Meningoencephalocele is a type of encephalocele, which is an abnormal sac of fluid, brain tissue, and meninges (membranes that cover the brain and spinal cord) that extends through a defect in the skull. There are two main types of meningoencephalocele, which are named according to the location of the sac. The frontoethmoidal type is located at the frontal and ethmoid bones while the occipital type is located at the occipital bone. Hydrocephalus, abnormalities of the eyeball and tear duct, and other findings have been associated with the condition. Some affected individuals have intellectual or physical disabilities while others have normal development and abilities.

The condition is typically congenital (present at birth) but has been reported to develop by chance in older individuals in rare cases. The underlying cause of the condition is uncertain, but environmental factors are thought to play a role. Treatment depends on the size, location and severity of the defect but mainly includes magnetic resonance imaging (MRI) to determine the severity of the defect, followed by surgery to repair it.

The prognosis for each individual with meningoencephalocele depends on the size and location of the sac, whether brain tissue is present in the sac, and if other brain abnormalities are also present. Survival is generally better when brain tissue is not involved in the sac. Individuals with encephaloceles located in the face (at the frontal and nasal bones) tend to have better survival and development than those located at the back of the head (at the occipital and parietal bones). Several studies have found that approximately two-thirds (66%) of individuals with meningoencephalocele in the back of the head survive; of those survivors, approximately half have normal intelligence. Infections, such as meningitis, may develop and could also affect the outcome.