Endoscopic pituitary surgery is a minimally invasive procedure used to access and treat the pea-sized pituitary gland located at the base of the brain. The gland sits in a bony pocket called the sella turcica, directly behind the nasal cavity and sphenoid sinus. The procedure is performed to remove abnormal growths, most commonly benign tumors, without requiring a traditional open-skull incision. Surgeons use advanced imaging and a slender, lighted instrument called an endoscope, which provides a high-definition view for precise tissue removal.
Conditions Requiring Pituitary Surgery
The primary reason for this surgery is the presence of a pituitary adenoma, a tumor originating from the gland that accounts for the majority of sellar masses. These adenomas are benign, but their growth causes problems either through mass effect or by disrupting hormone production.
A large tumor, known as a macroadenoma (over 10 millimeters), can compress nearby structures, such as the optic chiasm where the optic nerves cross. This compression often leads to a gradual loss of peripheral vision, which surgery is intended to relieve or prevent from worsening.
Adenomas are also classified as functioning if they over-secrete pituitary hormones, leading to specific diseases. For instance, excess growth hormone causes acromegaly in adults, resulting in the enlargement of hands, feet, and facial features. Prolactin-secreting tumors (prolactinomas) can lead to irregular menstrual cycles in women and reduced sex drive in men. An adenoma producing too much adrenocorticotropic hormone (ACTH) causes Cushing’s disease, resulting in weight gain, easy bruising, and muscle weakness. Surgery is generally the preferred treatment for most functioning tumors and for non-functioning tumors that cause vision problems.
Navigating the Endoscopic Technique
The modern endoscopic technique uses the transsphenoidal approach, where the surgical path goes through the sphenoid sinus, an air-filled cavity behind the nose. This collaborative method often involves both a neurosurgeon and an ear, nose, and throat (ENT) surgeon. The ENT surgeon inserts the endoscope directly into one nostril.
The endoscope provides a magnified, high-resolution view, allowing the surgical team to navigate toward the sphenoid sinus wall without external incisions or extensive disruption of nasal tissues. This approach is an advancement over older microscopic techniques, which often required more extensive removal of the nasal septum.
Once the endoscope reaches the back of the nose, the surgeon opens the front wall of the sphenoid sinus to access the posterior wall covering the sella turcica. Real-time imaging guidance, called neuronavigation, functions like a global positioning system (GPS), helping the surgeon confirm the precise location of instruments relative to the tumor and surrounding structures. This is helpful for identifying structures like the carotid arteries and the optic nerves.
A small opening is then made in the bone of the sella to expose the dura mater, the protective covering of the brain. The neurosurgeon uses specialized instruments passed alongside the endoscope to open the dura and access the tumor. The tumor is removed in small pieces, separating the abnormal tissue from the normal, hormone-producing parts of the gland.
After the tumor is removed, the surgeon inspects the cavity to ensure maximum removal while preserving the normal gland. The surgical site is then secured to prevent cerebrospinal fluid (CSF) from leaking out of the skull base. This sealing is often accomplished using a small piece of tissue, sometimes a fat graft taken from the patient’s abdomen, to create a barrier over the opening.
Recovery and Post-Operative Management
The recovery following endoscopic pituitary surgery is generally faster than with traditional cranial surgery due to the minimally invasive nature of the procedure. Patients typically spend only one to three days in the hospital, often in a specialized unit for close monitoring. In the immediate post-operative period, monitoring for fluid and electrolyte balance is important, as the gland’s function can be temporarily disrupted.
One common temporary side effect is diabetes insipidus, a condition where the body produces large amounts of dilute urine because of a temporary inability of the pituitary to regulate water balance. If this occurs, patients may require desmopressin, a medication that helps the kidneys conserve water. Patients are also monitored for headache and nasal congestion, which are expected for a few weeks, and are advised to sleep with their head slightly elevated.
Activity restrictions are put in place to protect the surgical repair site and prevent complications like a CSF leak. Patients are instructed to avoid blowing their nose forcefully, sneezing with their mouth closed, or engaging in strenuous physical activity for several weeks. These actions can increase pressure in the head and potentially compromise the seal placed over the sella.
A crucial aspect of post-operative management involves careful monitoring of hormone levels, especially cortisol, which is produced by the adrenal glands under the direction of the pituitary. Many patients are temporarily placed on glucocorticoid replacement therapy, such as hydrocortisone, to manage the body’s stress response and prevent adrenal insufficiency. Blood tests are used to determine if a patient’s hypothalamic-pituitary-adrenal axis has recovered, often six to eight weeks after surgery.
Long-term follow-up with an endocrinologist is necessary to assess the function of the remaining pituitary gland and determine the need for permanent hormone replacement therapy. If the surgery has affected the gland’s ability to produce other hormones, patients may require thyroid hormone, sex hormones, or growth hormone replacement. Regular monitoring is essential to ensure a stable hormone balance and to check for any signs of tumor recurrence.