How to choose the surgical side when cerebral blood flow and cerebrovascular response are contradictory in bilateral moyamoya disease?: A case report

Introduction: Moyamoya disease (MMD) is a rare cerebrovascular disease characterized by progressive occlusion of the internal carotid artery and the secondary formation of collateral vessels. Bypass surgery is an effective treatment for MMD. Comprehensive evaluation of cerebral blood flow (CBF) and cerebrovascular response (CVR) is the common hemodynamic indication to surgery, the changes of which are usually identical. The patient's main concerns and important examinations: We reported a rare case of MMD in a 34-year-old pregnant woman with transient ischemic attacks (TIAs) for 1 month, manifesting as frequent weakness in right limbs for several minutes without obvious cause. The diagnostic digital subtraction angiography (DSA) examination revealed Suzuki Grade I in left side and Grade IV in right side under modified Suzuki scoring. No-hyperventilation test single-photon emission computed tomography (no-HVT SPECT) showed more decreased CBF in the right side of the brain, but HVT SPECT demonstrated a more impaired CVR on the left side. Comprehensively, which side should be operated on is confusing when the changes of CVR and CBF are inconsistent. The main diagnosis, therapeutics interventions, and outcomes: The patient was diagnosed with bilateral MMD and underwent combined bypass surgery on the left side of the brain. The symptoms of admission were completely relieved after surgery and there were no further cerebrovascular events during the follow-up period of 4 months. Conclusion: CVR is a primary surgical indication of MMD, especially when the impairment of CVR and CBF are not consistent in the ipsilateral hemisphere. Meanwhile, HVT is the vital vasoactive challenges test for measuring CVR in MMD.