Clinical significance of the double-peak sensory response in nerve conduction study of normal and diabetic patients.

OBJECTIVE

The aim of this study was to understand the meaning of the double-peak responses in digital nerve conduction study in normal and diabetic patients.

DESIGN

This was a cross-sectional and correlative study. Sixty healthy subjects (10 people per decade from 20 to 79 yrs of age; 26 men; mean age, 48 yrs) and 60 diabetic patients (10 people per decade from 22 to 79 yrs of age; 36 men, mean age, 53 yrs) were included. The composite score of the nerve conduction study was obtained. Orthodromic sensory nerve conduction studies were performed on the median nerves using submaximal stimulation. The latencies and amplitudes of first and second peaks were measured. The Toronto clinical scoring system for diabetic neuropathy was applied to all diabetic patients.

RESULTS

The first and second peak latencies of both 3- and 4-cm interpeak distance in diabetic patients were significantly increased compared with those of age-matched control subjects (P < 0.05). The correlation between the Toronto clinical scoring system and first and second peak latency and amplitude were significantly high, and the correlation between the composite score and first and second peak latency and amplitude was also related.

CONCLUSIONS

The double-peak response represents the far distal nerve pathophysiology. The authors suspect that they will find an increasing role in diagnosing the peripheral neuropathy, which starts at the distal nerve in centripetal pattern.