Peripheral neuropathy caused by antiepileptic drugs. Neurophysiological study of the A δ and C fibers

The risk that antiepileptic drugs may cause damage to the peripheral nervous system led us to investigate 12 patients on carbamazepine and 12 patients on phenobarbital with the thermal threshold test. The heat and cold thresholds were measured at the ankle and wrist and, compared with those in 30 healthy subjects, they proved to be significantly higher. When the two groups of epileptics were compared separately with the controls, their thresholds were always higher. These findings are consistent with a toxic effect of both drugs on fine peripheral nerve fibers.