Prospective neurometric studies during the beginning of carbamazepine and phenytoin therapy.

We studied 23 epileptic outpatients to assess carbamazepine and phenytoin therapy effects on the peripheral nerve conduction velocity, the electromyogram, and the EEG background activity. Immediately before and 3, 5, 11, 22 months after beginning treatment with 300-800 mg carbamazepine or 200-400 mg phenytoin, the patients were examined with electroneuromyographic and quantified EEG tests. Carbamazepine, phenytoin, folate, and vitamin B12 serum concentration were simultaneously monitored. Clinical signs of intoxication or polyneuropathy were not observed. The mean serum concentrations were 29 mumol/l for carbamazepine and 43 mumol/l for phenytoin. There was little evidence that anticonvulsants' serum concentration at these levels are related to changes in the electroneuromyographic tests or the alpha rhythm.