Davies, Jenny L.

AbstractIntroduction/AimsIn the Diabetes Control and Complications Trial (DCCT), the minimal nerve conduction (NC) criterion for diabetic sensorimotor polyneuropathy (DSPN) was abnormality of NC in more than one peripheral nerve without specifying the attributes of NCs to be evaluated. In the present study, we assess individual and composite scores of NCs meeting the DCCT criterion and signs for improved diagnosis and assessment of DSPN severity.MethodsEvaluated were 13 attributes and 6 composite NC scores and signs and symptoms in 395 healthy subjects (HS) and 388 persons with diabetes (DM).ResultsPercent abnormality between subjects with DM and HS was remarkably different among individual attributes and the six composite NC scores. For diagnosis of DSPN using the DCCT criterion, assessment of conduction velocities (CVs) and distal latencies (DLs) provided sensitive diagnoses of DSPN. NC amplitudes provided stronger measures of severity. In studied cohorts, DSPN was staged: N0, no NC abnormality using NC score 2 (CVs and DLs), 60.0%; N1, NC abnormality only, 18.4%; N2, NC abnormality and signs of feet or legs, 16.3%; and N3, NC abnormality and signs of thighs, 5.3%.DiscussionFor sensitive and standard diagnosis of DSPN using the DCCT NC criterion, specifically defined composite scores of CVs and DLs, e.g., score 2, is recommended. A composite score of amplitudes, e.g., score 4, provides a stronger measure of neuropathy severity. Also, provided are HS reference values of evaluated attributes of NCs and estimates of staged severity of DSPN of mid North American DM cohorts.

ABSTRACTIntroduction: For sequential and somatotopic assessment of small fiber neuropathy, heat pain (HP) tests of hypoalgesia might be used instead of decreased counts of epidermal nerve fibers (ENFs), but then healthy subject reference values of HP thresholds are needed. Methods: Using the Computer Assisted Sensation Evaluator IVc system, HP thresholds of hypoalgesia were estimated for 10 unilateral sites and counts of ENFs for 4 of them in healthy subjects. Results: In healthy subjects, small but statistically significant differences of both HP thresholds of hypoalgesia and counts of ENFs were observed among tested sites. Significant correlations between HP thresholds and counts of ENFs were not found. Discussion: For the studied somatotopic sites, we provide ≥95th and ≥99th percentile reference limits for HP 0.5 and 5 of 1–10 HP thresholds of hypoalgesia and decreased counts of ENFs at ≤5th and ≤1st percentile levels. Muscle Nerve 58: 509–516, 2018

ABSTRACTIntroductionPolyneuropathy signs (Neuropathy Impairment Score, NIS), neurophysiologic tests (m+7Ionis), disability, and health scores were assessed in baseline evaluations of 100 patients entered into an oligonucleotide familial amyloidotic polyneuropathy (FAP) trial.MethodsWe assessed: (1) Proficiency of grading neurologic signs and correlation with neurophysiologic tests, and (2) clinometric performance of modified NIS+7 neurophysiologic tests (mNIS+7Ionis) and its subscores and correlation with disability and health scores.ResultsThe mNIS+7Ionis sensitively detected, characterized, and broadly scaled diverse polyneuropathy impairments. Polyneuropathy signs (NIS and subscores) correlated with neurophysiology tests, disability, and health scores. Smart Somatotopic Quantitative Sensation Testing of heat as pain 5 provided a needed measure of small fiber involvement not adequately assessed by other tests.ConclusionsSpecially trained neurologists accurately assessed neuropathy signs as compared to referenced neurophysiologic tests. The score, mNIS+7Ionis, broadly detected, characterized, and scaled polyneuropathy abnormality in FAP, which correlated with disability and health scores. Muscle Nerve 56: 901–911, 2017

ABSTRACTIntravenous immunoglobulin [IVIg], plasma exchange [PE], and corticosteroids are efficacious treatment in chronic inflammatory demyelinating polyneuropathy [CIDP]. IVIg is effective in multifocal motor neuropathy [MMN]. NIS, NIS‐weakness, sum scores of raw amplitudes of motor fiber (CMAPs) amplitudes, and Dyck/Rankin score provided reliable measures to detect and scale abnormality and reflect change; they are therefore ideal for office management of response‐based immunotherapy (R‐IRx) of CIDP. Using efficacious R‐IRx, a large early and late therapeutic response (≥ one‐fourth were in remission or had recovered) was demonstrated in CIDP. In MMN only an early improvement with late non‐significant worsening was observed. The difference in immunotherapy response supports a fundamental difference between CIDP (immune attack on Schwann cells and myelin) and MMN (attack on nodes of Ranvier and axons). Muscle Nerve 52: 488–497, 2015

ABSTRACTIntroductionThe Cl. NPhys Trial 3 showed that attributes of nerve conduction (NC) were without significant intraobserver differences, although there were significant interobserver differences. Methods: Trial 4 tested whether use of written instructions and pretrial agreement on techniques and use of standard reference values, diagnostic percentile values, or broader categorization of abnormality could reduce significant interobserver disagreement and improve agreement among clinical neurophysiologists. Results: The Trial 4 modifications markedly decreased, but did not eliminate, significant interobserver differences of measured attributes of NC. Use of standard reference values and defined percentile values of abnormality decreased interobserver disagreement and improved agreement of judgment of abnormality among evaluators. Therefore, the same clinical neurophysiologist should perform repeat NCs of therapeutic trial patients. Conclusions: Differences in interobserver judgment of abnormality decrease with use of common standard reference values and a defined percentile level of abnormality, providing a rationale for their use in therapeutic trials and medical practice. Muscle Nerve 50: 900–908, 2014

ABSTRACTIntroduction: We assessed proficiency (accuracy and intra‐ and intertest reproducibility) of smart quantitative sensation tests (smart QSTs) in subjects without and with diabetic sensorimotor polyneuropathy (DSPN). Methods: Technologists from 3 medical centers using different but identical QSTs independently assessed 6 modalities of sensation of the foot (or leg) twice in patients without (n = 6) and with (n = 6) DSPN using smart computer assisted QSTs. Results: Low rates of test abnormalities were observed in health and high rates in DSPN. Very high intraclass correlations were obtained between continuous measures of QSTs and neuropathy signs, symptoms, or nerve conductions (NCs). No significant intra‐ or intertest differences were observed. Conclusions: These results provide proof of concept that smart QSTs provide accurate assessment of sensation loss without intra‐ or intertest differences useful for multicenter trials. Smart technology makes possible efficient testing of body surface area sensation loss in symmetric length‐dependent sensorimotor polyneuropathies. Muscle Nerve 49: 645–653, 2014

ABSTRACTIntroductionThe aim of this study was to test the proficiency (accuracy among evaluators) of measured attributes of nerve conduction (NC).MethodsExpert clinical neurophysiologists, without instruction or consensus development, from 4 different medical centers, independently assessed 8 attributes of NC in 24 patients with diabetes mellitus (DM) on consecutive days.ResultsNo significant intraobserver differences between days 1 and 2 were found, but significant interobserver differences were seen. Use of standard reference values did not correct for these observed differences.ConclusionsInterobserver variability was attributed to differences in performance of NC. It was of sufficient magnitude that it is of concern for the conduct of therapeutic trials. To deal with interrater variability in therapeutic trials, the same electromyographers should perform all NC assessments of individual patients or, preferably, NC procedures should be more standardized. A further trial is needed to test whether such standardization would eliminate interobserver variability. Muscle Nerve 48: 369–374, 2013

OBJECTIVE To test whether diabetic polyneuropathies (DPNs), retinopathy, or nephropathy is more prevalent in subjects with impaired glycemia (IG) (abnormality of impaired fasting glucose [IFG], impaired glucose tolerance [IGT], or impaired HbA1c [IA1C]) than in healthy subjects (non-IG). RESEARCH DESIGN AND METHODS Matched IG and non-IG volunteers were randomly identified from population-based diagnostic and laboratory registries, restudied, and reclassified as non-IG (n = 150), IG (n = 174), or new diabetes (n = 218). RESULTS Frequency (%) of DPN in non-IG, IG, and new diabetes was 3 (2.0%), 3 (1.7%), and 17 (7.8%) narrowly defined (no other cause for polyneuropathy) and 19 (12.7%), 22 (12.6%), and 38 (17.4%) broadly defined. Mean and frequency distribution of composite scores of nerve conduction and quantitative sensation tests were not significantly different between IG and non-IG but were worse in new diabetes. Frequency of retinopathy and nephropathy was significantly increased only in new diabetes. In secondary analysis, small but significant increases in retinopathy and nephropathy were found in IGT, IFG, and IGT combined groups. CONCLUSIONS In population studies of Olmsted County, Minnesota, inhabitants, prevalence of typical DPN, retinopathy, and nephropathy was significantly increased only in subjects with new diabetes—not in subjects with IG as defined by American Diabetes Association (ADA) criteria of abnormality of IFG, IGT, or IA1C. For atypical DPN, such an increase was not observed even in subjects with new diabetes. In medical practice, explanations other than IG should be sought for patients with atypical DPN (chronic idiopathic axonal polyneuropathy) who have IG.