Objective: To study the clinical and electrophysiological features of diabetic peripheral neuropathy in 700 patients to elucidate the relationships between them and evaluate the value of electromyography in the diagnosis of diabetic peripheral neuropathy.
Methods: Standard sensory and motor nerve conduction studies were performed in the 700 patients, sensory nerve conduction velocity (SCV), amplitude of sensory nerve action potential (SNAP), distal motor latency (DML) and amplitude of compound muscle action potential (CMAP) of median nerve, ulnar nerve, posterior tibial nerve and common peroneal nerve were studied simultaneously. Needle electromyogram (EMG) test was performed in 239 patients.
Results: (1) The most common symptoms of peripheral neuropathy were numbness and pain in limbs, while impaired or lost tendon reflexes were the most common abnormal signs in lower limbs. (2) The abnormal rate of nerve conduction studies was 72.4% in the 700 patients. Slow SCV, prolonged DML and decreased amplitude of SNAP and CMAP were detected. (3) More severe abnormal nerve conduction was found in lower limbs than in upper limbs. The abnormal degree was more severe in sensory nerve than in motor nerve and severity was more in amplitude than in conduction velocity (P < 0.05). (4) Abnormal motor and/or sensory nerve conduction was detected in 67.3% of the patients with clinical manifestations of neuropathy and 5.1% patients without signs or symptoms of neuropathy, while motor or sensory nerve conduction was normal in 27.6% patients with manifestations of neuropathy. Needle EMG showed neurogenic lesion in 4.6% of the patients with normal motor and sensory nerve conduction. (5) polyneuropathy is the most common type of diabetic neuropathy and carpal tunnel syndrome the next.
Conclusions: The most common clinical and electrophysiological manifestation of diabetic neuropathy is sensory disturbance, which is more severe in lower limbs. The electrophysiological changes are not always accordant with clinical manifestations. Subclinical diabetic peripheral neuropathy can be detected by electrophysiological tests, which are useful to verify the range and extent of the nerve lesion involved in the early stage of diabetic peripheral neuropathy. Needle EMG is not recommended for screening diabetic neuropathy.