Lower prefrontal blood flow associated with intraindividual weakness in successive processing: a neurocognitive study of pediatric moyamoya disease

OBJECTIVE Selective intraindividual weakness in successive processing, which is a unique verbal working memory scale included in the Das-Naglieri Cognitive Assessment System (CAS), is considered one of the intrinsic neurocognitive characteristics in pediatric moyamoya disease (MMD). The aim of the study was to elucidate the association between cerebral blood flow (CBF) and weakness in successive processing, and to identify regions related to the weakness. METHODS The present cross-sectional study included children who had been diagnosed with MMD and were assessed using neuropsychological tests before surgery between June 2016 and December 2023. According to the CAS manual, intraindividual difference was calculated by subtracting the mean of the 4 standard scores from each standard score. Each patient was classified as either manifesting "intraindividual weakness in successive processing" (intraindividual difference of successive processing < 0) or not (intraindividual difference of successive processing ≥ 0), and CBF acquired with resting-state SPECT was compared between groups. Three-dimensional stereotactic surface projection (3D-SSP) was also used for topographical comparison of CBF. RESULTS Of 51 children (mean age ± SD at admission 8.0 ± 2.6 years) who underwent preoperative neuropsychological tests, 43 were included in the CBF analysis. Both standard scores and intraindividual difference of the CAS significantly varied across 4 domains (p = 0.006 and p < 0.001, respectively), and those of successive processing were the lowest. Of the children analyzed, 35 (68.7%) were classified as having intraindividual weakness in successive processing. Multiple logistic regression analysis revealed the severest ischemic grade was significantly associated with intraindividual weakness in successive processing (OR 5.49 [95% CI 1.12–27.06]). Three-dimensional SSP analysis demonstrated a significant CBF decrease in the left dorsolateral and medial prefrontal cortexes in the children showing intraindividual weakness in successive processing compared with those who did not. CONCLUSIONS Intraindividual weakness in successive processing typical of MMD might be associated with reduced CBF in the dorsolateral and medial prefrontal cortex, predominantly in the left hemisphere. Further studies in this area could contribute to the improvement of long-term social outcomes for patients with MMD.