Neuropsychological functioning following surgery for pediatric low-grade glioma: a prospective longitudinal study

Abstract

Objective: High survival rates have led to an increased emphasis on the functional outcomes of children diagnosed with low-grade glioma. Most outcomes research has focused on risks associated with radiotherapy, but less is known about neuropsychological risks for patients treated with surgery alone. Here, the authors sought to examine the neuropsychological trajectories of children diagnosed with a low-grade glioma and monitored up to 6 years postsurgery. Secondarily, they explored demographic and clinical predictors of neuropsychological performance.

Methods: The neuropsychological functioning of 32 patients (median age at diagnosis 10.0 years) was prospectively assessed annually for up to 6 years after surgery (median days from surgery at baseline = 72). Tumor location was predominately supratentorial (65.6%). A combination of performance-based and parent-reported measures was used to assess intelligence, memory, executive functioning, and fine motor control in all patients.

Results: Binomial tests at the postoperative baseline revealed that the proportion of children falling below the average range (< 16th percentile) was significantly higher than the rate expected among healthy peers on measures of verbal memory, processing speed, executive functioning, and fine motor control (p < 0.05). Even so, linear mixed models indicated that neuropsychological functioning at the postoperative baseline did not significantly change over time for up to 6 years after surgery across all domains. A larger tumor size was associated with a slower reaction time (p < 0.01). A supratentorial tumor location and history of seizures were associated with more parent-reported executive difficulties (p < 0.01).

Conclusions: While radiotherapy is a known risk factor for neuropsychological deficits in pediatric brain tumor patients, findings in this study indicate that children treated for low-grade glioma with surgery alone (without radiotherapy or chemotherapy) remain susceptible to difficulties with memory, executive functioning, and motor functioning that persist over time. Over half of the children in the study sample required school support services to address neuropsychological weaknesses. Although low-grade glioma is often conceptualized as a benign tumor, children treated for this lesion require ongoing monitoring and intervention to address neuropsychological weaknesses resulting from the tumor itself as well as the surgery.

Keywords: brain tumor; executive functioning; low-grade glioma; neuropsychology; oncology; pediatric; surgery only.

FIG. 1.

Proportions of scores falling below the average range at the baseline postoperative assessment. *Proportion of scores below average (1 SD, standard score ≤ 85) that were significantly greater than the expected 16% in the normative population based on a binomial test (p < 0.05). The dashed line represents the 16% expected to score below average in the normative population. FM = Fine Motor; PRI = Perceptual Reasoning Index; PSI = Processing Speed Index; VCI = Verbal Comprehension Index; WMI = Working Memory Index.

FIG. 2.

Longitudinal neurocognitive performance. The individual graphs display longitudinal performance on the Wechsler indices, including verbal reasoning and comprehension (A), nonverbal and fluid reasoning (B), working memory (C), and processing speed (D). Colored lines represent individual performance, and bolded black lines represent change in standard score performance (beta) across patients per linear mixed models.