The intraarterial amytal procedure (IAP) is used to assess hemispheric
support for language and memory. The test requires producing hemianes
thesia without rendering the patient unconscious. We retrospectively s
tudied factors that relate to undersedation and oversedation in the LA
P in 52 patients. Initial amytal dose was 125 mg. To reduce angiograph
ic risk, injections were performed only ipsilateral to the side of pla
nned surgery unless injection results were unclear. Overall, 31% of pa
tients were judged to be ''undersedated'' due to excessively brief dur
ation of amytal response; 15% were ''oversedated'' to the point of ina
ttentiveness or unconsciousness during the test. Patients with mesial
temporal sclerosis (MTS) manifest on magnetic resonance imaging (MRI)
were more than twice as likely to have excessive sedation as compared
with patients with normal MRI results or with lesions. All patients wi
th mixed dominance were oversedated (100%), and patients with nondomin
ant injection were less Likely to be oversedated (4%) than patients wi
th dominant injections (14%). Patients with Full-Scale IQ (FSIQ) <80 w
ere more likely to be oversedated. Presence of angiographic cross-fill
ing did not relate to degree of sedation. Sedation level did not predi
ct surgical outcome. Knowledge of these factors may enable planning to
help avoid ineffective injections and increase patient safety. (C) 19
97 by Elsevier Science Inc.