Amgad Hanna , Eli M. Baron, and James S. Harrop

Description

The transoral procedure uses an anterior midline approach, through the oropharynx, to gain access to the osseous anterior craniocervical junction.

Expectations

This procedure, combined with posterior stabilization, provides decompression and stabilization of craniocervical pathology and affords immediate mobilization in a cervical collar with a low surgical morbidity. Careful selection of candidates is important. As with all surgical patients, for those with poor health, optimization of preoperative nutritional status is essential. Nasopharyngeal incompetence is a frequent postoperative finding, but typically recovers in a delayed manner.

Indications

• Dental or periodontal abscess
  
• Reducible lesions; need only posterior stabilization, without decompression
  
• Inability to open the mouth >25 mm, which could be due to associated temporomandibular joint disease. This is a relative contraindication; these lesions can be approached through a transmandibular approach.

Special Considerations

• There is a potential for instability after this procedure due to resection of the anterior osseous and ligamentous structures. Although some people do not routinely perform a posterior internal fixation, we recommend posterior arthrodesis as an adjunct to this procedure.
  
• The vertebral arteries are 24 mm from the midline at the arch of C1, 11 mm from the midline at the foramen magnum and at the C2-C3 junction. However, this anatomy could be distorted by pathology or congenital abnormalities.
  
• Patients with irregular dentition may require a gum guard to be fashioned prior to surgery to fit the retractor and the dentition. Edentulous patients may require special adjustments in the retractor to avoid slippage during the procedure.

Special Instructions, Position, and Anesthesia

• Preoperative magnetic resonance imaging (MRI)/magnetic resonance angiography helps plan the procedure by identifying the degree of compression, the anatomy and dominance of the vertebral arteries, and the relationship of the internal carotid arteries to the anterior arch of C1.
  
• Topical hydrocortisone ointment (1%) to the oral cavity before and after surgery reduces significantly the amount of perioral swelling.
  
• Somatosensory and motor evoked potentials should be considered to monitor neural function.
  
• Intraoperative guidance could be achieved by fluoroscopy, intermittent intraoperative x-ray imaging, or image-guidance by intraoperative navigation.
  
• A nasogastric tube helps to prevent postoperative wound contamination.
  
• The endotracheal tube should be left in place for 24 to 48 hours after surgery, or until the surgeon is sure that the airway is not compromised.
  
• Postoperative palatal dehiscence should be immediately closed, whereas late (>1 week) postoperative pharyngeal dehiscence is better left to granulate because of friable edges with diversion of particulate food via the nasogastric tube or gastrostomy. However, direct repair may be attempted in early postoperative pharyngeal dehiscence.

Tips, Pearls, and Lessons Learned

• If the interdental distance is =25 mm with mouth opening, the transoral approach is feasible.
  
• Perioperative antibiotics, usually cephalosporins, are used to decrease the rate of infection. Infection rate is also diminished by protecting the mucosal edges during the surgery to allow the apposition of cleanly incised healthy edges at the end of the procedure, obliterating the dead space by two-layer closure of the posterior pharyngeal wall, and avoidance of particulate food until the wound has healed.
  
• Release of the tongue retractor blade from time to time during the procedure helps to prevent postoperative swelling. The surgeon always needs to avoid catching the tongue between the teeth and the retractor.
  
• Magnification is achieved by surgical loupes, operative microscope, or endoscopy.
  
• The anterior tubercle of atlas with the attached longus colli and anterior longitudinal ligament is an important landmark to the midline.
  
• The lateral exposure should not exceed 2 cm from the midline to avoid injury to the vertebral arteries, hypoglossal nerves, or eustachian tubes.
  
• A freely pulsating dura or soft tissue is a good sign of adequate decompression.

Key Procedural Steps

Fiberoptic laryngoscopy with nasotracheal or orotracheal intubation is less hazardous than tracheostomy. However, elective tracheostomy is sometimes indicated, especially with preoperative brainstem dysfunction or persistent postoperative swelling. Lateral position has been used by some surgeons to access both the mouth for decompression and the back for fusion. However, it presents the surgeon with unfamiliar anatomic relationships, both from the front and from the back. The transoral approach is therefore typically performed with the patient in a supine position with the head slightly extended. Head extension moves the dens caudally in the operative field. The head is held either fixed in a Mayfield headrest or without fixation. The mouth and oropharynx are prepared with 1% Betadine or cetrimide. The upper esophagus is packed with a collagen sponge or gauze to minimize the ingestion of blood.