Recovery of Intrinsic Cognitive Weakness in Successive Processing After Bypass Surgery for Pediatric Moyamoya Disease

Successive processing, a form of working memory function detected with the Das Naglieri Cognitive Assessment System, is selectively impaired in pediatric moyamoya disease. We aimed to test whether successive processing in children with moyamoya disease was improved after bypass surgery under the control of confounding.

The present retrospective cohort study included children with moyamoya disease who underwent direct or combined bypass surgery. Neuropsychological tests including the Das Naglieri Cognitive Assessment System were administered at 2 time points, before and after surgery, approximately 1 year apart. The least squares (LS) mean standard score and LS mean difference between time points were calculated using a mixed model for repeated measures, which included 5 clinical factors along with the time point. Models including an interaction term were also generated to assess the effect of each clinical factor. Cognitive intra-individual variability across 4 domains of the Das Naglieri Cognitive Assessment System was assessed with an analysis of variance at each time point.

Of 60 patients who underwent surgery, 42 fulfilled the inclusion criteria. The median duration between assessments was 15 months. The LS mean standard scores of successive processing increased after surgery (LS mean, 95.8 versus 100.2; LS mean difference, 4.4 [95% CI, 1.5-7.3]; P = 0.004). The increase was more pronounced in those with a younger age at onset of neurological symptoms, shorter delay before surgery, preexisting infarct, posterior cerebral artery involvement, and more severe ischemic stage before surgery. Intraindividual variability, shown as the lowest score of successive processing at baseline, resolved after surgery (F = 3.56, P = 0.016 versus F = 1.21, P = 0.31). Successive processing was the domain most likely to be improved after surgery.

The present results suggest that successive processing is improved after bypass surgery. Larger and longer follow-up studies are required to confirm the influencing factors and long-term effects.