PSP-progressive non fluent aphasia (PSP-PNFA) is an atypical variant of progressive supranuclear palsy (PSP; see this term), a rare late-onset neurodegenerative disease. Unlike classic PSP (Richardson syndrome) patients present with an isolated speech production problem years before developing other motor features of PSP. The disease is Progressive supranuclear palsy - progressive non fluent aphasia (Orphanet_240112). Also known as: PSP-AOS, PSP-PNFA, Progressive supranuclear palsy - apraxia of speech.