[Cerebrovascular disorder and the language areas].
Recent progress of imaging techniques has achieved precise descriptions of aphasic syndromes associated with cerebrovascular disorders. Infarction of the left anterior cerebral artery brings about transcortical motor aphasia. Occlusion of each branches of the left middle cerebral artery produces characteristic language symptoms. Recently, cases with infarction of the areas of prefrontal and precentral arteries were reported to manifest fluent aphasia indistinguishable from the classical transcortical sensory aphasia. Rare cases with lesions restricted to the Broca's area (territory of the precentral artery) produces aphasia with normal fluency, word finding difficulty and deficit in sentence comprehension. Classical non-fluent Broca's aphasia is caused by infarctions which at least involves the areas of precentral and central arteries. Aphemia or pure word dumbness results from damages which involves territory of the central artery. Conduction aphasia is most often associated with lesions of the posterior parietal artery territory. As in the case of Broca's aphasia, Wernicke's aphasia is a composite of conduction aphasia, pure word deafness, transcortical sensory aphasia, and alexia with agraphia. The lesion of Wernicke's aphasia naturally involves the areas of all of these aphasic symptoms. Transcortical sensory aphasia is associated with lesions in the posteroinferior temporal region, and is often associated with watershed infarctions of the middle and posterior cerebral arteries. Aphasia which results from putaminal hemorrhage has ambiguous manifestation, and is difficult to be classified into Wernicke-Lichtheim's model. Assessment of its fluency is notoriously difficult. Thalamic aphasia is similar to either anomic aphasia or transcortical sensory aphasia. It was pointed out that classical aphasic syndromes are still valid as cerebral arterial occlusion syndromes, but are insufficient for the purpose of more precise anatomo-clinical correlation.
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Department of Neurology, Niigata University.
D001037:Aphasia / Q000209:etiology*; D002561:Cerebrovascular Disorders / Q000150:complications*; D006801:Humans