Jenny L. Davies

Longitudinal assessment of diabetic polyneuropathy using a composite score in the Rochester Diabetic Neuropathy Study cohort

Because there are little satisfactory data on change in severity of diabetic polyneuropathy (DP) over time from study of population-based cohorts of diabetic patients in epidemiologic surveys of DP, it is difficult to predict outcome or morbidity or to identify risk factors; it is also difficult to estimate statistical power for use in controlled clinical trials. In this longitudinal study of almost 200 patients from the Rochester Diabetic Neuropathy Study (RDNS) cohort, we assess which symptoms, clinical examinations, tests, or combinations of examinations and tests (composite scores) are best used as minimal criteria for the diagnosis of DP and as a quantitative measure of severity of DP. An abnormality (≥97.5th percentile) of a composite score that included the Neuropathy Impairment Score of the lower limbs plus seven tests (NIS(LL)+7 tests), was a better minimal criteria for DP than clinical judgment alone or previously published minimal criteria. First, it provided a more comprehensive assessment of neuropathic impairment. Second, it avoided the overestimated frequency of DP when the minimal criteria for DP was any one or two abnormalities from multiple measurements. Minimal criteria using nerve conduction and reduced heart beat response to deep breathing identified approximately twice as many patients with DP than did clinical examination and vibration detection threshold using CASE IV. This difference could be used to subclassify stage 1 DP. Although various individual measures of DP, for example, vibration detection threshold (as evaluated by CASE IV and the 4, 2, and 1 stepping algorithm [see text]), were good measures of worsening, the composite score NIS(LL)+7 tests (assessing neuropathic impairment) was much better at showing monotone worsening. Using this composite score, the average diabetic patient in the RDNS worsened by 0.34 points per year, whereas patients with diabetic polyneuropathy worsened by 0.85 points per year. On the assumption that a therapeutic agent may prevent worsening of DP but not cause improvement, controlled clinical trials of patients with DP would need to be conducted for a period of 3 years to achieve a meaningful change of 2 NIS points (the level of abnormality considered by a Peripheral Nerve Society consensus group to be clinically meaningful).

Individual attributes versus composite scores of nerve conduction abnormality: Sensitivity, reproducibility, and concordance with impairment

Composite scores may be more sensitive and reproducible than single attributes of nerve conduction for detection of peripheral neuropathy, but this requires validation in large patient cohorts. Also, the concordance of individual attributes versus composite scores with clinical measures of severity has not been tested. Here, we study these issues in prospectively studied cohorts: diabetic patients from Rochester, Minnesota (RDNS; n = 396); chronic inflammatory demyelinating polyneuropathy (CIDP) patients (n = 55); and multifocal motor neuropathy (MMN) patients (n = 18). With specificity fixed at the 97.5 percentile, we found that, in generalized polyneuropathies (diabetic and CIDP), composite scores (especially ones including conduction velocity, distal latencies, and F‐waves) of individual or multiple nerves tended to be more sensitive than individual attributes. By contrast, for multiple mononeuropathies, some individual attributes or composite scores of individual nerves were more sensitive than composite scores. In diabetic polyneuropathy, composite scores tended to be more reproducible than individual attributes of nerve conduction. Highly significant correlations were found between individual attributes or composite scores and neurologic impairment in diabetic polyneuropathy and in CIDP; in general, correlation coefficients were higher for composite scores. These correlations were higher for amplitudes than for conduction velocities or distal latencies. We conclude that, with the availability of microprocessors and normative databases, electromyographers may increasingly seek to express nerve conduction abnormality also as composite scores of individual or several nerves. Muscle Nerve 27: 202–210, 2003

Impaired Glycemia and Diabetic Polyneuropathy The OC IG Survey

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.

Electronic case-report forms of symptoms and impairments of peripheral neuropathy

BACKGROUND AND OBJECTIVE For the conduct of controlled clinical trials, epidemiologic surveys or even of medical practice of varieties of peripheral neuropathy, the usefulness, error rate and cost-effectiveness of scannable case-report forms has not been studied. MATERIALS AND METHODS The overall performance, the frequency of the problems identified and corrected, and the time saved from use of a standard paper case report form was evaluated in multicenter treatment trials, single center epidemiologic surveys and in our neurologic practice. The paper case report form (Clinical Neuropathy Assessment [CNA]) for pen entry at study medical centers for patient, disease and demographic information (Lower Limb Function [LLF] and Neuropathy Impairment Score [NIS]) can be faxed to a core Reading and Quality Assurance Center where the form and data is electronically and interactively evaluated and corrected, if needed, by participating medical centers before electronic entry into database. OBSERVATIONS AND CONCLUSIONS 1) The approach provides a standard, scannable paper case report form for pen entry of neuropathy symptoms, impairments and disability at the bedside or in the office which is retained as a source document at the participating medical center but a facsimile can be transferred instantaneously, its data can be programmed, interactively evaluated, modified and stored while maintaining an audit trail; 2) it allowed efficient and accurate reading, transfer, analysis, and storage of data of more than 15,000 forms used in multicenter trials; 3) in 500 consecutive CNA evaluations, software programs identified and facilitated interactive corrections of omissions, discrepancies, and disease and study inconsistencies, introducing only a few readily identified and corrected entry errors; and 4) use of programmed, as compared to non-programmed assessment, was more accurate than double keyboard entry of data and was approximately five times faster.

No Evidence for Axonal Atrophy in Human Diabetic Polyneuropathy

In rats with streptozin-induced diabetes mellitus, the caliber of distal myelinated fiber (MF) axons in relation to the number of myelin lamellae is smaller than in controls. This finding usually has been attributed to axonal atrophy, but shrinkage or maldevelopment has also been considered. For human diabetic polyneuropathy (DP), axonal atrophy has been assumed by some investigators, but convincing evidence has not been demonstrated. We morphometrically evaluated transverse sections of 33 sural nerves from carefully evaluated diabetic patients ≥ 30 years old without (8 patients) or with (25 patients) DP and compared them with 24 nerves from healthy subjects ≥ 30 years old. Nerves from diabetic patients and controls were obtained under identical conditions and processed and evaluated in the same way, using an observer blind to the disease condition. Using computer digitization of electron micrographs, we evaluated the axonal area, perimeter, index of circularity, number of myelin lamellae, and frequency of adaxonal sequestration of 50.4 (mean) ± 5.8 (SD) MF per sural nerve for healthy subjects and diabetic patients ≥ 30 years old. The regression lines of the natural log (In) of axonal area on number of myelin lamellae of diabetic patients (with or without DP) were not significantly different from the regression lines of nerves of healthy subjects for large MFs—the most reliable group in which to recognize atrophy. Likewise, the regression lines of index of circularity (IC) (an index that is decreased with atrophy or shrinkage) on number of myelin lamellae for large fibers was not significantly different between the disease and control groups. The rate of adaxonal sequestration was not significantly higher in DP than in healthy subjects. These results do not support the hypothesis that axonal atrophy occurs in human DP. For small MF. or all MF. some significant differences in regression lines of In axonal area or IC on number of lamellae were found, but these changes are probably explained by events of remyelination and axonal regeneration, which can affect these relationships and are known to occur in DP.

A trial of proficiency of nerve conduction: greater standardization still needed.

The aim of this study was to test the proficiency (accuracy among evaluators) of measured attributes of nerve conduction (NC).

Epidermal nerve fibers Confidence intervals and continuous measures with nerve conduction

ABSTRACT Objectives: Our first objective was to explore the value of estimating 95% confidence intervals (CIs) of epidermal nerve fibers (ENFs)/mm for number of sections to be evaluated and for confidently judging normality or abnormality. Our second objective was to introduce a new continuous measure combining nerve conduction and ENFs/mm. Methods: The 95% CI studies were performed on 1, 1–2, 1–3 - - - 1–10 serial skip sections of 3-mm punch biopsies of leg and thigh of 67 healthy subjects and 23 patients with diabetes mellitus. Results: Variability of differences of ENFs/mm counts (and 95% CIs) from evaluation of 1, 1–2, 1–3 - - - 1–9 compared with 1–10 serial skip sections decreased progressively without a break point with increasing numbers of sections evaluated. Estimating 95% CIs as sections are evaluated can be used to judge how many sections are needed for adequate evaluation, i.e., only a few when counts and 95% CIs are well within the range of normality or abnormality and more when values are borderline. Also provided is a methodology to combine results of nerve conduction and ENFs/mm as continuous measures of normality or abnormality. Conclusion: Estimating 95% CIs of ENFs/mm is useful to judge how many sections should be evaluated to confidently declare counts to be normal or abnormal. Also introduced is a continuous measure of both large-fiber (nerve conduction) and small-fiber (ENFs/mm) normal structures/functions spanning the range of normality and abnormality for use in therapeutic trials.

Proficiency of nerve conduction using standard methods and reference values (cl. NPhys Trial 4)

The 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

Assessing mNIS+7Ionis and International Neurologists' Proficiency in an FAP Trial.

Polyneuropathy 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.

Assessing mNIS+7Ionis and international neurologists' proficiency in a familial amyloidotic polyneuropathy trial

Polyneuropathy 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.