AUTONOMOUS VERSUS DEPENDENT - A CLASSIFICATION OF BILATERAL LANGUAGE REPRESENTATION BY INTRACAROTID AMOBARBITAL PROCEDURE

Many studies have reported and analyzed the results of the intracaroti d amobarbital procedure (IAP). Our study objective was to investigate bihemispheric language representation. We retrospectively reviewed the results of 165 IAPs performed in the evaluation of candidates for epi lepsy surgery. Language function was assessed primarily by the duratio n of speech arrest. Three different sets of criteria were used: absolu te duration, side-to-side difference, and laterality index. Only subje cts whose dominance for language was classified as bilateral by two of the three methods were considered bilateral. There were 126 (76%) pat ients with language representation only in the left hemisphere, and 20 (12%) had language representation only in the right. Nineteen patient s (12%) had evidence of speech in both hemispheres. Of these 19, 10 de monstrated return of speech soon after each injection; the remaining 9 patients demonstrated prolonged speech arrest after both injections. We conclude that two distinct patterns of bilateral language represent ation may exist: one in which each hemisphere is dependent on the othe r (''bilateral dependent'') and one in which each hemisphere can suppo rt language independently (''bilateral autonomous'').