Motor Action Potentials Research Articles

Demyelinating neuropathy requires differential diagnosis with vasculitic neuropathy in rheumatoid arthritis: Significance of sural nerve electrophysiology findings

AbstractObjectivesNeuropathy is considered a complication of rheumatoid arthritis (RA), whose underlying mechanisms are mainly entrapment, drug‐induced and rheumatoid vasculitis (RV). At Tokyo Women's Medical University, for the purpose of diagnosing vasculitic neuropathy, we carried out nerve and muscle biopsies in nine RA patients. Unexpectedly, we found three cases of demyelinating neuropathy, together with six cases of RV. Our aim was to investigate the neurophysiological features of demyelinating neuropathy in patients with RA, compared with those of patients with RV.MethodsWe reviewed the pathological, clinical and electrophysiological findings in patients with RA who underwent nerve and muscle biopsies. We compared patient demographics and nerve conduction study findings between patients with RV and other patients.ResultsThe histological findings showed necrotizing vasculitis in six of nine patients. Vasculitis was absent in the other three patients, which showed evidence of demyelination and remyelination. The absence of a sensory nerve action potential and compound motor action potential were observed more frequently in the RV cohort. Sural sparing, shown as the sural‐to‐median sensory nerve action potential ratio, was significantly higher in demyelinating neuropathy patients. Treatment was corticosteroid and cyclophosphamide in RV patients, and intravenous immunoglobulin was administered to three demyelinating neuropathy patients. Treatment response was satisfactory in seven of the nine patients.ConclusionDemyelinating neuropathy was found more often in patients with RA neuropathy than expected. Sural nerve sparing, as well as the absence of sensory nerve action potential or compound motor action potential, are useful for the differential diagnosis of demyelinating neuropathy with RV in RA patients with neuropathy.

Effect of Two Different Rehabilitation Approaches on Pulmonary Functional Tests, Neuromuscular Functions and Quality of Life in Juvenile Myasthenia Gravis: A Randomized Controlled Trial Study.

Background and Objectives: Children with juvenile myasthenia gravis have a variety of symptoms, ranging from isolated intermittent ocular complaints to overall muscle weakness with or without respiratory insufficiency. This study aimed to investigate the efficacy of a specialized physical therapy with or without partial body weight supported treadmill training on pulmonary functional tests, neuromuscular functions, and quality of life. Materials and Methods: Thirty children, ranging in age from 13 to 16 years, were distributed randomly into two study groups (A or B). Both groups underwent a designed physical therapy program. In addition, group A underwent the partial body weight supported treadmill training. The treatment was conducted three times a week for 12 weeks successively. Pulmonary functional tests (FVC, FEV1, PEFR, and MVV), neuromuscular function tests (compound motor action potential, isometric muscle force of biceps brachii and rectus femoris, balance, walking endurance, and fatigue), and quality of life were measured before and after 12 successive weeks. Results: A significant improvement in all investigated variables were recorded in both groups in favor of group A. Conclusions: Both a specialized physical therapy and partial body weight supported treadmill training are effective in terms of enhancing pulmonary functional tests, neuromuscular functions, and quality of life. Partial body weight supported treadmill training is an excellent adjunctive to the physical therapy program.

Diaphragmatic CMAP Monitoring During Cryoballoon Procedures: Surface vs. Hepatic Recording Comparison and Limitations of This Approach.

BackgroundCompound motor action potential (CMAP) monitoring is a common method used to prevent right phrenic nerve palsy during cryoballoon ablation for atrial fibrillation.ObjectiveWe compared recordings simultaneously obtained with surface and hepatic electrodes.MethodsWe included 114 consecutive patients (mean age 61.7 ± 10.9 years) admitted to our department for cryoballoon ablation. CMAP was monitored simultaneously with a hepatic catheter and a modified lead I ECG, whilst right phrenic nerve was paced before (stage 1) and during (stage 2) the right-sided freezes. If phrenic threat was detected with hepatic recordings (CMAP amplitude drop >30%) the application was discontinued with forced deflation.ResultsThe ratio of CMAP/QRS was 4.63 (2.67–9.46) for hepatic and 0.76 (0.55–1.14) for surface (p < 0.0001). Signal coefficients of variation during stage 1 were 3.92% (2.48–6.74) and 4.10% (2.85–5.96) (p = 0.2177), respectively. Uninterpretable signals were more frequent on surface (median 10 vs. 0; p < 0.0001). For the 14 phrenic threats, the CMAP amplitude dropped by 35.61 ± 8.27% on hepatic signal and by 33.42 ± 11.58% concomitantly on surface (p = 0.5417). Our main limitation was to achieve to obtain stable phrenic capture (57%). CMAP monitoring was not reliable because of pacing instability in 15 patients (13.16%). A palsy occurred in 4 patients (3.51%) because cryoapplication was halted too late.ConclusionBoth methods are feasible with the same signal stability and amplitude drop precocity during phrenic threats. Clarity and legibility are significantly better with hepatic recording (sharper signals, less far-field QRS). The two main limitations were pacing instability and delay between 30% CMAP decrease and cryoapplication discontinuation.

Anisotropic Ion Conducting Particulate Composites for Bioelectronics.

Acquisition, processing, and manipulation of biological signals require transistor circuits capable of ion to electron conversion. However, use of this class of transistors in integrated sensors or circuits is limited due to difficulty in patterning biocompatible electrolytes for independent operation of transistors. It is hypothesized that it would be possible to eliminate the need for electrolyte patterning by enabling directional ion conduction as a property of the material serving as electrolyte. Here, the anisotropic ion conductor (AIC) is developed as a soft, biocompatible composite material comprised of ion‐conducting particles and an insulating polymer. AIC displays strongly anisotropic ion conduction with vertical conduction comparable to isotropic electrolytes over extended time periods. AIC allows effective hydration of conducting polymers to establish volumetric capacitance, which is critical for the operation of electrochemical transistors. AIC enables dense patterning of transistors with minimal leakage using simple solution‐based deposition techniques. Lastly, AIC can be utilized as a dry, anisotropic interface with human skin that is capable of non‐invasive acquisition of individual motor action potentials. The properties of AIC position it to enable implementation of a wide range of large‐scale organic bioelectronics and enhance their translation to human health applications.

Regenerative peripheral nerve interfaces (RPNIs): current status and future direction

Despite significant advancements in neuroprosthetic control strategies, current peripheral nerve interfacing techniques are limited in their ability to facilitate accurate and reliable long-term control. The regenerative peripheral nerve interface (RPNI) is a biologically stable bioamplifier of efferent motor action potentials with demonstrated long-term stability. This innovative, straightforward, and reproducible surgical technique has shown enormous potential in improving prosthetic control for individuals with upper limb amputations. The RPNI consists of an autologous free muscle graft secured around the end of a transected peripheral nerve or individual fascicles within a residual limb. This construct facilitates EMG signal transduction from the residual peripheral nerve to a neuroprosthetic device using indwelling bipolar electrodes on the muscle surface. This review article focuses on the development of the RPNI and its use for intuitive and enhanced prosthetic control and sensory feedback. In addition, this article also highlights the use of RPNIs for the prevention and treatment of postamputation pain.

Polyneuropathy In Obstructive Sleep Apnea Patients

Aim: Hypoxemia due to obstructive sleep apnea (OSA) is thought to cause peripheral nerve damage. A case-control study was conducted to test the accuracy of this phenomenon. Material and Methods: The patient group consisted of 45 patients with OSA who had an apnea-hypopnea index (AHI) score of &gt;10 and were newly diagnosed with OSA and control group consisted of 37 individuals who did not have OSA. Sensory and motor nerve conduction investigations were performed on both the upper and right lower extremity Mann-Whitney U, chi square and independent sample T tests were carried out. Results: Both groups had the same average age of 46. The mean body mass index (BMI) in patients with OSA was 31.81; the average AHI was 55.17; the periodic leg movements in sleep (PLMS) was 30.71; the T90 value was 74.23; the lowest saturation was 37; the average saturation value was 72.97. The other nerves' sensory and motor distal latency lengths were more prolonged than the control group, except the ulnar nerve. The averages of the left median, ulnar, and right peroneal motor nerves’ compound motor action potential (CMAP) amplitude were lower in individuals with OSA than in the control group. Compared to the control group, patients with OSA had slower right tibial nerve motor conduction velocity. The mean snap amplitude of bilateral median and left ulnar sensory nerve were higher in patients with OSA. Conclusion: OSA-induced hypoxia may have an impact on peripheral nerve damage.

Safety and efficacy of an injectable nerve-specific hydrogel in a rodent crush injury model.

While the peripheral nervous system has the inherent ability to recover following injury, results are often unsatisfactory, resulting in permanent functional deficits and disability. Therefore, methods that enhance regeneration are of significant interest. The present study investigates an injectable nerve-tissue-specific hydrogel as a biomaterial for nerve regeneration in a rat nerve crush model. Nerve-specific hydrogels were injected into the subepineurial space in both uninjured and crushed sciatic nerves of rats to assess safety and efficacy, respectively. The animals were followed longitudinally for 12 wk using sciatic functional index and kinematic measures. At 12 wk, electrophysiologic examination was also performed, followed by nerve and muscle histologic assessment. When the hydrogel was injected into an uninjured nerve, no differences in sciatic functional index, kinematic function, or axon counts were observed. A slight reduction in muscle fiber diameter was observed in the hydrogel-injected animals, but overall muscle area and kinematic function were not affected. Hydrogel injection following nerve crush injury resulted in multiple modest improvements in sciatic functional index and kinematic function with an earlier return to normal function observed in the hydrogel treated animals as compared to untreated controls. While no improvements in supramaximal compound motor action potential were observed in hydrogel treated animals, increased axon counts were observed on histologic assessment. These improvements in functional and histologic outcomes in a rapidly and fully recovering model suggest that injection of a nerve-specific hydrogel is safe and has the potential to improve outcomes following nerve injury.

Amyotrophic lateral sclerosis mimicking radiculopathy: a case series.

ABSTRACTThe clinical findings of early stage amyotrophic lateral sclerosis (ALS) are similar to those of cervical or lumbar radiculopathy. In the current study, we describe 3 cases of ALS that were misdiagnosed as cervical or lumbar radiculopathy. Three patients (a 48-, a 52-, and an 80-year-old) visited our clinic due to motor weakness on either the upper or lower extremities. At other clinics or hospitals, they were diagnosed with radiculopathy due to herniated lumbar disc or cervical foraminal stenosis. The motor weakness in these patients was ipsilateral or bilateral but dominant on one side. Sensory deficits or bulbar symptoms were not observed. Of the 3 patients, 2 had neuropathic pain, but it was not dermatome related. We conducted an electrodiagnostic test and observed a low amplitude of compound motor action potential on the affected nerve and positive sharp waves on muscles of involved segments, including thoracic paraspinalis. All the patients were diagnosed with probable laboratory-supported ALS or possible ALS based on the established diagnostic criteria (El Escorial Criteria). In the present study, we showed three cases of ALS that were misdiagnosed as radiculopathy. Our study would be helpful for early and accurate diagnosis of patients with ALS.

Evaluation of Relationship Between Laboratory, Electrodiagnostic, and Functional Parameters in Patients With Amyotrophic Lateral Sclerosis; A Cross Sectional Study

Background: Amyotrophic lateral sclerosis (ALS) is an adult-onset motor neuron disease which leads to limb and/or bulbar muscle degeneration with a poor prognosis. Several demographic and biological factors have prognostic importance, but little data exist on the relationship between clinical, electrodiagnostic, and laboratory markers as predictors of disease progression. We aimed to assess the relationships between different aspects of clinical, electrodiagnostic, and laboratory features of ALS patients with their level of functioning. Methods: We included 27 patients with ALS who were diagnosed within two years before enrolment. Clinical assessment and electrodiagnostic studies were done by a neurology resident. The motor unit number index (MUNIX) and compound motor action potential (CMAP) were used as measures of motor unit loss. Serum creatinine, urea, Albumin, and creatine kinase were measured as laboratory markers. We used the Persian version of ALS functional rating scale (ALS-FRS) as the main outcome measure. Data were analyzed using the SPSS software. Pearson's correlation coefficient was calculated to test for correlations. Results: None of the demographic or laboratory parameters correlated with ALS-FRS. Patients with the onset of disease in the limbs had a higher MUNIX score compared to patients with a bulbar onset. Also, increased body mass index was associated with lower CMAP and MUNIX scores (p-value:0.02). Higher serum creatinine levels were significantly associated with higher lower limb MUNIX (p value:0.04). Higher lower limb MUNIX was in turn associated with higher lower limb functional score (ALS-FRS). Conclusion: Decreased serum creatinine may possibly be an indicator of lower limb motor unit loss in patients with ALS. Also, MUNIX scores may be used as surrogates for ALS-FRS in ALS trials. Further research is needed to elucidate the clinical application of these findings.Methods: We included 27 patients with ALS who were diagnosed within two years before enrolment. Clinical assessment and electrodiagnostic studies were done by a neurology resident. The motor unit number index (MUNIX) and compound motor action potential (CMAP) were used as measures of motor unit loss. Serum creatinine, urea, Albumin, and creatine kinase were measured as laboratory markers. We used the Persian version of ALS functional rating scale (ALS-FRS) as the main outcome measure. Data were analyzed using the SPSS software. Pearson's correlation coefficient was calculated to test for correlations. Results: None of the demographic or laboratory parameters correlated with ALS-FRS. Patients with the onset of disease in the limbs had a higher MUNIX score compared to patients with a bulbar onset. Also, increased body mass index was associated with lower CMAP and MUNIX scores (p-value:0.02). Higher serum creatinine levels were significantly associated with higher lower limb MUNIX (p value:0.04). Higher lower limb MUNIX was in turn associated with higher lower limb functional score (ALS-FRS). Conclusion: Decreased serum creatinine may possibly be an indicator of lower limb motor unit loss in patients with ALS. Also, MUNIX scores may be used as surrogates for ALS-FRS in ALS trials. Further research is needed to elucidate the clinical application of these findings.

Acellular nerve graft enriched with mesenchymal stem cells in the transfer of the phrenic nerve to the musculocutaneous nerve in a C5-C6 brachial plexus avulsion in a rat model.

Phrenic nerve transfer has been shown to achieve good nerve regeneration in brachial plexus avulsion. Acellular nerve allografts (ANAs) showed inferior results to autografts, which is why its use with mesenchymal stem cells (MSCs) is currently being studied. The aim is to study the effect of BM-MSCs associated with ANAs in a rat model of phrenic nerve transfer to the musculocutaneous nerve in a C5-C6 avulsion. 42 Wistar-Lewis rats underwent a C5-C6 lesion in the right forelimb by excising a 3 mm segment from both roots, followed by a phrenic nerve transfer to the musculocutaneous nerve associated with the interposition of a three types of nerve graft (randomly distributed): control (autograft) group (n=12), ANAs group (n=12), and ANAs + BM-MSCs group (n=18) After 12 weeks, amplitude and latency of the NAP and the compound motor action potential (CMAP) were measured. Biceps muscles were studied by histological analysis and nerve grafts by electron microscopy and fluorescence analysis. Statistically significant reductions were found in latency of the CMAP between groups control (2.48 ± 0.47 ms) and experimental (ANAs: 4.38 ± 0.78 ms, ANAs + BM-MSCs: 4.08 ± 0.85 ms) and increases in the amplitude of the CMAP between groups control (0.04388 ± 0.02 V) and ANAs + BM-MSCs (0.02275 ± 0.02 V), as well as in the thickness of the myelin sheath between groups control (0.81 ± 0.07 μm) and experimental (ANAs: 0.72 ± 0.08 μm, ANAs + BM-MSCs: 0.72 ± 0.07 μm) and in the area of the myelin sheath between groups control (13.09 ± 2.67 μm2 ) and ANAs (10.01 ± 2.97 μm2 ) (p < .05). No statistically significant differences have been found between groups ANAs and ANAs + BM-MSCs. This study presents a model for the study of lesions of the upper trunk and validates the autologous graft as the gold standard.

Physiologic signaling and viability of the muscle cuff regenerative peripheral nerve interface (MC-RPNI) for intact peripheral nerves

Background. Robotic exoskeleton devices have become a promising modality for restoration of extremity function in individuals with limb loss or functional weakness. However, there exists no consistent or reliable way to record efferent motor action potentials from intact peripheral nerves to control device movement. Peripheral nerve motor action potentials are similar in amplitude to that of background noise, producing an unfavorable signal-to-noise ratio (SNR) that makes these signals difficult to detect and interpret. To address this issue, we have developed the muscle cuff regenerative peripheral nerve interface (MC-RPNI), a construct consisting of a free skeletal muscle graft wrapped circumferentially around an intact peripheral nerve. Over time, the muscle graft regenerates, and the intact nerve undergoes collateral axonal sprouting to reinnervate the muscle. The MC-RPNI amplifies efferent motor action potentials by several magnitudes, thereby increasing the SNR, allowing for higher fidelity signaling and detection of motor intention. The goal of this study was to characterize the signaling capabilities and viability of the MC-RPNI over time. Methods. Thirty-seven rats were randomly assigned to one of five experimental groups (Groups A–E). For MC-RPNI animals, their contralateral extensor digitorum longus (EDL) muscle was harvested and trimmed to either 8 mm (Group A) or 13 mm (Group B) in length, wrapped circumferentially around the intact ipsilateral common peroneal (CP) nerve, secured, and allowed to heal for 3 months. Additionally, one 8 mm (Group C) and one 13 mm (Group D) length group had an epineurial window created in the CP nerve immediately preceding MC-RPNI creation. Group E consisted of sham surgery animals. At 3 months, electrophysiologic analyses were conducted to determine the signaling capabilities of the MC-RPNI. Additionally, electromyography and isometric force analyses were performed on the CP-innervated EDL to determine the effects of the MC-RPNI on end organ function. Following evaluation, the CP nerve, MC-RPNI, and ipsilateral EDL muscle were harvested for histomorphometric analysis. Results. Study endpoint analysis was performed at 3 months post-surgery. All rats displayed visible muscle contractions in both the MC-RPNI and EDL following proximal CP nerve stimulation. Compound muscle action potentials were recorded from the MC-RPNI following proximal CP nerve stimulation and ranged from 3.67 ± 0.58 mV to 6.04 ± 1.01 mV, providing efferent motor action potential amplification of 10–20 times that of a normal physiologic nerve action potential. Maximum tetanic isometric force (F o) testing of the distally-innervated EDL muscle in MC-RPNI groups produced F o (2341 ± 114 mN–2832 ± 102 mN) similar to controls (2497 ± 122 mN), thus demonstrating that creation of MC-RPNIs did not adversely impact the function of the distally-innervated EDL muscle. Overall, comparison between all MC-RPNI sub-groups did not reveal any statistically significant differences in signaling capabilities or negative effects on distal-innervated muscle function as compared to the control group. Conclusions. MC-RPNIs have the capability to provide efferent motor action potential amplification from intact nerves without adversely impacting distal muscle function. Neither the size of the muscle graft nor the presence of an epineurial window in the nerve had any significant impact on the ability of the MC-RPNI to amplify efferent motor action potentials from intact nerves. These results support the potential for the MC-RPNI to serve as a biologic nerve interface to control advanced exoskeleton devices.

P-NE003. Frequency of carpal tunnel syndrome in patients having diabetes mellitus with neuropathy in a tertiary care hospital

Introduction. Carpal tunnel syndrome (CTS) is one of the most frequent entrapment neuropathies of the upper limb. Carpal tunnel syndrome (CTS) and diabetic polyneuropathy (DPN) are common conditions in patients with diabetes and therefore frequently occur concomitantly. Diagnosis of CTS in patients with DPN is important, as therapeutic interventions directed toward relief of CTS may be effective irrespective of diffuse neuropathy. Methods. This study was a hospital based descriptive cross sectional study done in BIRDEM general hospital between July, 2015 and June, 2016, for a period of twelve months. The initial clinical diagnosis of DPN was made and was confirmed by doing nerve conduction study. After having informed written consents, a standard preformed questionnaire was filled up for each case. Results. A total of 354 cases were finally analyzed with 153 (43.2%) patients being symptomatic and among those 54 (58.7%) had electrophysiology proven CTS. It was observed that 26.0% of patients established as having DPN also had CTS. The frequency of CTS among those with symptoms was significantly higher than in asymptomatic participants. Majority (38.4%) of patients belonged to the age group of 51-60 years. The mean age was found to be 55.99 ± 9.25 years with a range from 28 to 80 years. Among all cases of electrophysiology proven CTS (92 patients), females (53.3%) numbered greater in comparison to males (46.7%). Study subjects with CTS had significantly higher BMI, higher fasting blood sugar and higher HbA1c in comparison to patients without CTS. The mean compound motor action potential was not significantly different between patients with and without CTS. Conclusion. Given the high prevalence of CTS in subjects with DPN, it is recommended that therapeutic decisions should be made carefully after nerve conduction study and proper diagnosis.

Extensor digitorum brevis bulk and associations with fibular motor nerve conduction amplitude.

Prior work demonstrates that fibular compound motor action potential (CMAP) amplitude <4.0 mV predicts impairment of ankle proprioceptive precision and increased fall risk. Extensor digitorum brevis (EDB) inspection may present a simple clinical surrogate for CMAP amplitude. (1) To estimate the inter-rater reliability of assessment of EDB bulk. (2) To determine whether inspection of EDB bulk is associated with fibular CMAP amplitude. Prospective inter-rater reliability study. Academic center outpatient Physical Medicine & Rehabilitation electromyography (EMG) clinics. Fifty-two adult participants (102 feet). (1) Inter-rater reliability of assessment of EDB bulk. (2) Mean fibular CMAP amplitude. (3) A binary measure of fibular CMAP amplitude at/above or below a 4.0mV threshold. Inter-rater reliability of EDB bulk grading was moderate (kappa: 0.65 [95% confidence interval (CI) 0.48-0.82]). The mean CMAP value was 5.9 ± 2.2mV when bulk was normal, 3.4 ± 2.1mV when diminished, and 0.6 ± 0.9mV when atrophied. A multivariable analysis demonstrated that EDB bulk, distal symmetric polyneuropathy (DSP), and lumbar radiculopathy were all associated with CMAP amplitude. The sensitivity and specificity of grading muscle bulk as normal versus abnormal in detecting CMAP amplitude above or below 4.0mV were 0.86 (95% CI 0.78-0.94) and 0.71 (95% CI 0.54-0.88), respectively. An atrophied EDB was a highly specific indicator that CMAP amplitude was abnormal (<4.0mV) in 100% of cases (8/8). EDB bulk was associated with fibular CMAP amplitude. Atrophy was a highly specific indicator for CMAP amplitude below 4.0mV. Evaluation of EDB bulk may represent a quick and easy clinical surrogate marker for CMAP amplitude and distal neuromuscular impairment.

Can Foraminal Stenosis Due to Lumbar Isthmic Spondylolisthesis Cause Axonopathy in the Lower Extremity?

This study aimed to investigate, using electrodiagnosis, whether foraminal stenosis due to isthmic spondylolisthesis (IS) causes peripheral nerve axonopathy. We retrospectively reviewed the medical records of the Yeungnam University Hospital and included 46 patients (mean age = 60.8 ± 13.7 years; male:female = 24:22) with foraminal stenosis due to IS. We classified foraminal stenosis grading based on T2 and T1 sagittal spinal magnetic resonance imaging (MRI). Patients were divided into mild (n = 18) and severe foraminal stenosis (n = 28) groups. To evaluate axonopathy in the lower extremity, results of compound motor action potential (CMAP) of the extensor digitorum brevis muscle (EDB) and abductor hallucis brevis muscle (AHB), and sensory nerve action potential (SNAP) of the sural nerve were retrieved. No statistically significant difference was observed in the amplitude of CMAP of the EDB and AHB and SNAP of the sural nerve with the severity of foraminal stenosis. However, age showed a statistically significant relationship with the amplitude of NCS in the EDB, AHB, and sural nerves (p < 0.001). The severity of foraminal stenosis due to IS showed no relationship with axonopathy beyond age-related degeneration of the lower extremities. Therefore, if there is robust axonopathy in lower extremities, physicians should consider pathologies other than foraminal stenosis due to IS.

Long-term course of phrenic nerve injury after cryoballoon ablation of atrial fibrillation

While phrenic nerve palsy (PNP) due to cryoballoon pulmonary vein isolation (PVI) of atrial fibrillation (AF) was transient in most cases, no studies have reported the results of the long-term follow-up of PNP. This study aimed to summarize details and the results of long-term follow-up of PNP after cryoballoon ablation. A total of 511 consecutive AF patients who underwent cryoballoon ablation was included. During right-side PVI, the diaphragmatic compound motor action potential (CMAP) was reduced in 46 (9.0%) patients and PNP occurred in 29 (5.7%) patients (during right-superior PVI in 20 patients and right-inferior PVI in 9 patients). PNP occurred despite the absence of CMAP reduction in 0.6%. The PV anatomy, freezing parameters and the operator’s proficiency were not predictors of PNP. While PNP during RSPVI persisted more than 4 years in 3 (0.6%) patients, all PNP occurred during RIPVI recovered until one year after the ablation. However, there was no significant difference in the recovery duration from PNP between PNP during RSPVI and RIPVI. PNP occurred during cryoballoon ablation in 5.7%. While most patients recovered from PNP within one year after the ablation, PNP during RSPVI persisted more than 4 years in 0.6% of patients.

Diffusion Tensor Imaging of the Sciatic Nerve as a Surrogate Marker for Nerve Functionality of the Upper and Lower Limb in Patients With Diabetes and Prediabetes.

BackgroundNerve damage in diabetic neuropathy (DN) is assumed to begin in the distal legs with a subsequent progression to hands and arms at later stages. In contrast, recent studies have found that lower limb nerve lesions in DN predominate at the proximal sciatic nerve and that, in the upper limb, nerve functions can be impaired at early stages of DN.Materials and MethodsIn this prospective, single-center cross-sectional study, participants underwent diffusion-weighted 3 Tesla magnetic resonance neurography in order to calculate the sciatic nerve’s fractional anisotropy (FA), a surrogate parameter for structural nerve integrity. Results were correlated with clinical and electrophysiological assessments of the lower limb and an examination of hand function derived from the Purdue Pegboard Test.ResultsOverall, 71 patients with diabetes, 11 patients with prediabetes and 25 age-matched control subjects took part in this study. In patients with diabetes, the sciatic nerve’s FA showed positive correlations with tibial and peroneal nerve conduction velocities (r = 0.62; p < 0.001 and r = 0.56; p < 0.001, respectively), and tibial and peroneal nerve compound motor action potentials (r = 0.62; p < 0.001 and r = 0.63; p < 0.001, respectively). Moreover, the sciatic nerve’s FA was correlated with the Pegboard Test results in patients with diabetes (r = 0.52; p < 0.001), prediabetes (r = 0.76; p < 0.001) and in controls (r = 0.79; p = 0.007).ConclusionThis study is the first to show that the sciatic nerve’s FA is a surrogate marker for functional and electrophysiological parameters of both upper and lower limbs in patients with diabetes and prediabetes, suggesting that nerve damage in these patients is not restricted to the level of the symptomatic limbs but rather affects the entire peripheral nervous system.

Motor unit number index (MUNIX) in children and adults with 5q-spinal muscular atrophy: Variability and clinical correlations

Spinal muscular atrophy (SMA) is a motor neuron disease associated with progressive muscle weakness and motor disability. The motor unit number index (MUNIX) is a biomarker used to assess loss of motor units in later-onset SMA patients. Twenty SMA patients (SMA types 3 and 4), aged between 7 and 41 years, were clinically evaluated through the Hammersmith Motor Functional Scale Expanded and the Spinal Muscular Atrophy-Functional Rating Scale. The patients underwent compound motor action potential (CMAP) and MUNIX studies of the right abductor pollicis brevis, abductor digiti minimi and tibialis anterior (TA) muscles. Age-matched healthy controls (n = 20) were enrolled to obtain normative CMAP and MUNIX values from the same muscles. Compared to healthy controls, SMA patients showed significant reductions in MUNIX values among all muscles studied, whereas CMAP showed reductions only in the weaker muscles (abductor digiti minimi and TA). MUNIX variability was significantly higher in the SMA group than in the control group. MUNIX variability in TA correlated with CMAP variability. Motor functional scores correlated with TA MUNIX. The MUNIX study is feasible in later-onset SMA patients, and TA MUNIX values correlate with disease severity in patients with mild motor impairment.

Findings of Electrodiagnostic Studies in Moderate to Severe Lumbar Central Spinal Stenosis—Electrodiagnostic Studies in Lumbar Central Spinal Stenosis

Purpose: The purpose of this study was to investigate the findings of electrodiagnostic studies (nerve conduction study (NCS) and electromyography (EMG)) in patients with moderate and severe lumbar central spinal stenosis (LCSS). Methods: We retrospectively reviewed the medical records of Ulsan University Hospital and identified 32 consecutive patients (mean age = 66.9 ± 7.4 years; male:female = 8:24) with LCSS. Based on the results of T2 axial magnetic resonance imaging at the level of L4–5, patients were categorized as having severe (n = 14) or moderate LCSS (n = 18). Results from NCS and EMG were retrieved. Additionally, we included 15 age- and sex-matched volunteers without LCSS (mean age = 65.2 ± 8.0 years; male:female = 4:11) to serve as a control group. Results of NCS and EMG were compared between the three groups. Results: We found that, compared to normal subjects, patients with moderate or severe LCSS presented significantly lower distal amplitudes of the compound motor action potential of both peroneal and tibial nerves. Regarding EMG, positive sharp waves and fibrillation potentials were exclusively observed in patients with severe LCSS group (28.6%). Conclusion: Electrodiagnostic studies were significantly altered in patients with moderate and severe LCSS. Our results may be helpful to diagnose LCSS-induced radiculopathy and to differentiate it from other causes of peripheral nerve pathologies.

CMAP changes upon symptom onset and during treatment in spinal muscular atrophy patients: lessons learned from newborn screening

PurposeEarly identification and treatment of spinal muscular atrophy (SMA) are crucial but difficult. In this study, we aimed to assess the significance of compound motor action potential (CMAP) amplitude in patients identified through a newborn screening program. MethodsWe initiated a large-scale population newborn screening program for SMA in Taiwan in 2014. Patients had access to treatment through clinical trials or expanded use programs. Symptomatic patients were evaluated regularly, including CMAP exams. ResultsAmong 364,000 screened newborns, 21 were diagnosed with SMA. The incidence of SMA was around 1 in 17,000 live births, and 70% developed SMA type 1. All infants with two SMN2 copies became symptomatic before the age of 1 month. CMAP amplitudes of 12 newborns were available, including 6 who were subsequently treated with nusinersen. We found that a rapid decrease of CMAP amplitude was an early predictor of symptom onset. Pretreatment CMAP and rapid increment of post-treatment CMAP could predict better treatment outcomes. ConclusionThis study prospectively demonstrated the incidence of SMA and its types. Our results imply the importance of pretreatment CMAP amplitude and rapid reversal of post-treatment CMAP amplitude with regard to disease presentation and also treatment outcomes.

Chemotherapy-induced peripheral neuropathy: longitudinal analysis of predictors for postural control

Impaired postural control is often observed in response to neurotoxic chemotherapy. However, potential explanatory factors other than chemotherapy-induced peripheral neuropathy (CIPN) have not been adequately considered to date due to primarily cross-sectional study designs. Our objective was to comprehensively analyze postural control during and after neurotoxic chemotherapy, and to identify potential CIPN-independent predictors for its impairment. Postural control and CIPN symptoms (EORTC QLQ-CIPN20) were longitudinally assessed before, during and three weeks after neurotoxic chemotherapy, and in three and six months follow-up examinations (N = 54). The influence of peripheral nerve function as determined by nerve conduction studies (NCS: compound motor action potentials (CMAP) and sensory action potentials (SNAP)), physical activity, and muscle strength on the change in postural control during and after chemotherapy was analyzed by multiple linear regression adjusted for age and body mass index. Postural control, CIPN signs/symptoms, and CMAP/SNAP amplitudes significantly deteriorated during chemotherapy (p < .01). During follow-up, patients recovered from postural instabilities (p < .01), whereas CIPN signs/symptoms and pathologic NCS findings persisted compared to baseline (p < .001). The regression model showed that low CMAP and high SNAP amplitudes at baseline predicted impairment of postural control during but not after chemotherapy. Hence, pre-therapeutically disturbed somatosensory inputs may induce adaptive processes that have compensatory effects and allow recovery of postural control while CIPN signs/symptoms and pathologic peripheral nerve function persist. Baseline NCS findings in cancer patients who receive neurotoxic chemotherapy thus might assist in delineating individual CIPN risk profiles more precisely to which specific exercise intervention programs could be tailor-made.