Rathke’s Cleft Cyst
Rathke’s cleft cyst is a benign congenital fluid filled cyst that is found between the anterior and posterior parts of the pituitary gland. Symptomatic Rathke cleft cysts are fairly rare and make up less than 1 percent of all brain tumors. Rathke’s cleft cysts are thought to arise when Rathke’s pouch, the embryonic precursor to the anterior pituitary, does not develop properly. Small asymptomatic cysts are very common and frequently detected incidentally on an MRI study. Rathke cleft cysts only rarely cause problems during childhood and are not usually diagnosed until adulthood. Symptomatic Rathke’s cleft cysts typically cause various problems with the pituitary gland’s normal function and compress the optic nerves to leading visual disturbances especially peripheral vision loss.
Symptoms
The symptoms of a Rathke’s cleft cyst are usually caused by compression of the surrounding pituitary gland and optic nerves above in the suprasellar space. Compression of the pituitary stalk may result in pituitary hormone deficiency that contributes to developmental delay, short stature, obesity, and a range of other hormonal problems. Compression of the optic nerves may lead to visual deficits, usually a bitemporal hemianopsia. Without treatment, Rathke’s cleft cysts can continue to cause problems with pituitary gland function and issues with weight, hormones, and vision. Larger cysts can cause headache and nausea because of backup of the cerebrospinal fluid that surrounds the brain and spinal cord.
Diagnosis
The diagnosis of a Rathke’s cleft cyst is based on your symptoms, physical exam and specialized testing including an endocrine and ophthalmic assessment. For an endocrine assessment, special blood tests determine your hormone levels. An ophthalmologist may examine your eyes and perform a visual field test to determine if the cyst is affecting your visual acuity or impairs your peripheral vision.
Imaging studies are also an important component of the diagnosis of Rathke’s cleft cyst. Magnetic resonance imaging (MRI) and Computed tomography (CT) scans are often used. The scan is usually performed with a contrast dye that makes the border and details of the cyst more visible in relation to the surrounding normal brain. The scan also provides detail information regarding the exact size, location and other structures involved by the cyst. In some cases, neurological surgeons may employ an MRI or CT scan with frameless stereotactic guidance for preoperative planning purposes. For this study, a high-resolution contrast MRI or CT is performed and then processed by a computer to create a three-dimensional model of the brain and skull base. This can be used in the operating room when performing endoscopic minimally invasive skull base surgery.
Treatment
Most small and non-symptomatic Rathke’s cleft cysts can be observed over time with surveillance MRI scans and do not require any treatment. Larger Rathke’s cleft cysts that lead to significant symptoms usually require surgery to drain the cyst. This can usually be done without damaging the normal pituitary gland. The cyst walls are not usually excised as they are adherent to important brain structures and removal would cause unnecessary harm. Surgery for drainage of Rathke’s cleft cysts is usually performed with an endoscope through the sinuses using minimally invasive endoscopic skull base techniques together with an ENT surgeon that specializes in skull base surgery. The neurosurgeon and ENT specialist may evaluate your particular anatomy before surgery and perform endoscopy of the sinuses.