The pituitary gland controls endocrine function and straddles a region between the nose and the brain. Given these features, pituitary tumors are best managed through the coordinated approach by an interdisciplinary surgical and medical team.
Mayo Clinic has one of the largest pituitary tumor practices in the world, performing more than 120 pituitary surgeries annually. The team of pituitary experts is anchored by an endocrinologist and includes, as needed, physicians in neuroradiology, neurosurgery, neurology, otorhinolaryngology (ENT), ophthalmology, radiation oncology and laboratory medicine.
Pituitary tumors are usually benign and nonmetastatic. Often extremely small, they can be either functioning (hormone-producing clinical syndrome) or nonfunctioning (nonhormone-producing or no clinical syndrome).
As John L D Atkinson, M.D., a Mayo Clinic neurosurgeon with expertise in pituitary surgery, explains, patients with functioning tumors producing an excess of such hormones as prolactin, adrenocorticotropic hormone (ACTH), thyrotropin, or growth hormone typically experience symptoms and seek medical care.
However, not all functioning tumors have clinical sequelae and, like nonfunctioning tumors, they may go undetected unless they are visualized coincidentally on MRI. Some become large enough to compress the optic nerves or the pituitary gland, causing symptoms of visual loss or pituitary failure.
When a pituitary tumor is suspected, additional tests may include:
Since it opened in 1976, Mayo's Endocrine Testing Center has conducted more than 145,000 tests and procedures.
MRI is a standard diagnostic technique for pituitary tumors. Mayo has advanced 3-Tesla MRI scanning, which generates the high-resolution images necessary for detecting what are often very small tumors.
However, some pituitary tumors, such as those secreting excess ACTH in Cushing's disease, may be too small to be detected with radiologic imaging. When laboratory tests indicate excess ACTH production, patients are referred to radiology for petrosal sinus sampling, conducted by injecting corticotropin-releasing hormone through a catheter and measuring the pituitary response. The test can not only determine if a tumor is present but can also help identify its location.
Surgery is the primary means of treating pituitary tumors, and it, too, is a collaborative effort. Surgeons at Mayo Clinic use an endoscopic transnasal approach rather than a sublabial transseptal approach. An ENT surgeon advances a nasal endoscope through the nostril to the anterior wall of the sphenoid sinus. The neurosurgeon then uses either an endoscope or an endoscopic-microscopic combination to enter the sella turcica and resect the tumor.
Because the surgery does not require an external incision and resection, it can be accomplished without interfering with other brain structures. Thereby, the duration of the surgery, postsurgical recovery time, and patient postoperative pain is reduced.
Dr. Atkinson notes that unless there are complications, most patients leave the hospital the following day. He goes on to say, "Expected complications may include a spinal fluid leak, which occurs in about 30 percent of patients. Another might be increased urine output from transient diabetes insipidus, for which there are medications. Serious complications such as stroke, death and blindness are very rare. It is one of the lowest risk brain operations we perform, in part because the transnasal approach makes the tumor very accessible."
After discharge, patients are typically seen the same day by the endocrinologist for medical follow-up. If they remain in the hospital longer than overnight, the endocrinologist does an in-patient consultation. It is very important that the endocrinologist evaluate the patient preoperatively and postoperatively because the function of the gland is so diverse and regulates so many other endocrine organs.
Postoperative management of remaining tumor, depending on its size, location and other features, may be amenable to radiosurgery with a single-day dosing Gamma Knife procedure. Other residual or recurrent tumor, depending on size or configuration, may be treated with radiation oncology, observation or medical therapy, if appropriate.
Dr. Atkinson sums up the team approach at Mayo by noting that the primary objective is to relieve the patient of symptoms through medical management, tumor resection or irradiation and that it takes a collaborative effort to maintain normal pituitary function.
"The advantages of our multispecialty practice," Dr. Atkinson says, "are that patients benefit not only from a coordinated care plan, but also from state-of-the-art advances across the spectrum of the disciplines involved, be they improved radiologic and imaging techniques, new endocrine laboratory tests and verification methods, the latest medications, advanced surgical techniques, or innovations in radiation delivery, such as the heavy particle proton beam, soon to be acquired. The needs of the patient come first at Mayo, and this is certainly true in patients with conditions as complex as pituitary disease."