Abstracts

We previously reported our experience using etomidate in place of sodium amobarbital for intracarotid speech and memory procedures¹. Using our new etomidate speech and memory test ([italic]e[/italic]SAM), we have solved the problem of frequent shortages of amobarbital, and have also introduced an important change from the traditional intracarotid amobarbital procedure (IAP) in that the anesthetic effect is maintained by infusion after the initial injection. This impacts especially on the memory application of these procedures, because the short duration of the hemianesthesia in IAP often necessitated cautious conclusions about memory when some items were introduced after the drug was no longer active. We report a description of our procedure and a comparison of memory-test outcomes in [italic]e[/italic]SAM vs. those in a retrospective sample of the last 40 patients to undergo IAP in our center before ambobarbital became unavailable in 2003. Our behavioral procedure for [italic]e[/italic]SAM and IAP is the same except for the issues of urgency and timing. We developed it (in 5 versions) based on a 4-year retrospective analysis of our data (259 injections), and tested it in 25 patients without injection to provide [ldquo]norms[rdquo]. Speech tests comprise naming, comprehension, serial speech, spelling, reading and repetition (words, sentences), presented in rotation at two items per task to ensure sampling of all tasks. Memory tests use 24 real objects: 8 before injection, 8 [ldquo]critical[rdquo] items shown beginning 60 sec after injection, and 8 new [ldquo]foil[rdquo] items added to the other 16 for recognition testing. Timing and interpretations from the 49 [italic]e[/italic]SAM tests (26 patients) performed to date are compared with the last 75 IAP tests (40 patients) done at our site. In IAP, [ldquo]critical[rdquo] memory items were shown on average between 90 and 202 sec after injection in dominant-, and between 83 and 160 sec in nondominant-hemisphere tests: on average 3.3 of 7 speech tasks were sampled before memory item presentation began. Rapid return of function according to EEG resulted in 30% of dominant and 25% of nondominant-hemisphere memory tests being interpreted cautiously; speech results were unambiguous. In [italic]e[/italic]SAM we no longer aim for presentation of memory items to begin at 60 sec, but instead present them after all speech tasks have been sampled. Thus, in [italic]e[/italic]SAM, [ldquo]critical[rdquo] memory items were shown between 201 and 326 sec after injection of the bolus in dominant-, and between 201 and 297 sec in nondominant-hemisphere tests. Function did not return before speech and memory had been tested adequately, and unambiguous results were obtained for both. For IAP, our behavioral procedure produced 100% interpretable speech results and 70 to 75% unambiguous memory results. The same procedure using [italic]e[/italic]SAM presents a further advantage by allowing all tasks to be sampled during full anesthesia and without rushing. To date, all [italic]e[/italic]SAM tests have yielded clearly interpretable results.
¹Jones-Gotman et al. [italic]Epilepsia [/italic](2004);[italic]45:[/italic]345.