Alexia

Alexia (or acquired dyslexia) is a neurological term refers to an acquired impairment of reading resulting from damage of critical brain areas.

Clinical presentation

Alexia can manifest itself as an impairment of oral reading and reading comprehension alike and can occur in combination with various other disturbances of written or spoken language skills .

Major forms of alexia with language impairment:

• aphasic alexia: the patients demonstrate impaired oral reading, along with weakened expression, or understanding of spoken language (e.g. in Broca's and Wernicke's aphasia)
• alexia with agraphia: reading disturbances complicated by weakened writing skills, with preserved spoken language (e.g caused by injuries to the left angular gyrus)

Forms of alexia without impaired language:

• pure (agnosic) alexia:
  • patients cannot understand or read aloud written text, yet paradoxically they can express themselves in writing (are unable to read their own writing)
  • pure alexia is most commonly caused by left occipital lobe injury and is therefore commonly associated with right-sided vision loss
• neglect alexia: patients suffering from unilateral neglect syndrome may ignore text written on the neglected side of a page, or substitute letters on the neglected side of individual words
• attentional alexia:
  • relatively preserved single word reading, but an impaired reading of text as a whole
  • letters within individual words are also often incorrectly identified by the patients, whilst the word itself can be spelled correctly