Amplitude Comparison between Sural and Distal Sural Nerves in Diabetic Neuropathy

ABSTRACT

OBJECTIVE: Sural nerve conduction study is known to be one of the sensitive tests for detecting neuropathies. In peripheral neuropathy, the distal sural nerve, lateral dorsal cutaneous branch of sural nerve (LDCBSN), may be more easily affected than proximal portion of the sural nerve. To evaluate the clinical application of LDCBSN conduction study and amplitude comparison between sural nerve and LDCBSN in peripheral neuropathy. METHOD: Antidromic conduction studies were performed for sural nerve and LDCBSN and amplitude between two nerve responses were obtained in 30 controls (mean age, 46) and 30 patients with diabetic neuropathy (mean age, 54), but obtainable sural sensory response. The active recording electrodes were placed were placed over the dorsolateral surface at the midpoint of the fifth metatarsal for LDCBSN and posterior aspect of lateral malleolus for sural nerve. The stimulating electrodes were placed 12 cm proximal to the active electrodes in both nerves. RESULTS: LDCBSN response was obtainable in all controls and not obtainable in 7 diabetic patients in whom the amplitude of sural response was less than 5 uV. The amplitude of LDCBSN to sural nerve was approximately 35% in controls and 22% in diabetic patients, which was statistically significant (p=0.00). CONCLUSION: LDCBSN conduction study is sensitive test to detect peripheral neuropathies and amplitude ratio of LDCBSN to sural nerve can be used in the evaluation of peripheral neuropathies.