APHASIA. — Difficulty or inability to speak due to alterations in specific areas of the cerebral cortex (language centers), located on the left in right-handed individuals and on the right in left-handed individuals. The destruction or functional blockage of these centers makes it impossible to articulate language or to recognize sounds and signs (v. ASTHENO-BOLIA) by which others communicate their thoughts. Two forms of aphasia are distinguished: *motor* and *sensory*.
Those affected by *motor aphasia* hear like a healthy person, recognize sounds, retain the memory of words heard, and understand their meaning; however, they lack the ability to form words themselves, even though the innervation and musculature of the naso-oro-pharyngo-laryngeal apparatus remain intact (v. DYSARTHRIA). In other words, they have lost the ideation of the movements required to articulate speech. There is a form of "complete Broca motor aphasia" (*cortical form*) in which the ability to speak is completely suppressed, and since written language depends largely on spoken language, the ability to write is also lost; however, comprehension of language remains intact. In contrast, in "pure word mutism" (*transcortical form*), the patient, though unable to speak at all, retains the ability to read and write.
In *sensory aphasia*, patients can speak and hear but no longer understand words and grasp nothing of what is said to them; they treat language as if it were an unknown tongue. In *complete sensory aphasia* (*Wernicke’s cortical form*), the afflicted hear but do not understand the meaning of words. In this form, secondary manifestations such as paraphasia and paragraphia occur (*i.e.*, in speaking and writing, they substitute one word for another). "Pure word deafness" (*subcortical form*) is similar to the above but lacks paraphasia and paragraphia. In *total aphasia*, a combination of the two preceding forms, both speaking and understanding are completely abolished, and the disorder reaches its highest degree due to the simultaneous loss of internal (*rational development of ideas*) and external (*spoken language*) discourse.
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