Prospective and retrospective studies of recovery in aphasia - Changes in cerebral blood flow and language functions

Prospective and retrospective language evaluations and single photon emissi on computed tomography (SPECT) scans were performed in order to study the r elationship between post-stroke recovery from aphasia and changes in cerebr al blood flow (CBF) in groups of patients who had made a good recovery and those who]aad not. For the prospective study, 20 right-handed patients with aphasia secondary to an acute cerebrovascular accident (CVA) in the left m iddle cerebral artery territory received language evaluations with a Japane se Standard Language Test of Aphasia (SLTA), and SPECT scans performed twic e, at a mean of 3.2 and a mean of 9.2 months post-onset. Only one slice of SPECT data was analysed. A significant correlation was observed between the severity of the initial language deficit and initial CBF on the left side, but not the right, Initial CBF was not a predictor for future language rec overy in either hemisphere. There was a correlation between the change in t he left mean hemispheric CBF (but not the right) and the change in the over all SLTA severity rating from 3 to 9 months poststroke. In the retrospectiv e study, 16 right-handed patients with residual aphasia secondary to CVA in the left middle cerebral artery territory received SLTA and SPECT at a mea n of 82.8 months post-onset, The patients had also received initial languag e evaluation with SLTA at a mean of 6.5 months post-onset. In contrast to t he prospective study, the results demonstrated that the mean left hemispher ic CBF at similar to 7 years post-onset did not differ between good and poo r recovery groups, However, the mean right hemispheric CBF of the good reco very group was higher than that of the poor recovery group in the frontal a nd the thalamic regions, and also in the left frontal region. The results o f these complementary studies suggest that the initial language recovery wi thin the first year post-onset may be linked primarily to functional recove ry in the dominant hemisphere, where an increase in CBF was observed at 9 m onths post-onset. The increased perfusion adjacent to the lesion may be cru cial for early recovery in aphasia, Subsequent language recovery and the lo ng-term recovery in aphasia may be related to slow and gradual compensatory functions in the contralateral hemisphere, specifically in the homotopic f rontal and thalamic areas.