Sickle Cell Disease Associated Moyamoya Syndrome
Moyamoya syndrome (MMS) is a relatively uncommon vascular complication of sickle cell disease (SCD) characterized by progressive stenosis of the supraclinoid carotid arteries and development of typical collaterals
Sickle Cell Disease is associated with moyamoya-like changes on cerebral angiographic imaging in 43% of patients. Cerebral aneurysms,arteriovenous malformations, and dural arteriovenous fistulas (AVFs) have been described in association with SCD and moyamoya disease.
Moyamoya syndrome increases the risk of stroke in sickle cell disease
Collaborative management between hematology and neurosurgery offers effective strategies to reduce stroke risk in these patients.
Revascularization is associated with a significant reduction in stroke risk, both relative to prerevascularization rates and compared with medical management. According to these findings, surgical revascularization offers a safe and durable preventative therapy for stroke and should be pursued aggressively in this patient population 1).
A retrospective cohort study of medically managed vs surgically revascularized patients with moyamoya syndrome and sickle cell disease was conducted. Demographic data and outcomes including the number of prediagnosis, postdiagnosis, and postrevascularization strokes were collected. Risk factors for stroke were identified using a binary logistic regression model, and stroke rates and mortality between groups were compared.
Of the 29 identified patients, 66% were medically managed and 34% underwent surgical revascularization (50% direct and 50% indirect). Calculated stroke rates were 1 per 5.37 (medical management), 1 per 3.43 (presurgical revascularization), and 1 per 23.14 patient-years (postsurgical revascularization). There was 1 surgical complication with no associated permanent deficits. No risk factors for stroke after time of diagnosis were found to be significant.
The results of this study demonstrate that revascularization is associated with a significant reduction in stroke risk, both relative to prerevascularization rates and compared with medical management. According to these findings, surgical revascularization offers a safe and durable preventative therapy for stroke and should be pursued aggressively in this patient population 2).
Lo Presti et al. present the case of a 15-year-old boy with Sickle cell disease SCD-associated moyamoya disease harboring a intracranial pial arteriovenous fistula pAVF who developed a de novo venous aneurysm 8 months after undergoing indirect superficial temporal artery–middle cerebral artery (MCA) bypass that was complicated by bilateral ischemia of the MCA territory. The pAVF was successfully treated with transarterial embolization using Onyx. The authors describe the possible pathophysiological mechanisms and management strategies for this rare occurrence 3).
Slingerland et al. described a challenging case where a patient with sickle cell disease undergoing standard of care management as prescribed by the Stroke Prevention Trial in Sickle Cell Anemia (STOP) and revascularization with pial synangiosis subsequently developed rapidly progressive disease in other cerebral vessels and suffered ischemic hemispheric stroke. This case demonstrates the success of management in accordance with American Heart Association (AHA) and American Stroke Association (ASA) guidelines, but also demonstrates critical areas where we lack understanding of disease progression 4).