Understanding patterns of language lateralization and brain health in patients with epilepsy is important as this may inform risk for cognitive decline and prognosis. Despite extensive research characterizing language lateralization in monolingual, English-speaking patients with epilepsy, little is known about language patterns in bilingual patients, and how the organization of multiple languages in the brain may interact with the disease itself. In addition, bilingualism may serve as a proxy for cognitive or brain reserve in dementia, and could also be neuroprotective in epilepsy.

Neuropsychological and neuroimaging (functional and diffusion MRI) data collected from several sites will be reviewed. The patient sample consists of a heterogenous group of bilinguals residing in the United States, with the majority being Spanish-English bilinguals who learned English as a second language.

Compared to monolinguals, bilingual patients showed a more bilateral pattern of fMRI-derived language lateralization in their second-learned language. This was especially true for patients with a left hemisphere seizure focus, though this finding depended on the type of language task used and the region-of-interest studied. In addition, bilingual patients showed evidence of cognitive and brain reserve in white matter networks.

Preliminary studies suggest that bilingualism is associated with functional and structural adaptations in epilepsy. However, this is modulated by linguistic, clinical, and task-related factors. This highlights bilinguliasm as a complex and important factor to consider in presurgical evaluations and invites future fine-grained investigations to constrain neurocognitive models and improve clinical practice.