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Título

The Importance of Biomarker to Identify the Etiology of Posterior Cortical Atrophy Spectrum: a case report

RESUMO

Case Report:
A 66-year-old female patient with a Law degree was evaluated at an outpatient clinic due to a series of cognitive deficits for the past 2 years: difficulty reading, spatial perception impairment and environmental agnosia. In the past year, she would forget the password for her credit card, developed agraphia, apraxia of dressing, acalculia and impaired perception of objects. The ophthalmological clinical evaluation was unremarkable. She more recently has been repeating stories and had difficulty establishing a line of reasoning within them.
On physical examination, she had no pathological signs, except for simultanagnosia. In the Addenbrooke test, she was unable to perform the task of counting dots without pointing at them. In the MoCA test, she achieved a score of 9 and performed notably worse in visual tasks.
Brain MRI showed parieto-occipital cortical atrophy mainly on the left hemisphere. In the neuropsychological evaluation, difficulties in verbal and semantic fluency and in visuomotor coordination were observed, as well as executive dysfunction. Brain SPECT showed hypoperfusion in frontotemporal and parietal regions of the left cerebral hemisphere, extending to the hippocampus and posterior cingulate, with a nonspecific scintigraphic appearance. Finally, the PET-CT with Florbetaben-F18 indicated accumulation of b-amyloid plaques predominantly in the prefrontal, orbitofrontal, parietal, temporal, cingulate and occipital regions.

Discussion:
In 1988, Frank Benson and colleagues described five unusual patients with progressive visual difficulties that they termed posterior cortical atrophy (PCA). Subsequent autopsies of cases of posterior cortical atrophy showed a predominance of Alzheimer's neuropathology, but other diagnoses such as prion disease and Lewy body dementia were also reported. Currently, we can use biomarkers that help diagnose the etiology of PCA. This case, the patient had clinical criteria for PCA, that could be related to Alzheimer's disease through PET-CT performed with Florbetaben-F18.

Final Commentary:
The use of functional neuroimaging as a biomarker, especially for amyloid deposition, is a helpful tool for identifying the etiology within the spectrum of PCA. Consequently, new clinical trails will be able to investigate atypical phenotypes within the same etiology. Getting to a more specific diagnosis using biological markers is the first step towards finding effective targeted therapies for PCA patients.

Palavras Chave

Posterior Cortical Atrophy, PET-CT, amyloid, Alzheimer's Disease