Remission Rates and Efficacy Profile of Endoscopic Endonasal Surgery for Prolactinomas Based on their Cavernous Sinus Invasiveness

Introduction: The surgical indications for prolactinomas remain limited. Endonasal endoscopic approaches have significantly improved our ability to treat invasive tumors, but cavernous sinus invasion likely still impacts surgical outcomes.

Methods: Seventy-eight consecutive patients with prolactinomas undergoing endoscopic endonasal resection over the last 17 years were retrospectively reviewed. Immediate post-operative remission was defined as prolactin < 20 ng/mL within 14 days of surgery without adjuvant therapy. Late remission was defined as prolactin < 20 ng/mL at a minimum 1-year after surgery without adjuvant therapy. Cavernous sinus invasion was quantified by Knosp score.

Results: Of the 78 patients treated, 46 were males (59%), with a mean age of 37±13 years. Indications for surgery were medication resistance in 38 patients (48.7%), patient preference in 29 (37.2%), and medication intolerance in 11 (14.1%). Thirteen patients (16.7%) had Knosp grade 0, 10 (12.8%) Knosp grade 1, 14 (18%) Knosp grade 2, 17 (21.8%) Knosp grade 3, and 24 patients (30.8%) Knosp grade 4 tumors. Knosp grade had a significant effect on indication for surgery with higher Knosp grade tumors being more likely to have failed medical therapy (p = 0.033). Knosp grade 4 tumors had significantly higher tumor volume (23.3 ± 13 cm³ vs. less than 4 cm³ in grade 0–2 and 3, p < 0.001) and preoperative prolactin level (1,629 ± 930 vs. less than 600 ng/mL, p = 0.009).

The indication for surgery was predictive of immediate remission: 20 out of 38 patients (53%) who underwent EEA for medication resistant tumors had immediate remission; 22 of 29 patients (76%) who had surgery for their preference had immediate remission; and 9 of 11 (82%) medication intolerant patients had immediate remission. As depicted in [Fig. 1], patients with Knosp grades 0–2 achieved higher immediate remission rates (30/36, 83%) compared to patients with Knosp grades 3 and 4 patients (p < 0.001). However, 59% (10/17) of Knosp grade 3 and 44% (11/25) of Knosp grade 4 tumors were able to achieve immediate remission. Regarding late remission, Knosp grades 0–2, 3, and 4 patients achieved late remission rates of 68, 29, and 21%, respectively (Fig. 2). A total of 24 patients (30.8%) did not achieve remission despite all treatment modalities.

There were a total of 21 complications, including hormonal deficits (n = 14), transient cranial neuropathies (n = 2), seizure (n = 1), ICA injury without sequelae (n = 1), deep venous thrombosis (n = 1) vasospasm/stroke (n = 1) and postoperative epistaxis (n = 1). Interestingly, cerebrospinal fluid leak was not encountered in the series

Conclusion: The management of invasive prolactinomas utilizing the endoscopic endonasal approach is a safe and effective modality that should be employed in properly selected patients. EEA can improve control and even remission despite cavernous sinus invasion, though at a lower rate than without invasion. A multidisciplinary approach and multimodality treatment is essential for optimal patient selection, perioperative care and successful management.

Fig. 1

No conflict of interest has been declared by the author(s).

Publication History

Article published online:
12 February 2021