Single-fiber electromyography of facial and limb muscles in diabetic patients with or without neuropathy.

PURPOSE: In diabetic patients, single-fiber electromyography (SFEMG) is often abnormal in the limb muscles and is considered unreliable in diagnosis of synaptic disorders. We aimed to compare SFEMG abnormalities of frontalis muscle (FM) and extensor digitorum communis muscle in diabetic patients with neuropathy and without neuropathy.

METHODS: Stimulation SFEMG of FM and extensor digitorum communis muscle was performed in matched groups of 30 diabetic patients with neuropathy and 20 diabetic patients without neuropathy.

RESULTS: Single-fiber electromyography in the FM was abnormal in four diabetic patients with neuropathy and in one diabetic patient without neuropathy. Changes were rather mild. Extensor digitorum communis abnormalities were significantly more frequent-in 20 diabetic patients with neuropathy and in 7 diabetic patients without neuropathy (P < 0.001). We never observed a patient with abnormal FM but normal extensor digitorum communis muscle.

CONCLUSIONS: In diabetes, FM exhibits rare and quite mild SFEMG changes. This muscle may be suitable for SFEMG in diabetic patients with clinical suspicion for synaptic disorder.