Imaging

• Magnetic resonance imaging to assess need for neural element decompression (transoral odontoidectomy, enlargement of foramen magnum, C1 or subaxial laminectomies)
  
• Computed tomography with thin-cut reconstructions for bone depth and screw lengths, relationship of vertebral artery to C2 pedicle

Preoperative Care

• Patients with traumatic occipitocervical dislocation should be placed in halo.
  
• Patients with basilar invagination are frequently admitted before surgery and placed in traction to determine if odontoidectomy needed.

Equipment

• Occipital screw set and connector to secure rods to cervical construct, standard lateral mass system of choice, or
  
• Threaded Steinmann pin, double Songer cable (DePuy Spine Inc., Raynham, MA) for sublaminar wires, single Songer cable for occiput, BendMeister Stein-mann pin bender (Sofamor Danek, Memphis, TN)
  
• Halo adapter for Mayfield head holder and halo vest removal tools

Operating Room Set-up

• Somatosensory and motor evoked potential monitoring (optional)
  
• Fluoroscopy

Positioning

• Regular bed with rolls with head in Mayfield holder or Jackson table (Mizuho OSI) and foam or horseshoe headrest with traction
  
• If in halo, turn prone in halo vest, fix head to Mayfield with halo adapter, then remove the posterior part of the vest and posts.
  
• Head must be in neutral position; confirm with lateral fluoroscopy.

Exposure

• Subperiosteal exposure from inion to each lamina and lateral mass
  
• Decompression of neural elements if necessary

Screw-Rod Technique

• Place C1 lateral mass, C2 pedicle or pars screws, subaxial lateral mass screws as indicated