Predictors of Cognitive Functions in Children With Sturge-Weber Syndrome: A Longitudinal Study

Abstract

Background: Sturge-Weber syndrome is often accompanied by seizures and neurocognitive deterioration, although previous studies have suggested that early functional brain reorganization may diminish the cognitive sequelae in some children with unilateral Sturge-Weber syndrome. The "rules" governing these plasticity mechanisms are poorly understood. In this study, we evaluated longitudinal changes of cognitive functioning (intelligence quotient [IQ]) and assessed the performance of clinical, electroencephalography (EEG), and magnetic resonance imaging (MRI) variables for predicting IQ in children with Sturge-Weber syndrome.

Methods: Thirty-three young children (mean age: 3.3 years at baseline) with unilateral Sturge-Weber syndrome underwent MRI, scalp EEG, and neuropsychology evaluation twice, with a median follow-up of 2 years. None of the children had epilepsy surgery. Longitudinal IQ changes were calculated. Seizure variables, interictal EEG abnormalities, and extent and location of MRI brain involvement were correlated with IQ assessed at follow-up.

Results: Global IQ showed a highly variable course with both increases and decreases over time. Lower IQ at baseline was associated with interval IQ increase. In univariate analyses, lower outcome IQ was associated with baseline EEG abnormalities (P < 0.001), young age at seizure onset (P = 0.001), high seizure frequency (P = 0.02), and early frontal-lobe involvement on MRI (P = 0.01). In multivariate analysis, EEG abnormalities at baseline remained a robust, independent predictor of outcome IQ.

Conclusions: The early trajectory of cognitive changes in children with unilateral Sturge-Weber syndrome is highly variable; children with improving IQ likely undergo effective unimpeded functional reorganization. Early onset, frequent seizures, and interictal epileptiform abnormalities on EEG likely interfere with this process resulting in poor cognitive functions. Future studies assessing interventions should target this high-risk subgroup to optimize cognitive outcome in Sturge-Weber syndrome.

Keywords: EEG; MRI; Sturge–Weber syndrome; cognitive functions; epilepsy; longitudinal study.

Figure 1

Distribution of global IQ (GIQ) changes [Time 2−Time 1] in 17 patients. GIQ changes are categorized into five groups (shown in the five columns). The first and second columns include patients with declining GIQ, the third with minimal/no changes, and the fourth and fifth columns are patients with improving GIQ during follow-up. Only 4 of the 17 patients showed a robust GIQ decrease (−10 or more), while 5 patients showed a moderate or robust increase.

Figure 2

Negative correlation between baseline global IQ (GIQ) and interval GIQ change (r=−0.66, p=0.004). Low baseline IQ was associated with increasing outcome IQ.

Figure 3

Negative correlation between EEG severity scores at baseline and outcome global IQ (GIQ). Patients with worse baseline EEG scores had lower GIQ at follow up (r=−0.67; p<0.001).