Pathophysiologic Approach by Proximal Peroneal Nerve Conduction Study in Diabetic Neuropathy

ABSTRACT

BACKGROUND AND OBJECTIVES: Diabetes mellitus is known as a common cause of peripheral neuropathy. However, there is a continuous argument about the pathophysiologic mechanism of diabetic polyneuropathy axonal degeneration versus segmental demyelination. We studied the patients with diabetic polyneuropathy by peroneal nerve conduction study using identical segments recording from proximal and distal peroneal muscles. METHODS: We studied 18 diabetic patients who were confirmed to have diffuse symmectrical sensorimotor polyneuropathy by conventional nerve conduction study. We also studied 18 healthy subjects. We measured peroneal motor conduction velocities across the same nerve segment, recording from proximal and distal muscles in both lower extremities. Compound muscle action potentials(CMAP) were simultaneously recorded from extensor digitorum brevis(EDB) and tibialis anterior(TA) muscles using the tendon-belly method. RESULTS: There was no significant difference in conduction velocities recorded from proximal and distal muscles in healthy subjects(EDB 50.5 m/s, TA 53.3 m/s). However, in patients with diabetic polyneuropathies, there was a significant decrease in conduction velocity obtained from distal recording, compared with that from proximal recording(EDB 36.8 m/s, TA 47.0 m/s, p<0.05, paired t-test). CONCLUSION: These results of proximal peroneal nerve conduction study are considered as another supporting evidence that axonal degeneration is the main pathomechanism of diabetic polyneuropathy.