Background: Moyamoya disease is a rare, progressive vasculopathy that causes narrowing of intracranial arteries such as distal branches of the internal carotid artery (ICA) and proximal components of the middle anterior artery (MCA) and anterior cerebral artery (ACA). One of the ICA branches involved in Moyamoya syndrome include the anterior choroidal artery, which may develop an aneurysm, or more rarely like in this case, a pseudoaneurysm that may rupture and lead to a hemorrhagic stroke.

Case Presentation: The patient is a 24 year-old-woman with a past medical history of sickle cell disease who presented to our neighboring hospital with left sided numbness. The patient reported an associated headache, nausea, and vomiting prior to the episode that prompted her to seek medical attention. She was transferred to our hospital due to a basal ganglia hemorrhage found on CT. Upon arrival at our emergency department, her vitals were stable and she was somnolent but AAOx3. Neurological exam was remarkable for left side hemiparesthesia and associated mild left side hemiparesis with motor strength of 4/5 in left upper and lower extremities. Patient was admitted to ICU level of care and neurology and neurointerventional radiology were consulted for further management. Brain MRI was remarkable for right thalamic intra-axial hematoma. Subsequent brain MRA was recommended and showed occluded bilateral ACA and MCA suspicious for Moyamoya syndrome. Digital subtraction angiography (DSA) was then performed showing a 4mm pseudoaneurysm of the right distal anterior choroidal artery which underwent successful embolization.

Discussion: The association between Moyamoya syndrome and sickle cell disease in the pediatric population has been well established, however, current literature is limited in regard to this disease in the adult population. Although other reports have described distal anterior choroidal artery aneurysms in Moyamoya syndrome, seldom to none have described a pseudoaneurysm of this artery in the context of Moyamoya syndrome and Sickle cell disease. Thus, our case report highlights an uncommon finding of Moyamoya syndrome whilst raising awareness of Moyamoya syndrome in adults with sickle cell anemia.