Spontaneous Cranial Bone Regeneration After a Craniectomy in an Adult.

Spontaneous reossification is a very rare phenomenon following a large calvarial defect, particularly in adults. A 29-year-old woman with acute subdural hematoma and brain edema underwent emergent decompressive craniectomy and evacuation of hematoma. Follow-up examination 2 years later showed a well-formed bone along the craniectomy site. To our knowledge, this is the first case report with total spontaneous reossification in adults. A literature review is provided, and the physiology of the process is suggested. Pericranium, diploë, and, above all, dura mater collaborate in spontaneous bone formation. All these layers are very important, and they must be respected during dissection.