Symptoms Do Not Predict White Matter Injury in the Watershed Regions in Children with Moyamoya

Objective: To assess whether white matter injuries differ in symptomatic vs asymptomatic moyamoya-affected hemispheres using diffusion magnetic resonance imaging since there is controversy regarding when or if to revascularize children with asymptomatic moyamoya.

Study design: We conducted a cross-sectional study of children with moyamoya who underwent diffusion magnetic resonance imaging before revascularization surgery as well as controls without moyamoya. We measured the fractional anisotropy, mean diffusivity, radial diffusivity, and axial diffusivity of white matter tracts in the watershed regions. Moyamoya-affected hemispheres were included if they did not have any visible stroke or infarct. Moyamoya-affected hemispheres were labeled "symptomatic" if transient ischemic attack, seizure, or movement disorder were localizable to that hemisphere, or if the child experienced headaches. Moyamoya-affected hemispheres were "asymptomatic" if the child did not have symptoms attributable to that hemisphere. Asymptomatic and symptomatic hemispheres were compared with each other and control children using ANOVA.

Results: We included 17 children with moyamoya with 26 moyamoya-affected hemispheres and 27 control children. Compared with controls, mean diffusivity, radial diffusivity, and axial diffusivity were greater in both symptomatic and asymptomatic moyamoya-affected hemispheres but were not significantly different from each other.

Conclusions: Children with moyamoya without stroke or silent infarct have unrecognized white matter injury that is similar in both symptomatic and asymptomatic moyamoya-affected hemispheres, suggesting that symptoms do not accurately reflect moyamoya severity.