Pituitary adenomas are noncancerous tumours of the pituitary, the master gland that rules the endocrine system. Located in the skull base below the brain and behind the nasal cavity, the pituitary secretes powerful hormones that coordinate other glands, controlling such basic functions as growth and development, metabolism, the stress response, sexual function and water balance. Pituitary adenomas arise in about 1 in 1,000 individuals; about 10% are giant adenomas, 4 cm in diameter or larger.
As adenomas enlarge, they can cause pituitary gland failure by cutting off the flow of hormones. Headaches, visual loss and other symptoms may develop slowly over months or years, but can also happen rapidly over just a few hours if there is bleeding into the tumour, called “pituitary apoplexy.” Giant adenomas often grow around the pituitary gland and skull base into areas where critical blood vessels and nerves travel, making complete surgical removal impossible.
Endonasal surgery allows doctors to remove many kinds of brain tumours through a nostril. Reaching the tumour through a natural opening eliminates the need for traditional open-skull surgery (craniotomy) and in experienced hands, creates less trauma, fewer complications and a shorter recovery time. “Patients prefer the idea of a minimally invasive procedure through a natural opening,” said Daniel F. Kelly, MD, Director of Saint John's Brain Tumour Centre, faculty member at the John Wayne Cancer Institute at Saint John's, and senior author of the study.
The procedure is performed using an operating microscope and an endoscope (a surgical telescope) for highly magnified, high-definition panoramic views of the surgical site. Specialized instruments are passed through the nasal cavity into the skull base to remove the tumour. Like GPS for the brain, a computerized guidance system for surgical navigation completes the high-tech arsenal of modern endonasal skull base surgery.
The new study reviewed 10 years worth of cases involving 51 giant adenoma patients operated on by Dr. Kelly. Their symptoms included progressive visual loss, hormonal problems, tumour bleeding and/or headaches. Using a multimodality approach combining surgery with focused radiation therapy and/or medical therapy, tumours were effectively controlled in 96% of patients. Approximately 60% required only endonasal surgery, while about 40% received surgery plus one or more additional treatments to control residual tumour.
82% of 38 patients who had pre-operative visual loss regained some or all of their vision; no patients experienced new visual loss. Also, prior to surgery, 80% of the study group had suffered hormonal loss such as low sex hormones (hypogonadism), low thyroid (hypothyroidism) or growth hormone deficiency. Of these patients, nearly half had improved hormonal function after surgery, while only 15% showed a deterioration in hormonal function. Ultimately, 75% of the 51 patients still required hormone replacement therapy to compensate for the loss of normal pituitary function due to damage caused by the tumour.
“This study shows that endonasal surgery has evolved into a safe and effective treatment of these large and difficult tumours,” Dr. Kelly said. “The vast majority of such tumours can now be removed or effectively debulked through this minimally invasive approach.
“This is particularly welcome because our patients are typically in the prime of life,” Dr. Kelly continued. “To be struck with a deteriorating quality of life related to hormonal loss, headaches or severe visual impairment can be devastating. Fortunately, treating these tumours through a nostril and avoiding a craniotomy is the first step in getting these patients back to health.
“Many patients may need radiation or medical therapy, and long-term hormonal replacement therapy,” Dr. Kelly noted. “But with properly coordinated care, most can look forward to an excellent quality of life.”
Endonasal surgery is a highly specialized area of neurosurgery, and Dr. Kelly urged patients diagnosed with a pituitary adenoma or brain tumour to seek out a centre of excellence such as Saint John's Brain Tumour Centre where a high volume of these surgeries are performed, and where patients receive a comprehensive treatment approach including close collaboration with endocrinologists and radiation oncologists.
Manoel Antonio de Paiva Neto, Alexander Vandergrift, Nasrin Fatemi, Alessandra A. Gorgulho, Antonio A. DeSalles, Pejman Cohan, Christina Wang, Ronald Swerdloff and Daniel F. Kelly. “Endonasal transsphenoidal surgery and multimodality treatment for giant pituitary adenomas.” (Electronically published ahead of print: Clinical Endocrinology (Oxf). 2009 Jun 25.)
