21 - 7. Language

7. Language

© SPMM Course 7. Language  Aphasia refers to a higher-level language defect despite intact hearing, sound production, articulation mechanisms.  Aphasia is almost always organic. Naming defects (anomia) accompanies any aphasia in various degrees.  To understand aphasia, consider the following facts  Sound received by ears is transmitted to Wernicke’s area and auditory association cortex that processes the language component.  Arcuate fasciculus connects Wernicke’s area to Broca’s area. (NOTE: this is different from the uncinate fasciculus that interconnects the anterior temporal and inferior frontal gyrus)  Broca’s area is the higher motor area of language production. Signals from Broca’s area are relied on onto the motor area to coordinate the delivery of language via the tongue, lips and vocal cords.  Three important components of language are  Fluency depends on intact Broca’s area and its forward connections.  Comprehension depends on intact Wernicke’s area and its connection with association cortex and sensory input  Repetition requires no high-level processing. Repetition can occur if Broca’s, Wernicke’s and arcuate fasciculus are intact. Repetition does not need relay of signals from either Broca’s or Wernicke’s areas to higher association areas. Adapted from Harrison’s Textbook of internal medicine; 15 e

 In Broca's aphasia the speech is nonfluent; it often appears laboured with any interruptions and pauses. Function words (propositions, conjunctions) are most affected though the good degree of meaning-appropriate nouns and verbs are still produced. Abnormal word order and a characteristic agrammatism are noted. Speech is telegraphic. Harrison’s Textbook of Medicine quotes the following example: "I see...the dotor, dotor sent me...Bosson. Go to hospital. Dotor...kept me beside. Two, tee days, doctor send me home”.  In Wernicke's aphasia, the comprehension is impaired for both spoken and written language. Language output is fluent but is highly paraphasic, sometimes with string of neologisms and circumlocutions. Hence, it is also termed as "jargon aphasia." The speech contains large numbers of function words (e.g., prepositions, conjunctions) but few substantive nouns or verbs that refer to specific actions. The output is, therefore, voluminous but uninformative, mimicking schizophrenic speech disturbance at times. Type of aphasia Fluency Repetition Comprehension Naming Wernicke’s sensory aphasia Intact Lost Lost Lost Broca’s motor aphasia Lost Lost Intact Lost Conduction aphasia Intact Lost Intact Lost Transcortical sensory aphasia Intact Intact Lost Lost Transcortical motor aphasia Lost Intact Intact Lost

© SPMM Course  Pure word deafness: Patient can speak read & write fluently, but comprehension is impaired only for spoken language. Bilateral (or left sided with disrupted connections to non-dominant circuit) damage to the superior temporal pole is suspected.  Pure word blindness (alexia no agraphia): Here the patient can speak normally and comprehend what is spoken; he can also write spontaneously and to dictation, but reading comprehension is impaired. It almost always involves an infarct to the left posterior cerebral artery affecting splenium of the corpus callosum and left visual cortex. So the affected person, who is still able to see with the right visual cortex, cannot undertake lexical word processing making him unable to read.  Pure word dumbness: Spoken language cannot be produced clearly, but the patient can comprehend language well, can read and write.  Pure agraphia: This is an isolated inability to write while other faculties of language are preserved.