<p>Transsphenoidal Surgery in Canines: Safety, Efficacy and Patient Selection</p>

Abstract

Pituitary-dependent hyperadrenocorticism (PDH) is the cause of approximately 80-85% of naturally occurring cases of hyperadrenocorticism(HAC) in canines and is triggered by an adrenocorticotropic hormone (ACTH)-producing pituitary adenoma or hyperplasia of the corticotroph in the pituitary anterior lobe or intermediate lobe. Transsphenoidal surgery(TSS) is an effective treatment that can directly remove pituitary tumors that cause PDH in canines under a single course of general anesthesia. However, careful evaluations of the definitive diagnosis, adenoma size and growth rate, relationship with surrounding tissue, general condition, and neurosurgical procedural skill involved in each case are important to determine TSS suitability. The basic principle is to confirm that the present HAC case is PDH, that is, an ACTH-producing adenoma or the hyperplasia of the corticotroph originating from either the pituitary anterior or intermediate lobe. Evaluations based on endocrinology, particularly plasma ACTH concentration, and imaging diagnosis, particularly MRI is essential for definitive diagnosis. Enlarged pituitary tumors can shorten the post-TSS survival time, increase the recurrence rate of clinical symptoms, and increase the risk for developing permanent central diabetes insipidus. Therefore, complete removal of adenomas of up to Grade IIIA according to the MRI-based classification system is relatively easy to achieve with TSS, and long-term remission and survival can be expected.

A 3-Dimensional Printed Patient-Specific Surgical Guide to Facilitate Transsphenoidal Hypophysectomy in Dogs

“…Eighty seven percent of the dogs (7 dogs) survived more than 4 weeks and of those cases, all but one (case 4), are alive at the time of writing. These survivals are similar to those previously published ( 4 , 8 , 9 , 18 ). Further, in our cases (except case 4), there was no involvement of the arterial circle of Willis or cavernous sinus, similar to grade 2 and 3A cases presented by Sato et al ( 18 ) and for which a good clinical outcome is expected ( 18 ).…”

“…All dogs were positioned in sternal recumbency with their head held by hooking the canine teeth on a bar supported by a metal frame secured to the surgical table ( n = 4, Figure 2 ) or using a commercially available surgical headframe ( n = 4; Brainsight TM , Rogue Research, Canada), while avoiding pressure to the jugular veins, as previously described ( 1 , 8 , 15 , 16 , 20 , 22 ). The mandible was kept hanging to allow opening of the mouth during the different steps of the surgery.…”

“…Historically, pituitary masses have been classified using computed tomography (CT) or magnetic resonance imaging (MRI) by the pituitary height (mm)/brain area (mm 2 ) ratio (P/B); a P/B ratio > 0.31 defines enlarged adenomas, whereas a P/B ratio < 0.31 defines non-enlarged adenomas. Enlarged adenomas can cause compression of adjacent brain structures and lead to a variety of neurological signs (7)(8)(9).…”

Adrenocorticotropic hormone-producing pituitary adenoma with pituitary apoplexy treated by surgical decompression: a case report

“…TSS was performed in accordance with the method reported by Meij and colleagues [ 17 , 18 ]. Briefly, a burr hole was made in the basisphenoid bone, and the ventral aspect of the pituitary gland was exposed.…”

Three Cases of Transtracheal Catheter Oxygenation for Postoperative Dyspnoea with Pituitary-Dependent Hyperadrenocorticism in Dogs Treated by Surgery

“…The favourable outcome of TSS has resulted in its increased application [ 5 – 7 ]. However, fatal postoperative complications have been reported within 4 weeks of surgery, including prolonged coma, intraoperative arterial haemorrhage, hypernatraemia, and dyspnoea [ 5 , 8 – 10 ].…”