The Learning Curve in Endoscopic Endonasal Resection of Craniopharyngiomas

Object: There is a paucity of literature regarding the learning curve associated with endoscopic endonasal cranial base cases. The purpose of this study was to determine to what extent a learning curve might exist for endoscopic endonasal resection of craniopharyngiomas.

Methods: A retrospective review was performed for all endoscopic endonasal craniopharyngioma resections performed at our institution from 2005 – 2015. To assess for a learning curve effect, cases were divided into an early cohort (2005 – 2009, 20 cases) and a late cohort (2010 – 2015, 23 cases). Preoperative demographics, clinical presentation, imaging characteristics, extent of resection, complications, tumor control, and visual and endocrine outcomes were obtained. Categorical variables and continuous variables were compared using a two-sided Fisher’s exact test and t-test, respectively.

Results: Only the index operation performed at our institution was included leaving 43 patients/operations for analysis. There were no statistically significant differences between early and late cohorts in patient age, gender, presenting symptoms, prior surgical or radiation history, tumor size, tumor consistency, hypothalamic involvement, or histological subtype. Gross total resection (GTR) rate increased from 20% to 65% (p = 0.005) and subtotal resection (STR) rate decreased from 40% to 13% (p = 0.078). Major neurologic complications including new hydrocephalus, meningitis, carotid artery injury, or stroke occurred in 6 (15%) patients (8 complications) in the early cohort compared with only 1 (4%) in the late cohort (p = 0.037). CSF leak decreased from 40% to 4% (p = 0.007). Discharge to home increased from 64% to 95% (p = 0.024). Visual improvement was high in both cohorts (88% and 81%). Rate of new panhypopituitarism and new permanent diabetes insipidus both increased from 6% to 39% (p = 0.025) and 21% to 61% (p = 0.013), which correlated with a significant increase in intentional stalk sacrifice in the late cohort (0% to 70%, p < 0.001).

Conclusion: High rates of near or total resection and visual improvement can be achieved with endoscopic endonasal approach for craniopharyngiomas. However, we did find evidence for a learning curve. After 20 cases, we found a significant decrease in major neurologic complications and CSF leak and a significant increase in GTR and discharge status to home. There was a significant increase in new panhypopituitarism and diabetes insipidus, which is attributable to increase rates of intentional stalk sacrifice and significant increase in the rate of GTR.