Recovery of localized brain function in learning disabled children -regional cerebral blood flow and cognitive-neuropsychological study-

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Neuropsychological assessment batteries were used to detect higher brain dysfunction, and single photon emission tomography to measure regional cerebral blood flow (rCBF). 15 learning disabled (LD) children, with normal intellectual ability in psychological performance and no brain lesions detected by magnetic resonance imaging (MRI) or computed tomography, were examined from 1997 to 1999. They manifested specific cognitive disorders, namely, specific Kanji writing disorders, specific dyslexia with dysgraphia for Kanji, specific dyslexia with dysgraphia for both Kanji and Kana, and verbal semantic disorders. We supposed their dysfunction parts of their brain based on the place where rCBF is reduced compared with the contralateral area. Four of 15 children were evaluated twice for rCBF and cognitive neuropsychological abilities. As results, we found that the area with reduced rCBF in LD children correspond to the brain lesion in adults with an acquired brain damage showing similar symptoms. For example, all LD children who showed writing or reading disorders manifested reduced rCBF in their temporal and/or parietal lobe, and those showed verbal semantic disorders without non-verbal semantic disability, manifested reduced rCBF in their temporal lobe. These results suggest that LD is caused by a localized brain dysfunction.Two children showed almost no changes of their cognitive-neuropsychological symptoms. One had specific Kanji writing disorder and the other had dyslexia with dysgraphia for both of Kanji and Kana. Their rCBF showed almost no changes in the reduced rCBF for two years. On the other hand, a child, who manifested verbal semantic disorder, showed improvement in cognitive neuropsychological performance and rCBF in the left temporal lobe.Thus the change of cognitive neuropsychological performance and rCBF showed parallel in these LD children.