Neuropsychological and linguistic correlates of atypical language lateralization: evidence from sodium amytal studies

The intracarotid injection of sodium amytal is a technique that has been used to determine on which hemisphere language functions depend. Based on use of this technique in a series of patients (n = 99), three groups of patients - one with left hemisphere language lateralization, one right hemisphere language lateralization, and one bilateral language representation - were identified. These three groups were compared in relation to demographic variables, variables related to seizure disorder and neuropsychological variables. Comparisons were also made between the groups on incidence of speech blockage, naming errors and reading errors and on patterns of linguistic breakdown during reading under conditions of left and right amytal perfusion. The nature, potential etiology and effects of atypical (right hemisphere or bilateral) as opposed to the more common left hemisphere language organization are discussed.