Postoperative Basal Ganglia–Dominant Perfusion Pattern Predicts Lower Risk of Transient Neurological Events After Direct Revascularization in Moyamoya Disease

BACKGROUND AND PURPOSE: Early postoperative transient neurological events are common after direct revascularization for moyamoya disease (MMD). We investigated whether the redistribution of perfusion between the basal ganglia and cortical territories on early postoperative SPECT is associated with transient neurological events. MATERIALS AND METHODS: We retrospectively analyzed 78 hemispheres from 61 patients with MMD who underwent superficial temporal artery–MCA bypass. N-Isopropyl-p-[¹²³I]iodoamphetamine SPECT was performed within 3 months preoperatively and on postoperative day 1. Relative CBF was normalized to the contralateral cerebellum using automated region-of-interest segmentation. Postoperative-to-preoperative relative CBF ratios were calculated for the basal ganglia and the anterior MCA territory. The balance index was defined as the ratio of the basal ganglia to the anterior MCA relative CBF ratio. Receiver operating characteristic analysis was performed to assess predictive performance. RESULTS: Transient neurological events occurred in 17 (21.8%) hemispheres. The postoperative basal ganglia relative CBF ratio was greater in hemispheres without transient neurological events compared to those with transient neurological events (118.5% ± 15.3% vs. 106.0% ± 9.9%, P = 0.002). The balance index was higher in the hemispheres without transient neurological events (1.15 ± 0.13 vs. 1.01 ± 0.13, P < 0.001). Receiver operating characteristic curve analysis identified a balance index cutoff of 1.052 (area under the curve = 0.841; sensitivity = 76.5%; specificity = 82.0%). Hemispheres with a balance index < 1.052 had a higher incidence of transient neurological events (50.0% vs. 7.7%; odds ratio, 12.0; 95% CI, 3.35–43.04; P <0 .001). CONCLUSION: Postoperative basal ganglia-dominant perfusion was associated with postoperative neurological stability and a lower risk of transient neurological events.