Transoral Approach/Decompression

87	Transoral Approach/Decompression K. Michael Webb and Volker K. H. Sonntag

Imaging

Magnetic resonance imaging to assess brain stem or spinal cord compression
Plain x-rays in traction to determine the extent of reduction
Computed tomography to assess the vertebral artery at C2 for posterior fusion planning

Preoperative Care

Patients with degenerative ventral compressive lesions or basilar invagination are admitted preoperatively and placed in traction. If the patient–s symptoms improve with reduction, treat with posterior fusion only.
Start with 5 pounds of traction and slowly increase to a maximum of 15 pounds. Make sure the vector of traction is neutral or with slight extension. Obtain lateral x-ray films after each change in weight.

Equipment

Operating Room Set-up

Supine on operating table
Head fixed in Mayfield head holder in slight extension
Attach self retaining transoral retractor to table.
Tongue and endotracheal tube are retracted inferiorly; make sure tongue is not pinched by the teeth to avoid necrosis or excessive swelling.
Soft palate and uvula retracted superiorly
Use fluoroscopy or lateral radiography before draping to determine the extent of the exposure.

Exposure

Midline incision with either scalpel or Bovie through the posterior pharynx (Fig. 87.1A)
Take down to bone in one layer and elevate subperiosteally; insert additional self retaining pharyngeal muscle retractors.
With curettes and/or periosteal elevators, expose the clivus, anterior arch of C1, lateral margins of the odontoid, and body of C2.
Remove the inferior portion of C1 arch to expose the base of the odontoid.

Odontoid Resection

Divide the alar and apical ligaments from the tip of the odontoid with curved curettes.
Transect the base of the odontoid process at the body of C2 with a high-speed drill and cutting bit to the posterior cortex.
The posterior cortex can be removed with a small Kerrison or diamond drill bit with irrigation (Fig. 87.1B).
Once the odontoid has been completely transected, it can be grabbed with a pituitary rongeur and pulled ventrally.
Any remaining compressive soft tissue can be removed in a piecemeal fashion. The transverse ligament can be divided to expose the dura and confirm adequate decompression.
Close pharyngeal muscles and remaining ligaments in one layer with interrupted 2–0 Vicryl suture.
Pass a nasogastric feeding tube under direct microscopic vision to avoid damaging the incision.

Place patient in a hard cervical collar immediately after surgery.
Leave intubated for 24 hours after surgery or until tongue swelling subsides. Observe in intensive care unit for 24 hours after extubation with an emergency airway cart in the room.