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.

It localizes to Broca's area (think:* posterior inferior frontal gyrus (pars opercularis and pars triangularis)) and also involves the precentral gyrus, basal ganglia, insula, and related white matter pathways.

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.