Beyond the learning curve: Comparison of microscopic and endoscopic incidences of internal carotid injury in series of highly experienced operators

Abstract 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 ICA injury between the techniques, yet results have been equivocal and contradictory. Our objective was to evaluate MS versus EEA regarding ICA injury in a cohort of highly experienced neurosurgeons. Methods Systematic literature review of publications from 2002-2017 reporting ICA injury outcomes in ≥250 cases using MS or EEA. Results Seventeen series met inclusion criteria, reporting a total 11,149 patients. Three were MS series, 13 were EEA, and 1 included adequate samples for each. Cohorts ranged from 275-3000, reporting ICA injury incidences from 0.0-1.6%. MS series documented 5 ICA injuries in 2672 operations, an overall incidence of 0.2% (range 0.0-0.4%), while EEA series reported 30 injuries in 8477 operations, a 0.4% injury rate (range 0.0-1.6%), a non-significant difference (p=0.25). Increased operative experience was associated with decreased incidence of ICA injury, a finding preserved in the overall study cohort, and within the discretely examined MS and EEA subgroups (overall r2=0.08, MS r2=0.23, EEA r2=0.07). Conclusion ICA injury is the most threatening complication of TSR of pituitary neoplasms, and operator inexperience may present 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.