Crossed aphasia confirmed by fMRI in a case with nonfluent variant of primary progressive aphasia carrying a GRN mutation.

We provided evidence of the right language lateralization in a previously suspected crossed nfvPPA. Despite the long disease duration and the large amount of atrophy at the right side, there was no fMRI evidence of a left-hemisphere contribution to language function. We might speculate that compensatory effects do not appear when the premorbid language lateralization is purely right. The investigation of the underlying functional brain substrates in crossed nfvPPA cases may help understanding disease vulnerability in these neurodegenerative conditions.