AFASIA. – Difficulty or impossibility of speaking caused by alteration of particular areas of the cerebral cortex (language centres), on the left in right-handed persons and on the right in left-handed persons. The destruction or functional blockage of these centres makes it impossible to articulate speech or to recognise the sounds and signs (v. ASIMBOLIA) by which others communicate their thoughts. Two forms of a. are distinguished: motor and sensory.
A person affected by motor a. hears normally, recognises sounds, retains the memory of words heard and understands their meaning; he nevertheless lacks the ability to form the word itself, although the innervation and musculature of the naso-bucco-pharyngo-laryngeal apparatus remain intact (v. DISARTRIA). In other words, he has lost the ideation of the movements by which speech is articulated. There is a form of «complete motor a. of Broca» (cortical form) in which the ability to speak is entirely suppressed; and since written language depends to a great extent on articulated language, the ability to write is also lost; comprehension of language remains intact. In «pure verbal mutism» (transcortical form), on the other hand, the patient, although not speaking at all, retains the ability to read and write.
In sensory a., patients can speak and also hear, but they no longer understand words and grasp nothing of what is said to them; they behave towards language as though it were an unknown language. In «complete sensory a.» (Wernike’s cortical form), the patients hear but do not understand the meaning of words. In this form, paraphasias and paragraphias occur as secondary manifestations (that is, in speaking and writing they use one word in place of another). «Pure verbal deafness» (subcortical form) is identical to the preceding condition, but paraphasia and paragraphia are absent. In total a., a combination of the two preceding forms, both speaking and understanding are completely abolished, and the disorder reaches its highest degree through the simultaneous loss of internal discourse (the reasoned development of ideas) and external discourse (language).
lin 1925; O. Bumke, Trattato di Psichiatria, Turin 1927; U. Cerletti, Riassunto delle lezioni di clinica delle malattie nervose e mentali, Rome 1946. Giuseppe de Nanno