The learning curve of endoscopic endonasal transsphenoidal surgery for pituitary adenomas with different surgical complexity

Single Center Neurosurgical Outcomes and Trends in Endoscopic Endonasal Resection of 297 Sellar/Suprasellar Tumors Stratified by Duration of Neurosurgical Career

BACKGROUND/OBJECTIVE

Endoscopic endonasal transsphenoidal surgery (EETS) is a common treatment for sellar and suprasellar tumors. While endoscopic training has improved over the years and formal fellowship training is now broadly available, the operative nuances of EETS conjectures the existence a learning curve as a neurosurgeon matures with experience. We aim to evaluate operative outcomes of 3 different experience levels of neurosurgeons over time at a single institution.

METHODS

We reviewed all adult patients who underwent EETS at Loyola University Medical Center by 3 early career, 1 midcareer, and 2 late career neurosurgeons from 2007 to 2023. A comparative assessment of patient demographics, tumor features, and surgical outcomes was done using metrics such as length of surgery, rates of gross total resection (GTR) and symptomatic improvement, new postoperative steroid dependence, and development of diabetes insipidus (DI). T-tests and χ2 were used to statistically evaluate the study cohorts.

RESULTS

A total of 297 patients underwent EETS. One hundred three (35%) were operated on by an early career, 122 (41%) by a mid-career, and 72 (24%) by a late career neurosurgeon. Late-career surgeons had shorter operation times (144 vs. 180 minutes with early and mid-career, P = 0.029) and increased GTR rates (P = 0.008). There were no significant differences between the symptomatic improvement rates amongst various surgeon experience levels. Although not statistically significant, early-career neurosurgeons had lower rates of new postoperative steroid dependence. Patients of early career surgeons experienced significantly less DI (15% vs. 40%, P = 0.004).

CONCLUSIONS

Late-career neurosurgeons had shorter operation lengths, achieved higher rates of GTR, and their patients experienced significantly higher rates of DI. Overall outcomes remained stable throughout the course of 16 years between different surgeon experience levels.

The Learning Curve for Endoscopic Endonasal Transsphenoidal Pituitary Surgery: Evaluating Endocrine Outcomes

OBJECTIVE

In South Australia endoscopic endonasal approach (EEA) pituitary surgery has been practiced since 2006, largely by two neurosurgeons with a small fellowship-trained otolaryngology team. The aim of this cohort study was to determine if a "learning curve" can be established over this time period, as represented by structural and endocrine patient outcomes.

METHOD

Retrospective cohort study of patients undergoing EEA surgery between 2006 and 2021 in Adelaide, South Australia at three tertiary teaching hospitals.. Cases were divided by each surgeon and split into groups of sequential 40 cases. Endocrine assessment pre- and post-operatively involved static pituitary and end-organ hormones, with dynamic tests as required, assessed by an pituitary endocrinologist. Each hormonal axis (gonadal, cortisol, thyroid, prolactin and growth hormone) was documented preoperatively and at an early and long term follow up at 1-2 and 12 months, respectively.

RESULTS

The study included a cohort of 443 pituitary adenomas managed with endoscopic endonasal transsphenoidal surgery in a consecutive fashion between two neurosurgeons over 16-years. Gross tumour resection but not visual visual outcomes improved with surgical experience but this outcome may be neurosurgeon dependent. Endocrine outcomes were not consistently improved with experience, but lower rates of hypopituitarism were seen with experience with one neurosurgeon. Average follow up was approximately 5 years, and a minimum follow up of 12 months for all patients.

CONCLUSIONS

We present long term endocrine follow up for patients with functional and non-functional adenomas. Improved rates of gross tumour resection were evident with with surgical experience. However, there was no apparent change in post-operative endocrine outcomes.

The learning curve for endoscopic endonasal pituitary surgery: a systematic review

Recent literature demonstrates that a learning curve exists for endoscopic pituitary surgery. However, there is significant variability in the way these studies report their outcomes. This study aims to systematically review the literature regarding outcomes for endoscopic pituitary surgery and how this may be related to a surgical learning curve. An electronic search of the databases Medline, Scopus, Embase, Web of Science and Cochrane Library databases was performed and data extracted according 2020 Preferred Reporting Items of Systematic Reviews and Meta-Analyses (PRISMA) statement. Ten articles were included in the review as they examined the following: rates of gross total resection, average operative time, CSF leak rate, visual outcomes, endocrine outcomes and how these results were influenced by surgical experience. We have demonstrated that a learning curve exists for some outcome variables for endoscopic pituitary surgery. However, there is significant heterogeneity in the current body of literature which makes clear comparisons difficult.