Encephalocele/Meningocele

An encephalocele is a region of herniated brain. The term meningocele refers to herniated dura (covering of the brain).

Etiology for Encephalocele/Meningocele

The brain and/or dura can herniate into the mastoid bone. There are four explanations for this anomaly.  First, there may have been a congenital (present since birth) bony defect in the base of the skull when the cranial base was forming.  With time and continued pulsations of the brain, the brain and/or dura can herniate through these openings.  Secondly, a portion of the bone at the base of the brain may have been surgically removed during a previous operation.  Again, with continued pulsations of the brain, these openings can enlarge, allowing herniation. Thirdly, severe head injury can lead to a loss of this bony partition. Lastly, a chronic middle ear and mastoid infection can also cause erosion of the bony partition.