The pattern of neuropsychological impairment associated with left posterior cerebral artery infarcts

Abstract

We investigated the neuropsychological correlates of left posterior cerebral artery (LPCA) infarcts with a quantitative systematic approach and found a pattern of impairment extending well beyond the classical syndrome of alexia without agraphia. Sixteen consecutive patients with CT scan evidence of an infarct confined to the territory of LPCA were given a battery of tests assessing the following abilities. (1) Reading and writing; (2) naming and pointing to colours; (3) naming the same 30 objects on visual (objects and coloured photographs), tactile and verbal presentation; and (4) verbal memory. These tests were administered to large control samples and the performance of LPCA patients was considered pathological if it fell below the score of the last or second to last control patient. Seventy five per cent of PCA patients had alexia without agraphia. Although a lesion of the CT scan slice where the pineal is represented appeared to be crucially associated with alexia, the severity of the disorder increased when contiguous upper or lower slices were also involved. Not only colour anomia, but also object and especially photograph anomia could almost always be shown in alexics and were highly correlated with the degree of the reading impairment. The naming deficit was also present when items were presented in the tactile and verbal modality, in spite of the integrity of the oral language areas. Every right-handed patient, alexic as well as nonalexic, was impaired on at least two of the three verbal memory tests and most on all of them. The findings are discussed in terms of the anatomofunctional mechanisms subserving verbal memory and the transmission of visual information to the speech areas.