Moyamoya Syndrome Treated With Encephaloduroarteriosynangiosis Followed by Bone Marrow Transplantation in a Patient With Sickle Cell Disease: A Case Report

Patients with sickle cell disease (SCD) have a high risk of intracranial large vessel vasculopathy. This can lead to a proliferation of microvasculature at the base of the brain known as moyamoya syndrome. If untreated, there is a high risk of intraventricular hemorrhage and permanent neurologic deficits. There have been several reports describing patients with SCD and moyamoya syndrome successfully undergoing revascularization procedures, including encephaloduroarteriosynangiosis (EDAS). Hematopoietic cell transplantation from a compatible sibling is the most effective way of preventing central nervous system (CNS) complications in SCD patients at risk for CNS events. To our knowledge, there have been no reports of SCD patients undergoing EDAS followed by bone marrow transplantation (BMT). We describe the case of a 14-year-old girl with SCD who developed severe stenosis of the right internal carotid artery, which progressed and extended to the anterior cerebral and middle cerebral arteries, with silent infarcts and changes on magnetic resonance angiography (MRA) consistent with moyamoya syndrome. Due to worsening of her stenosis, at the age of 11 she underwent EDAS without complications. Eighteen months after the procedure, she developed a left lower extremity monoparesis. Magnetic resonance imaging (MRI) did not show any new areas of ischemia. Three months later she underwent high-dose chemo-immunotherapy followed by BMT from her compatible sibling. Her mixed-donor chimerism on day +32 was 98% donor, with concomitant hemoglobin S of 0.9%, confirming donor engraftment and eradication of her SCD. The patient is now 10 months post-transplant and has not had any SCD-related complications. Her neurologic exam and neuroimaging studies remain stable. This is the first case report of EDAS successfully followed by BMT in a patient with SCD and moyamoya syndrome. BMT is considered standard of care in patients with SCD at risk for CNS complications, leading to stroke-free survival rates of 93-96%. Patients with moyamoya syndrome and SCD who have a CNS event are more than twice as likely to experience a recurrent CNS complication even while on chronic transfusions. Transplant-eligible SCD patients who develop moyamoya syndrome may benefit from EDAS prior to undergoing BMT in order to minimize peri- and post-transplant CNS complications. Further investigation is needed to determine the long-term outcome of this therapeutic combination.