Median and Ulnar Nerve Conduction Measurements in Patients with Symptoms of Diabetic Peripheral Neuropathy Using the NC-Stat®System

Abstract

Diabetic peripheral neuropathy (DPN) is a common, disabling, and costly complication of diabetes mellitus. Although there are multiple methods for detecting and monitoring DPN, nerve conduction studies (NCS) are generally considered to be the most sensitive and reproducible. However, utilization of NCS in patients with diabetes is low, presumably because of limited access and economic issues. Advanced point-of-service NCS systems, already widely used in the assessment of entrapment neuropathies, may address these issues in the arena of diabetes. Seventeen patients with diabetes and clinical evidence of neuropathy were enrolled in the study. NCS were performed using the NC-stat nerve conduction testing system (NEUROMetrix, Inc., Waltham, MA) and compared against results from a neurologist-supervised study using a standard electromyography system, which was considered the reference method. Results for ulnar and median distal motor latencies (DMLs) and F-waves, obtained by both methods, were compared with each other. The NC-stat measurements were also compared with a historical control population. A high correlation between the two methods of NCS assessment was demonstrated. The Pearson correlation coefficients between the NC-stat system and the reference measurements were 0.96 (DML) and 0.89 (F-wave latency) for the median nerve and 0.70 (DML) and 0.78 (F-wave latency) for the ulnar nerve. Significant differences were observed between the NC-stat and reference median (P < 0.001, paired t test) and ulnar (P < 0.05, paired t test) nerve DMLs. F-wave latencies did not demonstrate significant differences (P > 0.05, paired t test). The rate of abnormalities ranged from 17.7% for the median nerve DML to 26.7% for the ulnar nerve F-wave latency. The rate of upper extremity nerve involvement in DPN according to a case definition requiring both median and ulnar nerve abnormalities was 25.0%. The rate of median neuropathy at the wrist, which is the second most common neuropathy in individuals with diabetes, was 17.6%. NC-stat-based NCS of the median and ulnar nerves provide results similar to those obtained with traditional neurologist-supervised NCS using a standard electromyography system. The number of subjects meeting electrophysiological criteria for DPN, affecting the upper extremities, is similar to prior studies. The widespread availability of the NC-stat system may provide a robust and objective method for identifying DPN and other neuropathies in patients with diabetes.