Pituitary adenomas are tumors that occur in the pituitary gland, and account for about 15% of intracranial neoplasms. They often remain undiagnosed, and small pituitary tumors have an estimated prevalence of 16.7% (14.4% in autopsy studies and 22.5% in radiologic studies).

Ependymoma is a tumor that arises from the ependyma, a tissue of the central nervous system. Usually, in children the location is intracranial, while in adults it is spinal. The common location of intracranial ependymoma is the fourth ventricle. Rarely, ependymoma can occur in the pelvic cavity.

Syringomyelia is a generic term referring to a disorder in which a cyst or cavity forms within the spinal cord. This cyst, called a syrinx, can expand and elongate over time, destroying the spinal cord and eventually causing paralysis without the right procedures.

Encephalitis is an acute inflammation of the brain.
Encephalitis with meningitis is known as meningoencephalitis.