Hypophysis

Introduction
Transsphenoidal selective adenomectomy is the primary therapy for Cushing’s disease in humans. The most common approach in humans is by the standard microsurgical submucosal transseptal transsphenoidal procedure using a neurosurgical operating microscope. There are many virtues of the midline transsphenoidal approach. Most importantly, it is the least traumatic route of surgical access to the sella. The lack of visual scars, lower morbidity and mortality as compared with transcranial procedures, the necessity of only a brief hospital stay, the relatively brief recuperative period add to the procedure’s appeal. More and more human pituitary surgeons employ the pure endoscopic endonasal transsphenoidal surgical approach for pituitary tumor removal using rigid endoscopes. The pure endoscopic approach is facilitated by the air-filled sphenoid sinus that is only separated by a thin bony floor from the pituitary fossa.

In dogs the most common method of treatment for Cushing’s disease or pituitary-dependent hypercortisolism (PDH) remains medical treatment with mitotane (o,p’-DDD) or trilostane. However, medical therapy leaves the pituitary adenoma untreated. Also, it may be hypothesised that the removal of the chronic negative feedback exerted by the glucocorticoid excess at the pituitary level, may actually stimulate pituitary tumor proliferation and expansion.

At the Utrecht University transsphenoidal hypophysectomy was re-started in 1993 and has become an important addition in the management of Cushing’s disease in the Netherlands (and occasionally for patients coming from other European countries). Until now 300 dogs and 20 cats have undergone pituitary surgery. Surprisingly, pituitary surgery in dogs and cats is, besides the Netherlands, only advocated in a few other institutions (Japan and only very recently the USA, UK, and Italy). In dogs the indications for pituitary surgery include pituitary corticotroph adenomas (causing Cushing’s disease), debulking of clinically non- functioning pituitary macroadenomas (causing diabetes insipidus or central neurological signs by the tumor mass effect) and occasionally sellar meningiomas.  [...]