CROSSED APHASIA - FUNCTIONAL BRAIN IMAGING WITH PET OR SPECT

Objectives: To study patients with crossed aphasia (aphasia secondary to lesions in the right hemisphere in right-handed patients) with func tional brain imaging using positron emission tomography (PET) or singl e photon emission computed tomography (SPECT); to see whether left hem isphere structures were metabolically depressed during the acute phase and, in 1 patient, during recovery; and to review the modern literatu re on crossed aphasia, with special reference to left hemisphere invol vement. Design: Case studies of 3 patients with crossed aphasia, inclu ding language testing, computed tomographic scanning, and functional i maging with PET or SPECT. Setting: Hospital case studies. Patients: Th ree-right-handed patients with crossed aphasia secondary to acute infa rctions in the right hemisphere and left hemiparesis. Methods: All 3 p atients were studied by means of bedside language testing, computed to mographic scanning, and functional brain imaging with PET or SPECT. Pa tient 1 also underwent serial testing with the Boston Diagnostic Aphas ia Examination and follow-up PET scanning after 2 months of recovery. Outcome Measures: Clinical examination in all 3 patients and follow-up Boston Diagnostic Aphasia Examination and PET scanning in patient 1. Results: Two patients had severe global aphasia and 1 had Broca aphasi a. In all cases, computed tomographic scans failed to reveal any left hemispheric lesions. Functional imaging with PET or SPECT showed exten sive hypometabolism or hypoperfusion in the right hemisphere, with ini tial reductions in the left hemisphere as well. In patient 1, a follow -up PET image showed only persistent hypometabolism in the right hemis phere. Conclusions: These findings suggest that abnormal dominance for at least some language functions in the right hemisphere underlies th e syndrome of crossed aphasia. Diaschisis, or functional depression of the anatomically normal left hemisphere, was seen in all 3 patients d uring the acute phase, but not in patient 1 after recovery had begun.