Skull Base Encephalocele and Meningocele
An encephalocele is a rare condition in which there is a small gap within the bones of the skull through which the coverings of the brain, cerebrospinal fluid and sometimes brain tissue can protrude in a small sac-like structure. Encephaloceles can occur in a variety of locations throughout the skull including the base of the skull. They usually arise secondary to an abnormality during fetal development, which results in a small groove along the middle of the skull. Skull base encephaloceles can be located along the forehead, nose or within the sinuses. Some encephaloceles can be large deformities that are immediately visible but others can be very small and go undetected especially when in the nose or sinus cavities.
Although encephaloceles are generally congenital lesions in children, they can also occur in adults as the result of trauma or prior surgery along the skull base where the paper thin bones between the sinus cavities and the skull are disrupted allowing an encephalocele to form. Encephaloceles are also associated with hydrocephalus (the buildup of cerebrospinal fluid within the brain) and with pseudotumor cerbri a condition where the pressures within the skull and brain are abnormally elevated for reasons that are not entirely well understood.