Electrophysiological evaluation of peripheral nerve in patients with impaired glucose tolerance

Abstract

This study retrospectively reviewed 75 patients with impaired glucose tolerance(IGT)admitted in our hospital from March 2015 to October 2015. All patients underwent Toronto clinical scoring system(TCSS) evaluation. Patients with IGT were further divided into normal score group(TCSS-N, n=50)and abnormal score group(TCSS-A, n=25)according to their scoring results, and 30 healthy volunteers were served as control group. All patients and controls underwent motor and sensory nerve conduction studies, as well as sympathetic skin response(SSR)test using the Keypoint.Net(Medoc Ltd)electromyogram device. The results showed that the SSR amplitude of lower limbs was reduced [(0.61±0.44 vs 1.00±0.33)mv, P<0.05] and latency of lower limbs was extended [(1 880±282 vs 1 642±256)ms, P<0.05]in IGT group compared with control group. But median, ulnar, tibial, and peroneal nerve sensory and motor conduction revealed no difference between two groups. In TCSS-A group, the SSR amplitude of lower limbs was reduced [(0.47±0.39)mv, P<0.05], latency of lower limbs was extended [(2 062±291)ms, P<0.05]and the sensory nerve action potential(SNAP)amplitude of the tibial nerve was significantly lower compared with control group [(1.83±0.37 vs 2.07±0.30)μv, P<0.05]. Compared to TCSS-N group, latency of lower limbs was extended [(2 062±291 vs 1 808±246)ms, P<0.05]in TCSS-A group. The SSR amplitude of lower limbs were reduced[(0.66±0.44)mv, P<0.05]and latency were prolonged(P<0.05)in TCSS-N group compared with control group. Pearson correlation analysis showed that the SSR amplitude and latency of the lower limbs were correlated with the postprandial blood glucose, blood glucose fluctuation, body weight, as well as body mass index. These results suggest that there exists peripheral nerve damage in the patients with IGT, mainly involving the small fiber nerve of the lower limbs. Large fibers may also be mildly affected as the disease progresses. (Chin J Endocrinol Metab, 2017, 33: 574-577) Key words: Peripheral nerve; Impaired glucose tolerance; Nerve conduction; Sympathetic skin response