Long-Term Outcomes of Cerebral Blood Flow and Neurotransmitter Receptor Function on Iodine-123-Iomazenil Single-Photon Emission Computed Tomography and Cognitive Assessments After Parent Artery Occlusion Combined with Cerebral Revascularization for Internal Carotid Artery Aneurysms

OBJECTIVE: Many studies of external-internal carotid artery (EC-IC) bypass as cerebral revascularization for nclippable internal carotid artery (ICA) aneurysms have re-ported surgical outcomes, including bypass patency and aneurysm resolution. However, no previous studies have assessed the long-term outcomes of cerebral blood flow (CBF), brain neural density, and cognition. The purpose of the present study was to evaluate the long-term outcomes of CBF and neurotransmitter receptor function using early and late images of iodine-123 (I-123)-iomazenil (IMZ) single-photon emission computed tomography (SPECT) and the cognitive function of patients who had undergone EC-IC bypass for symptomatic aneurysms in the cavernous portion of the ICA. METHODS: We performed a prospective observational study of 11 patients who had undergone superficial temporal artery-middle cerebral artery bypass or bypass using a saphenous vein graft for symptomatic aneurysms in the cavernous portion of the ICA. One patient experienced extensive infarction and, therefore, did not undergo postoperative testing. I-123-IMZ SPECT was performed with scanning at 23 minutes (early) and 180 minutes (late) after tracer administration before and after surgery. The preoperative and follow-up neuropsychological test scores from 6 patients were also analyzed. RESULTS: None of 10 patients who had undergone EC-IC bypass showed reductions in CBF and brain neural density. In addition, the neuropsychological test scores had not changed significantly from preoperatively to postoperatively. CONCLUSION: Using early and late I-123-IMZ SPECT, the present study has demonstrated that patients undergoing u ncomplicated cerebral revascularization for unclippable ICA aneurysms will not experience reductions in CBF or neurotransmitter receptor function, and their cognitive function was not impaired.