Predictors of cognitive functions in children with Sturge-Weber syndrome: A longitudinal study

Abstract

OBJECTIVE

Sturge-Weber syndrome (SWS) 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 SWS. The ‘rules’ governing these plasticity mechanisms are poorly understood. In this study we evaluated longitudinal changes of cognitive functioning (IQ) and assessed the performance of clinical, EEG, and MRI variables for predicting IQ in children with SWS.

METHODS

Thirty-three young children (mean age: 3.3 years at baseline) with unilateral SWS underwent MRI, scalp EEG and neuro-psychology evaluation twice, with a median follow-up of two years. None of the children had epilepsy surgery. Longitudinal IQ changes were calculated. Seizure variables, interictal EEG abnormalities, as well as 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 SWS 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 SWS.