Aphasia (pronounced /əˈfeɪʒə/ or pronounced /əˈfeɪziə/) is an acquired language disorder in which there is an impairment of any language modality. This may include difficulty in producing or comprehending spoken or written language.
Traditionally, aphasia suggests the total impairment of language ability, and dysphasia a degree of impairment less than total. However, the term dysphasia is easily confused with dysphagia, a swallowing disorder, and thus aphasia has come to mean both partial and total language impairment in common use.
Depending on the area and extent of brain damage, someone suffering from aphasia may be able to speak but not write, or vice versa, or display any of a wide variety of other deficiencies in language comprehension and production, such as being able to sing but not speak. Aphasia may co-occur with speech disorders such as dysarthria or apraxia of speech, which also result from brain damage.
Aphasia can be assessed in a variety of ways, from quick clinical screening at the bedside to several-hour-long batteries of tasks that examine the key components of language and communication. The prognosis of those with aphasia varies widely, and is dependent upon age of the patient, site and size of lesion, and type of aphasia.
Aphasia usually results from lesions to the language-relevant areas of the frontal, temporal and parietal lobes of the brain, such as Broca's area, Wernicke's area, and the neural pathways between them. These areas are almost always located in the left hemisphere, and in most people this is where the ability to produce and comprehend language is found. However, in a very small number of people, language ability is found in the right hemisphere. In either case, damage to these language areas can be caused by a stroke, traumatic brain injury, or other brain injury. Aphasia may also develop slowly, as in the case of a brain tumor or progressive neurological disease, e.g., Alzheimer's or Parkinson's disease. It may also be caused by a sudden hemorrhagic event within the brain. Certain chronic neurological disorders, such as epilepsy or migraine, can also include transient aphasia as a prodromal or episodic symptom. Aphasia is also listed as a rare side effect of the fentanyl patch, an opioid used to control chronic pain.
People with aphasia may experience any of the following behaviors due to an acquired brain injury, although some of these symptoms may be due to related or concomitant problems such as dysarthria or apraxia and not primarily due to aphasia.
* inability to comprehend language * inability to pronounce, not due to muscle paralysis or weakness * inability to speak spontaneously * inability to form words * inability to name objects * poor enunciation * excessive creation and use of personal neologisms * inability to repeat a phrase * persistent repetition of phrases * paraphasia (substituting letters, syllables or words) * agrammatism (inability to speak in a grammatically correct fashion) * dysprosody (alterations in inflexion, stress, and rhythm) * incompleted sentences * inability to read * inability to write
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