The contribution of the left and right hemispheres to early recovery from aphasia: a SPECT prospective study.

This prospective study examined the relationship between post-stroke recovery of aphasia and changes in cerebral blood flow (CBF). To address the question of right hemisphere (RH) involvement in restitution of language, we tested the hypothesis that the increase in perfusion of the RH is crucial for early recovery from aphasia. Twenty-four right-handed patients with acute aphasia following left hemisphere (LH) ischaemic stroke were examined twice with a six-month interval. At each session CBF and language scores were measured on the same stroke patients. Language was measured by selected tasks derived from the Boston Diagnostic Aphasia Examination (BDAE). The SPECT scans were obtained using (99m)Tc-ECD on a triple-head gamma camera Multispect-3. Although initial CBF measured for the whole group of aphasic patients was not a predictor for future language recovery for either hemisphere, increased perfusion of the RH during a six-month interval was found to parallel the recovery of aphasic disorders. There was a correlation between the change in the right parietal CBF (but not the left) and a change in numerous language abilities. Nevertheless, only CBF values on the left predicted performance on the language tests at initial and follow-up examinations. When the area damaged on structural imaging was excluded from perfusion analysis, only subcortical CBF change on the left showed a positive correlation with language improvement. Thus, the cerebral mechanism associated with early recovery from aphasia is a dynamic and complex process that may involve both hemispheres. Probably this mechanism involves functional reorganisation in the speech-dominant (damaged) hemisphere and regression of haemodynamic disturbances in the non-dominant (structurally intact) hemisphere.