What is the pathophysiology of reading disorders in posterior cerebral artery (PCA) stroke?

Updated: Jul 30, 2018
  • Author: Erek K Helseth, MD; Chief Editor: Helmi L Lutsep, MD  more...
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Answer

Pure alexia may result from infarction of the dominant occipital cortex. Words are treated as if they are from a foreign language. Patients may retain the ability to formulate a word and its meaning if spelled out to them orally or if they trace the letters with their hand. Patients may then learn to read, albeit terribly slowly, in a letter-by-letter fashion, being unable to integrate multiple letter groups.

Classic alexia without agraphia was described by Dejerine in the late 19th century. In his case study, he emphasized a left occipital cortex lesion and also infarction of the splenium of the corpus callosum, which disconnected fibers from the right occipital lobe, preventing them from reaching the angular gyrus.

Rarely, the dominant-hemisphere posterior temporal lobe is supplied by the PCA. Damage to this area results in a Wernicke-type aphasia with associated dyslexia and right hemianopia due to concomitant left occipital infarction.


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