Quantitative sensation testing in small-diameter sensory fiber neuropathy.
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Humans↗
Biomedical subjects
Peter J Dyck
Publications and source records attributed to Peter J Dyck.
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.
Canada↗
Clinical versus quantitative vibration assessment: improving clinical performance.
In 3 large cohorts (total of 787 patients), clinical vibration impairment (CVI) of the great toe using a tuning fork was compared with quantitative vibration threshold (QVT). Using a stepwise multivariate analysis, we assessed demographic and anthropomorphic patient characteristics associated with the difference between CVI and QVT for the various cohorts and the chosen QVT ranges of percentile abnormality. We also compared CVI or QVT abnormality with a composite score of nerve conduction abnormality to confirm that QVT is a valid measure of severity of neuropathy. Highly significant associations between CVI and QVT were found in all 3 cohorts studied, regardless of the chosen QVT percentile level of abnormality. However, in the 2 cohorts evaluated by many different physicians, CVI overestimated QVT much more often than underestimated it. The discordance between CVI and QVT in all QVT abnormality percentile levels was associated with age, height and body surface area (BSA) in 1 cohort, with age and BSA in another cohort, and with age in the third cohort. In the third cohort, the correlation between QVT and the composite score of nerve conduction abnormality was significantly higher than the correlation between CVI and the composite score. Using a tuning fork, neuromuscular physicians overestimate vibration sensation loss more often than when QVT testing is done, which employs quantitative stimuli, a broad range of stimulus magnitudes, null stimuli, validated algorithms of testing and validated reference values. To improve assessment of vibration sensation, physicians should take into account age, height and weight (or body surface area) when judging vibration abnormalities. Applying some useful approaches to quantitative sensory testing might improve the accuracy of clinical sensory testing.
Adult↗
Double-blind, placebo-controlled study of the application of capsaicin cream in chronic distal painful polyneuropathy.
We have completed a 12-week double-blind, placebo-controlled randomized study on the efficacy of the application of capsaicin (CAPS) cream (0.075%) in the treatment of chronic distal painful polyneuropathy. Forty patients were enrolled and 39 completed the study. The 2 limbs were randomly assigned to CAPS or placebo (PLAC). The cream was applied 4 times a day. The first tube contained the active PLAC, methyl nicotinate. In the final 4 weeks (single-blind wash-out phase), PLAC was administered bilaterally. Efficacy was evaluated using the following scales: (1) investigator global, (2) patient global, (3) visual analog (VAS) of pain severity, (4) VAS of pain relief, (5) activities of daily living, and (6) allodynia. Patients were examined at onset and at monthly intervals using a neurologic disability scale, nerve conduction studies, computer-assisted sensory examination for vibration and thermal cooling and warming, QSART (quantitative sudomotor axon reflex test) and quantitative flare response. There was no statistical evidence of efficacy of CAPS cream over PLAC for any of the pain indices. At early time points (1-4 weeks), there were a small number of indices that favored the PLAC. The percent of limbs that improved on the investigator's global scale were 51.3 vs. 53.8 at 4 weeks, 56.4 vs. 64.1 at 8 weeks and 59 vs. 66.7 at 12 weeks for CAPS vs. PLAC; no statistically significant difference was found. All the safety indices showed no difference between sides. We interpret the early hyperalgesia on the CAPS side as being responsible for the better performance of PLAC at early time points. The large percentage of limbs that improved may be a pronounced PLAC response.
Adult↗
Effects of duration of type 2 diabetes mellitus on insulin secretion.
OBJECTIVE: To gain insight into the effects of duration of type 2 diabetes on insulin secretion in patients with type 2 diabetes mellitus. METHODS: C-peptide concentrations were measured every 2 years before and after intravenous injection of 1 mg of glucagon in 89 patients with type 2 diabetes (51 men and 38 women) as part of the Rochester Diabetic Neuropathy Study in those subjects who participated in follow-up (median, 12 years; range, 6 to 14). RESULTS: Although insulin secretion decreased over time (P<0.001) in the group as a whole, both the pattern and the rate of decline in C-peptide concentration differed considerably among the study subjects. Insulin secretion, whether measured as fasting C-peptide, 6-minute C-peptide, or postglucagon increment in C-peptide concentrations, declined with increasing duration of diabetes in approximately half of the patients but either increased or remained essentially constant over time in the other half. The decrease in insulin secretion was not associated with a deterioration in glycemic control because hemoglobin A1c also declined (P<0.005) during the same interval. CONCLUSION: We conclude that insulin secretion decreases over time in many patients with type 2 diabetes. Because the rate of decline is variable, the predictive value of any single measurement is limited. These data indicate that although a decrease in insulin secretion over time is characteristic of type 2 diabetes mellitus, it is not inevitable.
Blood Glucose↗