Abstract
Background: Ictal and postictal language dysfunction is common and strongly predictive of language laterality in monolingual patients. For bilingual patients, selective dysfunction has been reported for a single language with focal cerebral lesions, electrical brain stimulation, and intracarotid sodium amytal.
Methods: Two right-handed Ukrainian-English bilingual patients with left perisylvian structural lesions, late onset complex-partial seizures, and postictal aphasia for English are presented and discussed with regard to mechanisms of selective aphasia and factors contributory to language lateralization in bilingual patients.
Results: Ukrainian was the native language of both patients with English acquired after 7 years of age. Regular/video-EEG showed left temporal epileptogenesis. A 56-year-old man, who had a left hemorrhagic stroke at age 50 and had not spoken Ukrainian for 40 years, was unable to speak English for similar to 20 minutes postictally but had global preservation of Ukrainian. A 71-year-old woman, who had a left temporal epidermoid cyst and had not spoken Ukrainian since childhood, had 10- to 15-minute postictal expressive aphasia in English but not Ukrainian and preservation of comprehension in both languages.
Conclusions: These cases are instructive and consistent with the literature on cerebral organization of language in bilingual individuals. For both patients, postictal aphasia with preservation of Ukrainian is consistent with findings from clinical and experimental studies indicating that later age of second language acquisition (> 6 years) rather than language proficiency is a primary factor in language laterality. Second, global aphasia in the man with a late lesion vs expressive aphasia with preservation of comprehension of English in the woman with a prenatal/early lesion is consistent with the atypical language laterality described for individuals with left-sided lesions sustained prior to age 5. Although neither Wada test nor fMRI was done to assure left hemisphere laterality of spoken Ukrainian and English, this is probable, and the selective postictal aphasia observed for both patients is consistent with the differential intrahemispheric organization reported for the two languages of bilingual individuals. Possible mechanisms of selective postictal aphasia, e. g., active inhibition, and differences in language networks in bilingual patients are discussed.