Transsphenoidal Approach for Pituitary Macroadenoma: Complications

Abstract

Transsphenoidal surgery (TSS) is a popular method for resecting pituitary tumors, but it has been associated with severe consequences such as perioperative medical issues, endocrine problems, and surgical complications. The pituitary gland, a bilobed endocrine organ, contains eight hormones and is surrounded by the sella turcica, tuberculum sellae, dorsum sellae, and cavernous sinus dura. The gland's structure is complex, with the optic chiasm and sphenoid sinus being significant structures. The sphenoid sinus, which grows with age and has variable septal and cavitary architecture, can make the transsphenoidal approach more difficult to perform in cases of bleeding, vision loss, or cranial nerve palsy. Understanding the anatomy of the sphenoid sinus is crucial for a safe sellar approach and tumor removal. The operative microscope introduced in the 1960s has further improved surgical outcomes with low morbidity and mortality rates.

Pituitary adenomas are extra-arachnoidal tumors that develop outside the boundaries of the cerebrospinal fluid (CSF). They can cause iatrogenic leaks if the arachnoid membrane is ruptured and a cerebrospinal fluid fistula is introduced. Delayed postoperative epistaxis can result from the sphenopalatine artery and the intracavernous internal carotid artery (ICA). Loss of vision can result from physical injuries to the optic nerves or chiasm, which can occur at multiple stages of the operation. Other causes include cerebral vasospasm, traction injury, empty sella syndrome with chiasm prolapse, ophthalmoplegia, and internal injuries to the carotid artery.

Injuries to the sphenoid sinus, including proximity to essential tissues, thin or absent bone, and loss of bone, increase the risk of iatrogenic injury. Packing is the initial therapy, and postoperative angiography should be performed afterward. Embolization is considered in situations where packing is inadequate or when there is development to pseudo-aneurysms or carotid cavernous fistulae.

Chronic Insipidus Diabetes (DI) is a common disturbance in patients following transsphenoidal surgery (TSS), causing water and electrolyte problems. DI can manifest in various clinical patterns, including transitory, permanent, and triphasic phenotypes. Postoperative syndrome of antidiuretic hormone secretion (SIADH) is also a risk factor, with hyponatremia often delayed and symptomatic. Improved or newly developed hypopituitarism is a risk, with the hypothalamic-pituitary-adrenal (HPA) axis being the most susceptible. Transcranial procedures with HPA or other axis deficits may cause damage to normal residual glands, especially in large tumors. Transsphenoidal techniques can mitigate the risk of dissecting an attenuated gland, but understanding pituitary physiology and sellar anatomy is crucial for improving the procedure and encouraging innovation. Transcranial procedures have a low death rate and risk of significant impairment, but understanding the underlying medical, endocrine, and surgical consequences is essential for successful PA excision.