Infants with a high-risk distribution of port-wine stains are commonly screened for Sturge-Weber syndrome using brain magnetic resonance imaging. There is no consensus about which port-wine stain phenotypes to screen, optimal timing, screening sensitivity, or whether presymptomatic diagnosis improves neurodevelopmental outcomes. This state-of-the-art review examines the evidence in favor of screening for Sturge-Weber syndrome, based on its effect on neurodevelopmental outcomes, against the risks and limitations of screening magnetic resonance imaging and electroencephalography. A literature search of PubMed/MEDLINE was conducted between January 2005 and May 2017 using key search terms. Relevant articles published in English were reviewed; 34 articles meeting the search criteria were analyzed according to the following outcome measures: neurodevelopmental outcome benefit of screening, diagnostic yield, financial costs, procedural risks, and limitations of screening magnetic resonance imaging and electroencephalography. There is no evidence that a presymptomatic Sturge-Weber syndrome diagnosis with magnetic resonance imaging results in better neurodevelopmental outcomes. The utility of electroencephalographic screening is also unestablished. In Sturge-Weber syndrome, neurodevelopmental outcomes depend on prompt recognition of neurologic red flags and early seizure control. Small numbers and a lack of prospective randomized controlled trials limit these findings. For infants with port-wine stain involving skin derived from the frontonasal placode (forehead and hemifacial phenotypes), we recommend early referral to a pediatric neurologist for parental education, counselling, and monitoring for neurologic red flags and seizures and consideration of electroencephalography regardless of whether magnetic resonance imaging is performed or its findings. K E Y W O R D Selectroencephalography, epilepsy, magnetic resonance imaging, neurodevelopmental outcomes, port-wine stain, screening, Sturge-Weber syndrome

Findings from this small cohort of individuals with port-wine stains that put them at high risk of Sturge-Weber syndrome suggest that children with positive screening magnetic resonance imaging will almost certainly develop Sturge-Weber syndrome but that negative screening magnetic resonance imaging cannot exclude Sturge-Weber syndrome (in up to 23.1% of cases). False-negative magnetic resonance imaging may delay seizure recognition. Seizure education, monitoring, and consideration of adjunctive electroencephalography are important irrespective of magnetic resonance imaging findings.