Abstracts

Rationale: Accurate cognitive testing during the IAP requires full patient participation. Amobarbital-induced drowsiness can preclude adequate testing. Various factors may contribute to such sedation, like posterior circulation filling and individual differences in susceptibility to amobarbital sedative side effects. Psychosocial factors may also be important. Patients may sleep less than usual the preceding night due an early morning wake-up for an early morning IAP. Anxiety over the IAP may cause sleep disruption. Lastly, instructions for no food after midnight may cause patients to miss their usual morning coffee. We present two patients with medically refractory left temporal lobe epilepsy who required IAPs as part of their epilepsy surgery evaluation. Both had IAP sleepiness that prevented adequate testing. IV caffeine was administered to combat IAP drowsiness and allow adequate testing. Methods: A left IAP was planned for the first patient, a 34 year old man. His left internal carotid artery (ICA) angiogram showed perfusion of the left anterior cerebral artery (ACA) and middle cerebral artery (MCA) with a small amount of posterior cerebral artery (PCA) but no basilar artery filling. Injection speed was slowed to 6 seconds to successfully reduce posterior filling. 125mg amobarbital in 10ml saline was injected into the left ICA over 6 seconds. The patient became densely obtunded, non-responsive to pain and unable to be awakened. The patient recovered, and the team decided to wait at least 30 minutes and repeat the injection at a lower dose. The patient was sleeping between injections, and it was discovered he normally drinks caffeinated coffee in the morning. To avoid similar issues of drowsiness with the second injection, 500mg IV caffeine was administered prior to the second IAP. A left IAP was planned for the second patient, a 53 year old female. Her left ICA angiogram showed perfusion of the left ACA and MCA. The PCA was minimally perfused but reduced with a slower injection. 125mg amobarbital in 10ml saline was injected into the left ICA over 9 seconds. Cognitive testing was limited due to extreme drowsiness, requiring continual arousal with loud auditory and physical stimulation. Due to results of baseline memory scores and results of the left IAP, a right IAP was then planned. The right ICA angiogram showed perfusion of the right ACA and MCA with no perfusion of the PCA. To avoid a similar degree of drowsiness during the second IAP, 500mg IV caffeine was given. Results: Upon receiving IV caffeine injection, the first patient went from asleep and snoring to completely awake. Then, 110mg amobarbital in 10ml saline was injected into the left ICA over 6 seconds. No sedation occurred, and cognitive testing was successfully completed. The second patient had a right IAP 45 minutes after the left IAP. 125mg amobarbital in 10ml saline was injected into the right ICA over 7 seconds. Sedation did not interfere with cognitive testing. Conclusions: IV caffeine may be useful in select IAP cases in which drowsiness precludes adequate cognitve testing.