Mixed Transcortical Aphasia Without Anatomic Isolation of the Speech Area

Steven Z. Rapcsak, MD, Lauren B. Krupp, MD, Alan B. Rubens, MD, and Johannes Reim, MD

"We report two patients with mixed transcortical aphasia following left frontal lobe infarctions. Although there was no evidence of anatomic isolation of the speech area on computed tomograms or magnetic resonance imaging scans, single-photon emission computed tomogra- phy in one case demonstrated diminished blood flow over the left parietal convexity suggestive of "functional isolation" of the posterior perisylvian language zone. (Stroke 1990^1:953-956)

Mixed transcortical aphasia is characterized by reduced or absent spontaneous speech, severely impaired language comprehen- sion, and preserved repetition. Although the localization of lesions producing mixed transcortical aphasia is variable, the syndrome is seen most often with diffuse or multifocal pathologic changes that involve both anterior and posterior left hemisphere cortical association areas but spare the perisylvian language core. According to Goldstein, the critically placed lesions produce an "isolation of the speech area" posteriorly from the "ideational field" of the parietal association cortex and anteriorly from frontal areas important for the production of volitional speech. Since Broca's area, Wemicke's area, and the arcuate fasciculus are usually spared, repetition remains intact.

Acute mixed transcortical aphasia is uncommon. Recently, Bogousslavsky et al described four cases of acute mixed transcortical aphasia in the setting of internal carotid artery occlusion with computed tomographic (CT) evidence of simultaneous anterior precentral-central sulcus artery territory embolic infarction and posterior watershed infarction related to hemodynamic insufficiency. These cases support Goldstein's contention by demonstrating both ante- rior and posterior anatomic isolation of the speech area.

We report two cases of mixed transcortical aphasia in which CT and magnetic resonance imaging (MRI) showed only frontal left hemisphere infarcts.

Case Reports

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