The sural sensory/radial motor amplitude ratio for the diagnosis of peripheral neuropathy in type 2 diabetic patients.

BACKGROUND AND AIM The diagnosis of peripheral diabetic neuropathy is based on clinical examination. Nerve conduction study (NCS) enables earlier diagnosis, but it is demanding and requires specialised personnel. In an attempt to simplify the procedure, this study aimed to identify a new electrophysiological index, which might correlate with results obtained on standardised NCS in patients with long-standing type 2 diabetes. PATIENTS AND METHODS Medical records of type 2 diabetic patients evaluated for neuropathy by NCS were reviewed retrospectively. This analysis included 104 patients (50 men, 54 women) with a mean age of 67.1±5.5 years and mean diabetes duration of 13.1±2.7 years. NCS was performed on radial, ulnar, sural, and peroneal nerves. Neuropathy was defined as impaired NCS. Ratios of neurophysiological parameters from these nerves were calculated and each of them was compared with diagnosis of neuropathy. RESULTS The sural sensory/radial motor amplitude ratio had the best combination of sensitivity (85%) and specificity (71%) for neuropathy. It also remained the strongest independent predictor of neuropathy in multivariate regression analysis: low levels of this ratio yielded an odds ratio of 7.7 for neuropathy. CONCLUSIONS The sural sensory/radial motor amplitude ratio has a high sensitivity and a moderately high specificity for the diagnosis of neuropathy, low levels being associated with a nearly eightfold increase in the risk for neuropathy. These results encourage further evaluation of this and other electrophysiological indices to enable wider availability of NCS.