Electrophysiological changes in sensorimotor nerves in diabetes mellitus & usefulness of nerve conduction studies for early diagnosis of diabetic neuropathy

Background: Diabetes Mellitus(DM) a metabolic disorder is the most common cause of peripheral neuropathy. As a result of long term hyperglycemia there is damage to nerves that develops diabetic neuropathy. Nerve conduction studies(NCS) are commonly employed to detect the neuropathy. The present study was undertaken to find out the utility of NCS as an early indicator of neuropathy in diabetic patients. Materials & methods: Study was carried out in 50 diagnosed DM patients attending outpatient department(OPD) in Medicine, Civil Hospital, Ahmedabad. 25 age matched non-diabetic & healthy males were selected for control group. Diabetic patients having FBS>110 mg/dL were selected for studies with duration of DM for more than 5 years. Their glycosylated Hb(HbA1c) levels were measured for glycaemic control. NCS was performed by standard Nerve Conduction Velocity-Electromyography(NCS-EMG) equipment at Institute of Spine, Civil Hospital Campus, Ahmedabad. Nerve conduction parameters like compound muscle action potential(CMAP), sensory nerve action potential(SNAP), nerve conduction velocity(NCV) & distal latency(DL) were studied. Results: In our study there is increase in DL of peroneal & sural nerves in group B subjects. NCV of peroneal, sural, median sensory & ulnar sensory nerves decreases in group B subjects. SNAP of median sensory, sural nerves is decreased in group B & SNAP of sural nerve is decreased in group A also. Datas were summarized with Pearson’s Correlation test, p-value < 0.05 were considered as significant (S), < 0.001 as highly significant (HS) & > 0.05 as not significant (NS). Conclusion: As DM progress further, it increases risk of neuronal involvement which can be accelerated by poor glycaemic control. Our result indicates demyelinating type of neuropathy with some changes of axonopathy. Therefore NCS is done for early detection of neuropathy in DM patients. Key words:Diabetes Mellitus (DM), hyperglycaemia, Nerve conduction studies (NCS), Diabetic neuropathy (DN)