Beyond the Learning Curve: Comparison of Microscopic and Endoscopic Incidences of Internal Carotid Injury in a Series of Highly Experienced Operators

BACKGROUND: As the endoscopic endonasal approach (EEA) has gained popularity as an alternative to microsurgery (MS) for transsphenoidal resection (TSR), numerous studies have attempted to assess the differential risk of internal carotid artery (ICA) injury between the techniques, yet results have been equivocal and contradictory. The aim of this study was to evaluate ICA injury in MS versus EEA among highly experienced neurosurgeons. METHODS: We performed a systematic literature review of publications from 2002-2017 reporting ICA injury outcomes in >= 250 cases using MS or EEA. RESULTS: Seventeen series reporting 11,149 patients were included: 3 MS series, 13 EEA series, and 1 series with adequate samples for each. ICA injury incidences were 0.0%-1.6% in cohorts of 275-3000. MS series documented 5 ICA injuries in 2672 operations, for an overall incidence of 0.2% (range, 0.0%-0.4%), and EEA series reported 30 ICA injuries in 8477 operations, for a 0.4% injury rate (range, 0.0%-1.6%); the difference was nonsignificant (P = 0.25). Increased operative experience was associated with decreased incidence of ICA injury, a finding preserved in the overall study cohort and within discretely examined MS and EEA subgroups (overall r(2) = 0.08, MS r(2) = 0.23, EEA r(2) = 0.07). CONCLUSIONS: ICA injury is the most serious complication of TSR of pituitary neoplasms. Operator inexperience may be a more important risk factor than choice of surgical technique, given the comparably low rates of injury obtained by highly experienced surgeons independent of technique. This emphasizes the need for consolidated care in pituitary centers of excellence, improvement of high-fidelity simulators, and skull base mentorship between senior and junior staff.