Alternatives to Sodium Amobarbital in the Wada Test

Abstract

Objective: To review the literature and identify alternatives to sodium amobarbital for use in the Wada test. Data Sources: A search of PubMed (1960-October 2010) was performed using the following key words alone or in combination: Wada test, intracarotid amobarbital procedure, intracarotid, intraarterial, sodium amobarbital, methohexital, Brevital, pentobarbital, etomidate, propofol, and alternative anesthetics. References of the identified articles were reviewed for relevant information. Study Selection and Data Extraction: All articles in English identified from the data sources were evaluated. Review included comparative, prospective, and retrospective studies along with case series and case reports. Data Synthesis: Methohexital, pentobarbital, etomidate, and propofol have all been studied as alternatives to sodium amobarbital in the Wada test. Four controlled experimental trials, 1 uncontrolled experimental trial, 6 retrospective chart reviews, and 2 case reports were reviewed. Methohexital, pentobarbital, and propofol required a second injection due to their short duration of action. Etomidate was studied as a bolus injection followed by a continuous infusion until the critical speech and memory tests were administered, which differed from the standard Wada test procedure. Patients had an increased risk of seizures with methohexital, whereas 1 patient developed transient respiratory depression immediately after receiving pentobarbital. Furthermore, propofol caused increased tone with twitching and rhythmic movements, which interfered with the completion of the Wada test for 1 patient. All authors concluded that these agents were equivalent to amobarbital for the Wada test. Conclusions: Methohexital, pentobarbital, etomidate, and propofol are viable alternatives to sodium amobarbital for use in the Wada test, but each has shortcomings.