Core Terms & Classification
Herniation
Herniation is the abnormal pushing of an organ or tissue through an opening.
In short: Herniation
- In encephalocele, brain and meninges herniate through a skull defect.
- The herniated tissue forms the encephalocele sac.
- Surgery addresses the herniated contents and closes the opening.
- Functional herniated tissue is preserved; non-functional tissue may be removed.
What it is
Herniation is the general medical term for tissue protruding where it should not. In encephalocele, the herniated tissue is the brain's membranes — and sometimes brain tissue — pushing through an opening in the skull.
Understanding Herniation
The encephalocele sac is herniated intracranial content. During repair, surgeons evaluate whether the herniated tissue is functional brain (to protect and return) or non-functional (to remove), then close the dura and rebuild the bone. The same word, "herniation," is used in many other medical contexts, but in encephalocele it specifically describes the protrusion through the skull.
Why it matters
Understanding herniation clarifies what the surgery is actually addressing: returning or removing protruding tissue and sealing the opening. It also helps families grasp why the contents of the sac — what has herniated — matter so much to the plan.
Common questions
What herniates in an encephalocele?
Meninges and cerebrospinal fluid, and sometimes brain tissue.
Can herniated brain be put back?
Functional tissue is preserved and returned when possible.
Is herniation the same as the sac?
The herniated tissue forms the sac.
Bottom line
Herniation is tissue protruding through an opening, which in encephalocele means brain and membranes through the skull.
Browse all 265 Encephalocele definitions
Read the Encephalocele patient guides
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