Acute effects of diphenylhydantoin on peripheral and central somatosensory conduction.

We studied the acute effects of an intravenous loading dose of DPH (16 mg/kg body weight) on peripheral and central somatosensory conduction in 10 normal volunteers. Somatosensory evoked potentials were recorded before and at regular intervals after DPH infusion. There was no effect on peripheral conduction. DPH significantly delayed N13 peak latency without changing conduction in the posterior spinal columns. Although the N13-N20 interpeak interval remained stable because of the parallel shift of the 2 peaks, the central conduction time measured from onset latencies of N11 and N20 significantly increased. We conclude that acute administration of DPH at serum levels below 30 micrograms/ml induces a reversible delay of synaptic transmission in spinal and central somatosensory structures.