Pituitary Surgery

Abstract

Today, more than 95% of pituitary adenomas are removed using transsphenoidal surgery. The complication rates both for the traditional microscopic technique and for the more recently introduced endoscopic technique are comparably low. In acromegaly, the overall surgical cure rate of the transsphenoidal operation is approximately 50% in experienced hands. In Cushing’s disease, the cure rate is high if an adenoma is visible on MRI. In prolactinomas, surgery should be preferentially offered to patients with microadenomas (<10 mm) as their chance of surgical cure is >90%. Adequate perioperative endocrinological management is pivotal. Replacement therapy for adrenal insufficiency must be adapted to the perioperative demand. Diabetes insipidus (DI) with impaired ADH secretion is encountered frequently on days 1-5 after surgery while the opposing syndrome of inappropriate antidiuretic hormone secretion (SIADH) with excessive ADH release typically presents on days 3-10. Thorough surveillance of water and electrolyte balance in the postoperative course is paramount for early detection and treatment of these typical postoperative dysregulations of the posterior pituitary lobe. Postoperative endocrine care includes early assessment of remission status and pituitary function. It is recommended that neuro-endocrine and neurosurgical follow- up appointments be scheduled prior to discharge to guarantee professional ongoing follow-up. For non-functioning pituitary adenomas (NFPA), radiotherapy (RT) may be considered for invasive residual tumour after surgery. The timing of radiotherapy is still a subject of controversy. For functioning adenomas, radiotherapy is indicated if surgery and medical therapy cannot control hormonal oversecretion. Fractionated radiotherapy (fRT) is used for large adenoma volumes to minimize secondary injury to surrounding structures. Stereotactic radiosurgery (SRS) is used for small target volumes with a sufficient distance from the optic apparatus. These two principle techniques have different risk profiles. Both fRT and SRS are highly effective in preventing further adenoma growth. Biochemical cure is less frequent. Reportedly, the biochemical cure rates are slightly higher for Cushing’s disease than for acromegaly and are least favourable in prolactinomas. Biochemical remission is often delayed and the cure rates increase over the years after RT.