Transient bulging fontanelle after vaccination: case report and review of the vaccine adverse event reporting system

OBJECTIVE: To describe the features of transient bulging fontanelle (TBF) after vaccination. STUDY DESIGN: We searched the Vaccine Adverse Event Reporting System database for reports describing bulging fontanelle. We defined a definite TBF case as a patient with a bulging fontanelle, normal neuroimaging and cerebrospinal fluid analysis, and absence of a depressed level of consciousness, focal neurologic findings, or identified cause. Follow-up had to reveal normal development. Probable cases lacked either lumbar puncture or neuroimaging or both but met all other criteria. RESULTS: We identified 18 patients with definite or probable TBF. The median age at presentation was 4.5 months, interval from vaccination to symptom onset was 18 hours, and time to resolution was 3 days. Fifteen children were febrile. CONCLUSIONS: We cannot conclude that vaccines cause TBF. Further controlled studies are necessary. Even if further research verifies TBF as a rare side effect, immunization benefits would still vastly outweigh this hypothetical risk. However, confirmation of a vaccine association could modify the management of infants who develop TBF after immunizations.