Authors: Ephraim W. Church, MD; Teresa Bell-Stephens, BSN; Mark Bigder, MD; Gary Steinberg, MD, PhD (Stanford, CA)


The natural history of unilateral moyamoya disease remains an enigma in modern vascular neurosurgery. Few, small series with limited follow up have reported relatively high rates of contralateral stenosis progression. We sought to review a large series of unilateral moyamoya patients at our medical center.


We included all unilateral moyamoya cases treated from 1991 through 2017 and followed at least 1 year. We examined time to contralateral radiographic progression as well as contralateral progression requiring surgery. Using a time to event analysis, we sought to create a prediction model for contralateral progression, including variables such as baseline stenosis, sex, age, syndrome (NF1, Down syndrome, hemaglobinopathy), race, family history, hypertension, hyperlipidemia and smoking history. This study was approved by our IRB.


There were 184 patients treated for unilateral moyamoya. One hundred twenty-nine (70%) were female, and the average age at first surgery was 33 (range 2-68). Average follow up was 5.4 yrs (range 1-22 yrs). Fifteen (8.2%) patients developed contralateral progression. Seven (3.8%) of these developed progression requiring bypass surgery. A time to event analysis revealed potential predictors of contralateral progression.


Previous series showed relatively high rates of progression in unilateral moyamoya, but these studies were small and long term follow up was not available. Our large series with long term follow up indicates that the rate of progression is lower than previously reported but still warrants yearly non-invasive screening.