A complete absence of previously acquired language skills, caused by a brain disorder that affects the ability to speak and write, and/or the ability to comprehend and read. Related disabilities that may occur in aphasia are alexia (word blindness) and agraphia (writing difficulty). Language function in the brain lies in the dominant cerebral hemisphere (see cerebrum). Two particular areas in this hemisphere, Broca’s and Wernicke’s areas, and the pathways connecting the two, are important in language skills. Damage to these areas, which most commonly occurs as a result of stroke or head injury, can lead to aphasia. Some recovery from aphasia is usual following a stroke or head injury, although the more severe the aphasia, the less the chances of recovery. Speech therapy is the main treatment. (See also dysphasia; speech; speech disorders.)


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