Irreducible atlantoaxial subluxation with compression of cervicomedullary junction

Ventrally located pathology of the lower clivus or atlantoaxial complex

Unstable odontoid fractures or os odontoideum with spinal canal stenosis

Oral cavity or oropharyngeal infection—increases risk of postoperative infection

Intradural lesions—better approached from a lateral approach

Trismus

Low-riding hard palate—requires a more extensive approach

Preoperative computed tomography (CT) angiography should be performed to evaluate the level of the hard palate and position and course of the carotid arteries.

Magnetic resonance imaging (MRI) should be considered for evaluation of the ligamentous complex and soft tissue masses.

Dynamic radiographs are obtained to evaluate craniocervical stability.

The patient is placed supine on the operating table with the head in a Mayfield head holder in slight extension.

An optional preoperative tracheostomy is recommended if splitting of the mandible is required to facilitate exposure in patients unable to open their mouths.

Disruption of the anterior osteoligamentous complex may destabilize the spine and necessitate a dorsal arthrodesis.

Consider the use of intraoperative neuronavigation.

Patients with spinal cord compression should have mean arterial pressure maintained intraoperatively at greater than 85 mm Hg.