[A study on restriction of the areas working in speech function--application of multivariate analysis of aphasia test data and of lesions on CT images, by composing a "restricted-aphasia-lesion-map"].

Computed tomography (CT) gave a large contribution to morphological analysis of the aphasia syndromes. The aphasia problems are, however, still controversial and have many unresolved issues, even from a morphological point of view. In most cases with cerebral vascular lesion causing speech dysfunction, we are able to define an extent of density change on CT images. But its extent seems to be often not consistent with the area supposed to be deranged in functional work-up of speech. CT appearance of some areas may be little changed or normal when those areas are to be in poor condition in their functional maintenance. This may be due to such a vascular supply which permits brain tissues to be sustained but which does not work for their function to be normally performed. From 642 cases with cerebral vascular lesion we reviewed CT images of 382 cases: 171 cases having a lesion in the left hemisphere and 46 of them showing aphasia syndrome; 151, a lesion in the right hemisphere alone and 3, aphasic; and 60 cases having lesions on both sides and 7 showing aphasia syndrome. First, we determined anatomically the extent of CT change in 102 cases, all right-handed, with a lesion in the left hemisphere. The extents were piled and made up to a "non-aphasia-lesion-map". This map was used for eliminating those areas as not working in speech function. The other map of the areas was made out of CT images of aphasia cases (33 cases including one agraphia). The latter map was put upon the "non-aphasia-lesion-map", so that the very area working in speech function could be more restricted. The third map, "restricted-aphasia-lesion-map" demonstrated those areas related to speech function: (1) the region limited around the three rami in the Sylvian fissure (Broca A); (2) the inferior frontal gyrus and the posterior aspect of the middle frontal gyrus (Broca B); (3) the inferior aspect of the cortex and subcortex of the Reil's island; (4) most of the middle temporal gyrus, the posterior third of the superior temporal gyrus, a large portion of the supramarginal gyrus and a part of the limbic system; (5) a large portion of the limbic system; (6) the anterior aspect of the superior frontal gyrus; and (7) the corpus callosum. The Standard Language Test for Aphasia (SLTA) was applied for 33 cases of aphasia.(ABSTRACT TRUNCATED AT 400 WORDS)