Extreme Lateral Transodontoid Approach to the Ventral Craniocervical Junction

The treatment of chordomas and other pathological processes involving the ventral craniocervical junction (CCJ) represent a surgical challenge. Although complete surgical resection combined with adjuvant radiation therapy remains the treatment of choice, extirpation is often complicated by the deep-seated ventral location of these lesions, their close proximity to vital neurovascular structures, and their locally infiltrative nature. In some cases, bilateral extension contributes to suboptimal surgical resection, particularly when lesions extend beyond the midline to the contralateral side. Traditionally, anterior and posterolateral skull base approaches have been employed as corridors to the ventral CCJ. In such cases with significant lateral extent, anterior surgical approaches (e.g., transnasal or transoral with endoscope) will not enable removal of the lateral tumor. Herein, we describe a lateral skull base approach to this region illustrated via a cadaveric dissection and a surgical case where our approach was employed to treat a ventral extradural CCJ chordoma with bilateral extension involving the lower clivus, C1 anterior arch, and odontoid process. Coined as the “extreme lateral transodontoid (ELTO) approach” by the senior author, this technique uses a unilateral operative corridor developed along an extreme lateral trajectory to the anterior aspect of the clival and upper cervical dura, with exposure of the contralateral side. Drilling of the C1 anterior arch and resection of the odontoid process allows access to the contralateral component of lesions across the midline, maximizing surgical resection. In cases with intradural tumor extension, this approach also provides a surgical trajectory to the ventral brain stem and its neurovascular structures that is both sterile and wide. Notably, the ELTO approach can be combined or added to other lateral approaches or posterior infratemporal approaches to remove more extensive lesions involving the more rostral clivus, jugular foramen, and temporal bone. Removal of the C1 lateral mass, occipital–cervical joint, or the dens in the ELTO approach renders the craniovertebral junction unstable, necessitating occipitocervical fusion that can be achieved concurrently through the same surgical incision. The ELTO approach provides a safe and direct surgical corridor to treat complex lesions at the ventral CCJ with bilateral extension, through a single operative corridor. The anatomical features and implementation of this approach in surgical cases will be discussed.