Quantitative vibration perception thresholds in patients under prolonged antiepileptic treatment

Quantitative vibration perception threshold (VPT) measurements were performed on 134 healthy subjects and 147 epileptics undergoing prolonged (more than one year) antiepileptic treatment, 28 patients received diphenylhydantoin, 71 carbamazepine and 11 some other drug. 37 subjects received a combination of drugs, which included diphenylhydantoin and/or carbamazepine. VPT was measured quantitatively at the dorsum of the right foot with a device vibrating at 100 Hz. The mean of the four successive threshold values was calculated. VPTs of the epileptic groups treated with diphenylhydantoin, carbamazepine or combined medication were all significantly (P less than 0.001) higher than those of the control group. The group receiving other medication showed no difference in this respect. The percentage of patients with abnormal thresholds was about the same (10-16) in the epileptic groups. An exception was the group taking other medication, in which no abnormal VPTs were found. It is suggested that such quantitative measurement may be a useful screening method for detecting dysfunction in the peripheral nervous system due to prolonged antiepileptic treatment. It will, however, be necessary to test the clinical validity of the method for diagnosing manifest or subclinical polyneuropathies.