Language Disorders
Language Disorders
GENERAL
In 90% of individuals, the language centers lie within the left hemisphere.
BROCA'S APHASIA
- A non-fluent aphasia with preserved comprehension and impaired repetition.
- Broca's aphasia is agrammatic, has a monotonous melody, is dysarthric, effortful, and hesitant.
WERNICKE'S APHASIA
- Is a fluent aphasia with poor comprehension and impaired repetition.
- In Wernicke's aphasia, there is preserved melody and rhythm but the speech content is empty or meaningless, producing a word salad (a high-frequency, unintelligible jumble of words), and there are paragrammatic and paraphasic substitution errors, and even the production of new, meaningless words, called neologisms.
- It localizes to Wernicke's area (posterior superior temporal gyrus) and the neighboring supramarginal gyrus and angular gyrus and the surrounding temporal lobe and parietal lobe and insula.
GLOBAL APHASIA
- Most easily thought of as a combined Broca's and Wernicke's aphasia
- It is a nonfluent aphasia with poor comprehension and impaired repetition is due to extensive injury to the left middle cerebral artery territory.
TRANSCORTICAL MOTOR APHASIA
- Nonfluent aphasia with preserved comprehension, different from Broca's aphasia, in that repetition is intact.
- Commonly due to anterior and middle cerebral artery watershed injury with resultant injury to the dorsolateral prefrontal cortex and with sparing of the perisylvian region: the presumptive reason for the preserved repetition.
TRANSCORTICAL SENSORY APHASIA
- Fluent aphasia with poor singleword comprehension, different from Wernicke's in that repetition is intact.
- Due to middle and posterior cerebral artery watershed distribution injury with involvement of the temporoparieto-occipital junction and with sparing of the perisylvian region.
MIXED TRANSCORTICAL APHASIA
- Nonfluent aphasia with poor comprehension, different from global aphasia in that repetition is intact.
- Can occur with combined anterior and middle cerebral artery and middle and posterior cerebral artery watershed distribution strokes that spare the perisylvian region.
ECHOLALIA
- The parrot-like tendency to repeat words and sentences, commonly found in transcortical aphasias.
CONDUCTION APHASIA
- Fluent aphasia with normal comprehension but impaired repetition: in essence, the opposite of mixed transcortical aphasia.
- Speech is hesitant and paraphasic.
- Classically and commonly considered to localize to the arcuate fasciculus, however, may actually occur through the superior longitudinal fasciculus, middle longitudinal fasciculus, and the extreme capsule.