The bean-sized pituitary gland or "master gland" is extremely important in regulating the function of many other glands and organs of the body. It lies behind and between the eyes at the base of the brain, just beneath the hypothalamus to which it is connected by a thin stalk.
The pituitary gland is controlled by substances (releasing or inhibitory factors) that are sent by the hypothalamus. The pituitary gland, in turn, secretes hormones into the bloodstream. Most of these hormones are chemical messengers that instruct various glands to secrete their own hormones.
Hormones control or regulate many different bodily functions, such as how bones and muscles grow, sexual development and the ability to fight disease and stress. In addition to performing their various tasks around the body, these hormones complete a feedback loop by affecting (usually inhibiting) the hypothalamus' production of releasing or inhibitory factors. "Functioning" or hormonally-active pituitary tumors fall into this broad category.
The pituitary gland is divided into two main parts: The anterior pituitary (adenohypophysis) and the posterior pituitary (neurohypophysis). Two-thirds of all pituitary tumors occur in the anterior or front portion of the gland.
The two types of pituitary tumors are functioning and non-functioning.
Functioning pituitary tumors
These tumors are named after the hormone they secrete which include:
Approximately 10 to 15 percent of all brain tumors are pituitary adenomas. While these tumors of glandular tissue are almost benign, they can be difficult to remove completely. Click here to learn more about treatment options for functioning pituitary tumors.
Non-Functioning Pituitary Tumors
Non-functioning or non-secreting tumors are characteristically slow-growing. If they are not compressing the visual nerves, such tumors are often merely observed.
However, some non-functioning pituitary tumors may compress or damage the normal gland, leading to insufficient production of one or more hormones, or compress visual nerves. These tumors can grow to be quite large because they go undetected. They are usually found only when symptoms of compression are noted.
Loss of peripheral vision is often the first sign. The patient may bump into doorways frequently or have repeated minor motor vehicle accidents.
Symptoms of Non-Functioning Pituitary Tumors:
- decreased energy
- hair loss
- low blood pressure
- weight gain
- impotence
- menstrural irregularity
Click here to learn more about treatment options for non-functioning pituitary tumors.
Treatment Options
The pinpoint targeting of the Gamma Knife makes it the preferred instrument when treating pituitary tumors radiosurgically. As of June 1997, more than 6,000 people have received Gamma Knife radiosurgery for their pituitary tumors.
Radiosurgery on linear accelerator (Linac) based equipment is less commonly attempted with pituitary tumors because of the close proximity of the pituitary to the optic chiasm and the brain stem. Some Linac authorities advocate a "fractionated radiosurgical approach" where a relocatable frame is used to deliver a low dose radiosurgical treatment once a week for three to six weeks. There is little data comparing these different approaches.
For more information, please contact:
Rebecca O. Heitkam, RN, BSN, CCRN, coordinator
Gamma Knife Center
Saint Joseph's Hospital
404-851-5513
or toll free at 1-866-SJGAMMA
or email
rheitkam@sjha.org
