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Posterior cortical atrophy
Posterior Cortical Atrophy (PCA) is a rare progressive neurodegenerative disorder with a typical onset between 50-65 years of age characterized by progressive impairment of higher visual processing skills and other posterior cortical functions without any evidence of ocular abnormalities.
ORPHA:54247Classification level: Disorder
- Benson syndrome
- Biparietal Alzheimer disease
- Prevalence: Unknown
- Inheritance: Unknown
- Age of onset: Adult
- ICD-10: G31.1
- OMIM: -
- UMLS: -
- MeSH: -
- GARD: -
- MedDRA: -
Prevalence is unknown, largely due to the lack of awareness of the syndrome and the inaccurate terminology referring to it.
All patients with PCA show impairment in at least one basic visual process. Early PCA symptoms include visuoperceptual and visuospatial dysfunction, apraxia and alexia. Features of Bálint syndrome (simultanagnosia, optic ataxia and oculomotor apraxia) and Gerstmann syndrome (acalculia, agraphia, finger agnosia and left-right disorientation) are commonly described. Earliest reported symptoms include difficulties with complex visual behaviors (e.g. driving, reading, and telling the time from an analogue watch). Reading problems include getting lost on the page (visual disorientation), overlapping or miscombined letters (visual crowding) or better reading of small than large print. Odd visual manifestations like abnormally prolonged color after-images and perception of movement of static stimuli are also reported. People with PCA tend to have relatively well preserved memory, language, insight, and judgment are relatively preserved until late in the disease course. Individuals with PCA often experience anxiety and depression from early on. Extrapyramidal signs, myoclonus, and grasp reflex have also been reported in PCA patients.
Etiology is unknown. PCA is considered a clinico-radiological syndrome with Alzheimer's disease is the most common underlying pathology, but cases attributable to Dementia with Lewy Bodies, corticobasal degeneration or prion disease have also been reported.
PCA is an under-recognized disorder resulting often in a significant delay in diagnosis. Diagnosis of this clinico-radiological syndrome is based on neurological assessment, specific visual and cognitive testing, and brain imaging and routine blood tests. MRI characteristically shows bilateral atrophy in the occipital, parietal and posterior temporal lobes, often asymmetric being more pronounced in the right hemisphere. Single photon emission computed tomography (SPECT) or PET show hypometabolism of the posterior cerebral areas as well as in the frontal eye fields in more advanced stages. Conclusive diagnosis of the underlying disease is confirmed on brain autopsy, though CSF and amyloid imaging may help to refine the clinical diagnosis.
Differential diagnosis includes the most commonly associated neuropathology Alzheimer disease, but may also include dementia with Lewy bodies, cortico-basal degeneration, and prion diseases such as Creutzfeldt-Jakob disease (see these terms).
Management and treatment
There is no cure for PCA. Medications like acetylcholinesterase inhibitors, used in the treatment of Alzheimer's disease, are available and might bring relief for some symptoms. Management of PCA is based on visual aids, rehabilitation programs that include psychoeducation, compensatory strategies, and cognitive exercises to cope with visual disabilities. Antidepressant treatments may benefit individuals with PCA who have relatively preserve insight into their decline and often deal with depression, irritability, frustration and a loss of self-confidence.
Prognosis is poor as PCA is progressive disorder. Life expectancy after PCA diagnosis is thought to be similar (8-12 years) or superior at times compared to individuals affected with Alzheimer's disease.
- Review article
- English (2012)