Hypophysectomy involves the surgical removal of the pituitary gland, a small, pea-sized gland located at the base of the brain, behind the eyes. This gland produces hormones that regulate various bodily functions, including growth, metabolism, and reproduction. The procedure is primarily performed to remove tumors, which can be cancerous or non-cancerous (benign), that develop in or around the pituitary gland. Removing these tumors aims to alleviate symptoms such as hormonal imbalances and vision problems caused by their presence.
Acute Surgical Complications
Hypophysectomy, like any major surgery, carries inherent risks. Patients may experience bleeding, which is managed by the surgical team. Infections are another possibility; preoperative nasal disinfection minimizes this risk. Adverse reactions to anesthesia, though rare, can also occur.
The surgical approach influences the type of acute complications observed. The transsphenoidal approach, performed through the nose and sphenoid sinus, is a common minimally invasive method. This technique may lead to issues with the nasal septum, such as perforation, or cause nasal synechiae (adhesions) and sinusitis. Patients might also experience temporary nasal congestion or mild nasal bleeding in the first one to two weeks after surgery.
A transcranial approach (open craniotomy), involving a skull incision, is used for larger or complex tumors and carries different risks. A rare but serious complication is brain swelling (pseudohypoxic brain swelling), which can manifest as clinical deterioration with changes in consciousness and pupillary abnormalities. This swelling may be linked to intracranial hypotension caused by suction drainage used during the procedure.
Hormonal Imbalance Complications
Removal of the pituitary gland often leads to hypopituitarism, a condition where the body produces insufficient pituitary hormones. This deficiency can significantly impact various bodily systems, necessitating lifelong hormone replacement therapy. The specific hormonal deficiencies and their symptoms vary depending on which hormones are affected and the extent of the gland’s removal.
A common deficiency is Antidiuretic Hormone (ADH), or vasopressin, leading to Diabetes Insipidus (DI). This condition is characterized by abnormally large volumes of dilute urine (typically 4-18 liters daily) and excessive thirst. DI usually begins within 24-48 hours after surgery and can be transient or, in 2-10% of cases, permanent if a significant portion of ADH-secreting neurons are damaged.
Adrenocorticotropic Hormone (ACTH) deficiency results in secondary adrenal insufficiency. ACTH stimulates the adrenal glands to produce cortisol, a hormone that helps the body respond to stress and regulates blood sugar, blood pressure, and metabolism. Symptoms of adrenal insufficiency include fatigue, weakness, weight loss, low blood pressure, dizziness, nausea, and vomiting.
Thyroid-Stimulating Hormone (TSH) deficiency can lead to secondary hypothyroidism, where the thyroid gland produces insufficient thyroid hormones. Symptoms of hypothyroidism include fatigue, weight gain, cold intolerance, constipation, dry skin, and hair loss. TSH levels may be normal or slightly elevated in secondary hypothyroidism, making free T4 levels a more reliable indicator for diagnosis and monitoring.
Deficiencies in gonadotropins (Luteinizing Hormone (LH) and Follicle-Stimulating Hormone (FSH)) cause hypogonadism. These hormones regulate reproductive function. In men, hypogonadism can lead to decreased sex drive, erectile dysfunction, infertility, reduced muscle mass, and loss of body hair. For women, symptoms include irregular or absent menstrual periods, hot flashes, infertility, and decreased libido.
Growth Hormone (GH) deficiency is a frequent postoperative complication, leading to short stature and delayed puberty in children. In adults, GH deficiency can cause decreased energy, increased body fat (especially around the belly), reduced muscle mass, poor exercise tolerance, and low bone mineral density, increasing the risk of osteoporosis. Lifelong hormone replacement therapy, carefully monitored by endocrinologists, is often necessary to manage these deficiencies and improve overall quality of life.
Neurological and Sensory Complications
Hypophysectomy carries specific risks related to the delicate neurological structures surrounding the pituitary gland. A potential complication is a Cerebrospinal Fluid (CSF) leak, where clear fluid drains from the nose or surgical incision. This occurs when there is a defect in the coverings of the brain and spinal cord. CSF leaks can cause headaches and increase the risk of meningitis.
Vision impairment or loss can occur due to the close proximity of the pituitary gland to the optic nerves and optic chiasm. If the tumor was pressing on these structures or if they are damaged during surgery, patients may experience partial or total vision loss, blurred vision, or double vision. While vision often improves after tumor removal, the extent of recovery depends on the duration and severity of the pre-existing visual loss.
Meningitis, a serious infection of the membranes surrounding the brain and spinal cord, is a possible complication, especially with a CSF leak. Symptoms can include fever, headache, neck stiffness, confusion, and agitation. Although uncommon, occurring in less than 2% of procedures, meningitis requires prompt recognition and aggressive antibiotic treatment.
Damage to other cranial nerves can result in cranial nerve palsies. The third cranial nerve, which controls eye movement and pupil size, is most frequently affected, followed by the sixth and fourth cranial nerves. This damage can lead to symptoms such as double vision, facial numbness, or weakness. The recovery period for cranial nerve palsy is often correlated with the duration of symptoms before surgery.
While rare, stroke or vascular injury is a possible risk if blood vessels supplying the brain, such as the internal carotid artery, are damaged. Such injuries can lead to serious bleeding or, in rare instances, a stroke. Preoperative imaging and careful surgical techniques are employed to mitigate these risks.