Conventional Nerve Conduction Studies Research Articles

Utility of single fibre electromyography (SFEMG)and motor unit number estimation technique (MUNE) in the diagnosis and differentiation of polyneuropathies of different aetiology.

To determine whether single fibre electromyography and motor unit number index can distinguish between axonal and myelin lesions in polyneuropathies. This case-control study was conducted at the Department of Medical Physiology, School of Medicine, University of Duhok, Iraq, and the Neurophysiology Department, Hawler Teaching Hospital, Erbil, Iraq, from January 2021 to March 2022. Group A had patients diagnosed with polyneuropathy regardless of the aetiology, while group B had age-matched healthy controls. Both groups were subjected to single fibre electromyography and motor unit number index as well as conventional nerve conduction study and concentric needle electromyography. Data was analysed using SPSS 26. Of the 140 subjects, 60(43%) were patients in group A; 40(67%) males and 20(33%) females with mean age 55.3±7.2 years. There were 80(57%) controls in group B; 43(54%) females and 37(46%) males with mean age 53.81±7.15. Group A had significantly higher single fibre electromyography jitter, and mean consecutive difference (MCD) values than group B (p<0.05). Group A patients with axonal polyneuropathy had a higher mean jitter (MCD) value (36.476.7ms) than those with demyelinating polyneuropathy (23.262.31 ms) (P <0.05). Patients in group A had a motor unit number index value with a significantly lower mean value (p<0.05) when compared to the controls. Axonal polyneuropathy patients had a lower MUNIX value (99.612.8) than demyelinating polyneuropathy patients (149.845.7) (P< 0.05). Single fibre electromyography and motor unit number index could help differentiate between the pathophysiology of axonal and demyelinating polyneuropathy.

FM latency, FM ratio, F-wave latency versus F-wave index in the diagnosis of diabetic neuropathy

BackgroundDiabetes is one of the most common causes for peripheral neuropathy which warrants early diagnosis and treatment. The conventional nerve conduction studies appear to be normal if few of the nerve roots are escaping the lesion. In view of identifying a better clinical testing method, a late response index comprising most of the parameter of F wave was constructed and compared with the diagnosing ability of other parameters.MethodsThis hospital-based cross-sectional study was conducted among male diabetics aged 30 to 50 years in a tertiary care hospital. Maintaining an ambient temperature of 28 °C and following a supramaximal stimulation of the median nerve of both upper limbs, using a digitalized nerve conduction/electromyography/EP machine, the F-wave tracing was obtained.ResultsThe F-wave index detected a greater number of subjects with diabetic peripheral neuropathy when compared to F-wave mean latency, F M latency and F–M ratio.ConclusionF-wave index can be used as a surrogate electrophysiological study to detect peripheral neuropathy at an early stage and aids in better prognosis.

Motor Nerve Conduction Slowing in Diabetic Distal Symmetrical Polyneuropathy: A Novel Approach (P11-8.011)

<h3>Objective:</h3> To evaluate the use of novel regression equations to investigate the profile of conduction slowing in diabetic distal symmetric polyneuropathy (DSP). <h3>Background:</h3> Conduction slowing beyond what is expected from pure axonal loss have been reported in diabetic DSP and have been attributed to an additional demyelinating component. Conventional nerve conduction studies do not allow for a clear distinction between pure axonal loss and loss of large fibers with contributing demyelination. <h3>Design/Methods:</h3> Electrodiagnostic data from CIDP patients was plotted, transformed and linear regression analysis was performed to create confidence intervals to determine abnormal nerve conduction ranges of distal latency (DL), conduction velocity (CV) and F latency for compound muscle action potential (CMAP). These ranges were then used to evaluate abnormal nerve conduction values in 219 patients with diabetic DSP and 219 non-diabetic axonal DSP. <h3>Results:</h3> The mean CV was significantly slower in diabetic DSP than in non-diabetic DSP groups for all tested nerves. There was a significantly higher number of patients fulfilling the regression equation above criteria in the diabetic group compared to the axonal non-diabetic group (47.0% vs. 23.3%; p &lt; 0.0001). There are significantly more patients with more than 2 motor nerves with CV in the demyelinating range in the diabetic DSP group compared to the axonal non-diabetic group (25.6% vs. 7.8%; p &lt; 0.0001). Furthermore, there are significantly more patients that fulfilled an additional criteria of at least one motor nerve with the corresponding F response in the demyelinating range by AAN criteria in the diabetic DSP group compared to the axonal non-diabetic group (21.0% vs. 4.1%; p &lt; 0.0001). <h3>Conclusions:</h3> Regression analysis identified conduction slowing in diabetic DSP, beyond what is expected from exclusive axonal loss. Combining regression analysis for conduction slowing with adequate clinical evaluation may improve the identification of demyelination in diabetic DSP. <b>Disclosure:</b> Mr. Jaffry has nothing to disclose. Mr. Jaffry has nothing to disclose. Mr. Mandava has nothing to disclose. Miss Shaikh has nothing to disclose. Mr. Trivedi has nothing to disclose. Mr. Ors has nothing to disclose. Ms. Faiz has nothing to disclose. Ankit Pahwa has nothing to disclose. Dr. Patel has nothing to disclose. Abu Nasar, MD has nothing to disclose. Dr. Sander has received personal compensation for serving as an employee of Grifols. Dr. Sander has received personal compensation in the range of $10,000-$49,999 for serving as a Consultant for Grifols. Dr. Sander has received personal compensation in the range of $10,000-$49,999 for serving as an Expert Witness for Law firm. Dr. Souayah has received publishing royalties from a publication relating to health care.

Prospective Assessment of Motor Neurotoxicity and Sarcopenia in CD30+ Lymphoma Patients Treated with Brentuximab Vedotin. Single Center Multidisciplinary Unit Experience

Introduction: Brentuximab Vedotin (BV), a CD30-targeting antibody-drug conjugate, has been increasingly used for the treatment of several CD30+ lymphomas, being BV-induced motor peripheral neurotoxicity (BVIMN) one of the greatest concerns for treating physicians. Patients may develop weakness with hand and foot paresis as most severe manifestation. Risk factors associated with BVIMN are scarcely known. Before treatment, severe muscle mass depletion (sarcopenia) has been associated with increased chemotherapy-related toxicity in several cancer types. To date, the association between BVIMN and sarcopenia is unknown. Aim: to assess in a multidisciplinary approach the BVIN development in CD30+ lymphoma patients treated at our institution and try to identify those risk factors associated with motor BVIMN development. Material and Methods: Since January 2019, adult patients from our institution receiving BV are prospectively evaluated in a multidisciplinary unit including hematologists, neurologists and nutritionists. Patients are assessed periodically before, during and after completion of treatment. Neurological assessment includes the clinical version of the Total Neuropathy Score (TNSc©), including muscle strength, NCI.CTC gradation scale, patient reported outcomes (PROMs), handgrip dynamometry and conventional nerve conduction studies (NCS) at upper and lower extremities. Nutritional assessment includes anthropometry, laboratory parameters, and body composition analysis of the cross-sectional CT o CT-PET scan at the level of the 3rd lumbar vertebra (L3). Skeletal muscle index (SMI), reflecting muscle mass, and skeletal muscle density (SMD), associated with muscle strength, are used to determine sarcopenia. The association between sarcopenia and BVIMN are evaluated. Results: A total of 58 patients were included in the analysis, of which, 62% had Hodgkin lymphoma and 38% had CD30+ T cell lymphomas, including 8 patients with Mycosis Fungoides. The median age at BV-based treatment initiation was 45 years [21-92], with a predominance of men (55.2%). ECOG was 0,1,2 in 59.6%, 29.8% and 10.6% of patients. In 24% and 76% of patients, BV was administered in monotherapy or in combination with chemotherapy, respectively. The mean total dose of BV received was 856.85 +/- 170 mg. At baseline, 45.2% of patients had sarcopenia. Serum albumin was 42 g/L [28-50]. No differences in cumulated received BV dose between patients with or without sarcopenia were identified. At finishing chemotherapy, BVIN was developed in 72.2% patients, mostly of mild severity (66.7%). Rates of sensory BVIN were: 44.4% grade 1, 22.4% grade 2 and 3.7% grade 3. Motor BVIN was observed in one third (27.8%) of patients: 7.4% (grade 1), 14.8% (grade 2) and 5.6% (grade 3). Patients with moderate (> grade 2) motor BVIN were younger (37 vs 59 years old, p=0.04). Baseline sarcopenia was more frequent in the group of patients developing moderate BVIMN (35% vs 6%, p=0.06). No association with baseline demographic, anthropometric characteristics, or handgrip results were identified. Motor neurotoxicity correlated significatively with motor NCS impairment in upper (r= -0.472, p=0.023) and lower (r=-0.331, p=0.07) extremities. Conclusions: Motor neurotoxicity may develop in one third of patients receiving BV alone or in combination. Sarcopenia, which is common (45.2%) in BV candidates, could be associated with a higher risk of developing motor BVIN. Motor severity of BVIN can be objectively assessed with neurophysiological tests.

Serum neurofilament levels correlate with electrodiagnostic evidence of axonal loss in paclitaxel-induced peripheral neurotoxicity.

Paclitaxel-induced peripheral neurotoxicity (PIPN) typically manifests as a predominantly sensory axonopathy. Nerve conduction studies (NCS) represent the gold standard method to quantify axonal impairment in PIPN. Serum neurofilament light chain (sNfL) levels are emerging biomarkers for quantifying axonal damage in peripheral neuropathies. To date, the association between NCS abnormalities and sNfL levels during paclitaxel-based chemotherapy has not been specifically addressed. We prospectively conducted longitudinal measurement of sNfL levels in 27 chemotherapy-naïve breast cancer patients and correlated conventional NCS recordings with sNfL in 22 of them, before (T0) and after (T1) 12 cycles of weekly paclitaxel-based therapy. PIPN was diagnosed in 24/27 patients (88%) after completion of the 12-week paclitaxel-based chemotherapy regimen. Serum NfL levels (pg/mL) were significantly higher at T1 compared to T0 (T0: 18.50 ± 12.88 vs T1: 255.80 ± 194.16; p < 0.001). The increase of sNfL levels at T1 significantly correlated with the decrease or abolishment of amplitudes recorded from the sural nerve (r = 0.620; p = 0.0035), sensory radial (r = 0.613; p = 0.005), sensory ulnar (r = 0.630; p = 0.005), and peroneal motor (r = 0.568; p = 0.024) nerves. sNfL levels proportionally increase during chemotherapy administration and significantly correlate with NCS axonal abnormalities in patients with PIPN. A multimodal testing approach employing both sNfL and NCS might improve the PIPN diagnostic accuracy.

A new method to quantify innervation of the ulnar intrinsic hand muscles by the anterior interosseous nerve in Martin‐Gruber anastomosis and nerve transfer surgery

It is important to quantify the amount of crossover innervation from the anterior interosseous nerve (AIN) through Martin-Gruber anastomosis (MGA) particularly in patients with high ulnar nerve injury who undergo nerve transfer surgery. The objective of this study is to describe a novel electrophysiological method for quantifying innervation from the AIN that can be done using conventional nerve conduction study setup and commonly available software for analysis. Seven subjects with MGA and nine patients who had undergone AIN to ulnar nerve transfer underwent conventional motor nerve conduction studies. Recording was done over the hypothenar and first dorsal interosseous muscles while stimulating the median and ulnar nerves at the wrist and elbow. Datapoint-by-datapoint subtraction of the compound muscle action potentials evoked at the elbow and wrist was performed after they had been onset-aligned. The results were compared to the collision technique and innervation ratio method. Results from the digital subtraction method were highly correlated with the collision technique (r= 0.96, p< 0.05). In contrast, its correlation with the innervation ratio method is substantially lower. In comparison to previously described techniques, the digital subtraction method has a number of practical advantages. It uses conventional nerve conduction study setup, and the added step of digital alignment and subtraction can be done through commonly available software. With the increasing use of nerve transfer surgery in severe high ulnar nerve injury, this could be a useful method to identify the presence of MGA prior to surgery and for evaluating nerve recovery following surgery.

Assessing carpal tunnel syndrome with magnetoneurography

ObjectiveTo measure the neuromagnetic fields of carpal tunnel syndrome patients after electrical digital nerve stimulation and evaluate median nerve function with high spatial resolution. MethodsA superconducting quantum interference device magnetometer system was used to record neuromagnetic fields at the carpal tunnel after electrical stimulation of the middle digital nerve in 10 hands of nine patients with carpal tunnel syndrome. The patients were diagnosed based on symptoms (numbness, tingling, and pain) supported by a positive Phalen or Tinel sign. A novel technique was applied to remove stimulus-induced artifacts, and current distributions were calculated using a spatial filter algorithm and superimposed on X-ray. ResultsIn 6 of the 10 hands, the amplitude of the inward current waveform attenuated to <70% or the nerve conduction velocity was <40 m/s. The results of conventional nerve conduction studies were normal for two of these six hands. All four hands that could not be diagnosed by magnetoneurography had severe carpal tunnel syndrome superimposed on peripheral neuropathy secondary to comorbidities. ConclusionsTechnical improvements enabled magnetoneurography to noninvasively visualize the electrophysiological nerve activity in carpal tunnel syndrome patients. SignificanceMagnetoneurography may have the potential to contribute to the detailed diagnosis of various peripheral nerve disorders.

The additional diagnostic value of motor nerve excitability testing in chronic axonal neuropathy

ObjectiveTo explore potential differences in motor nerve excitability testing (NET) variables at group levels between patients with a clinical diagnosis of polyneuropathy (PNP), which did not fulfil diagnostic criteria of conventional nerve conduction studies (NCS) and patients without polyneuropathy. Such differences could support a role for NET in increasing the diagnostic sensitivity of NCS in chronic axonal PNP. MethodsMotor NET was performed using the median nerve in patients with a clinical suspicion of PNP in addition to conventional NCS, skin biopsies, corneal confocal microscopy and structured clinical evaluation including scoring of neuropathy symptoms and signs. ResultsOf the 57 patients included, 32 had PNP, half of which had NCS, which fulfilled criteria for PNP (NCS+ PNP). There were no significant differences for any of the NET variables between PNP patients with non-diagnostic conventional NCS (NCS− PNP) and patients without PNP. Rheobase was increased, and Ted (undershoot) and subexcitability were decreased in NCS+ PNP. Sural amplitude, peroneal nerve F-wave latency and tibial nerve F-wave-latency were correlated with subexcitability, and tibial nerve motor amplitude was correlated with rheobase. ConclusionsNET was correlated with conventional NCS and no differences were found between NCS− PNP patients and patients without PNP. SignificanceNET does not seem to offer any additional diagnostic value in chronic mixed etiology neuropathy.

Lower / upper extremity F-wave ratio for detecting early diabetic neuropathy.

Results of conventional nerve conduction studies may be within normal limits in early diabetic neuropathy. Previous studies demonstrated that F-wave latency should be used to detect this early neuropathic process. The aim of this study is to evaluate the sensitivity of lower/upper extremity F latency ratios in detecting the early neuropathy in patients with diabetic neuropathic pain. 44 patients with diabetic neuropathic pain (DNP) and 44 control subjects whose both conventional nerve conduction studies and F-wave latencies were within normal limits were included to the study. We compared the nerve conduction parameters and lower/upper extremity (tibial/ulnar) F latency ratios of the groups. Tibial F latency was significantly prolonged and tibial/ulnar F latency ratio was significantly higher in DNP group. Our results support that F-waves are useful for detecting early diabetic neuropathy and suggest that comparison with a control group will demonstrate a difference even when the individuals' F-wave latencies are within the normal limits. The difference was significant for tibial but not for ulnar F latency values supporting the length dependent involvement. The tibial/ ulnar F-wave latency ratio was significantly higher in the DNP group, suggesting that it might also be useful to detect early neuropathy and to demonstrate that the underlying process was predominant in lower extremity. Further studies may provide additional information about the utility of this ratio for detecting early neuropathy even when F-wave latencies are within normal limits.

The First Electropysiological Abnormality In New-onset DM: Autonomic Tests

Conventional nerve conduction studies (NCS) are used in the electrodiagnosis of diabetic neuropathy. The aim of our study was to investigate diabetic small fiber neuropathy in newly diagnosed type 2 diabetes mellitus (DM) patient group by using autonomic tests. Our study was conducted on 49 patients (24 female, 25 male) who were newly diagnosed with type 2 DM in the last 3 months and a control group of 25 volunteers. In addition to conventional NCS, sympathetic skin response (SSR) and RR interval variability (RRIV) tests were performed. The mean upper limb SSR latency of the patient group was more prolonged than that of the control group, whereas the mean lower limb SSR amplitude of the patient group was lower than that of the control group (p=0.002, p<0.001; respectively). The mean resting (R) and deep inspiration (D) RRIV values of the patient group were lower than that of the control group (p=0.037, p<0.001; respectively). In the patient group, the mean R-RRIV and D-RRIV values were found to be positively correlated with the lower limb SSR amplitude (r=0.006, r=0.011; respectively). The mean R-RRIV and D-RRIV change rate of the patient group (D-R)/R was found to be lower than that of the control group (p=0.002). In our study, we showed that autonomic function tests were impaired in newly diagnosed type 2 DM patients who were found not to have diabetic polyneuropathy by standard electrophysiological study. These findings suggest that standard electrophysiological tests are not sufficient in the early stages of the disease.

Localization of Ulnar Neuropathy at the Wrist Using Motor and Sensory Ulnar Nerve Segmental Studies.

Background and PurposeDiagnosing ulnar neuropathy at the wrist (UNW) is often challenging, and performing several short segmental studies have been suggested for achieving this. We aimed to determine the utility of ulnar nerve segmental studies at the wrist (UNSWs) in patients with suspected UNW.MethodsFourteen patients with typical symptoms of unilateral UNW were evaluated using conventional electrophysiological tests, UNSWs, and ultrasonography (US). In UNSWs, the ulnar nerve was stimulated at three sites (3 cm distal, just lateral, and 2 cm proximal to the pisiform), and recordings were made at the first dorsal interosseous (FDI) muscle and the fifth digit. Four types of UNW were identified by conventional ulnar nerve conduction studies based on motor and sensory fiber involvement. UNW was also categorized as either a proximal or distal lesion relative to the pisiform based on the UNSWs. The relationships between the conventional electrophysiological type, UNSW categorization results, and lesion location as verified by US were analyzed.ResultsProximal UNW lesions were associated with involvement of the entire deep motor and the superficial sensory fibers (type I). Distal lesions were more closely related to deep motor fibers that innervated the FDI (type III). All five proximal and six distal lesions seen in US matched the lesion locations found on UNSWs.ConclusionsMotor and sensory UNSW are considered useful assistive techniques for diagnosing UNW and localizing its lesion sites.

High rate of autonomic neuropathy in Cornelia de Lange Syndrome

BackgroundCornelia de Lange Syndrome (CdLS) is a rare congenital disorder characterized by typical facial features, growth failure, limb abnormalities, and gastroesophageal dysfunction that may be caused by mutations in several genes that disrupt gene regulation early in development. Symptoms in individuals with CdLS suggest that the peripheral nervous system (PNS) is involved, yet there is little direct evidence.MethodSomatic nervous system was evaluated by conventional motor and sensory nerve conduction studies and autonomic nervous system by heart rate variability, sympathetic skin response and sudomotor testing. CdLS Clinical Score and genetic studies were also obtained.ResultsSympathetic skin response and sudomotor test were pathological in 35% and 34% of the individuals with CdLS, respectively. Nevertheless, normal values in large fiber nerve function studies.ConclusionsAutonomic nervous system (ANS) dysfunction is found in many individuals with Cornelia de Lange Syndrome, and could be related to premature aging.

Early diagnosis of amyotrophic lateral sclerosis by threshold tracking and conventional transcranial magnetic stimulation.

Background and purposeShort‐interval intracortical inhibition by threshold tracking (T‐SICI) has been proposed as a diagnostic tool for amyotrophic lateral sclerosis (ALS) but has not been compared directly with conventional amplitude measurements (A‐SICI). This study compared A‐SICI and T‐SICI for sensitivity and clinical usefulness as biomarkers for ALS.MethodsIn all, 104 consecutive patients referred with suspicion of ALS were prospectively included and were subsequently divided into 62 patients with motor neuron disease (MND) and 42 patient controls (ALS mimics) by clinical follow‐up. T‐SICI and A‐SICI recorded in the first dorsal interosseus muscle (index test) were compared with recordings from 53 age‐matched healthy controls. The reference standard was the Awaji criteria. Clinical scorings, conventional nerve conduction studies and electromyography were also performed on the patients.ResultsMotor neuron disease patients had significantly reduced T‐SICI and A‐SICI compared with the healthy and patient control groups, which were similar. Sensitivity and specificity for discriminating MND patients from patient controls were high (areas under the receiver operating characteristic curves 0.762 and 0.810 for T‐SICI and A‐SICI respectively at 1–3.5 ms). Paradoxically, T‐SICI was most reduced in MND patients with the fewest upper motor neuron (UMN) signs (Spearman ρ = 0.565, p = 4.3 × 10−6).ConclusionsAmplitude‐based measure of cortical inhibition and T‐SICI are both sensitive measures for the detection of cortical involvement in MND patients and may help early diagnosis of ALS, with T‐SICI most abnormal before UMN signs have developed. The gradation in T‐SICI from pathological facilitation in patients with minimal UMN signs to inhibition in those with the most UMN signs may be due to progressive degeneration of the subset of UMNs experiencing facilitation.

Myopathic changes in patients with long-term fatigue after COVID-19

ObjectiveTo investigate the peripheral nerve and muscle function electrophysiologically in patients with persistent neuromuscular symptoms following Coronavirus disease 2019 (COVID-19). MethodsTwenty consecutive patients from a Long-term COVID-19 Clinic referred to electrophysiological examination with the suspicion of mono- or polyneuropathy were included. Examinations were performed from 77 to 255 (median: 216) days after acute COVID-19. None of the patients had received treatment at the intensive care unit. Of these, 10 patients were not even hospitalized. Conventional nerve conduction studies (NCS) and quantitative electromyography (qEMG) findings from three muscles were compared with 20 age- and sex-matched healthy controls. ResultsqEMG showed myopathic changes in one or more muscles in 11 patients (55%). Motor unit potential duration was shorter in patients compared to healthy controls in biceps brachii (10.02 ± 0.28 vs 11.75 ± 0.21), vastus medialis (10.86 ± 0.37 vs 12.52 ± 0.19) and anterior tibial (11.76 ± 0.31 vs 13.26 ± 0.21) muscles. All patients with myopathic qEMG reported about physical fatigue and 8 patients about myalgia while 3 patients without myopathic changes complained about physical fatigue. ConclusionsLong-term COVID-19 does not cause large fibre neuropathy, but myopathic changes are seen. SignificanceMyopathy may be an important cause of physical fatigue in long-term COVID-19 even in non-hospitalized patients.

Early detection of evolving critical illness myopathy with muscle velocity recovery cycles

ObjectiveTo investigate the sensitivity of muscle velocity recovery cycles (MVRCs) for detecting altered membrane properties in critically ill patients, and to compare this to conventional nerve conduction studies (NCS) and quantitative electromyography (qEMG). MethodsTwenty-four patients with intensive care unit acquired weakness (ICUAW) and 34 healthy subjects were prospectively recruited. In addition to NCS (median, ulnar, peroneal, tibial and sural nerves) and qEMG (biceps brachii, vastus medialis and anterior tibial muscles), MVRCs with frequency ramp were recorded from anterior tibial muscle. ResultsMVRC and frequency ramp parameters showed abnormal muscle fiber membrane properties with up to 100% sensitivity and specificity. qEMG showed myopathy in 15 patients (63%) while polyneuropathy was seen in 3 (13%). Decreased compound muscle action potential (CMAP) amplitude (up to 58%) and absent F-waves (up to 75%) were frequent, but long duration CMAPs were only seen in one patient with severe myopathy. ConclusionsAltered muscle fiber membrane properties can be detected in patients with ICUAW not yet fulfilling diagnostic criteria for critical illness myopathy (CIM). MVRCs may therefore serve as a tool for early detection of evolving CIM. SignificanceCIM is often under-recognized by intensivists, and large-scale longitudinal studies are needed to determine its incidence and pathogenesis.

Asymptomatic Median Neuropathy in Patients with Diabetic Polyneuropathy

Aim: This study aims to investigate whether asymptomatic median neuropathy (AMN) in patients with diabetic peripheral polyneuropathy (DPNP) is a result of polyneuropathic involvement of median nerve (MN) or its true entrapment. Subjects and Methods: We determined the grades of the Michigan severity scale and the rates of peripheral nerve conduction abnormalities in study subgroups, including patients with carpal tunnel syndrome (CTS), AMN, and normal MN conductions to highlight if the severity of polyneuropathic involvement was different between them. In addition, the results of conventional and comparative nerve conduction studies (NCSs) were compared between these study subgroups. Results: Distributions of Michigan grades and rates of abnormalities in peroneal and sural NCSs were similar between the subgroups (P &gt; 0.05 for all analyses). Abnormality rates of ulnar NCSs were higher in the AMN group than in the other groups, whereas those of comparative transcarpal NCSs were higher in the CTS group. The mean distal sensory latency (DSL) and motor latency (DML) of MN were longer, sensory conduction velocity (SCV) was slower in the CTS group than AMN group, whereas MN motor conduction velocity (MCV) was slower, UN DSL was longer, SCV was slower, SNAP amplitude was smaller, DML was longer, and MCV were slower in the AMN group (P &lt; 0.05 for all analyses). Discussion: Our findings reveal that grade of polyneuropathic involvement is more prominent in AMN, whereas transcarpal MN conduction delay is greater in CTS. The results of the study suggest that the prominence of polyneuropathic impairment in addition to a lesser degree of MN sheet compression obscures the clinical signs in patients with diabetes with AMN.

Standard Clinical Screening Tests, Sural Radial Amplitude Ratio and F Wave Latency Compared to Conventional Nerve Conduction Studies in the Assessment of Sensorimotor Polyneuropathy in Patients with Type 2 Diabetes Mellitus.

Background and Aims:The measuring tools used for assessment of neuropathy include various questionnaires, monofilament testing, Biothesiometry and the gold standard test, nerve conduction studies (NCS). This study aims to evaluate the diagnostic accuracies of Michigan Neuropathy Screening Instrument (MNSI), Biothesiometry, Semmes Weinstein Monofilament (SWMF), Sural Radial Amplitude Ratio (SRAR) and minimal F wave latency as compared to conventional NCS and arrive at a simple diagnostic algorithm for early detection of Diabetic Peripheral Neuropathy (DPN).Methods:In a cross-sectional observational study on 48 Type 2 diabetes mellitus patients, MNSI, Biothesiometry, SWMF and NCS including F waves and SRAR were done and diagnostic accuracies (sensitivity, specificity, positive and negative predictive values) calculated taking NCS as gold standard.Results:MNSI, Biothesiometry, SWMF, SRAR and minimal F wave latency had a sensitivity of 64.3%, 78.6%, 14.3%, 100% and 78.6% and specificity of 67.7%, 52.9%, 94.1%, 23.53% and 76.47% respectively, with reference to NCS. Based on combined sensitivities and specificities, we arrived at a simple algorithm for early diagnosis of DPN, which showed that DPN could either be diagnosed or ruled out in 75% of the patients by a combination of the Biothesiometry, SRAR and left lower limb minimal F wave latency results.Conclusions:In the setting of an outpatient, multidisciplinary diabetic clinic, simple tests such as questionnaires, monofilament testing and biosthesiometer could be performed with greater ease while considering NCS as the gold standard. This algorithm, combining Biothesiometry, SRAR and left lower limb minimal F wave latency would be less time consuming and help in early diagnosis of DPN.

Age-related characteristics and normative values of F waves in healthy infants

ObjectiveTo establish age-related characteristics and normative values of F waves in healthy Chinese infants. MethodsWe studied median, ulnar and tibial nerves on one side distally in 229 healthy Chinese infants (108 males) ranging from 1 to 12 months old. ResultsMinimal F-wave latencies (Fmin) showed a strong negative correlation to the age for median, ulnar and tibial nerves (P < 0.01) but no correlation to the height. Statistical analyses revealed a significant (P < 0.01) decrease of Fmin during the second month of life and no change (P > 0.05) thereafter. Dividing the infants into 1 month old (Group 1) and 2–12 months old (Group 2), normal values (Mean ± SD ms) of Fmin for tibial, median and ulnar nerves consisted of 23.38 ± 1.68, 17.19 ± 0.95 and 16.47 ± 1.06 for Group 1 and 21.42 ± 1.25, 14.50 ± 1.15 and 14.52 ± 0.90 for Group 2. ConclusionF-wave latencies shorten in the 2nd month of life and change little thereafter when age-related maturation counters the concomitant growth of the nerve length. SignificanceF waves can assess infantile neuropathies as a reliable measure, complementing the technically difficult conventional nerve conduction study in short limbs.

Muscle Velocity Recovery Cycles to Examine Muscle Membrane Properties.

Although conventional nerve conduction studies (NCS) and electromyography (EMG) are suitable for the diagnosis of neuromuscular disorders, they provide limited information about muscle fiber membrane properties and underlying disease mechanisms. Muscle velocity recovery cycles (MVRCs) illustrate how the velocity of a muscle action potential depends on the time after a preceding action potential. MVRCs are closely related to changes in membrane potential that follow an action potential, thereby providing information about muscle fiber membrane properties. MVRCs may be recorded quickly and easily by direct stimulation and recording from multi-fiber bundles in vivo. MVRCs have been helpful in understanding disease mechanisms in several neuromuscular disorders. Studies in patients with channelopathies have demonstrated the different effects of specific ion channel mutations on muscle excitability. MVRCs have been previously tested in patients with neurogenic muscles. In this prior study, muscle relative refraction period (MRRP) was prolonged, and early supernormality (ESN) and late supernormality (LSN) were reduced in patients compared to healthy controls. Thereby, MVRCs can provide in vivo evidence of membrane depolarization in intact human muscle fibers that underlie their reduced excitability. The protocol presented here describes how to record MVRCs and analyze the recordings. MVRCs can serve as a fast, simple, and useful method for revealing disease mechanisms across a broad range of neuromuscular disorders.

Role of High Frequency Ultrasound in Diagnosing Carpal Tunnel Syndrome as Compared with Conventional Nerve Conduction Studies.

Objective:Our aim was to evaluate High Frequency Ultrasonography as a tool for diagnosis in patients withcarpal tunnel syndrome in comparison with electrophysiological study.Methods:Thirty- one patients [56 hands] with CTS and twenty-five asymptomatic controls [50 hands] were assessed and underwent ultrasonography of the wrists and electrophysiological testing. Data from the patient and the control groups was compared for both the investigations to determine the CTS and the grade of severity.Results:There was a high degree of correlation between the conduction abnormalities of the median nerve as detected by electrodiagnostic tests, historic and objective scale [Hi-Ob] and the measurement of the cross-sectional area of the nerve by US (P < 0.05). A cut-off point of 0.88 mm2 for the mean cross-sectional area of the median nerve was found to be the upper limit for normal values. Compared to Ultrasonography which found one hand negative, six hands (10%) were negative on the electrophysiological tests. Using critical CSA value of 1.0 mm2 in these CTS cases by US with sensitivity and specificity of 100% and 88%. Based on the results of this study, ultrasonography of wrist is another useful tool along with nerve conduction studies as per sensitivity and specificity patterns found in our study in diagnosis of carpal tunnel syndrome.Conclusion:High-frequency US examination of the median nerve and measurement of its cross-sectional area can be strongly considered as useful diagnostic diagnostic modality for the evaluation of CTS along with nerve conduction studies. In addition to its high diagnostic accuracy it is able to define the cause of nerve compression, aids treatment planning and provides a reliable method to follow response to therapy.