Early experiences with image-guided transoral surgery for the pathologies of the upper cervical spine

Study Design, Technical note. Objectives. Three years of convincing experience with cranial neuronavigation suggested the application of the cranial software and registration method for the transoral access to the C1-C2 vertebrae. Background Data. The C1-C2 vertebrae are located in close vicinity to the cranial base. If the intersegmental movements of the C0-C1/C1-C2 segments are prevented with HALO fixation, the upper cervical spine can be considered as a caudal part of the skull base and included in the extended navigation space of the skull. Methods. Three patients were selected for navigationassisted transoral odontoidectomy. Before surgery the patients were fixed and scanned in a HALO device. The fiducials were attached supraorbitally and to both mastoids, determining a wide registration area and allowing the caudal extension of the navigation space. The Brain-LAB VectorVision navigation system was used in cranial mode during the operations. Results. Neuronavigation and fluoroscopy-controlled transoral surgery were performed with success in ail three cases. The registration accuracy was 1.5, 2.7, and 3.1 mm. Conclusion. Image guidance during transoral exposure of the upper cervical spine offered excellent three-dimensional guidance on the ventral surface of the craniocervical junction, allowing a safer, more controlled surgery. As the targets of the transoral spinal surgery are fixed bony and ligamentous structures, no shifting occurs and continuous high navigation accuracy can be achieved. The use of the navigation can reduce the significance of the intraoperative fluoroscopy, diminishing the radiograph load of the patient and the operating room team.