Critical analysis of anatomical landmarks within the sphenoid sinus for transsphenoidal surgery

Abstract

The transsphenoidal approach to the sellar region has been introduced more than a 100 years ago. It is the accepted standard operative corridor to pathologies of the pituitary gland and surrounding structures. There are anatomical landmarks within the sphenoid sinus that are used for orientation directing to the sella floor or the cavernous sinus. Yet, little data can be found on the consistency of these landmarks. It is the aim of this study to evaluate the reliability of these anatomical landmarks for the surgeon's orientation. A total of 245 computed tomography (CT) volume data sets of the cranium performed according to a standardized protocol were analyzed for study purposes. CT scans of the cranium of 125 patients admitted to the emergency room of our hospital receiving a trauma spiral according to the local protocol were employed as a control group when no pathology in the sellar region was observed. In addition, preoperative CT scans of a group of 120 patients diagnosed with pituitary adenomas between 2009 and 2013 were analyzed. Image analysis of the anatomical landmarks included the minimal intercarotid distance (ICD), diameter of the sphenoid sinus (DSS), direction of the septum sinuum sphenoidalium (SSS), and the distance between vomer and clivus (VCD). The overall mean ICD was 16.2 mm, with patients suffering from adenomas showing a mean ICD of 15.8 mm compared with an average 16.5 mm in the control group. DSS was equal for both groups (adenoma group: mean 31.5 mm; controls: mean 31.3 mm). Mean VCD was 27.9 mm in patients with pituitary adenomas compared with 26.7 mm in controls. A septum of the sphenoid sinus located in the midline was found in overall 23 % only. SSS was directed into the bony shield of the internal carotid artery in 28 % of underlying tumors and in 37 % of the control group. This is the first detailed description of landmarks of the sphenoid sinus based on a large radiologic-anatomical analysis of CT scans yielding a wide variation and high inconsistency of these landmarks. From out data, we suggest that the surgeon approaching the sphenoid sinus should handle the anatomical landmarks with care bearing their inconsistency in mind. A thorough planning of the procedure up front is highly recommended. Usage of a navigation system considering the bony structures might as well facilitate as steady the approach to the sellar region in some cases for the patient's sake.

ACR Appropriateness Criteria® Neuroendocrine Imaging

“…There is variable literature regarding the frequency and duration of routine follow-up for nonfunctioning tumors [90,91]; however, postoperative imaging is often performed >3 months following trans-sphenoidal surgery [88]. Imaging of suspected operative complications-such as intracranial hemorrhage, vascular injury, infarct [92], infection [93], or cerebrospinal fluid leak [94]-are beyond the scope of this document.…”

A computed tomography comprehensive evaluation of the ostium of the sphenoid sinus and its clinical significance

“…When surgically approaching the sphenoid sinus, its ostium is typically found medially and inferiorly to the rim of the superior turbinate [1]. Having identified the ostium, the anterior wall of the sphenoid sinus is typically excised around the both ostia, allowing for a facilitated access into the sinus [3].…”

“…Having identified the ostium, the anterior wall of the sphenoid sinus is typically excised around the both ostia, allowing for a facilitated access into the sinus [3]. In order to perform a safe transsphenoidal endoscopic or microscopic procedure, it is also imperative for the surgeon to be spatially orientated about the maximum diameter of the sinus, location of the carotid canal, the optic canal and other major surrounding neurovascular entities [1,11,13].…”

Use of Neuronavigation and Augmented Reality in Transsphenoidal Pituitary Adenoma Surgery

“…However, due to the limited line of sight, surgical orientation can especially be difficult in case of anatomical variants such as reduced intercarotid artery distance that is more frequently seen in patients with acromegaly [ 19 , 20 ], anatomic variation of the sphenoid sinus [ 21 ], or previous transsphenoidal surgery (adhesion, fibrosis, and obscured/distorted/missing surgical landmarks) [ 21 , 22 ]. As recently reported, there is also a high inconsistency and wide variation of anatomical landmarks; it is important to bear this inconsistency in mind when relying only on anatomical landmarks and also to comprehensively plan the procedure before surgery [ 23 ].…”