Sural nerve conduction velocity and refractory period in diabetics without clinical signs of neuropathy.

Twentysix patients aged 22-76 years with a duration of diabetes of 1 month to 23 years but without signs of symptoms of a peripheral nerve disease were studied. The nerve conduction velocity, the amplitude of the compound action potential and its restitution during the relative refractory period were examined in sural nerves. Nerve conduction velocity of the motor fibers were determined in the median, ulnar, tibial, and peroneal nerves. A reduced conduction velocity in motor nerves of the lower extremities were found in 10%, a reduced sensory nerve conduction velocity in 25%, and pathological changes of the refractory period in 50% of the patients. It is concluded that the determination of the relative refractory period can be used as a sensitive test in the early diagnosis of diabetic neuropathy.