The learning curve in endoscopic endonasal resection of craniopharyngiomas

OBJECTIVE There is a paucity of literature regarding the learning curve associated with performing endoscopic endonasal cranial base surgery. The purpose of this study was to determine to what extent a learning curve might exist for endoscopic endonasal resection in cases of craniopharyngiomas. METHODS A retrospective review was performed for all endoscopic endonasal craniopharyngioma resections performed at Thomas Jefferson University from 2005 to 2015. To assess for a learning curve effect, patients were divided into an early cohort (2005-2009, n = 20) and a late cohort (2010-2015, n = 23). 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 2-sided Fisher's exact test and t-test, respectively. RESULTS Only the index operation performed at the authors' institution was included. There were no statistically significant differences between early and late cohorts in terms of patient age, sex, presenting symptoms, history of surgical or radiation treatment, tumor size or consistency, hypothalamic involvement, or histological subtype. The rate of gross-total resection (GTR) increased over time from 20% to 65% (p = 0.005), and the rate of subtotal resection decreased over time from 40% to 13% (p = 0.078). Major neurological complications, including new hydrocephalus, meningitis, carotid artery injury, or stroke, occurred in 6 patients (15%) (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% [early cohort] and 81% [late cohort]). Rate of postoperative panhypopituitarism and permanent diabetes insipidus both increased from 50% to 91% (p = 0.005) and 32% to 78% (p = 0.004), which correlated with a significant increase in intentional stalk sacrifice in the late cohort (from 0% to 70%, p < 0.001). CONCLUSIONS High rates of near- or total resection and visual improvement can be achieved using an endoscopic endonasal approach for craniopharyngiomas. However, the authors did find evidence for a learning curve. After 20 cases, they found a significant decrease in major neurological complications and significant increases in the rates of GTR rate and discharge to home. Although there was a large decrease in the rate of postoperative CSF leak over time, this was largely attributable to the inclusion of very early cases prior to the routine use of vascularized nasoseptal flaps. There was a significant increase in new panhypopituitarism and diabetes insipidus, which is attributable to increase rates of intentional stalk sacrifice.