18 Executive Dysfunction Following Treatment for Pediatric Low Grade Brain Tumors: Increased Risk Associated with Infratentorial Tumor Location

Abstract

Objective:

Treatment for pediatric brain tumors (PBTs) is associated with neurocognitive risk, including declines in IQ, executive function, and visual motor processing. Low grade tumors require less intensive treatment (i.e., focal radiotherapy (RT) or surgical resection alone), and have been associated with more favorable cognitive outcomes. However, these patients remain at risk of cognitive problems, which may present differently depending on tumor location. Executive functioning (EF), in particular, has been broadly associated with both frontal-subcortical networks (supratentorial) and the cerebellum (infratentorial). The current study examined intellectual functioning, executive functioning (set-shifting and inhibition), and visual motor skills in patients who were treated for low-grade tumors located in either the supratentorial or infratentorial region.

Participants and Methods:

Participants were survivors (age 8-18) previously treated with focal proton RT or surgery alone for infratentorial (n=21) or supratentorial (n=34) low grade glioma (83.6%) or low grade glioneuronal tumors (16.4%). Survivors >2.5 years post-treatment completed cognitive testing (WISC-IV/WAIS-IV; D-KEFS Verbal Fluency (VF), Color-Word Interference (CW), Trail Making Test (TM); Beery Visual-Motor Integration). We compared outcomes between infratentorial and supratentorial groups using analysis of covariance (ANCOVA). Demographic and clinical variables were compared using Welch’s t-tests. ANCOVAs were adjusted for age at evaluation, age at treatment, and history of posterior fossa syndrome due to significant or marginally significant differences between groups.

Results:

Tumor groups did not significantly differ with respect to sex (49.0% male), length of follow-up (M 4.4 years), or treatment type (74.5% surgery alone, 25.5% proton RT). Marginally significant group differences were found for age at evaluation (infratentorial M = 12.4y, supratentorial M = 14.1y, p = .054) and age at treatment (infratentorial M = 7.9y, supratentorial M = 9.7y, p =.074). Posterior fossa syndrome only occurred with infratentorial tumors (n=5, p = .003). Adjusting for covariates, the supratentorial group exhibited significantly superior performance on a measure of inhibition and set-shifting (CW Switching Time (t(32) = -2.05, p=.048, n2 =.11). There was a marginal group difference in the same direction on CW Inhibition Time (t(32 = -1.77, p = .086, n2 =.08). On the other hand, the supratentorial group showed significantly lower working memory than the infratentorial group (t(50) = 2.45, p = .018, n2 = .11), and trends toward lower verbal reasoning (t(50)=1.96, p = .056, n2 = .07) and full-scale IQ (t(50)=1.73, p = .090, n2 = .055). No other group differences were identified across intellectual, EF, and visualmotor measures.

Conclusions:

Infratentorial tumor location was associated with weaker switching and inhibition performance, while supratentorial tumor location was associated with lower performance on intellectual measures, particularly working memory. These findings suggest that even with relatively conservative treatment (i.e., focal proton RT or surgery alone), there remains neurocognitive risk in children treated for low-grade brain tumors. Moreover, tumor location may predict distinct patterns of long-term neurocognitive outcomes, depending on which brain networks are involved.