Progressive nonfluent aphasia (PNFA) is one of three clinical syndromes associated with frontotemporal lobar degeneration.
PNFA has an insidious onset of language deficits over time as opposed to other stroke-based aphasias, which occur acutely following trauma to the brain.
Problems with writing, reading, and speech comprehension can occur, as can behavioural features similar to frontotemporal dementia.
[citation needed] Imaging studies have shown differing results which probably represents the heterogeneity of language problems than can occur in PNFA.
Comprehensive meta-analyses on MRI and FDG-PET studies identified alterations in the whole left frontotemporal network for phonological and syntactical processing as the most consistent finding.