Electrophysiologic Study Of Carpal Tunnel Syndrome In Patients With Diabetes Mellitus

Background: Carpal tunnel syndrome (CTS) is one of the most common compression-entrapment neuropathy, and type 2 diabetes mellitus(T2DM) is one of the predisposing causes of CTS.Electrophysiologic test has been used as a routine test in patients with T2DM. In the course of examination, selective injury to median nerve at wrist (CTS) has been found in patients with T2DM.Objective: 1.To investigate the positive rate of carpal tunnel syndrome(CTS) in patients with type 2 diabetes mellitus(T2DM), and the relationship between CTS and the relative factors( age, sex and course) in patients with T2DM. 2.to investigate the electrophysiologic characteristics of CTS with T2DM.3. To investigate the value of early diagnosis of CTS in patients with T2DM with the method of electrophysiologic test. Methods: Oxford EMG/EP instrument was used. 1036 patients with T2DM were examined with routine nerve conduction velocity (NCV) and needle electromyography (EMG) test. In upper limbs, motor and sensory nerve conduction velocities were tested in median, ulnar and radial nerves. In lower limbs, sensory nerve conduction velocities(SCV)were tested in sural nerves, motor nerve conduction velocities(MCV) were tested in tibial nerves. The measurement indexes were MCV, SCV, distal motor latency(DML), compound muscle action potential(CAMP), sensory nerve action potential(SNAP). The indexes in median nerve were MCV from elbow to wrist, DML from wrist to abductor pollicis brevis muscle (APB), CAMP in APB,SCV from digitI to wrist and from digitIII to wrist, and its SNAP, spontaneous activity in APB. The normal value referred to thestandard range of our electrophysiologic Laboratory. The standard value is mean±2sd. Statistical analysis: SPSS11.5 software was used in Statistical analysis. X2 test was used in counting data. P<0.05 was considered Statistically significant.Results: 1.With electrophysiologic test, 112 cases were diagnosed as CTS from 1036 cases of patients with T2DM, the positive rate was 10.8%(112/1036). These cases showed some clinical manifestations of CTS which was called clinical CTS. Male to female ratio was 1to2.0. The positive rate of CTS in female was significantly higher than that in male(P<0.05).The positive rate of CTS was increased with the course time(P<0.05), and it had no relationship with age(P>0.05). 2.The main electrophysiologic characteristics of CTS with T2DM were slowed SCV and reduced SNAP in median nerve below wrist. prolonged DML and reduced CAMP were the second electrophysiologic characteristics. The positive rate in median sensory nerve was higher than that in median motor nerve(P<0.05). 3. With electrophysiologic test,113 cases were diagnosed as CTS from 1036 cases of patients with T2DM, the positive rate was 10.9%(113/1036). These cases never showed any clinical manifestations, such cases was called subclinical CTS.Conclusion: 1.There was higher positive rate of CTS in patients with T2DM,and female was more vulnerable than male.The longer the course of T2DM,The more possibility complicating with CTS. 2. The electrophysiologic characteristics of CTS in patients with T2DM showed that sensory nerve was affected first, and then the motor nerve when median nerve was compressed at wrist.3. subclinical CTS can be found in patients with T2DM through electrophysiologic test, so there were a great value in early diagnosis of CTS in patients with T2DM with the method of electrophysiologic test.