Hypophysectomy is the surgical removal of the pituitary gland, a small endocrine gland located at the base of the brain. This neurosurgical procedure addresses medical conditions primarily involving the pituitary gland, aiming to resolve issues caused by its malfunction or abnormal growths.
Understanding the Pituitary Gland
The pituitary gland, also known as the hypophysis, is a pea-sized structure located at the base of the brain. It functions as the “master gland” of the endocrine system, controlling many other hormone-producing glands throughout the body. The gland is divided into an anterior and posterior lobe, each releasing different hormones.
The anterior lobe produces hormones like growth hormone, thyroid-stimulating hormone (TSH), and adrenocorticotropic hormone (ACTH). These regulate bodily functions including growth, metabolism, and reproduction. The posterior lobe stores and releases antidiuretic hormone (ADH) and oxytocin, which regulate water balance and reproductive processes.
Medical Reasons for the Procedure
Hypophysectomy is most commonly performed to treat pituitary tumors, which can be benign (adenomas) or, less frequently, malignant. These tumors cause problems by either overproducing hormones or by pressing on nearby structures. For instance, tumors that secrete excessive ACTH can lead to Cushing’s disease, characterized by high cortisol levels.
An overproduction of growth hormone can result in acromegaly, causing abnormal growth. Prolactin-secreting tumors may also require intervention if unresponsive to medication. Beyond hormonal imbalances, tumors can compress the optic nerves, leading to vision problems, or cause headaches, which surgery can alleviate.
How Hypophysectomy is Performed
The most common surgical approach for hypophysectomy is the transsphenoidal method. This minimally invasive technique accesses the pituitary gland through the nose or an incision under the upper lip, proceeding through the sphenoid sinus, a hollow space behind the nasal passages. Surgeons use specialized instruments, often guided by an endoscope or microscope, to reach the sella turcica, the bony compartment housing the pituitary gland.
Once the bone covering the gland is opened, the tumor or pituitary tissue is carefully removed. This approach avoids external incisions and minimizes disruption to brain tissue, leading to a faster recovery. For larger or more complex tumors not safely reached via the transsphenoidal route, a transcranial approach, or craniotomy, may be necessary. This involves opening a section of the skull to access the brain, which is a more invasive procedure.
Post-Surgical Care and Management
Following hypophysectomy, patients undergo close monitoring for potential complications. Immediate concerns include bleeding, cerebrospinal fluid (CSF) leaks, and the development of diabetes insipidus. A CSF leak, indicated by clear fluid draining from the nose, can occur if the surgical site does not seal completely, and may require additional intervention like a lumbar drain. Diabetes insipidus, characterized by excessive thirst and urination, arises from a temporary or permanent deficiency of antidiuretic hormone (ADH) and is often managed with medication.
Most patients require lifelong hormone replacement therapy (HRT) because the pituitary gland is removed or significantly damaged. This therapy replaces hormones that the body can no longer produce adequately. Common replacements include cortisol (often as hydrocortisone) to support adrenal function, thyroid hormone (levothyroxine) for metabolism, and sex hormones (testosterone, estrogen, or progesterone) to maintain reproductive function and bone health. Growth hormone replacement may also be necessary, especially for children. Regular follow-up appointments and blood tests are essential to monitor hormone levels and adjust medication dosages. Patients are typically advised to avoid activities that increase pressure in the head, such as nose blowing, heavy lifting, or straining, for several weeks post-surgery.
Current Role in Medicine
In contemporary medicine, hypophysectomy remains a significant procedure, though its overall frequency has evolved with advancements in other treatments. The development of targeted medications for pituitary tumors, such as dopamine agonists for prolactinomas or somatostatin analogs for growth hormone-secreting tumors, often provides effective non-surgical alternatives. These medical therapies can control hormone levels and shrink tumors, reducing the need for surgery in some cases.
Despite these advancements, hypophysectomy continues to be a treatment option for specific situations. It is often recommended for large or aggressive pituitary tumors that do not respond to medical management or radiation therapy. The procedure is also crucial when rapid decompression of vital structures, such as the optic nerve, is necessary to preserve vision. The decision to perform a hypophysectomy involves a multidisciplinary team, including neurosurgeons, endocrinologists, and ear, nose, and throat (ENT) specialists, ensuring a comprehensive approach to patient care.