When you have a massive stroke, many faculties are affected and harmed as a result. One of the most devastating side effects of a massive stroke is the inability to read afterward. This can either be a problem with language itself, or it can be a result of other acute stroke issues, such as visual field disturbances. For that reason, the rehabilitation of reading after a massive stroke is not an easy case. You have to pinpoint the type of difficulty you are having with reading and then take specific rehabilitation actions to attempt to restore those functions. Most stroke victims who have trouble with reading after an acute stroke have brain damage on the left side of the brain where the language functions are located. However, any massive stroke can directly or indirectly affect the ability to read, write, and understand language.
Alexia is the inability to read effectively after an acute stroke. It is not to be confused with dyslexia, which is the inability to read correctly as an innate trait. Strokes in the brain cause many different alexias, and some of them are referred to as peripheral. These alexias do not directly impact the language center of the brain, but are more likely caused by some other brain abnormality, such as the inability to see in certain visual fields.
The most common type of peripheral alexia is hemianopic alexia. Essentially, this is vision loss after a stroke and is caused by damage to the visual cortex. When the problem with vision gets close enough to the center of the field, it can create problems with trying to see the whole word on the paper. For this reason, stroke victims have to constantly go over words, or they miss part of words that are on the page. Rehabilitation therapies for this symptom of a massive stroke focus primarily on improving the eye movements themselves. The best way to combat this symptom of a massive stroke is to read aloud from a scrolling text bar while a therapist watches you read. This keeps the eyes moving in the correct way to compensate for the missing visual field and improves reading speed. Although speeds never return to normal, they do improve substantially with this method.
Pure and global alexia is another type of peripheral alexia. Stroke victims can generally make out and recognize letters and parts of words, but they cannot put them together. Therapists usually make stroke patients read words out loud many times or trace the letters of the word they are trying to read. This is thought to stimulate the part of the brain that puts the words together. Neglect alexia is the inability to see prefixes or suffixes of words due to a problem in the visual field. Reading through a prism is used to help stroke patients see more of the word they are trying to read and circumvent the neglect.
Central alexias are most often the result of language loss. Stroke patients who have this type of reading problem will generally have aphasia, or trouble speaking, and trouble discerning auditory language, as well. Again, this is damage to a specific part of the brain and requires a different type of rehabilitation to overcome damage to these sections. Most stroke victims with this type of alexia will experience more difficulty with the speech and auditory problems they are having, but if the aphasia is minor, the ability to read becomes more of a focus.
Phonological alexia is the type of central alexia where a patient cannot sound out the words. Stroke victims are able to read words they have seen in the past, but when confronted with a new word, stroke victims are unable to sound the word out and read it. Therapists will usually pair words that are unknown with known words that have the same beginning sounds to prompt the brain to remember the section of the word and hopefully, put them together with the rest of it. Rereading aloud is also used in this form of alexia to correct the stroke victim and reinforce the pronunciation and understanding of new words.
Deep alexia builds on phonological alexia but adds semantic errors into the mix. For instance, stroke victims will read the word fork, but say and understand spoon. Stroke victims know the words, but the wrong mental association comes up along with it. One way to combat this type of alexia is to read words with the picture associated with it. This will help the brain make the connection between what the word actually says and what it means. Another type of therapy focuses on repeatedly writing words over and over to lock in the meaning of the word. This shows great gains for the treated words, but does not help with other words.
Surface alexia is the opposite of phonological alexia. Stroke patients are able to see and recognize the patterns of words, but they pronounce them only as fragments of the word. For instance, colonel would be pronounce col-on-nel instead of the correct way. Treatments for this include pairing the words with pictures and repeated drilling of the correct pronunciation. Of course, only words that are likely to come up in a stroke patient’s lexicon are included in this form of therapy.
International Encyclopedia of Rehabilitation; Rehabilitation of acquired alexia; Alexander P. Leff and T.M. Schofield; 2012