A 67 year old woman is being evaluated for progressive cognitive decline and decreased speech.
At her imaging appointment, the technologist reports she has difficulty responding to the pre-imaging screening questions. She appears to understand all the instructions, but takes great effort in speaking even short phrases. She appears frustrated when answering and “can’t seem to get the words out”.
There is no evidence of acute findings on the unenhanced CT, but there are somewhat subtle abnormalities.
Axial CT images show left sulcal dilation (arrowheads), widened left sylvian fissure (arrow), and slight ex-vacuo dilatation of the left lateral ventricle (asterisk).
Close inspection reveals left-sided cerebral atrophy, predominantly around the sylvian fissure (posterior frontal lobe and anterior temporal lobe). This results in left sulcal dilation (arrowheads), a widened left sylvian fissure (arrow), and slight ex-vacuo dilatation of the frontal horn of left lateral ventricle (asterisk). The atrophy is most pronounced in the anterior left frontal lobe (right image).
The patient underwent FDG PET to evaluate for dementia:
PET images demonstrate a widespread left > right hypometabolism involving the frontal, temporal, and parietal lobes, which is more severe in the left temporal region. There is sparing of the sensorimotor cortex and occipital lobes.
The clinical description and imaging findings in this case are characteristic of nonfluent variant primary progressive aphasia (also called progressive nonfluent aphasia).
Primary progressive aphasia is a neurodegenerative condition, sometimes classified among the subtypes of frontotemporal degeneration, but distinct in that the dominant abnormality is difficulty speaking, writing, reading, or understanding language. The nonfluent variant is an expressive aphasia, presenting with decreased ability to produce speech (taught in medical school as pathology involving Broca’s area – inferior frontal lobe gyrus).
Peri-sylvian atrophy on anatomic imaging, with associated hypometabolism on FDG PET, are often seen in this condition. Early evidence with amyloid PET imaging suggests that amyloid deposition is more common with logopenic variant primary progressive aphasia (impaired single word retrieval / word-finding pauses). Villarejo-Galende A, et al. J Neurol 2017;264:121-130.
