Endoscopic Approaches to the Skull Base: The Coronal Plane

Background: Endoscopic endonasal skull base surgery has become an important part of the arsenal of contemporary skull base surgery. The coronal or paramedian plane is defined as the region lateral to the internal carotid artery (ICA) as it courses along the ventral skull base. The endoscopic approaches performed in the coronal plane for paramedian pathology are the most complex of the expanded extrasellar procedures. Method: We reviewed our experience with over 1,000 patients who underwent fully endoscopic expanded endonasal skull base surgery. In this report, we describe a modular system organized around the course of the ICA oriented in the anterior, middle, and posterior coronal planes. Results: The anterior coronal plane has an intimate relation with the anterior fossa and orbit, the mid-coronal plane with the middle fossa and temporal lobe and the posterior coronal plane with the posterior fossa and jugular foramen. The middle and posterior paramedian approaches are further divided in 7 modular zones based on the anatomy of the ICAs. Conclusion: The standardization of anatomic modular approaches to the skull base in the coronal plane simplifies the complexity of accessing paramedian lesions through a midline endonasal corridor optimizing the surgical strategy and, consequently, outcomes. The standardization of modular approaches herein provides for a systematic way of approaching segments via individual or combined endoscopic endonasal corridors.