While many encephaloceles are caught on prenatal scans, some are not found until birth — or, for small and hidden ones, even later. This article explains those situations.
Diagnosis at delivery
Most encephaloceles are visible deformities, so when one wasn't detected prenatally, it is usually obvious at birth: a sac-like swelling along the midline of the skull. The delivery and newborn team will recognize it immediately and arrange urgent imaging and specialist evaluation.
When small or hidden ones are missed
Some encephaloceles are easy to miss before birth, especially:
- Small nasal or forehead encephaloceles, which can look like a minor bump.
- Basal (skull-base) encephaloceles, which protrude inward toward the nose or throat instead of outward, so there may be no visible lump at all.
These hidden types may not be diagnosed until a child is older, when symptoms appear — for example, a persistent nasal mass, nasal obstruction, recurrent nasal fluid leakage, or even meningitis. A "nasal polyp" in a young child that doesn't fit the usual picture sometimes turns out to be an encephalocele, which is why specialists are cautious about biopsying nasal masses in infants before imaging.
How later diagnosis is confirmed
When an encephalocele is suspected later, doctors use imaging — CT and especially MRI — to confirm the diagnosis, define the defect, and determine whether brain tissue is involved before any procedure is done.
Why catching hidden ones matters
Hidden encephaloceles aren't just cosmetic. A skull-base defect can create a pathway between the brain's fluid spaces and the nose or sinuses, which raises the risk of cerebrospinal fluid leaks and infections like meningitis. That's why correctly identifying them — rather than treating them as ordinary nasal growths — is so important.
Sources
- Boston Children's Hospital — Encephaloceles
- StatPearls (NCBI Bookshelf) — Encephalocele (nasal/basal types)
- Cleveland Clinic — Encephalocele
- CHOP — Encephalocele