Encephalocele or Meningocele

An encephalocele is a region of herniated brain. The term meningocele refers to herniated dura (covering of the brain). A combination of herniated brain and dura is called a meningoencephalocele.

The brain and/or dura can herniate into the mastoid bone. There are four explanations for this anomaly. There may have been a congenital-bony defect in the base of the brain 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, 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. A chronic middle ear and mastoid infection can also cause erosion of the bony partition.

The symptoms of an encephalocele, or meningocele are watery discharge from a tube in the eardrum, watery discharge from the nose and/or headaches. The watery discharge is spinal fluid that finds its way from the surrounding brain tissue into the mastoid bone. The fluid then enters the middle ear and drains out an inserted tympanostomy tube or drains down the eustachian tube and out the nose. Headaches occur from temporary loss of spinal fluid.

In all instances this condition requires surgical intervention to prevent meningitis and brain abscess.