The main treatment of many pituitary tumors is surgery. The effectiveness of surgery depends on the type of tumor, its exact location, its size, and whether it has spread into nearby tissues.
The usual operation for pituitary tumors is trans-sphenoidal adenectomy. Adenectomy means "removal of the pituitary tumor."
First the surgeon makes a small incision under the upper lip (above the upper teeth) or along the nasal septum (the cartilage between the 2 sides of the nose). Then he or she advances along the septum back toward the sphenoid sinus. This is a hollow compartment, and its back wall covers the pituitary gland. To reach the pituitary, the surgeon opens the boney walls of the sphenoid sinus with small surgical chisels, drills, or other bone dissecting instruments depending on the thickness of the bone and sinus.
The advantages of this approach are that no other part of the brain is touched, the neurologic complication rate is very low, and there is no visible scar. The disadvantage of this technique is that it is difficult to remove large tumors. If the tumor is a microadenoma, then the cure rates are high (greater than 80%) if surgery is done by an experienced neurosurgeon (a doctor specializing in operations to treat disorders involving the brain, spinal cord, or nerves. If the tumor is large or has invaded the nearby nerves, brain tissue or its coverings, the chances for a cure by surgery are lower.
Recently, surgeons have been using endoscopic surgery. This involves the use of a thin fiberoptic tube (endoscope) that allows the surgeon to see well without making an incision under the upper lip or the front part of the nasal septum (only a small incision is made in the back of the nasal septum). The surgeon passes instruments through normal nasal passages and opens the sphenoid sinus to reach the pituitary gland and remove the tumor. This procedure may take less time than the usual one and causes fewer complications, but its use is limited by the tumor size and position, and the character of the sphenoid sinus. More surgeons are now using this procedure. As they become more familiar with it, they may use it more often.
Sometimes the tumor is removed by a craniotomy (an operation in which the surgeon makes an opening through the skull bones). This approach is used only for large and complicated tumors. It has a much higher rate of permanent neurologic complications than trans-sphenoidal surgery.
The overall surgical cure rate for patients with growth hormone-secreting adenomas is about 50% to 90%, depending on the size of the tumor. Smaller tumors have a higher cure rate.
The cure rate is slightly higher for corticotropin-secreting adenomas because these tend to be smaller tumors. Most prolactinomas are treated with medication. Only complicated prolactinomas are treated surgically. As a general rule for pituitary tumors, the larger and more invasive the tumor, the less likely the tumor can be cured by surgery. (Treatments for the different types of pituitary tumors are described later in this section.)
Complications of pituitary surgery can be serious but, fortunately, are rare. Damage to large arteries, to nearby brain tissue, or to nerves near the pituitary rarely can result in brain damage, a stroke, or blindness. Damage to the membranes surrounding the brain, in very rare cases, can result in meningitis (infection of this protective membrane), or leakage of cerebral spinal fluid (the normally produced fluid that bathes and cushions the brain).
Diabetes insipidus (discussed further in the sections
""How Are Pituitary Tumors Diagnosed?"
and "Can Pituitary Tumors Be Found Early?"") is a common occurrence after surgery but is usually temporary. This condition usually improves on its own within 1 to 2 weeks after surgery. If it is permanent, this complication can be treated effectively with vasopressin, which is usually taken as a nasal spray.
Damage to the pituitary (leading to symptoms due to lack of pituitary hormones) is rare after surgery for small adenomas. This may be unavoidable when treating some larger macroadenomas. This complication can be treated by medicine to replace certain hormones normally produced by the pituitary and other glands.