The Clinical Usefulness of Current Perception Threshold in Diabetic Neuropathy

ABSTRACT

OBJECTIVE: To evaluate the clinical usefulness of current perception threshold (CPT) test in diagnosing the diabetic neuropathy. METHOD: We have recorded the neuropathic symptom score (NSS), CPT and the parameters of nerve conduction study (NCS) in 45 patients with diabetes. NSS was calculated according to the clinical symptom and signs, and the score more than 3 was regarded as abnormal (neuropathic). CPT was measured at the 2nd finger and 1st toe delivering the three different frequencies (2000, 250 and 5 Hz) of current and conventional NCS were performed at the median, peroneal motor and sural nerves. All the patients were assigned to three groups according to the result of NSS and NCS; group A, abnormal NSS and NCS; group B, abnormal NSS only; group C, normal NSS and NCS. CPT was compared between groups, and we investigated the correlation between CPT and NSS, and parameters of NCS. Also the sensitivity and specificity of CPT test were calculated. RESULTS: The mean CPT was significantly increased in the entire diabetic groups as compared with control group (p<0.05). CPTs measured by 2000 Hz stimulation at the finger and toe were positively correlated with the most parameters of NCS (p<0.05), and CPT was more highly correlated with NCS (p<0.05) than NSS. The sensitivity and specificity of the CPT were 94.1% and 10.7%, respectively. CONCLUSION: The CPT test may have added value in diagnosing the diabetic neuropathy as a screening.