evaluate the correlation between the Compound Muscle Action Potential (CMAP) of the muscles affected. Materials and methods One hundred and four NCS data of BP cases were retrospectively collected over the period of two years. Statistical analyses of variables were done using the Chi-square test, one-way ANOVA, and Pearson correlation coefficient. Result The greater amplitude loss was seen in the orbicularis oris muscle innervated by buccal and mandibular branches of the facial nerve. The bivariate correlation between the Right Nasalis versus Right Orbicularis Oculi and Left Orbicularis Oculi versus Left Nasalis showed a highly significant moderately Strong Positive Correlation with an R-value of 0.687 and 0.558, respectively. The amplitude drop percentage was statistically significant in the affected left and right sides with P values of 0.008 and 0.007 respectively (P value < 0.05). The amplitude drop between the nasalis, orbicularis oculi and orbicularis oris muscles of both sides was statistically significant with a P value of 0.001. Conclusion NCS should be mandatorily included as an assessment protocol in BP cases for quantification of nerve degeneration and as a prognostic tool during the course of treatment.

Facial Paresis After Mandibular Reconstruction

Condylar neck fractures are common injuries that occur in the facial and mandibular regions. The proximity of this area to the vital neurovasculature creates the increased importance of proper surgical intervention to limit damage to the underlying structures. Here, we report a case of a condylar neck fracture that resulted in temporary paresis of the facial nerve. In addition, a review of the literature regarding condylar fracture treatment and its complications was conducted.

Use of Electroneuromyography in the Diagnosis of Neurogenic Thoracic Outlet Syndrome: A Systematic Review and Meta-Analysis

Neurogenic thoracic outlet syndrome (NTOS) is a disabling condition. Its diagnosis remains challenging and is mainly guided by examination. Yet, electrophysiological evaluations are the gold standard for diagnosis of entrapment syndromes. We aimed to assess the interest of electrophysiological evaluation to diagnose NTOS. A systematic literature research was performed using PubMed, ScienceDirect, Embase, Cochrane and Google Scholar databases to collect studies reporting results of electrophysiological assessment of patients with NTOS. Then, a meta-analysis was conducted. Nine studies were eligible and concerned two hundred and thirteen patients. Results were heterogenous among studies and the quality of evidence was very low to moderate. Data could not evaluate sensitivity or specificity of electrophysiological evaluations for NTOS. The meta-analysis found significantly decreased amplitudes of medial antebrachial cutaneous nerve SNAP (sensory nerve action potential), ulnar SNAP, median CMAP (compound motor action potential) and ulnar CMAP. Needle examination found abnormalities for the abductor pollicis brevis, first dorsal interosseous and adductor digiti minimi. Unlike most upper-limb entrapment syndromes, nerve conduction assessment only provided clues in favour of NTOS. Decreased amplitude for ulnar SNAP, medial antebrachial cutaneous SNAP, median CMAP and ulnar CMAP should be assessed, as well as needle examination. Larger studies are needed to evaluate the sensitivity and specificity of electrophysiology in NTOS diagnosis.

Interpreting Electrodiagnostic Studies for the Management of Nerve Injury

Nerve injuries are common after trauma and can be life-altering for patients. Electrodiagnostic studies are the gold standard for diagnosing and prognosticating nerve injuries. However, most surgeons are not trained in the interpretation of these studies; rather, they rely on the interpretation provided by the electrodiagnostician, who in turn is unlikely to be trained in nerve reconstruction. This discrepancy between the interpretation of these studies and the management of nerve injuries can lead to suboptimal surgical planning and patient outcomes. This review aims to provide a framework for surgeons to take a more active role in collaborating with their colleagues in electrodiagnostic medicine in the interpretation of these studies, with an ultimate goal of improved patient care. The basics of nerve conduction studies, electromyography, and relevant terminology are reviewed. The relationship between the concepts of demyelination, axon loss, Wallerian degeneration, nerve regeneration, collateral sprouting, and clinical function are explained within the framework of the Seddon and Sunderland nerve injury classification system. The natural evolution of each degree of nerve injury over time is illustrated, and management strategies are suggested.

Prediction of lower extremity strength by nerve conduction study in cauda equina syndrome

An electrodiagnostic test is more useful than the lower extremity isometric strength test for objectively determining the degree of nerve damage and prognosis in cauda equina syndromes (CES). This study evaluated the correlation between nerve conduction study (NCS) parameters and the lower extremity isometric strength and manual muscle test (MMT) grades. The isometric strengths of knee extension (KE), ankle dorsiflexion (ADF), and ankle plantarflexion (APF) were measured. NCS parameters, MMT, and isometric strength of femoral, peroneal, and tibial nerves were evaluated, including their correlations with each other. A regression equation between the isometric strength and compound muscle action potential (CMAP) amplitudes was derived and cutoff values were used to confirm boundary values of strength and amplitude between the MMT grades. KE isometric strength and femoral nerve CMAP amplitude were significantly correlated (r = 0.738, P < .001). ADF isometric strength and peroneal nerve CMAP amplitude were significantly correlated (tibialis anterior, r = 0.707, P < .001). KE (r = 0.713, P < .001), ADF (r = 0.744, P < .001), and APF (r = 0.698, P < .001) isometric strengths were correlated with the MMT grades. For the regression curve, the second-order curve was more reasonable than the first-order curve. Cutoff femoral nerve CMAP amplitude and isometric strength cutoff values were ≥2.05 mV and 17.3, respectively, for MMT grades 2 to 3 and 2.78 ± 1.08 and 20.8 ± 9.33, respectively, for grade 3. The isometric strengths of the KE, ADF, and APF and the CMAP amplitude of the electrophysiologic parameters were correlated in CES patients and a significant correlation with MMT grade was also identified. Accordingly, it is possible to identify the precise neurological condition, objectively evaluate the degree of paralysis and disability, and determine the quantitative muscle strength from MMT in order to establish an appropriate rehabilitation treatment plan.

Nerve root magnetic stimulation improves locomotor function following spinal cord injury with electrophysiological improvements and cortical synaptic reconstruction

Following a spinal cord injury, there are usually a number of neural pathways that remain intact in the spinal cord. These residual nerve fibers are important, as they could be used to reconstruct the neural circuits that enable motor function. Our group previously designed a novel magnetic stimulation protocol, targeting the motor cortex and the spinal nerve roots, that led to significant improvements in locomotor function in patients with a chronic incomplete spinal cord injury. Here, we investigated how nerve root magnetic stimulation contributes to improved locomotor function using a rat model of spinal cord injury. Rats underwent surgery to clamp the spinal cord at T10; three days later, the rats were treated with repetitive magnetic stimulation (5 Hz, 25 pulses/train, 20 pulse trains) targeting the nerve roots at the L5–L6 vertebrae. The treatment was repeated five times a week over a period of three weeks. We found that the nerve root magnetic stimulation improved the locomotor function and enhanced nerve conduction in the injured spinal cord. In addition, the nerve root magnetic stimulation promoted the recovery of synaptic ultrastructure in the sensorimotor cortex. Overall, the results suggest that nerve root magnetic stimulation may be an effective, noninvasive method for mobilizing the residual spinal cord pathways to promote the recovery of locomotor function.

Longitudinal effects of one-leg standing time on neuropathy outcomes in association with glycemic control in non-elderly patients with type 2 diabetes

Aims/Introduction

Diabetic neuropathy leads to postural instability. This study compared longitudinal changes in neuropathy outcomes relative to long‐term glycemic control in patients aged <60 years with uncontrolled type 2 diabetes with and without a short one‐leg standing time (OLST <60 s).

Materials and Methods

In this retrospective study, 58 hospitalized patients with type 2 diabetes (glycated hemoglobin [HbA1c] >7.0%; aged 17–59 years), who underwent re‐evaluation of neuropathic sensory symptoms, ankle reflexes and nerve conduction attributes, and cardiac autonomic function (R‐R interval), >1 year after discharge were divided into OLST <60 and ≥60 s groups. Patients were followed up every 2–3 months for HbA1c levels for up to 8 years. Neuropathy outcomes relative to OLST and HbA1c levels at baseline and over follow up were compared.

Results

Additional development of sensory symptoms (one patient) and abnormal ankle reflexes (five patients) were identified during follow up, and decreased peripheral and cardiac autonomic function at both baseline and follow up, only in patients with OLST <60 s. Mean HbA1c levels were significantly higher in patients with OLST <60 s versus ≥60 s (7.8 ± 0.9% vs 7.2 ± 1.2%; P = 0.022). Better glycemic control during follow up was associated with better neuropathy outcomes only in patients with OLST ≥60 s.

Conclusion

Non‐elderly type 2 diabetes patients with OLST <60 s and decreased peripheral nerve function at baseline are at increased risk for intractable diabetic neuropathy. Better glycemic control alone might not improve neuropathy outcomes in these patients.

Clinical efficacy and safety of electro-acupuncture combined with beraprost sodium and α-lipoic acid for diabetic peripheral neuropathy

BACKGROUND

The pathogenic triggers of diabetic peripheral neuropathy (DPN) mainly include ischemia and hypoxic factors. The combined use of Chinese and Western medicine may be a new perspective for the treatment of DPN. Accordingly, this study explores the clinical efficacy and safety of electro-acupuncture (EA) combined with beraprost sodium (BPS) and α-lipoic acid (α-LA) in the treatment of patients with DPN.

METHODS

A total of 184 patients with DPN meeting the inclusion criteria were enrolled and divided into electric-acupuncture group (n=54), medication group (n=62) and combination group (n=68), which were treated by EA, BPS+α-LA, and EA+BPS+α-LA, respectively. The three groups were compared with respect to the following factors: clinical efficacy; motor conduction velocities (MCVs) of nervus medianus, nervus peroneus communis and tibial nerve and sensory conduction velocities (SCVs) of nervus medianus, sural nerve and ulnar nerve before and after treatment; the Toronto Clinical Scoring System (TCSS), total symptom score (TSS) and Michigan Diabetes Neuropathy Score (MDNS) before and after treatment; changes of serum homocysteine and cysteine (Cys) levels, oxidative stress indicators and inflammatory factors; incidence of adverse reactions.

RESULTS

The overall response rate of the combination group was higher than that of the electric acupuncture group or the medication group. After treatment, the SCV of nervus medianus, sural nerve and ulnar nerve and the MCV of nervus medianus, nervus peroneus communis and tibial nerve were the highest in the combination group among the three groups (P<0.05). After treatment, the scores of TCSS, TSS and MDNS in the combination group was notably lower than those in the medication group and the electric acupuncture group (P<0.05). The amelioration of inflammatory factors in the combination group were the best among the three groups (P<0.05). The incidence of adverse reactions was lower in the combination group compared with the electric acupuncture group and the medication group (P<0.05).

CONCLUSION

EA combined with BPS and α-LA is effective in the treatment of DPN, which can effectively reduce the levels of serum inflammatory factors in patients, with a lower complication rate and higher safety.

Feasibility of assessing progression of transthyretin amyloid polyneuropathy using nerve conduction studies: Findings from the Transthyretin Amyloidosis Outcomes Survey (THAOS)

Patients with transthyretin amyloid polyneuropathy (ATTR‐PN) show decreased motor and sensory nerve amplitudes and conduction. Electrophysiological changes over time may be sensitive indicators of progression. This analysis from the Transthyretin Amyloidosis Outcomes Survey (THAOS) assessed longitudinal changes in nerve conduction as signals of neurologic disease progression in patients with hereditary ATTR (ATTRv) amyloidosis. Patients with ATTRv in THAOS with recorded nerve conduction values were included (data cut‐off: January 6, 2020); changes in nerve amplitude and velocity over time were assessed. Patients (n = 1389) were 45.0% male; 80.4% were the Val30Met (p.Val50Met) genotype. Mean (SD) age at enrollment was 43.6 (14.5) years; duration of symptoms was 9.3 (6.4) years. Median (10th, 90th percentile) sural nerve amplitude and velocity was 18.0 (4.9, 35.0) μV and 50.7 (41.0, 57.9) m/s; peroneal conduction was 13.0 (4.4, 27.0) μV and 51.0 (41.7, 59.7) m/s, respectively. Median (10th, 90th percentile) percentage change from baseline in sural nerve amplitude was variable, but generally decreased over time from −7.4 (−43.2, 52.4) at year 1 to −14.4 (−76.9, 46.7) at year 8. Percent change from baseline in sural nerve velocity declined similarly: −0.1 (−14.5, 15.3) at year 1 and − 6.4 (−21.3, 10.5) at year 8. The decline was more pronounced in patients with greater disability at baseline. Similar patterns were observed for the peroneal nerve. These data show an association between nerve amplitudes and velocities and disease severity, suggesting progressive deterioration in nerve conduction may be an indicator of ATTRv amyloidosis disease progression.

Experiment for teaching virtual cathode in nerve conduction studies

INTRODUCTION/AIMS

The virtual cathode (VC) is a site near the anode where the nerve can be stimulated. Costimulation of neighboring nerves via the VC can affect recording and interpretation of responses. Hence, it is important to teach trainees the concept of the VC. The VC has been demonstrated previously with subtle changes in response latency, amplitude, and shape. Herein we describe an experiment that simply demonstrates a VC with its effects recognizable by gross changes in waveforms.

METHODS

Compound muscle action potentials of the abductor pollicis brevis were recorded using various placements of the cathode and anode at different stimulus intensity levels. Studies were performed in nine healthy subjects.

RESULTS

Three patterns were observed that demonstrated no stimulation, partial stimulation, and complete nerve stimulation by the VC. Partial stimulation yielded responses with long duration and low amplitude. Response patterns also depended on stimulus strength and proximity of the nerve from the skin surface.

DISCUSSION

This experiment demonstrates that nerve stimulation can occur near the anode when high-intensity stimulus is used. It also illustrates collision of action potentials. This exercise can help trainees understand potential pitfalls in nerve conduction studies, especially at very proximal stimulation sites or when high stimulus intensity is used.

Two-Year Responses of Heart Rate and Heart Rate Variability to First Occupational Lead Exposure

[Figure: see text].

Ensheathment and Myelination of Axons: Evolution of Glial Functions

Myelination of axons provides the structural basis for rapid saltatory impulse propagation along vertebrate fiber tracts, a well-established neurophysiological concept. However, myelinating oligodendrocytes and Schwann cells serve additional functions in neuronal energy metabolism that are remarkably similar to those of axon-ensheathing glial cells in unmyelinated invertebrates. Here we discuss myelin evolution and physiological glial functions, beginning with the role of ensheathing glia in preventing ephaptic coupling, axoglial metabolic support, and eliminating oxidative radicals. In both vertebrates and invertebrates, axoglial interactions are bidirectional, serving to regulate cell fate, nerve conduction, and behavioral performance. One key step in the evolution of compact myelin in the vertebrate lineage was the emergence of the open reading frame for myelin basic protein within another gene. Several other proteins were neofunctionalized as myelin constituents and help maintain a healthy nervous system. Myelination in vertebrates became a major prerequisite of inhabiting new ecological niches.

Posterior interosseous nerve syndrome caused by a ganglion cyst and its surgical release with intraoperative neurophysiological monitoring: A case report

RATIONALE

Intraoperative neurophysiological monitoring (IONM) has been utilized not only for the rapid detection of neural insults during surgeries, but also to verify the neurophysiological integrity of nerve lesions in the surgical field.

PATIENT CONCERNS

A 32-year-old woman presented with a wrist and finger drop that had lasted about 3 months.

DIAGNOSES

The result of the initial electrodiagnostic test was consistent with posterior interosseous nerve (PIN) syndrome. Ultrasonography and magnetic resonance imaging of the proximal forearm showed a cystic mass at the anterolateral aspect of the radial head, which was diagnosed as a ganglion cyst.

INTERVENTIONS

Surgical release of the ganglion cyst with IONM was performed. During the surgery, we induced nerve action potentials and compound motor action potentials across the ganglion cyst, which demonstrated neural continuity.

OUTCOMES

Three months after the surgery, the patient showed partial recovery of wrist and finger extensor muscle power. An electrodiagnostic test conducted 3 months after the surgery showed reinnervation potentials in PIN-innervated muscles.

LESSONS

IONM during peripheral nerve surgeries can support surgical decisions and confirm the location and degree of nerve damage.

Nerve ultrasound studies in POEMS syndrome

INTRODUCTION

The aim of our study was to assess the ultrasonographic features of peripheral nerves in patients with POEMS (polyneuropathy, organomegaly, endocrinopathy, M protein, and skin changes) syndrome.

METHOD

34 POEMS syndrome patients and 26 healthy control (HC) participants were recruited prospectively. Cross-sectional area (CSA) was measured in nerves of limbs, trunks of brachial plexus, and cervical nerve roots RESULTS: The CSAs were mildly enlarged at the arm segment of median nerve, elbow segment of ulnar nerve and upper trunk, moderately enlarged at the forearm segment of both median and ulnar nerve, upper trunk of brachial plexus, and C6, C7 cervical nerve roots, and markedly enlarged at the arm segment of ulnar nerve, middle and lower trunk of brachial plexus, as well as C5 cervical root.

DISCUSSION

The CSAs of upper limb nerves were larger in POEMS syndrome patients than in HCs, and the enlargements were most prominent proximally.

Obturator nerve injury diagnosed by nerve conduction: a case report

The obturator nerve lies deep within the pelvis, and it can be damaged by direct injury during surgery. In this study, nerve conduction was used to confirm an obturator nerve injury in a patient who presented with hip adductor weakness following gynecological surgery for endometrial cancer. A 56-year-old woman complained of weakness in the right adductor muscles after a laparoscopic hysterectomy due to endometrial cancer. Seven days after surgery, the degree of weakness of the right hip adductor was Medical Research Council (MRC) Scale 1; thus, a nerve conduction velocity test was conducted. To obtain the compound muscle action potentials of the obturator nerve, stimulation was performed (1.5 cm inferior and 1.5 cm lateral to the pubic tubercle) with a surface electrical simulator and recording (midpoint of the right medial thigh) of the adductor muscles. The compound muscle action potentials of the right obturator nerve showed lower amplitude (left side: 2.7 mV vs. right side: 0.3 mV) and delayed onset latency (left side: 3.2 ms vs. right side: 2.2 ms). These results indicate a partial right obturator neuropathy. Therefore, nerve conduction could be useful to diagnose an early-stage obturator nerve injury and provide information on the degree of damage.

Patients with Minimal Hepatic Encephalopathy Show Altered Thermal Sensitivity and Autonomic Function

Cirrhotic patients may experience alterations in the peripheral nervous system and in somatosensory perception. Impairment of the somatosensory system could contribute to cognitive and motor alterations characteristic of minimal hepatic encephalopathy (MHE), which affects up to 40% of cirrhotic patients. We assessed the relationship between MHE and alterations in thermal, vibration, and/or heat pain sensitivity in 58 cirrhotic patients (38 without and 20 with MHE according to Psychometric Hepatic Encephalopathy Score) and 39 controls. All participants underwent attention and coordination tests, a nerve conduction study, autonomic function testing, and evaluation of sensory thresholds (vibration, cooling, and heat pain detection) by electromyography and quantitative sensory testing. The detection thresholds for cold and heat pain on the foot were higher in patients with, than those without MHE. This hyposensitivity was correlated with attention deficits. Reaction times in the foot were longer in patients with, than without MHE. Patients with normal sural nerve amplitude showed altered thermal sensitivity and autonomic function, with stronger alterations in patients with, than in those without MHE. MHE patients show a general decrease in cognitive and sensory abilities. Small fibers of the autonomic nervous system and thermal sensitivity are altered early on in MHE, before large sensory fibers. Quantitative sensory testing could be used as a marker of MHE.

Peripheral Nerve Conduction And Sympathetic Skin Response Are Reliable Methods to Detect Diabetic Cardiac Autonomic Neuropathy

AIM

This study aimed to investigate the role of nerve conduction studies (NCS) and sympathetic skin response (SSR) in evaluating diabetic cardiac autonomic neuropathy (DCAN).

METHODS

DCAN was diagnosed using the Ewing test combined with heart rate variability analysis. NCS and SSR were assessed by electrophysiological methods. The association between NCS/SSR and DCAN was assessed via multivariate regression and receiver-operating characteristic analyses.

RESULTS

The amplitude and conduction velocity of the motor/sensory nerve were found to be significantly lower in the DCAN+ group (all P < 0.05). A lower amplitude of peroneal nerve motor fiber was found to be associated with increased odds for DCAN (OR 2.77, P < 0.05). The SSR amplitude was lower while the SSR latency was longer in the DCAN+ group than in the DCAN- group. The receiver-operating characteristic analysis revealed that the optimal cutoff points of upper/lower limb amplitude of SSR to indicate DCAN were 1.40 mV (sensitivity, 61.9%; specificity, 66.3%, P < 0.001) and 0.85 mV (sensitivity, 66.7%; specificity, 68.5%, P < 0.001), respectively. The optimal cutoff points of upper/lower limb latency to indicate DCAN were 1.40 s (sensitivity, 61.9%; specificity, 62%, P < 0.05) and 1.81 s (sensitivity, 69.0%; specificity, 52.2%, P < 0.05), respectively.

CONCLUSIONS

NCS and SSR are reliable methods to detect DCAN. Abnormality in the peroneal nerve (motor nerve) is crucial in predicting DCAN. SSR may help predict DCAN.

Predictive Outcome Modeling of Preoperative Clinical Symptoms and Electrodiagnostic Data in Tarsal Tunnel Surgery

Background  The relationship between tarsal tunnel syndrome (TTS), electrodiagnostic (Edx) findings, and surgical outcome is unknown. Analysis of TTS surgical release outcome patient satisfaction and comparison to Edx nerve conduction studies (NCSs) is important to improve outcome prediction when deciding who would benefit from TTS release. Methods  Retrospective study of 90 patients over 7 years that had tarsal tunnel (TT) release surgery with outcome rating and preoperative tibial NCS. Overall, 64 patients met study inclusion criteria with enough NCS data to be classified into one of the following three groups: (1) probable TTS, (2) peripheral polyneuropathy, or (3) normal. Most patients had preoperative clinical provocative testing including diagnostic tibial nerve injection, tibial Phalen's sign, and/or Tinel's sign and complaints of plantar tibial neuropathic symptoms. Outcome measure was percentage of patient improvement report at surgical follow-up visit. Results  Patient-reported improvement was 92% in the probable TTS group ( n  = 41) and 77% of the non-TTS group ( n  = 23). Multivariate modeling revealed that three out of eight variables predicted improvement from surgical release, NCS consistent with TTS ( p  = 0.04), neuropathic symptoms ( p  = 0.045), and absent Phalen's test ( p  = 0.001). The R 2 was 0.21 which is a robust result for this outcome measurement process. Conclusion  The best predictors of improvement in patients with TTS release were found in patients that had preoperative Edx evidence of tibial neuropathy in the TT and tibial nerve plantar symptoms. Determining what factors predict surgical outcome will require prospective evaluation and evaluation of patients with other nonsurgical modalities.

Neurophysiological and Neuroradiological Changes in Children With Chronic Kidney Disease

Background: Patients with chronic kidney disease (CKD) on maintenance hemodialysis frequently present with neurological complications. These complications include peripheral neuropathy, encephalopathy, and stroke. Objectives: To detect the prevalence of neurological manifestations and complications in children with CKD through neurophysiological and neuro-radiological findings. Methods: The study included 50 patients with CKD admitted to a pediatric nephrology unit. Their history and complete physical and neurological examination findings had been recorded. All patients underwent nerve conduction, electromyography, electroencephalography, and magnetic resonance imaging of the brain. Results: Fifty children of both sexes (23 males and 27 females) with a mean age of (12.08 ± 3.46 year) were studied. Eleven (22%) patients with CKD developed polyneuropathy, mostly of an axonal polyneuropathy pattern, while 39 (78%) of them showed normal electrophysiological studies. No myopathy was detected. Abnormal electroencephalography findings were detected in 18% of patients, mostly generalized and focal (temporal, occipital, and frontal) epileptogenic activity. Abnormal MRI brain findings were detected in 16% of patients, mostly of encephalomalacia. Conclusion: Uremic neuropathy was highly prevalent in children with CKD on maintenance hemodialysis. They developed polyneuropathy, mostly of an axonal polyneuropathy pattern. EEG is a useful method for early recognition of subclinical uremic encephalopathy and/or epileptogenic activity. Early demonstration and management of uremic neurological conditions may decrease the physical disability of CKD patients.

High prevalence of carpal tunnel syndrome in individuals with rare nerve growth factor-beta mutation

In Sweden, a large family with a point mutation in the nerve growth factor-beta gene has previously been identified. The carriers of this mutation have reduced small-fibre density and selective deficits in deep pain and temperature modalities. The clinical findings in this population are described as hereditary sensory and autonomic neuropathy type V. The purpose of the current study was to investigate the prevalence of carpal tunnel syndrome in hereditary sensory and autonomic neuropathy type V based on clinical examinations and electrophysiological measurements. Furthermore, the cross-sectional area of the median nerve at the carpal tunnel inlet was measured with ultrasonography. Out of 52 known individuals heterozygous for the nerve growth factor-beta mutation in Sweden, 23 participated in the current study (12 males, 11 females; mean age 55 years; range 25–86 years). All participants answered a health questionnaire and underwent clinical examination followed by median nerve conduction study in a case–control design, and measurement of the nerve cross-sectional area with ultrasonography. The diagnosis of carpal tunnel syndrome was made based on consensus criteria using patient history and nerve conduction study. The prevalence of carpal tunnel syndrome in the hereditary sensory and autonomic neuropathy group was 35% or 52% depending on whether those individuals who had classic symptoms of carpal tunnel syndrome but negative nerve conduction studies were included or not. Those who had a high likelihood of carpal tunnel syndrome based on classic/probable patient history with positive nerve conduction study had a significantly larger median nerve cross-sectional area than those who had an unlikely patient history with negative nerve conduction study. The prevalence of carpal tunnel syndrome was 10–25 times higher in individuals heterozygous for the nerve growth factor-beta mutation than the general Swedish population. Further studies are needed to better understand the underlying pathophysiological mechanisms.

A clinical study of the association and risk factors for lower limb neuropathy in patients with diabetic retinopathy

Purpose:

Association of peripheral neuropathy with diabetic retinopathy is known but the relationship of preclinical neuropathy with various grades of retinopathy is not well documented. This study evaluated the association of preclinical peripheral neuropathy using nerve conduction studies with various grades of retinopathy.

Methods:

Cases of diabetic retinopathy of various grades but asymptomatic for peripheral neuropathy underwent nerve conduction studies of the lower limbs using Caldwell machine and Sierra wave software. The risk factors for retinopathy and association of neuropathy with various grades of retinopathy were analyzed by bivariate and multivariate regression analysis.

Results:

The overall prevalence of neuropathy was 75.6% (sensory 58.54% and combined motor and sensory 17.1%) with increase in prevalence with increase in severity of retinopathy. Duration was positively associated with neuropathy (OR = 1.13, 95% CI = 1.02–1.24; P = 0.012); moderate nonproliferative diabetic retinopathy (NPDR) (OR = 5.60, P = 0.002), severe and very severe NPDR (OR = 5.8, P = 0.041), and PDR (OR = 16.05, P = 0.000) were significantly at higher risk for having neuropathy as compared to mild NPDR.

Conclusion:

Duration and severity of retinopathy are important risk factors for peripheral neuropathy. There is a high prevalence of peripheral neuropathy among diabetics with retinopathy especially with severe grades, when neuropathy is diagnosed using nerve conduction studies.

Evaluation of persons with suspected lumbosacral and cervical radiculopathy: Electrodiagnostic assessment and implications for treatment and outcomes (Part II)

The electrodiagnostic (EDX) examination with needle electromyography (EMG) is the most important means of testing for radiculopathy. This test has modest sensitivity but high specificity and complements imaging of the spine. In this second of a two-part review, the implications of electrodiagnostic findings for diagnosis and clinical management of persons with radiculopathy are reviewed. An EMG confirmed lumbosacral radiculopathy is associated with better clinical outcomes for persons undergoing aggressive conservative management. A positive EMG test portends a better clinical response to epidural corticosteroid injections. If a person undergoes spine surgery, a positive pre-operative EMG for radiculopathy is also associated with better outcomes.

Evaluation of persons with suspected lumbosacral and cervical radiculopathy: Electrodiagnostic assessment and implications for treatment and outcomes (Part I)

Persons with back, neck, and limb symptoms constitute a major referral population to specialists in electrodiagnostic (EDX) medicine. The evaluation of these patients involves consideration of both the common and less common disorders. The EDX examination with needle electromyography (EMG) is the most important means of testing for radiculopathy. This test has modest sensitivity but high specificity and well complements imaging of the spine. Needle EMG in combination with nerve conduction testing is valuable in excluding entrapment neuropathies and polyneuropathy-conditions that frequently mimic radicular symptoms. In this first of a two-part review, the optimal EDX evaluation of persons with suspected radiculopathy is presented. In part two, the implications of EDX findings for diagnosis and clinical management of persons with radiculopathy are reviewed.

Laboratory Tests for Neuropathies: What to do and to Avoid

OBJECTIVES

laboratory tests for work-up of hereditary and acquired neuropathies of peripheral nerves are frequently uncritically utilized. This overview focuses on the most common laboratory tests and investigations needed for diagnosing PNPs by the general neurologist.

METHOD

Literature search.

RESULTS

laboratory tests recommended for the work-up of hereditary and acquired neuropathies should be chosen according to the individual and family history, clinical presentation, and electrophysiological findings. Laboratory tests should be selected specifically according to the suspected type of neuropathy to avoid unnecessary tests and expenses. Work-up should include as few samples as necessary for uncovering the etiology and should consider the sensitivity/specificity of the tests applied.. Basic screening tests for neuropathies should include a blood cell count, thyroid, renal and liver function tests, blood glucose levels, HbA1c, vitamin-B12, and immunofixation. Other laboratory investigations should be carried out only if a specific phenotype is present or if unexpected changes of the disease course occur. In these cases referral to a neuromuscular center is recommended.

CONCLUSIONS

Laboratory tests are helpful for the diagnosis of acquired and hereditary neuropathies but these tests should be ordered according to the history, clinical presentation and findings on electrophysiological investigations. If basic laboratory parameters fail to uncover the etiology, patients should be referred to a center specialized in neuromuscular disorders.

Inhibition of Fast Nerve Conduction Produced by Analgesics and Analgesic Adjuvants-Possible Involvement in Pain Alleviation

Nociceptive information is transmitted from the periphery to the cerebral cortex mainly by action potential (AP) conduction in nerve fibers and chemical transmission at synapses. Although this nociceptive transmission is largely inhibited at synapses by analgesics and their adjuvants, it is possible that the antinociceptive drugs inhibit nerve AP conduction, contributing to their antinociceptive effects. Many of the drugs are reported to inhibit the nerve conduction of AP and voltage-gated Na⁺ and K⁺ channels involved in its production. Compound action potential (CAP) is a useful measure to know whether drugs act on nerve AP conduction. Clinically-used analgesics and analgesic adjuvants (opioids, non-steroidal anti-inflammatory drugs, ₂-adrenoceptor agonists, antiepileptics, antidepressants and local anesthetics) were found to inhibit fast-conducting CAPs recorded from the frog sciatic nerve by using the air-gap method. Similar actions were produced by antinociceptive plant-derived chemicals. Their inhibitory actions depended on the concentrations and chemical structures of the drugs. This review article will mention the inhibitory actions of the antinociceptive compounds on CAPs in frog and mammalian peripheral (particularly, sciatic) nerves and on voltage-gated Na⁺ and K⁺ channels involved in AP production. Nerve AP conduction inhibition produced by analgesics and analgesic adjuvants is suggested to contribute to at least a part of their antinociceptive effects.

Integrated Chinese and Western Medicine for Acute Guillain-barré Syndrome Treatment

Introduction

Guillain-Barré syndrome (GBS) is a worldwide demyelinating polyradiculopathy and polyneuropathy. Currently, there is no specific drug for GBS, and established treatment is generally based on immune-modulating treatment with plasma exchange or intravenous immunoglobulin in combination with supportive care. This study aimed to investigate the efficiency of integrated Chinese and Western medicine for acute GBS treatment.

Methods

We enrolled 73 subjects, and randomly divided them into two groups: 35 cases in the traditional Chinese medicine (TCM) group, and 28 in the Control group. The Control group was treated with the common Western medicine for one month; and the TCM group was administrated with one month of common treatment combined with TCM medication.

Results

Compared to the controls, TCM significantly enhanced the treatment efficiency in symptom expression, including the TCM syndrome score, the activity of daily living score, Hughes functional score and sensory dysfunction assessment. The total effective rate of the TCM group was 94.29%, significantly better than controls (78.59%). Moreover, TCM provide better improvement in motor nerve conduction functions (distal motor latency and motor conduction velocity) and sensory nerve conduction functions (sensory conduction velocity and sensory nerve action potential) in median nerve, ulnar nerve, and common fibular nerve.

Conclusion

When combined with TCM administration, the GBS treatment could acquire better outcomes.

Medial femoral cutaneous nerve conduction study with distal recording: A novel technique

BACKGROUND

A new technique to obtain the sensory nerve action potential (SNAP) of the medial femoral cutaneous nerve is described.

METHODS

SNAPs were recorded from 104 subjects with a bar recording electrode 10 cm proximal to the patella along an imaginary line drawn between the medial edge of the patella and the femoral pulse below the inguinal ligament. Stimulation was applied 14 cm proximal to the recording point.

RESULTS

There were 104 healthy subjects. Onset latency of the SNAPs was 2.20 ± 0.16 ms (mean ± SD), peak latency was 2.70 ± 0.16 ms, peak-to-peak amplitude was 7.5 ± 3.0 μV, and conduction velocity was 51.5 ± 3.0 m/s. The side-to-side difference in the mean amplitude was 22.27 ± 13.6%.

CONCLUSIONS

This new technique is easy, reliable, and reproducible, and should prove useful for the evaluation of neuropathies of the medial femoral cutaneous nerve.

Kilohertz high-frequency alternating current blocks nerve conduction without causing nerve damage in rats

Background

In recent years, 2-50 kHz high-frequency alternating current has been shown to block nerve conduction mostly based on simulation models or experiments in vitro. This study aimed to assess the nerve block effects and related parameters of kilohertz alternating current in a rat model.

Methods

High-frequency biphasic rectangular stimulus pulse was applied to rat's sciatic nerve in vivo, and its blockade frequency and intensity was studied by recording the changes of compound muscle action potential (CMAP) amplitude and muscle states before and after stimulation. Secondly, diameter and circumference of sciatic nerve was measured at stimulating point by ultrasound. The correlation between stimulus' frequency and the nerve's diameter and circumference was studied. Lastly, we assessed nerve damage causing by high-frequency electrical stimulation by measuring CMAP and nerve conduction velocity (NCV) in the following day and sciatic nerve hematoxylin-eosin staining, both blocked side and contralateral side.

Results

When the current intensity was fixed, the blockade only occurred in a specific frequency range, above or below might have partial block effect. Preliminary statistical results showed that the blocking frequency of high-frequency alternating current was negatively linearly correlated with the circumference of sciatic nerve (P<0.05); HE staining of the sciatic nerve showed no axon and myelin sheath damage on blocked or opposite side, and the CMAP and NCV of the sciatic nerve remeasured in the next day were normal, indicating high-frequency electrical stimulation produced no nerve injury.

Conclusions

High-frequency alternating current stimulation can block nerve conduction without causing nerve damage, and the complete block frequency is negatively linearly correlated with the circumference of sciatic nerve.

Mutations in the Scn8a DIIS4 voltage sensor reveal new distinctions among hypomorphic and null Nav 1.6 sodium channels

Mutations in the voltage-gated sodium channel gene SCN8A cause a broad range of human diseases, including epilepsy, intellectual disability, and ataxia. Here we describe three mouse lines on the C57BL/6J background with novel, overlapping mutations in the Scn8a DIIS4 voltage sensor: an in-frame 9 bp deletion (Δ9), an in-frame 3 bp insertion (∇3) and a 35 bp deletion that results in a frameshift and the generation of a null allele (Δ35). Scn8a ^Δ9/+ and Scn8a ^∇3/+ heterozygous mutants display subtle motor deficits, reduced acoustic startle response, and are resistant to induced seizures, suggesting that these mutations reduce activity of the Scn8a channel protein, Na_v 1.6. Heterozygous Scn8a ^Δ35/+ mutants show no alterations in motor function or acoustic startle response, but are resistant to induced seizures. Homozygous mutants from each line exhibit premature lethality and severe motor impairments, ranging from uncoordinated gait with tremor (Δ9 and ∇3) to loss of hindlimb control (Δ35). Scn8a ^Δ9/Δ9 and Scn8a ^∇3/∇3 homozygous mutants also exhibit impaired nerve conduction velocity, while normal nerve conduction was observed in Scn8a ^Δ35/Δ35 homozygous mice. Our results suggest that hypomorphic mutations that reduce Na_v 1.6 activity will likely result in different clinical phenotypes compared to null alleles. These three mouse lines represent a valuable opportunity to examine the phenotypic impacts of hypomorphic and null Scn8a mutations without the confound of strain-specific differences.

Hypertension Contributes to Neuropathy in Patients With Type 1 Diabetes

BACKGROUND

Diabetic peripheral neuropathy (DPN) can lead to foot ulceration and amputation. There are currently no disease-modifying therapies for DPN. The aim of this study was to determine if hypertension contributes to DPN in patients with type 1 diabetes mellitus (T1DM).

METHODS

Subjects with T1DM (n = 70) and controls (n = 78) underwent a comprehensive assessment of DPN.

RESULTS

Hypertension was present in 40 of 70 T1DM subjects and 20 of 78 controls. Hypertension was associated with abnormal nerve conduction parameters (P = 0.03 to <0.001), increased vibration perception threshold (P = 0.01) and reduced corneal nerve fiber density and length (P = 0.02) in subjects with T1DM. However, after adjusting for confounding factors only tibial compound motor action potential and nerve conduction velocity were associated with hypertension (P = 0.03) and systolic blood pressure (P < 0.01 to <0.0001). Hypertension had no effect on neuropathy in subjects without diabetes.

CONCLUSIONS

This study shows that hypertension is associated with impaired nerve conduction in T1DM. It supports previous small trials showing that angiotensin-converting enzyme inhibitors improve nerve conduction and advocates the need for larger clinical trials with blood pressure lowering agents in DPN.

TRPA1 Activation-Induced Myelin Degradation Plays a Key Role in Motor Dysfunction After Intracerebral Hemorrhage

Intracerebral hemorrhage (ICH) is a devastating disease that is characterized by high morbidity and high mortality. ICH has an annual incidence of 10-30/100,000 people and accounts for approximately 10%-30% of all types of stroke. ICH mostly occurs at the basal ganglia, which is rich in nerve fibers; thus, hemiplegia is quite common in ICH patients with partial sensory disturbance and ectopic blindness. In the clinic, those symptoms are considered to originate from the white matter injury in the area, but the exact mechanisms are unknown, and currently, no effective drug treatments are available to improve the prognosis. Clarifying the mechanisms will contribute to the development of new treatment methods for patients. The transient receptor potential ankyrin 1 (TRPA1) channel is a non-selective cation channel that plays a role in inflammatory pain sensation and nociception and may be a potential regulator in emotion, cognition and social behavior. Here, we report that TRPA1 is involved in myelin damage and oxidative stress injury in a mouse ICH model. Intervention with the TRPA1 channel may be a new method to improve the motor function of patients in the early stage of ICH.

Quantitative muscle ultrasound in upper extremity mononeuropathies

INTRODUCTION

We assessed the potential use of quantitative ultrasound (QUS) in the evaluation hand muscles affected by upper extremity mononeuropathies.

METHODS

The gray scale levels (GSLs) of abductor pollicis brevis (APB), abductor digiti minimi (ADM), and first dorsal interosseous (FDI) of 30 healthy and 30 upper extremity mononeuropathy patients were measured and compared with standard electrophysiological values.

RESULTS

Mean GSL was elevated in 34 APBs of carpal tunnel syndrome patients and 18 FDIs of ulnar neuropathy patients (e.g., FDI mean GSL (interquartile range) 31.5 (27.3~43.8) arbitrary units for patients and 24.0(23.0~29.0) for healthy subjects (P = 0.020)). GSL correlated with motor response amplitudes (Spearman's rho (ρ) = -0.39, P = 0.002 in APB, ρ = -0.72, P = 0.002 in FDI, and ρ = -0.43, P = 0.013 in ADM). The APB GSL correlated with electromyographic severity and disease duration (ρ = 0.46, P < 0.001 and ρ = 0.45, P = 0.003).

CONCLUSIONS

Muscle QUS may serve as a useful tool in upper extremity mononeuropathy evaluation. Further study of this concept is recommended.