Default Mode Network Changes in Moyamoya Disease Before and After Bypass Surgery: Preliminary Report

Objective: Neurocognitive impairment is often reported in moyamoya disease. We aimed to detect default mode network (DMN) alterations using resting-state functional magnetic resonance imaging and their association with neurocognitive impairments. In addition, the influence of surgical treatment was individually evaluated. Methods: Seven patients with moyamoya disease underwent preoperative resting-state functional magnetic resonance imaging and neuropsychologic tests. We compared the resting-state networks (RSNs) of our patients with those obtained from relatively large cohort datasets (127 healthy controls) using group independent component analysis with dual regression analysis. We also explored correlations between RSN alterations and neuropsychologic scores. We evaluated individuals again 6 months after surgery to identify changes. Results: Patients had statistically significant differences in DMN connectivity compared with healthy controls. There were marked changes in functional connectivity of the ventral DMN of patients with low working memory and performance speed scores. These changes were characterized by increases and decreases in various locations. In contrast, patients with average or high neuropsychologic scores showed similar connectivity to the controls. In 5 patients who underwent vascular reconstruction surgery, DMN functional connectivity changed to resemble that of healthy controls. Conclusions: In moyamoya disease, working memory and performance speed scores were inversely correlated to the degree of disruption of the DMN, suggesting a possible relationship between higher cognitive function and orderliness of fundamental brain networks. Vascular reconstruction surgery may contribute to normalization of brain networks. Analysis of RSNs may produce potential biomarkers for cognition in moyamoya disease.