Progressive non-fluent aphasia

Progressive nonfluent aphasia (PNFA), also known as agrammatic variant primary progressive aphasia, is generally considered to be one of three subtypes of primary progressive aphasia, along with semantic dementia and logopaenic dementia.

Terminology

It is important to note that the literature surrounding primary progressive aphasias, and neurodegenerative diseases generally, is large, rapidly evolving and heterogeneous, more so than many other fields ^2,3. The result is that there is great variation in terminology and classification of various conditions making it perilous for student and clinicians alike.

Clinical presentation

PNFA is typically characterized by "effortful, dysfluent and agrammatical speech".

Diagnostic criteria

Diagnostic criteria have been proposed as follows ^1:

• clinical diagnosis of PNFA
  • at least one of:
    1. agrammatism in language production
    2. effortful, halting speech with inconsistent speech sound error (apraxia of speech)
  • and at least 2 of:
    1. impaired comprehension of syntactically complex sentences
    2. spared single word comprehension
    3. spared object knowledge
• Imaging-supported diagnosis of PNFA
  • both of the following:
    1. clinical diagnosis of non-fluent/agrammatic variant PPA
    2. imaging showing predominant left posterior fronto-insular atrophy on MRI and/or predominant left posterior front-insular hypoperfusion on SPECT or PET
• PNFA with definite pathology
  • both of the following:
    1. clinical diagnosis of non-fluent/agrammatic variant PPA
    2. histopathologic evidence of a specific neurodegenerative pathology (eg. FTLD-tau, FTLD-TDP, AD, other) or presence of a known pathogenic mutation

Radiographic features

CT and MRI

Atrophy is variable, but generally most marked in the posterior frontal, insular cortex and temporal lobe, including the hippocampus ^1,2. Generally, the left hemisphere is thought as being most involved, although this is neither universally the case ^1,2.

Nuclear medicine

SPECT or FDG-PET demonstrate hypoperfusion in a similar distribution to morphological changes (see above).