Aphasia ( /əˈfeɪʒə/ or /əˈfeɪziə/, from Greek ἀφασία, "speechlessness") is an impairment of language ability. This class of language disorder ranges from having difficulty remembering words to being completely unable to speak, read, or write.
Aphasia disorders usually develop quickly as a result of head injury or stroke, but can develop slowly from a brain tumor, infection, or dementia, or can be a learning disability such as dysnomia.
The area and extent of brain damage determine the type of aphasia and its symptoms. Aphasia types include Broca's aphasia, non-fluent aphasia, motor aphasia, expressive aphasia, receptive aphasia, global aphasia and many others (see Category:Aphasias).
Medical evaluations for the disorder range from clinical screenings by a neurologist to extensive tests by a language pathologist.
Most aphasia patients can recover some or most skills by working with a speech and language therapist. This rehabilitation can take two or more years and is most effective when begun quickly. Only a small minority will recover without therapy, such as those suffering a mini-stroke. Patients with a learning-disorder aphasia such as dysnomia can learn coping skills, but cannot recover abilities that are congenitally limited.
Improvement varies widely, depending on the aphasia's cause, type, and severity. Recovery also depends on the patient's age, health, motivation, handedness, and educational level.