Tailored endoscopic endonasal transoculomotor triangle approach for pituitary neuroendocrine tumors invading the parapeduncular space through the oculomotor triangle.

Abstract

Pituitary neuroendocrine tumors (PitNETs) with parapeduncular space (PPS) invasion through the oculomotor triangle present significant surgical challenges. The endoscopic endonasal approach (EEA) has emerged as a well-established technique for treating PitNETs, but surgical strategies for tumors invading the PPS need further optimization. The aim of this study was to evaluate the safety and efficacy of a tailored EEA for the treatment of PitNETs invading the PPS. The authors conducted a retrospective analysis of 72 patients with Knosp grade III and IV PitNETs invading the PPS who underwent an extended EEA between June 2019 and February 2025. A novel MM ratio (the maximum diameter of PPS tumor divided by the maximum diameter of the oculomotor triangle tumor neck) and the width of tumor neck were introduced as references for surgical approach selection. All patients underwent surgery using either the transoculomotor triangle corridor (TOT) or transsupra-interclinoid ligament corridor (TSICL) approach. Clinical data, including growth characteristics, imaging characteristics, surgical strategies and prognosis, were summarized. The median MM ratio was 1.3. The TSICL approach achieved a higher gross-total resection (GTR) rate compared with the TOT approach (92% vs 70.2%). However, the TSICL approach was associated with higher rates of immediate postoperative oculomotor nerve paralysis (84% vs 34%). Recovery rates of oculomotor function were similar between the two approaches (TSICL: 61.9% at 3.6 months; TOT: 75% at 3.2 months). There was no statistically significant difference in the prognosis of postoperative oculomotor nerve paralysis between the two approaches. The data also showed that a smaller MM ratio, soft tumor texture, and TSICL approach were associated with complete resection. Logistic regression analysis showed that the MM ratio and the width of the tumor neck at the oculomotor triangle can serve as reference for whether to adopt the TSICL approach. An extended EEA can effectively resect PitNETs invading into PPS through the oculomotor triangle. For tumors with a narrower tumor neck and larger MM ratio, the parapeduncular tumor component usually cannot descend into the cavernous sinus through the oculomotor triangle after removal of the cavernous sinus tumor component. Therefore, a TSICL approach can achieve higher GTR rates despite temporarily increased oculomotor nerve dysfunction.