Imaging of pathophysiological mechanisms underlying the recovery from brain damage

• Published in: Japanese Journal of Stroke Vol. 27; no. 4; pp. 620 - 626
• Main Authors: Nagata, Ken, Yokoyama, Eriko, Kato, Haruhisa
• Format: Journal Article
• Language: Japanese
• Published: The Japan Stroke Society 2005
• Subjects: aphasia; CBF; CMRO2; PET; recovery; right hemisphere
• ISSN: 0912-0726; 1883-1923
• DOI: 10.3995/jstroke.27.620

The roles of the right non-dominant hemisphere and the residual areas of the damaged dominant left hemisphere have been discussed as to the recovery from aphasia. In this article, the results from our clinical investigations with positron emission tomography (PET) were reviewed in relation to the recovery from aphasia. In the long-term follow-up study with PET in patients with aphasia due to the left-hemisphere lesion who showed a gradual recovery, there was an increase in cerebral blood flow (CBF) and cerebral metabolic rate of oxygen (CMRO2) in the temporal and parietal cortices on the right hemisphere more than one year after the onset. The late increase in CBF and CMRO2 in the right temporal and parietal cortices may indicate a possible compensatory role of the right hemisphere during the recovery from aphasia. The results of the Standard Language Test for Aphasics (SLTA) was compared with the regional CBF and CMRO2 provided by PET in 41 patients with aphasia due to the left-hemisphere infarction. The SLTA score correlated significantly with the regional CBF from the bilateral inferior frontal, left prefrontal, bilateral superior temporal and right angular gyrus in 32 patients with a good aphasia outcome, whereas that correlated with the regional CBF from the left inferior frontal gyrus in 32 patients with a poor outcome. The SLTA score correlated with the regional CBF from the left inferior frontal, left prefrontal, and left superior temporal gyrus in 30 patients with a poor recovery from aphasia, whereas that correlated with regional CBF from the left inferior frontal, left prefron-tal, bilateral transverse, left supramarginal, and left angular gyrus in 34 patients with a poor recovery. Accordingly, a bilaterally re-organized language network may function effectively during the recovery from aphasia due to the left hemisphere lesion.