Navigation in Occipital and Cervical Spine Surgery

Introduction of Technology

In the occipital and cervical spine, posterior cervical instrumentation is a commonly selected procedure for stabilization in trauma, neoplasia, deformity, and spondylosis. The earliest techniques described wiring between the spinous processes to achieve bony arthrodesis. Several types of instrumentation systems and screws were subsequently developed, including compression clamps, hook-rod systems, and eventually pedicle screws. Roy-Camille et al. initially proposed the lateral mass screw in 1979, and the trajectory along with the technique was later modified by Anderson et al., An et al., and Jeanneret et al.

The use of lateral mass screws in the dorsal cervical spine has since increased for multiple reasons. The advantages include the relative safety of the anatomy around the lateral mass, the ability to place instrumentation post-laminectomy, ease of instrumenting multiple levels, ability to extend the construct, and biomechanical strength. The disadvantages of the lateral mass screw include possible injury to the vertebral artery and/or nerve root, junctional facet violation, and lateral mass fracture. Several studies have implicated misjudging screw length and trajectory as possible contributing factors to many of the aforementioned complications.

The introduction of CT image-guided neuronavigation has changed the landscape of modern spine surgery, with improved accuracy, increased visualization of deep spine anatomy and reduction of radiation exposure. Current generation CT image-guidance placement of instrumentation has been well demonstrated in thoracic and lumbar spine, as well as the pelvis. In the cervical spine, several studies have been conducted to determine the accuracy and complication rates in instrumentation placement with navigation. In addition, there have been more limited reports on the use of navigation in difficult-to-image areas of the cervical spine including the craniocervical junction, cervical-thoracic junction, and cervical pedicles. In this chapter, we present our technique for the safe and efficient placement of posterior cervical instrumentation from the occiput to the subaxial cervical spine under modern CT image-guided neuronavigation.

Surgical Treatment for Spinal Pathology

Clinical Studies

Clinical Presentation

There is no absolute contraindication for posterior cervical navigation. The indications for posterior cervical instrumentation include instability from traumatic, neoplastic, infectious, iatrogenic, or congenital etiologies, as well as multilevel cervical spinal stenosis with degenerative instability, deformity, or kyphosis. The use of CT image-guided navigation in the cervical spine is typically indicated in regions where visualization of the deep bony anatomy is extremely beneficial. At the occipitocervical junction, identifying the location of the occipital protuberance, spinal canal, and vertebral artery are necessary in order to safely introduce spinal instrumentation. In the subaxial and cervicothoracic junctions, the overlying soft tissue and bony structures of the shoulder girdles often obstruct conventional fluoroscopy, making navigation a superior alternative. Aside from improving accuracy and safety of cervical instrumentation, image-guided neuronavigation has the added benefit of smaller incisions and less soft tissue mobilization.

Preoperative Imaging

Carefully reviewing all available preoperative advanced imaging including CT, MRI, and radiographs of the cervical spine, may reveal anomalous anatomy such as presence of a ponticulus posticus. With a prevalence of 16.7% (range, 4.3%–52.9%), a ponticulus posticus can easily be mistaken for a thickened posterior arch, leading to a potentially devastating vertebral artery injury during C1 screw fixation. C2 and subaxial dorsal anatomy can also be highly variable. Atretic or congenitally abnormal bony C2 pedicles, abnormal subaxial cervical landmarks and variable anatomy of the intervertebral foramen can be identified with preoperative imaging review. The potential hazards associated with these anomalies can be carefully and safely avoided intraoperatively with neuronavigation systems.

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