Aphasia

Clinical Aphasic Syndromes

The clinical approach to aphasia identifies some 7 to 10 aphasic syndromes and classifies aphasic patients [Page 44]into these syndromes. These syndromes are the following:

• 1.
  Broca's aphasia, a severe expressive language disturbance reducing the fluency of speech in all tasks (repetition and reading as well as speaking) and affecting elements of language such as grammatical words and morphological endings, without an equally severe disturbance of auditory comprehension
• 2.
  Wernicke's aphasia, the combination of fluent speech with erroneous choices of the sounds of words (phonemic paraphasias) and an auditory comprehension disturbance
• 3.
  Pure motor speech disorders—anarthria, dysarthria, and apraxia of speech—output speech disorders due to motor disorders, in which speech is misarticulated but comprehension is preserved
• 4.
  Pure word deafness, a disorder in which the patient does not recognize spoken words, but spontaneous speech is normal
• 5.
  Transcortical motor aphasia, in which spontaneous speech is reduced but repetition is intact
• 6.
  Transcortical sensory aphasia, in which a comprehension disturbance exists without a disturbance of repetition
• 7.
  Conduction aphasia, a disturbance in spontaneous speech and repetition, consisting of fluent speech that contains many phonemic paraphasias, without a disturbance in auditory comprehension

Other syndromes include anomia (an inability to find words), global aphasia (affecting all aspects of language use), and isolation of the speech area (leading to a global aphasia except for sparing of repetition). There are also disorders affecting written language (pure alexia, in which a patient can write but not read), and various disturbances of writing (agraphia).

The clinical value of these syndromes largely comes from their relation to the location of lesions. Broca's aphasia, which affects expressive language alone, is due to lesions in Broca's area, the center for motor speech planning adjacent to the motor strip. Wernicke's aphasia follows lesions that disturb the representations of word sounds located in Wernicke's area, the cortex next to the auditory receptive areas. Pure motor speech disorders arise from lesions interrupting the motor pathways from the cortex to the brain stem nuclei that control the articulatory system. These disorders differ from Broca's aphasia because they are not linguistic; they affect articulation itself, not the planning of speech. Pure word deafness follows bilateral lesions cutting Wernicke's area off from the areas of the brain that affect the transmission of sound input into Wernicke's area. Transcortical motor aphasia results from the interruption of input from areas where concepts are formulated to Broca's area. Transcortical sensory aphasia follows lesions between Wernicke's area and areas where concepts are formulated. Finally, conduction aphasia follows from a lesion between Wernicke's area and Broca's area.

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