Midazolam and somatosensory evoked potentials.

The effect of intravenous midazolam on the somatosensory evoked potentials (SEP's) elicited from median nerve stimulation was investigated in a study on 20 volunteers. SEP's were recorded from contralateral scalp before and at 5, 30, and 60 min after drug administration. Relative amplitudes of the early components (N18-N20) were essentially stable, while relative amplitudes of the late components (N50-P90, P90-N160, N160-P250 and P250-N380) were reduced significantly after midazolam administration and had not returned to baseline 60 min after administration. Given the correlation between late SEP amplitude and subjective reports of experimental pain, the data support the possibility that administration of midazolam in conscious sedation doses may have some effect on pain in addition to its better documented sedative and amnesic properties.