A tense or bulging fontanelle occurs when fluid accumulates in the skull cavity or when pressure increases in the brain. Common causes are hydrocephalus or increased intracranial pressure due to illness.
Review Date 2/2/2021
Updated by: Neil K. Kaneshiro, MD, MHA, Clinical Professor of Pediatrics, University of Washington School of Medicine, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.