Neurolinguistic and follow-up study of an unusual pattern of recovery from bilingual subcortical aphasia

Abstract

We report on the neuropsychological and neurolinguistic features of a bilingual patient, E.M., who presented with an uncommon pattern of aphasic deficit consequent to subcortical lesions mainly involving the left basal ganglia. Not only are reports of bilingual subcortical aphasia rare, but E.M.'s deficit is particularly uncommon for it concerns the most used mother tongue (Venetian) much more than a less practiced second language (standard Italian). In this patient, the linguistic deficit in mother tongue production has been observed in spontaneous speech and in cross language translation tasks, where an asymmetrical paradoxical performance has been revealed. Indeed, unlike neurologically intact subjects, E.M. has more difficulties when translating into her mother tongue than into her second language. Although E.M.'s mother tongue is prevalently an oral language, the asymmetrical translation pattern is similar in written and oral translation tasks, thus ruling out the possibility that the deficit simply reflects differences between written and oral language codes. Finally, another remarkable feature of E.M.'s impairment is its stability over almost 5 years from the stroke. We propose that this unusual type of recovery in E.M. is related to the higher degree of automatization of the first language with respect to the second one. This proposal fits with the role of basal ganglia in automatized motor and cognitive performance.