The influence of cervical spine position on the three anterior endoscopic approaches to the craniovertebral junction: an imaging study

Abstract

Background contextThree endoscopic anterior approaches, the transnasal, transoral, and transcervical approaches, are used for ventral lesions of the craniovertebral junction and have been compared regarding surgical working distances and approach angles. However, how the position of the cervical spine influences the depths of surgical corridors and approach angles for the three approaches has not been evaluated. PurposeTo evaluate the depths of surgical corridors and the approach angles for the three endoscopic approaches, taking the influence of cervical spine position into account. Study designA radiographic study comparing three anterior endoscopic approaches to the craniovertebral junction. Patient sampleCervical extension and flexion radiographs for 34 patients and cross-sectional computed tomography scans for 30 additional patients were assessed. Outcome measuresThe depths of the surgical corridors and the approach angles for the three endoscopic approaches in the midsagittal planes. MethodsWe determined the mean angles of the surgical trajectories for the endoscopic transoral and transcervical approaches on cervical extension and flexion radiographs. In addition, we measured the depths of the surgical corridors and the approach angles for the three approaches in the midsagittal plane. ResultsThe average depths of surgical corridors were as follows: endonasal, 93.65 mm; transoral, 85.27 mm; transcervical, 62.97 mm (in extension). The average approach angles were as follows: endonasal, 31.22°; transoral, 30.87°; transcervical, 36.58° (in extension). ConclusionsThe position of the cervical spine does not influence the surgical convenience of the endoscopic transnasal approach, but it can influence the endoscopic transoral and transcervical approaches, especially the latter. The endoscopic transcervical approach offers several advantages over the endoscopic transoral and endonasal approaches.