Is initial unilateral revascularization acceptable in pediatric patients with bilateral moyamoya disease with mild contralateral hemodynamic disturbance?

OBJECTIVE Although asymmetrical vascular involvement between hemispheres is common in pediatric patients with bilateral moyamoya disease, whether hemispheres with mild vascular changes and hemodynamic impairment require immediate surgical revascularization or whether they can be observed until disease progression remains unclear. The authors evaluated the long-term outcomes of their strategy to initially perform unilateral surgery and withhold surgery to the contralateral hemispheres with mild vascular changes and hemodynamic impairment. METHODS The authors retrospectively evaluated Japanese pediatric patients (onset age ≤ 15 years) diagnosed with bilateral sporadic moyamoya disease who underwent unilateral revascularization. The authors investigated whether the patient underwent additional collateral surgery and the incidence of ischemic events during follow-up. They also compared visual assessments of arterial spin labeling (ASL) images obtained before initial surgery, before additional contralateral surgery, and at last follow-up. RESULTS Overall, 30/47 patients (63.8%) experienced progression of hemodynamic impairment in the contralateral hemisphere and underwent additional surgery. The age at initial surgery of the patients who needed additional contralateral surgery was significantly younger than that of the patients who did not require contralateral surgery (mean [SD] 7.0 [3.0] years vs 9.8 [2.6] years, p = 0.002). One patient (age 4 years) developed ischemic stroke before admission for preoperative evaluation 2 months after novel symptom onset, and another patient (age 6 years) experienced ischemic stroke in the contralateral hemisphere while discontinuing antiplatelet agents before surgery; both patients fully recovered from the neurological deficits. In contralateral hemispheres that required additional surgery, the ASL visual assessment scores significantly decreased before the additional contralateral surgery compared to those obtained before the initial surgery (p = 0.008). CONCLUSIONS In pediatric patients with bilateral moyamoya disease, withholding surgery for hemispheres with mild vascular changes and hemodynamic impairment is generally safe. Younger patients were more likely to experience contralateral progression and require additional surgery, so close follow-up is needed. ASL imaging is useful for detecting and following the progression of hemodynamic impairment in conservatively treated hemispheres.