Introduction: Silent cerebral microbleeds (CMB) are common in Moyamoya Disease (MMD) and Moyamoya syndrome (MMS) in Asia. The incidence was reported to be 30-40%. The presence of CMB was found to be a predictor for subsequent cerebral hemorrhage in MMD. The significance of CMB in MMD/MMS in non-Asian population has not been reported. We try to investigate the prevalence of CMB in MMD/MMS in United States and its predictive value for subsequent cerebral hemorrhage.
Methods: Moyamoya Database was established in our institution after reviewing patients with ICD9 code of Moyamoya Disease or Moyamoya Syndrome or cerebrovascular occlusive disease from 2007 to 2015. Patients in the database were reviewed retrospectively and included in the study if there were MR images (including GRE, SWI or T2* sequences) at diagnosis or during follow up and available for review. Patients with poor image quality were excluded. Patients were noted to have microbleeds if it was found on initial or follow up MRI. Multivariate logistic regression analysis was used to identify clinical and imaging predictors of CMB.
Results: Sixty-three females and fourteen males were included with average age of 39 ± 13 at the time of diagnosis. The majorities were MMD (79.2%) and presented with ischemic events (79.2%). Hemorrhagic stroke was found in 9 (11.7%) patients before diagnosis. Ethnicity included Caucasian (61%), Asian (10.4%), Black (11.7%), and Hispanic (16.9%). Of total 77 patients, 7 (9.1%) had CMB but none of them presented with hemorrhagic stroke. During follow up of average 36 ± 29 months in these 7 patients, no cerebral hemorrhage was reported while ischemic events occurred in 2 (28.6%) patients. Of 70 patients without CMB, 51 had follow up of average 47 ± 46 months. One (2%) had cerebral hemorrhage while 12 (23.5%) had ischemic events. No independent predictors for CMB were identified among age, gender, ethnicity, etiology, presenting stroke, and comorbidities.
Conclusions: Silent CMB was less prevalent in MMD/MMS in United States than in Asia. No specific risk factors were identified to be associated with the presence of silent CMB. It was not associated with increased risk of subsequent cerebral hemorrhage in non-Asian population. Further studies are needed to confirm these findings.