Prevalence and predictors of peripheral neuropathy in nondiabetic children with chronic kidney disease

Introduction: This study sought to determine the prevalence and predictors of peripheral neuropathy in nondiabetic children with chronic kidney disease (CKD). Methods: Fifty‐one consecutive normally nourished children, 3–18 years of age, with CKD stages IV and V of nondiabetic etiology were enrolled from May to December 2012. Nerve conduction studies were performed in 50 children. Blood samples were analyzed for the biochemical parameters, trace elements, and micronutrients. Results: The prevalence of peripheral neuropathy in our cohort was 52% (95% confidence interval 37.65, 66.34). The majority (80.8%) of the children had axonal neuropathy, and 11.5% had demyelinating neuropathy. Isolated motor neuropathy was identified in 92.3% of the children, and sensorimotor neuropathy was identified in 7.6%. The significant risk factors associated with peripheral neuropathy were older age, low serum copper, and dialysis therapy. Discussion: Electrodiagnostic studies should be performed in children with CKD to assess for peripheral neuropathy for the purpose of optimizing medical care. Muscle Nerve 57 : 792–798, 2018     

Temperature dependence of nerve conduction and EMG in neuropathy associated with gammopathy

The effects of warming on nerve conduction variables and electromyography were studied in 15 patients with a polyneuropathy associated with monoclonal gammopathy of undetermined significance. In each patient median nerve (motor, sensory) and tibial nerve (motor) conduction parameters were measured before and after warming in water at 36°C. Warming: (1) increased the conduction velocity (CV); (2) decreased the distal motor latency, amplitude, and duration of the corn f pound muscle or nerve action potential; and (3) caused fibrillations to appear in 1 patient. The increase in CV with temperature depended upon the CV after warming: the lower this CV, the smaller the increase in CV with temperature (ΔCV/Δ). Correction of median nerve motor CV before warming with 2.2 m/s per °C yielded CV values which were higher than the CV values after warming, because in most patients ΔCV/Δ was less than 2.2 m/s per °C. Because of differences in ΔCV/Δ values, it is more accurate to warm the extremity than to correct for temperature. © 1994 John & Sons, Inc.     

Effect of body mass index on ulnar nerve conduction velocity, ulnar neuropathy at the elbow, and carpal tunnel syndrome

Both high and low body mass index (BMI) have been reported as risk factors for ulnar neuropathy at the elbow (UNE), and a high BMI as a risk factor for carpal tunnel syndrome (CTS). To determine whether the extremes of BMI are risk factors for UNE or CTS, and whether BMI affects calculation of median and ulnar motor nerve conduction velocity (NCV), we retrospectively analyzed the electrodiagnostic records of control patients, UNE patients, and CTS patients. The BMI was calculated for 50 patients with a sole diagnosis of UNE and compared to the BMI of 50 patients with CTS and 50 control subjects. The mean BMIs were 25.9 +/- 4.4, 30.1 +/- 5.5, and 28.3 +/- 5.6 for the UNE, CTS, and controls, respectively. By one-way analysis of variance, the difference in BMI between the UNE patients and the normal patients was significant (P < 0.01). In the control groups, increasing BMI directly correlated with increasing ulnar motor NCV across the elbow but not with forearm NCV. Across-elbow (AE) ulnar motor NCV may be falsely increased in patients with a high BMI, probably due to distance measurement factors. Not only do relatively slender individuals have comparatively slower AE ulnar NCVs, they are also at increased risk for developing UNE. Patients with a high BMI are at increased risk for CTS.     

Sensory nerve conduction slowing is a specific marker for CIDP

Most current diagnostic criteria for chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) do not make use of sensory nerve conduction studies (NCSs). To investigate if surface sensory NCSs are clinically relevant in differentiating CIDP from axonal polyneuropathy, we conducted a retrospective cohort study of patients referred for electrodiagnostic testing to evaluate for CIDP. We found that sensory conduction velocity (CV) slowing is a highly specific, albeit insensitive, marker for differentiating CIDP from axonal polyneuropathy. Muscle Nerve 38: 1599–1603, 2008     

Median nerve ultrasound in diabetic peripheral neuropathy with and without carpal tunnel syndrome

Introduction: Median nerve ultrasound shows increased cross‐sectional area (CSA) in carpal tunnel syndrome (CTS) and diabetic peripheral neuropathy (PN). The role of ultrasound in diagnosing CTS superimposed on diabetic PN is unknown. The objective of this study is to evaluate ultrasound for diagnosis of CTS in diabetic PN. Methods: Prospective recruitment of diabetics with electrodiagnostically proven PN, subdivided into cases (with CTS) or controls (without CTS). The gold standard for CTS was clinical diagnosis. NCS were correlated with blinded median nerve CSA ultrasound measurements. Results: Eight cases (CTS) and eight controls (no CTS) were recruited. Nerve conduction studies (NCS): Median nerve distal latencies (antidromic sensory; palmar; lumbrical motor; and lumbrical motor to ulnar interosseous difference) were significantly prolonged in CTS cases. No ultrasound measurement (distal median CSA, wrist‐forearm ratio, wrist‐forearm difference) reached significance to detect CTS. Area under the curve was greatest for lumbrical distal latency by receiver operator characteristic analysis (0.85). Conclusions: In this pilot study, NCS may be superior to ultrasound for identification of superimposed CTS in diabetic PN patients, but larger numbers are needed for confirmation. Muscle Nerve 47: 437–439, 2013     

AAEM minimonograph #34: polyneuropathy: classification by nerve conduction studies and electromyography

Electrodiagnostic evaluation of patients with suspected polyneuropathy is useful for detecting and documenting peripheral abnormalities, identifying the predominant pathophysiology, and determining the prognosis for certain disorders. The electrodiagnostic classification of polyneuropathy is associated with morphologic correlates and is based upon determining involvement of sensory and motor fibers and distinguishing between predominantly axon loss and demyelinating lesions. Accurate electrodiagnostic classification leads to a more focused and expedient identification of the etiology of polyneuropathy in clinical situations.     

Class of nerve fiber involvement in sensory neuropathies: clinical characterization and utility of the plantar nerve action potential

Nerve conduction studies (NCS) in diabetic sensorimotor polyneuropathy (DSP) are sensitive, noninvasive, and associated with small coefficients of variation, and correlate well with underlying peripheral nerve morphological change. For these reasons, the current reference standard for DSP involves multivariate instruments that emphasize NCS results. However, the interside symmetry of NCS findings in different stages of DSP are unknown, although requirement for symmetry has been suggested in clinical trials of DSP. We therefore aimed to determine the degree of symmetry of NCS findings in DSP of differing severity stages. A cohort of diabetic patients, including patients without neuropathy and those with mild to severe DSP, was studied. We also studied a series of nondiabetic, healthy subjects. A variation of stratified sampling by means of a clinical neuropathy score ensured that a broad spectrum of neuropathy was studied. A total of 478 subjects was ascertained; patient accrual was discontinued when the smallest clinical group consisted of 50 subjects. Nerve conduction studies were conducted prospectively and in a blinded fashion using surface recordings, averaging for sensory action potentials, control of limb temperature, and standardized techniques. Median and ulnar motor and sensory, peroneal and tibial motor, and sural NCS were performed. Interside symmetry, independent of neuropathy severity, was observed for all investigated nerves, except for the median sensory nerve action potential amplitude, which was lower on the right side. These results confirm that abnormal NCS findings consistent with DSP are reliably symmetrical with the exception of the amplitude of the median sensory nerve action potential. Thus, unilateral evaluation of NCS in DSP is sufficient as a reference standard in clinical trials. We also conclude that great degrees of asymmetry in NCS results are reason to question inclusion of DSP patients in clinical trials.     

A prospective evaluation of phrenic nerve conduction in multifocal motor neuropathy and chronic inflammatory demyelinating polyneuropathy

The purpose of the study was to evaluate electrophysiologically phrenic nerve involvement in multifocal motor neuropathy (MMN) and chronic inflammatory demyelinating polyneuropathy (CIDP). The response latencies following phrenic nerve stimulation were increased in 11 of 14 (80%) patients in the CIDP group but in only 1 of 14 (8%) patients in the MMN group. The mean diaphragmatic compound muscle action potential (CMAP) was significantly lower in amplitude in the CIDP group compared to the MMN group and to a control group of 8 subjects (P < 0.001). There were no significant differences between the MMN and control groups. Only the reduction in CMAP amplitude correlated with the presence of restrictive lung function. Phrenic nerve conduction measurement should be performed more systematically, especially in CIDP and, when diaphragmatic CMAPs are reduced in amplitude, pulmonary function tests should be performed to look for a restrictive lung syndrome.     

Sensory and mixed nerve conduction studies in the evaluation of ulnar neuropathy at the elbow

The relative sensitivities of sensory, mixed nerve, and motor conduction studies in assessing ulnar neuropathy at the elbow have not yet been established. Using surface electrodes, we performed conduction studies across the elbow segment in 43 patients with symptoms referable to the ulnar nerve and 40 control subjects. Segmental slowing of motor conduction localized the lesion to the elbow in 14 of 21 patients (67%) with clear evidence of ulnar neuropathy on physical examination but only in 2 of 22 (9%) with subtle or no physical examination abnormalities. The diagnostic yield was increased by the finding of segmental slowing of sensory or mixed nerve conduction across the elbow to 86% and 68%, respectively, for each of the groups. We conclude that surface-recorded sensory and mixed nerve conduction studies appear to be more sensitive than motor studies in the electrodiagnosis of ulnar neuropathy at the elbow and are especially valuable in patients with subtle clinical involvement. © 1994 John Wiley & Sons, Inc.     

Electroneurography index based on nerve conduction study data: method and findings in control subjects

We developed a summary score of data obtained from nerve conduction studies (NCS). The principle of such approach is that when a nonrandom trend to lower amplitudes or conduction velocities is present, it may be revealed by a summary nerve conduction score. In a group of normal subjects, peroneal, sural, ulnar, and superficial radial nerves were studied; age- and height-related F-wave and soleus H-reflex latencies were also examined. Z-scores of distal latencies, amplitudes, conduction velocities, F-wave latencies, and H-index were averaged in order to obtain three electroneurography (ENG) indices: a simple arithmetic (ENG index 1) and two weighted means (index 2 and index 3), assigning a double or triple weight to lower limb z-scores. Reference limits were established using multiple regression equations of ENG indices against age and height. This technique could be useful in providing a better cut-off between normal and diseased populations and in improving test-retest variability of NCS when follow-up studies are required.     

Acupuncture treatment improves nerve conduction in peripheral neuropathy

The etiology of peripheral neuropathy (PN) often remains elusive resulting in a lack of objective therapeutic strategies. We conducted a pilot study to evaluate the therapeutic effect of acupuncture on PN as measured by changes in nerve conduction and assessment of subjective symptoms. One hundred and ninety-two consecutive patients with PN as diagnosed by nerve conduction studies (NCS) were evaluated over a period of 1 year. Of 47 patients who met the criteria for PN of undefined etiology, 21 patients received acupuncture therapy according to classical Chinese Medicine as defined by the Heidelberg Model, while 26 patients received the best medical care but no specific treatment for PN. Sixteen patients (76%) in the acupuncture group improved symptomatically and objectively as measured by NCS, while only four patients in the control group (15%) did so. Three patients in the acupuncture group (14%) showed no change and two patients an aggravation (10%), whereas in the control group seven showed no change (27%) and 15 an aggravation (58%). Importantly, subjective improvement was fully correlated with improvement in NCS in both groups. The data suggest that there is a positive effect of acupuncture on PN of undefined etiology as measured by objective parameters.     

Vibratory perception threshold compared with nerve conduction velocity in the evaluation of uremic neuropathy

Clinical signs of neuropathy, vibratory perception thresholds, nerve conduction velocities, and distal motor latencies were compared in 81 patients with chronic renal failure. During treatment with low protein diets (LPD), the vibratory thresholds correlated better with the clinical grading of the neuropathy than did the conduction velocities or the distal motor latencies, while during hemodialysis (HD), the situation was the reverse. The vibratory threshold on the foot was the single most useful test, since it correlated with the clinical grading of the neuropathy both during LPD and HD, and both between and within patients.     

Involvement of superficial peroneal sensory nerve in common peroneal neuropathy

Motor involvement in common peroneal neuropathy (CPN) frequently shows a selective pattern with regard to deep and superficial divisions of the peroneal nerve, by clinical examination and needle electromyography. The involvement of the sensory branch of the superficial peroneal nerve (SPN) has not been well established using nerve conduction studies. Among 42 cases of electrophysiologically defined CPN in 35 patients, 37 (88%) had clinical or electrophysiologic evidence for SPN involvement, but only 20 had diminished superficial peroneal sensory response (SPSR) amplitudes. Many of the cases involving normal SPSRs had significant axonal loss involving deep peroneal motor fibers. Sparing of the superficial peroneal sensory fibers provides further evidence for the selective vulnerability of different nerve fascicles to injury. This is an important pattern to recognize; from a practical standpoint, focal segmental conduction abnormalities in the motor nerve and EMG findings can help to differentiate these lesions from L-5 radiculopathy.     

Body mass index effect on common nerve conduction study measurements

This study was performed to determine whether there is a difference in nerve conduction study (NCS) measures based on body fat (body mass index; BMI). Two hundred fifty-three subjects had the following NCS tests performed on them: median, ulnar, peroneal, and tibial motor studies; median, ulnar, radial, and sural sensory studies; median and ulnar mixed nerve studies; and H-reflex studies. BMI was calculated as weight (kg) divided by height (m) squared. A repeated measures analysis of variance was run adjusting for age, sex, and height and using BMI as both a continuous variable and by dividing BMI into upper, middle, and lower thirds. The sensory and mixed nerve amplitudes correlated significantly (P ⩽ 0.01) with BMI for all nerves tested, with means being approximatly 20–40% lower in the obese than in the thin subjects. No correlation was noted between BMI and nerve conduction velocity, H-reflex latency, or most of the other motor/sensory/mixed measures. The correlation between increased BMI and lower sensory/mixed nerve amplitudes should be taken into account in clinical practice. © 1998 John Wiley & Sons, Inc. Muscle Nerve 21: 1398–1404, 1998     

Axonal neuropathy in chronic peripheral arterial occlusive disease

Chronic peripheral arterial occlusive disease of the lower limbs may cause tissue damage. Type and extent of peripheral nerve involvement is controversial. We examined 25 patients with peripheral arterial occlusive disease in various grades of severity and 37 age-matched healthy controls using conventional angiography and motor and sensory nerve conduction tests. Subjects with confounding factors for peripheral neuropathies were excluded. We found prolongation of distal motor latencies, decrease of motor and sensory nerve conduction velocities, and reduction in amplitude of the compound muscle action potential. Amplitudes of the compound muscle action potentials were lower in patients with pain at rest than in patients with intermittent claudication and decreased with increasing neurological disability score. Sural nerve conduction velocity, peroneal nerve F-wave chronodispersion, and tibial nerve F-wave persistence were the most frequent abnormal findings. Therefore we concluded that chronic peripheral arterial occlusive disease causes axonal degeneration, resulting in axonal polyneuropathy.     

Carbon disulfide induced polyneuropathy: sural nerve pathology, electrophysiology, and clinical correlation

We report the clinical features, electrophysiological studies, sural nerve pathology and recovery course of carbon disulfide-(CS2) induced polyneuropathy in a 48-year-old man who worked in a viscose rayon plant. Sural nerve biopsy 2 years later still showed degeneration of both axon and myelin with a predominant loss of large myelinated fibers and remyelination. Electrophysiologic studies revealed mixed axonal and demyelinating polyneuropathy. To our knowledge, this is the first human report of sural nerve pathology in the recovery stage due to CS2 intoxication. After diagnosis, the patient was removed from the toxic environment. In the following three years, he showed part recovery predominantly in motor function compatible with the serial nerve conduction studies. We conclude that CS2 polyneuropathy may partly recover years after cessation of exposure.     

Patterns of sensory nerve conduction abnormalities in demyelinating and axonal peripheral nerve disorders

The pattern of an abnormal median-normal sural (AMNS) sensory response is associated with acute and chronic inflammatory demyelinating polyradiculoneuropathy (AIDP and CIDP) and considered unusual in other types of neuropathy, although specificity and sensitivity of this pattern have not been evaluated. We compared sensory responses (patterns and absolute values) in patients with AIDP, CIDP, diabetic polyneuropathy (DP), and motor neuron disease (MND). Using strict criteria, the AMNS pattern occurred more frequently in recent onset AIDP (39%) compared with CIDP (28%), DP (14%–23%), or MND (22%) patients. This pattern was found in 3% of control subjects. The extreme pattern of an absent median-present sural response occurred only in AIDP and CIDP patients and in no other groups. Abnormalities of both nerves were more common in long-standing polyneuropathies such as CIDP and DP compared with AIDP or MND. Median nerve amplitudes were reduced significantly in AIDP, CIDP, and DP patients compared with MND patients, whereas sural nerve amplitudes were significantly reduced only in DP and CIDP patients. These findings may reflect early distal nerve involvement particularly in AIDP patients which is highlighted by differences in median and sural nerve recording electrode placement. We conclude that, in the appropriate clinical setting, the AMNS pattern, an absent median-present sural response pattern, or a reduced median amplitude compared with the sural amplitude supports a diagnosis of a primary demyelinating polyneuropathy. © 1993 John Wiley & Sons, Inc.     

Electroneurography index: A standardized neurophysiological method to assess peripheral nerve function in patients with polyneuropathy

An index based on 12 electrophysiological parameters (conduction velocities, F-latencies, and amplitudes) was constructed to obtain an overall estimation of peripheral nerve conduction. The index was expressed as the meandeviation (in SD) compared to controls standardized for age or height. The stability of the index was tested by repeated examinations during intervalsof several months in healthy subjects. The use of a compound index enabled detection of slight impairments of nerve conduction. The relatively low interrecording variability of the index makes it suitable to follow the progression of a polyneuropathy. © 1993 John Wiley & Sons, Inc.     

High insulin levels are positively associated with peripheral nervous system function

Objective – The aim of this study was to analyze peripheral nervous system (PNS) function in overweight and obese individuals. Materials and Methods – Forty‐four adult non‐diabetic overweight individuals were recruited. Peroneal motor nerve conduction and radial, sural, and medial plantar sensory nerve conduction were studied. Insulin and glucose levels were determined twice (over a 2‐ to 3‐year period) with an oral glucose tolerance test (OGTT). Multiple stepwise linear regression models adjusted for age, height, weight, and skin temperature were used to analyze the data. Results – Analysis revealed that baseline insulin levels measured 120 min after an OGTT explained 18% of the variation in peroneal F‐wave minimum latency, 8% of peroneal F‐wave maximum latency variation, 15% of sural sensory latency variation, 13% of sural sensory nerve conduction velocity (NCV) variation, and 10% of the variation in medial plantar sensory NCV. Discussion and Conclusion – Our study shows that serum insulin levels measured 120 min after an OGGT are positively associated with PNS function. High insulin levels without notably high glucose levels appear to be beneficial for the function of the PNS.     

Early diabetic neuropathy: thermal thresholds and intraepidermal nerve fibre density in patients with normal nerve conduction studies

Objectives   To determine whether neuropathy in diabetic patients with normal nerve conduction studies could be detected by measurements of thermal thresholds and quantification of intraepidermal nerve fibre (IENF) density, and to evaluate differences in parameters between patients with and without neuropathic symptoms. Methods   A total of 22 patients with and 37 patients without sensory symptoms suggesting distal neuropathy were included. Measurements of warm and cold perception thresholds and skin biopsy for quantification of IENFs were performed distally on the leg. Reference data were used to normalize test results for age and height or gender of individual patients by calculating the Z-scores. Results   IENF density was significantly reduced in both symptomatic and asymptomatic patients compared to controls (p < 0.001), and in patients with symptoms compared to those without (p = 0.01). Thermal thresholds were significantly elevated (more abnormal) in patients with symptoms compared to controls (p < 0.01), but only for cold perception threshold (CPT) (p < 0.001) in the asymptomatic group. When comparing symptomatic and asymptomatic patients, there was no statistically significant difference in thermal thresholds. Depletion of IENFs in skin biopsy was the most frequent abnormal finding in the subgroup of patients with neuropathic symptoms (36 %) followed by abnormal CPT (27 %). Conclusion   Patients with diabetes and normal nerve conduction studies had significantly lower IENF density and higher CPT than controls, whether they had symptoms of polyneuropathy or not. In patients with neuropathic symptoms, abnormal IENF density predominated and seemed thus to be the most sensitive tool of detecting small diameter nerve fibre involvement.