Resection of the medial wall of the cavernous sinus in functioning pituitary adenomas: Technical note and outcomes in a matched-cohort study

Highlights

• Resection of the medial wall of the cavernous sinus is safe and technically feasible using the endonasal endoscopic approach when performed by experienced surgeons.

• The present Knosp classification of cavernous sinus tumour involvement may not fully reflect microscopic invasion.

• The value of medial wall resection in improving biochemical remission and oncologic control rates remains to be determined by larger cohorts with matched controls.

Abstract

Background

Parasellar dural invasion can be associated with treatment failure after excision of functioning pituitary adenomas. Because the medial wall of the cavernous sinus is a common site of microscopic disease, we hypothesize that its resection may lead to improvement in biochemical remission and recurrence rates. We aim to describe our technique in the resection of the medial wall of the cavernous sinus using binasal endoscopic transsphenoidal surgery (BETS); and compare tumor control and biochemical remission rates against a matched cohort.

Methods

Patients with functioning pituitary adenomas who underwent resection of the medial cavernous wall in addition to tumor excision via BETS were compared to a cohort matched for tumor type, size, and Knosp grade. Biochemical remission rates, tumor control at follow-up, and complication rates were assessed.

Results

Sixteen patients underwent resection of the medial wall of the cavernous sinus. Of 14 cases with wall specimens deemed adequate for histopathologic analysis, 43 % had microscopic evidence of tumor. Two of three patients with Knosp grade 0 scores had microscopic tumor invasion of the medial wall. The mean blood loss in the cohort was 175 mL (comparable to control, p = 0.895), with no operative complications noted. Gross total excision was achieved in 81 % of cases in the treatment cohort. At a median follow-up of 11 months, no statistical difference was noted in the biochemical remission and oncologic control rates between groups.

Conclusion

Resection of the medial wall of the cavernous sinus is safe and technically feasible using BETS when performed by experienced surgeons. The Knosp classification may not be reliable for microscopic tumor invasion. The effect of this technique on clinical outcomes remains to be determined by larger cohorts with matched controls and long-term follow-up.

Introduction

Functioning pituitary adenomas comprise approximately half of pituitary adenomas and secrete one or more hormones produced by the anterior pituitary, namely prolactin (PRL), growth hormone (GH), adrenocorticotrophic hormone (ACTH), and thyroid-stimulating hormone (TSH) [14,23]. While they are histologically benign, these tumors are associated with a decreased quality of life and increased mortality rate as the patient is exposed to the pathophysiologic effects of hormone hypersecretion [1,3,7,10,11,14,16,23]. Timely biochemical control or cure of functioning pituitary adenomas is an important goal to ultimately improve morbidity and mortality from this disease.

A significant cause of failure after excision of these tumors is the presence of microscopic disease in the surrounding structures [2,8,9,13,20,21]. Microscopic deposits of tumor have been documented in the adjacent sellar dura, and the medial wall of the cavernous sinus [2,6,9,13,15,18,20,22]. It has been hypothesized that microscopic dural invasion decreases the rate of biochemical remission and increases the rate of recurrence after tumor excision [9,13,20,21]. Intuitively, resection of the medial wall of the cavernous sinus may potentially improve outcomes in terms of both biochemical cure and oncologic control.

Resection of the medial wall of the cavernous sinus is a highly technical and potentially morbid procedure due to the intimate relationship of the medial wall to important neurovascular structures including the internal carotid artery (ICA) and the venous plexi. The improvements provided by the fully endoscopic binasal approach to these tumors, however, have allowed for significantly improved lateral visualization and surgical manipulation to make this procedure a possibility [4,5]. Several groups have recently described their technique and presented the results of their early series [2,18,20].

The purpose of this manuscript is to describe our technique for the resection of the medial wall of the cavernous sinus using the BETS and discuss nuances to improve its safety and efficacy. We also compare the biochemical remission and tumor control rates in a cohort utilizing the technique with a cohort matched for tumor type, Knosp grade and size.