Etomidate speech and memory test (eSAM): a new drug and improved intracarotid procedure

The intracarotid amobarbital procedure (IAP) is an important part of comprehensive investigation of patients who are candidates for surgical treatment of epilepsy. Owing to repeated and lengthy shortages of amobarbital, causing delays in elective surgery, attempts have been made to find a suitable alternative anesthetic. The authors report their experience using etomidate, a widely used agent for the induction of anesthesia.

Sixteen consecutive patients requiring IAP to evaluate memory or to lateralize speech underwent the procedure using etomidate. Prior to the procedure a catheter was placed in the internal carotid artery and an angiogram was performed. EEG was recorded and read online by an electroencephalographer. An anesthetist injected the drug, administered by bolus followed by an infusion, which was maintained until each speech measure had been sampled and new memory items had been introduced. The infusion was then stopped and testing continued as in a standard IAP.

In all cases (30 hemispheres) contralateral hemiplegia followed injection. EEG slow waves were observed in every injected hemisphere, with some contralateral slowing anteriorly in 18. Global aphasia with preserved attention and cooperation followed dominant-hemisphere injections. These phenomena remained during infusion, and upon its termination returned gradually to baseline over a period of about 4 minutes.

Etomidate is a viable alternative to amobarbital, and its administration by bolus followed by infusion offers an improvement over the traditional intracarotid amobarbital procedure. Cognitive tests can be performed during an assured hemianesthesia of the injected hemisphere.