Core Terms & Classification
Bony defect (cranial defect)
The bony defect is the actual opening or gap in the skull through which the encephalocele protrudes.
In short: Bony defect (cranial defect)
- It is closed and reconstructed during surgery (cranioplasty).
- Its size and location are defined with CT imaging.
- Repairing it restores protection and a more typical head shape.
- It is one of two parts of repair, alongside watertight closure of the membranes.
What it is
It is the hole in the skull at the site of the encephalocele — the bone counterpart to the protruding tissue. The encephalocele protrudes through this defect.
Understanding Bony defect (cranial defect)
Closing and rebuilding the bony defect is a core part of surgery, alongside watertight closure of the dura. CT and 3D reconstruction help surgeons plan how to repair the opening, including its exact size and shape and what material (such as a bone graft) may be needed. In young children, the skull's ongoing growth and capacity for healing are factors in how the reconstruction is planned.
Why it matters
Understanding the bony defect clarifies why a repair has two goals — sealing the membranes and rebuilding the bone — and why imaging like CT is used in addition to MRI. Restoring the bone protects the brain and improves head contour.
Common questions
How is the bony defect closed?
Through cranioplasty, sometimes with bone graft or other materials.
How is its size measured?
Usually with CT imaging and 3D reconstruction.
Why is repairing the bone important?
It restores protection for the brain and a more typical head shape.
Bottom line
The bony defect is the skull opening behind an encephalocele, closed and reconstructed during repair.
Browse all 265 Encephalocele definitions
Read the Encephalocele patient guides
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