Case Series of Right-Hemisphere Nonfluent Variant of Primary Progressive Aphasia

Background and Purpose Nonfluent variant primary progressive aphasia (nfvPPA) is a neurodegenerative disorder characterized by the progressive deterioration of language functions that typically appears with atrophy predominating in the left peri-insular region (leftnfvPPA) on imaging. While both left-dominant and right-dominant presentations have been reported in semantic variant primary progressive aphasia, the other language presentation of frontotemporal dementia, no case series of nfvPPA with predominantly right-sided atrophy of the peri-insular region (right-nfvPPA) have been reported previously. This study explored whether such entities exist and what their clinical features might be. Methods A retrospective review of brain imaging data obtained from an established cohort of patients diagnosed with nfvPPA was performed to identify right-nfvPPA cases, followed by detailed analyses of their clinical profiles and imaging results compared to matched typical leftnfvPPA cases and healthy control group. Results Four of 55 individuals meeting the consensus diagnostic criteria for nfvPPA demonstrated right-nfvPPA. No significant differences were noted in their clinical and neuropsychological profiles. Detailed imaging analyses demonstrated that the individuals with right-nfvPPA did not demonstrate atrophy of the anterior cingulate gyrus, unlike those in the left-nfvPPA group. Conclusions This study has revealed several intriguing differences between right-nfvPPA and left-nfvPPA, particularly in the prevalence of impairments in motor speech and naming as well as imaging differences. These findings warrant further exploration in a larger cohort to improve our understanding of neural network organization and its dysfunction in neurodegenerative disorders.