Aphasia is an impairment of language. Someone suffering from aphasia has difficulty in producing or comprehending spoken or written language, but the patient may be able to speak but not write, or vice versa, depending on the area and extent of brain damage. Aphasia may also occur with speech disorders such as dysarthria or apraxia of speech, which also result from brain damage.
Aphasia usually results from lesions to the language centers of the brain, such as the Broca's area and the Wernickle's area, and/or the neural pathways between them. These areas are located in the left hemisphere in most people.