Two types of electroencephalographic activations were observed in 41 epileptics during sleep and intravenous administration of methohexital sodium. Type 1 was the induction of specific paroxysmal discharges (SPD) in an otherwise normal tracing; it occurred in four patients during sleep and in two patients during methohexital. Type 2 was an increase of 30% or more in the frequency of SPD in a preexisting abnormal tracing; it occurred in 20 patients during sleep and in 15 during methohexital administration.
Type 1 activation improved the sensitivity of electroencephalography as a diagnostic tool by 10%. However, this was achieved mainly with sleep, because whenever methohexital elicited a type 1 response a similar activation had already been obtained during sleep. Methohexital activation shows no further effectiveness than sleep and had little value in the diagnosis of the epilepsies.