What is a Rathke Cyst?
Rathke cyst refers to a benign cyst that is lined by epithelial cells and is situated within the pituitary gland in the brain. Typically, the cyst is filled with a thick gelatinous fluid and is lined by cells that form a thin wall.
What causes a Rathke Cyst?
They are formed from the remaining tissue from when the pituitary develops within an embryo. During the growth of the embryo, cells grow from 2 different embryonic tissues towards each other. The Rathke pouch grows upwards from the stomatodeum as a clump of cells, while cells grow upwards toward this from the diencephalon. They eventually join each other. In normal growth, the Rathke pouch forms different structures of the mouth, leaving behind some tissue that forms the Rathke cleft. This cleft normally disappears, but when it gets filled with fluid, it forms a cyst.
Symptoms and Diagnosis
Rathke cysts rarely produce any symptoms, so many patients are asymptomatic. The cysts are usually smaller than 2 mm in size and may only produce symptoms if they enlarge beyond this and compress upon the pituitary gland, hypothalamus or optic chiasm.
In cases of compression, patients complain of double vision, blurred vision and even loss of field of vision. Compression on the hypothalamus and pituitary can lead to an underactive pituitary gland along with amenorrhea in women and diabetes insipidus.
The best available diagnostic test is an MRI scan of the brain. CT scans may be used, but they are not as effective as MRI scans.
How is a Rathke Cyst treated?
Surgery is the main treatment option. The surgical approach is called a transsphenoidal approach, meaning the Rathke cyst is approached through the nostril and the sphenoid sinus. The cyst is then ruptured so as to drain into the sinus. This is the procedure of choice these days as it is simple to perform and has a low complication rate.
Follow up is carried out for a long period of time. The extent of the follow up period varies, but may be up to a few years. Many patients report a good recovery of symptoms following this procedure, and recurrence rates are lower when compared to more open surgical procedures that require making an opening in the skull, such as a craniotomy.
Complications resulting from the transsphenoidal approach to treat this condition are rare. One such complication that requires observation is CSF rhinorrhea, in which patients may complain of leakage of cerebrospinal fluid through the nostril. Meningitis is another complication, although it is rarer than CSF rhinorrhea.