[Effect of phenytoin on peripheral motor neurons]

The author reports the results of investigations on the effect of Phenytoin Polfa on the peripheral motor neuron in relation to the serum drug levels. The investigated group included 42 epileptics treated for 7 to 30 years with phenytoin in daily doses of 300--400 mg. In all cases neurological examination was done, the serum phenytoin level was determined, basic EMG investigation, conduction velocity measurement in motor fibres of peripheral nerves, and stimulation test for disclosing myasthenic fatiguability were performed. In the conclusion the author states that phenytoin in the doses used caused no changes in conduction velocity in the motor fibres. Changes suggesting possible lesion of the peripheral motor neuron were found in only 7.1% of basic EMG records. Evidence of fatiguability in stimulation test was found in 28.6% of cases, they were not correlated with the serum drug level duration of treatment, subjective changes and objective findings.