Aphasia

Aphasia (Greek, a, “not”; phanai, “to speak”), term introduced by the French doctor Armand Trousseau to denote inability to express thought by means of speech, as a consequence of certain brain disorders (it is also termed dysphasia). The meaning has since been extended to cover loss of the faculty of interchanging thought, so that it may even denote a temporary but complete loss of memory, difficulty in recognizing colours, problems of a mathematical type, and other complications. Aphasia is often caused by a stroke, where a lack of oxygen to the language areas of the brain (for even a short amount of time) can cause damage. It can also be caused by head injuries.

Aphasic disorders can affect different areas of a person’s language skills, including any one or several of the following: speech, writing, reading, comprehension, signing. Full or partial recovery from aphasia is possible, although it does not occur in all cases or in all language areas.

Several different types of aphasia have been identified. Broca’s aphasia refers specifically to damage to the part of the brain known as Broca’s area (see Paul Broca). It is also known as motor aphasia since it involves a loss of memory of the coordinated movements necessary for the formation of symbols, evoking slow and short utterances from the speaker. This type of aphasia usually affects gestures, speech, and writing, although comprehension is generally not affected. (The inability to write is commonly termed agraphia.) Victims of this disorder are unable to name any object shown to them, although they know what it is. Neither can they reply to any question, although they may understand it. Wernicke’s aphasia (after neurologist Carl Wernicke) occurs after damage to Wernicke’s area in the brain. In Wernicke’s, or sensory aphasia, a loss of memory of the meaning of symbols occurs. This may affect the recollection of spoken language, although the patient appears to be able to speak fluently. The person can hear every sound but has extreme difficulty with comprehension. Global aphasia presents symptoms from both Broca’s and Wernicke’s aphasia, and is also known as irreversible aphasia syndrome because of the very low recovery rate associated with it.