Transcortical mixed aphasia due to cerebral infarction in left inferior frontal lobe and temporo-parietal lobe

Abstract

We present a case of transcortical mixed aphasia caused by a cerebral embolism. A 77-year-old right-handed man was admitted to our hospital with speech disturbance and a right hemianopia. His spontaneous speech was remarkably reduced, and object naming, word fluency, comprehension, reading and writing were all severely disturbed. However, repetition of phonemes and sentences and reading aloud were fully preserved. Although magnetic resonance imaging (MRI) showed cerebral infarcts in the left frontal and parieto-occipital lobe which included the inferior frontal gyrus and angular gyrus, single photon emission CT revealed a wider area of low perfusion over the entire left hemisphere except for part of the left perisylvian language areas. The amytal (Wada) test, which was performed via the left internal carotid artery, revealed that the left hemisphere was dominant for language. Hence, it appears that transcortical mixed aphasia may be caused by the isolation of perisylvian speech areas, even if there is a lesion in the inferior frontal gyrus, due to disconnection from surrounding areas.

Why Is It Difficult to Predict Language Impairment and Outcome in Patients with Aphasia after Stroke?

“…This syndrome was introduced into the aphasiology literature to describe nonfocal lesions, and was referred to as "isolation of the speech area". Nevertheless, there have been several reports of patients demonstrating transcortical mixed aphasia resulting from focal left-hemisphere lesions affecting frontal and parietal regions,42 left superior and posterior parts of the frontal lobe and the parieto-temporo-occipital junction,43 and the left frontal and parieto-occipital regions, including the inferior frontal and angular gyrus 42. Mixed transcortical aphasia has also been reported in relation to focal lesions in the right hemisphere 39…”