초기 당뇨병성 다발신경병증에서 비복/척골 감각신경활동전위 진폭 비의 진단적 유용성

The Usefulness of Sural/Ulnar Amplitude Ratio in the Diagnosis of Early stage of Diabetic Polyneuropathy

Backgrounds and Objectives: In the length-dependent axonal polyneuropathy like diabetic polyneuropathy (DPN), the distal part of the longer axons are affected earlier. In cases of minimal distal axonal changes, nerve conduction studies (NCS) are frequently normal. If sural nerve is affected in the early stage of DPN, supportive parameters to detect the early axonal degeneration may be helpful. We investigated whether the sural/ulnar SNAP amplitude ratio (SUAR) may be a more sensitive indicator than sural amplitude alone in the diagnosis of early diabetic polyneuropathy. Methods: We analyzed medical records and electrophysiological studies of 141 patients with DM and 30 healthy subjects. The patients with early stage of DPN were defined as those having symptoms of neuropathy and normal NCS findings among the patients with DM. We compared SUAR between 57 patients with early stage of DPN and 71 agematched control subjects. Results: Fifty seven patients had an average SUAR of 0.8, compared to that of 1.1 in the 71 normal controls. The SUAR of less than 0.9 was supplementary predictor of axonal polyneuropathy, with the best balance of sensitivity and specificity (70%). The SUAR did not vary significantly with age, height or duration of DM. Conclusions: We conclude that the SUAR is a useful electrodiagnostic indicator to detect early stage of DPN.