CHICAGO – Screening infants with a port-wine stain for Sturge-Weber syndrome (SWS) with a magnetic resonance imaging brain scan had a 23% false-negative rate and actually delayed seizure detection, according to a recent study.
When infants with port-wine stains receive a dermatology consult, they may also be screened for SWS by means of MRI and by electroencephalography, particularly if their lesion phenotype puts them at higher risk for SWS. But the accuracy and benefit of the screenings has not been well established, said Michaela Zallmann, MD, the study’s first author. Hemifacial lesions that involve both the forehead and cheek and median lesions that are centered around the facial midline are both considered high-risk lesions.
Dr. Zallmann, a dermatologist at Monash University and the Royal Children’s Hospital, Melbourne, and her coinvestigators examined data on 126 patients with facial port-wine stains who came to a laser clinic over a 12-month period. Of these, 32 (25.4%) had a high-risk port-wine stain, and 9 of those 32 (28.1%) had a capillary-venous malformation characteristic of SWS. Of the high-risk patients, 14 received a screening MRI or EEG before having had a first seizure. Of those 14 scans, 1 resulted in a diagnosis of SWS; of the 13 patients with a negative MRI screen, 3 (23.1%) were later found to have SWS when their parents or caregivers detected seizures. Thus, a total of four of the high-risk infants who were screened eventually were diagnosed with SWS.
Of the 18 high-risk patients who did not receive a screening MRI, 3 (16.7%) developed seizures, while 2 (11.1%) were seizure free but developed glaucoma severe enough to require treatment. One patient who was also seizure free developed an autism spectrum disorder.
Two patients who were in the high-risk group received screening EEGs that detected abnormalities that were not yet clinically evident. These included sub-clinical seizures and posterior-quadrant focal slowing. Both of these patients had initial negative screening MRIs.
Scanning early in life, using inappropriate imaging protocols, and having an inexperienced radiologist were all factors associated with a higher probability of false negative screening MRI, according to the researchers’ analysis, which was presented in a poster session at the World Congress of Pediatric Dermatology.
All of the false negative MRIs in the study cohort were conducted in infants younger than 9 weeks old. But whether it is useful to reserve imaging for later in infancy is debatable. “While later imaging may have improved sensitivity, 75% of infants with SWS will have already had their first seizure by 12 months of age,” wrote Dr. Zallmann and her colleagues.
Of the infants involved in the study, two of the three patients with false negative scans did not receive a referral to a neurologist, nor did their parents receive seizure education. “False reassurance may delay seizure detection,” Dr. Zallmann said.
For infants with positive MRIs who went on to develop seizures, the mean age of when they experienced their first documented seizure was 10 weeks. For those who did not receive an MRI, the mean age was 14 months, compared with 28 months for patients who had received a false negative MRI.
In discussing the findings, Dr. Zallmann and her colleagues made the point that early referral to a pediatric neurologist is important, especially for infants with the higher-risk port-wine stain patterns of hemifacial and median lesions. Seizure education can help parents detect the often subtle signs of seizures in infants with SWS, which can include staring spells, subtle limb twitching, and lip smacking.
The fact that seizures were detected an average of 14 months later in patients with negative screening MRIs may mean that such subtle signs were missed. “False reassurance may delay the recognition and treatment of seizures and impact neurodevelopmental outcomes,” Dr. Zallmann and her colleagues wrote in the abstract that accompanied the poster.
The study, while small, helps fill in some knowledge gaps, the researchers pointed out; they noted that there is no consensus on what level or type of facial involvement warrants screening, which protocols are best for MRI and EEG, or even whether the screening will improve seizure detection or outcomes.
“Currently there is no evidence that screening improves neurodevelopmental outcomes,” they said. “Conversely, there is a role for early neurological referral, symptom education, and potentially of EEGs in the prevention of complications related to SWS.”
Dr. Zallmann reported no conflicts of interest.