Alexia (disorder)

Alexia (from the Greek ἀ, privative, expressing negation, and λέξις = "word") is an acquired type of sensory aphasia where damage to the brain causes a patient to lose the ability to read. It is also called word blindness, text blindness or visual aphasia.

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Causes

Alexia typically occurs following damage to the left hemisphere of the brain or to the areas of the occipital and temporal lobes, which are responsible for processing auditory, phonological and visual aspects of language. The region at the junction of occipital and temporal lobes (sometimes called the occipito-temporal junction) coordinates information that is gathered from visual and auditory processing and assigns meaning to the stimulus. Alexia can also occur following damage to the inferior frontal lobe, especially Broca's area. Damage to these different areas cortex result in somewhat different patterns of difficulty in affected individuals.

Presentation

Alexia may be accompanied by expressive and/or receptive aphasia (the inability to produce or comprehend spoken language). Alexia can also co-occur with agraphia, the specific loss of the ability to produce written language even when other manual motor abilities are intact. In other cases, damage is restricted to areas responsible for input processing. The result is known as alexia without agraphia. In this scenario, an individual's ability to produce written language is spared even though they are unable to understand written text.

Alexia without agraphia results from a left occipital splenium of the corpus callosum lesion.

See also

• strephosymbolia
• Visual agnosia
• Dyslexia