Transoral Approach to the Craniocervical Junction (C1–C2)

What it exposes. The transoral route provides the most direct midline anterior corridor to the lower clivus, the anterior arch of C1, the odontoid process, and the C2 vertebral body. No other anterior cervical approach reaches this level without extensive dissection or a mandibular swing. Why this approach is chosen. It is the classic and gold-standard anterior approach for pathology at the craniocervical junction that cannot be reduced posteriorly and requires direct ventral decompression — particularly irreducible basilar invagination, rheumatoid pannus, and selected tumours. Primary indications: - Irreducible anterior compression at the craniocervical junction (basilar invagination, rheumatoid pannus, tumours)

• Odontoid resection for basilar invagination with ventral cervicomedullary compression
• Selected C1–C2 tumours requiring anterior column access (chordoma, metastasis)
• Chronic irreducible atlantoaxial subluxation with anterior cord compression
• Selected infectious pathology (tuberculous abscess, osteomyelitis) needing anterior debridement Contraindications: - Patient unable to tolerate prone or sitting position for posterior stabilisation
• Severe trismus or limited mouth opening preventing retractor placement
• Active oral or pharyngeal infection
• Previous high-dose radiotherapy to the pharynx with poor tissue quality
• Isolated posterior pathology better addressed by posterior approaches alone Alternative approaches. When the anterior compression is reducible with traction or positioning, posterior C1–C2 fusion alone suffices and the transoral route is avoided. Purely clival pathology above the palate is reached endoscopically endonasally, and selected lateral mass pathology by a lateral extrapharyngeal route; complex tumours may need combined staged anterior–posterior procedures. Approach variants. Exposure is tailored to how rostral or how wide the access must be.

Position & landmarks. Supine on a radiolucent table with the head in a Mayfield clamp or horseshoe and slightly extended (about 15–20 degrees) to open the oral corridor; the surgeon stands at the head of the table. The mouth is opened maximally with a Dingman or Crowe-Davis gag and the tongue depressed with a blade. The anterior tubercle of C1 is the central reference point, palpable through the posterior pharyngeal wall; the odontoid is the midline prominence above it and the C2 body the inferior extension. The planned incision is a midline vertical cut in the posterior pharyngeal wall from the C1 tubercle to the C2–C3 disc (4–6 cm), staying strictly within 1 cm of the midline. A lateral fluoroscopy C-arm or O-arm and microscope or loupes are made available for the deep dissection.

Work down through the pharyngeal layers strictly in the midline, splitting the superior constrictor along its raphe and elevating longus colli subperiosteally to reach the anterior arch of C1, then deliver and resect the odontoid while protecting the dura. There is no classical internervous plane — safety comes from absolute midline discipline between the two vertebral arteries.

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Structures at risk, by layer.

Vertebral artery injury management. If brisk arterial bleeding is encountered lateral to the midline: apply immediate tamponade with bone wax or a muscle patty; do not attempt primary repair in the transoral field; obtain urgent endovascular consultation for possible stenting or sacrifice; and monitor the posterior circulation in ICU. Prevention is absolute midline discipline, with preoperative CTA to map a dominant or anomalous vertebral artery and intraoperative navigation or fluoroscopy to confirm position. Specific complications and their incidence.

Extensile options. Extend rostrally by splitting the soft palate to reach the lower clivus; further rostral access needs endoscopic assistance or, rarely, a mandibulotomy (high morbidity, seldom performed in modern practice). Extend inferiorly to C3 by continuing the pharyngeal incision and elevating longus colli further, though the standard corridor is limited to C2–C3. Lateral extension is deliberately avoided — the corridor is kept within 1 cm of the midline to protect the vertebral arteries, and wider lateral exposure requires an alternative extrapharyngeal or endoscopic route. For complex pathology the transoral decompression is combined with posterior C1–C2 fusion (Harms–Goel) in the same sitting or within 48 hours. Closure. Approximate the longus colli with absorbable suture and close the prevertebral fascia if possible; close the superior constrictor and submucosa with interrupted absorbable sutures, then the pharyngeal mucosa with continuous or interrupted absorbable suture — watertight closure in two layers is essential. If the palate was split, close it in three layers: nasal mucosa, the muscular layer (levator and tensor veli palatini), and oral mucosa, reconstructing the uvula if divided. Remove the mouth gag, inspect the pharynx for bleeding, and place a nasogastric tube for feeding if prolonged intubation is anticipated. Post-operative care. Maintain the nasotracheal tube or tracheostomy for 48–72 hours with ICU monitoring of the airway, neurological status and CSF leak; document a cuff leak and give steroids before extubation. Keep the patient nil by mouth with nasogastric feeding until a videofluoroscopic swallow study or FEES is safe, and immobilise in a cervical collar or halo until the posterior fusion is performed. Follow up at 2 weeks (wound and pharyngeal inspection), 6 weeks (flexion-extension radiographs), 3 months (CT for resection and fusion), 6 months and 1 year.

• Odontoid resection for basilar invagination or irreducible atlantoaxial subluxation.
• Anterior decompression of rheumatoid pannus or ventral tumour.
• Tumour biopsy or debulking (chordoma, metastasis).
• Drainage of a retropharyngeal or prevertebral abscess.
• Anterior C1–C2 discectomy (rare, usually combined with posterior). Always combined with posterior stabilisation. Any anterior decompression that removes the odontoid or disrupts the transverse ligament destabilises the C1–C2 complex — the transoral approach provides decompression but no stability. Posterior C1–C2 fusion — Harms–Goel technique (C1 lateral mass and C2 pedicle screws) or Magerl transarticular screws is mandatory, performed in the same sitting or within 48 hours; extend to an occipitocervical fusion if the occipital condyles are involved.

Guidelines, registries and global practice. The transoral approach is a specialised technique performed at major spine centres worldwide; the principles — CT and MRI planning, vertebral-artery mapping, and mandatory posterior stabilisation after anterior decompression — are near-universal across contemporary practice systems.

Registry and population evidence. Basilar invagination and rheumatoid craniocervical pathology are rare, so most series are single-centre retrospective. Harms–Goel C1–C2 fusion after transoral decompression achieves greater than 95 percent fusion rates with low morbidity in experienced hands. Infection rates of 2–8 percent are reported across series, and CSF leak is the strongest predictor of meningitis. Global practice variation. In high-resource centres, endoscopic-assisted transoral and purely endoscopic endonasal approaches are increasingly used to reduce soft-tissue morbidity; in resource-limited settings, the open transoral approach with meticulous technique remains standard. Posterior stabilisation uses C1 lateral mass and C2 pedicle screws (Harms–Goel) or transarticular screws (Magerl) depending on local expertise and anatomy. Consent (globally applicable). Discuss vertebral artery injury (less than 1 percent but catastrophic), CSF leak (5–10 percent), infection and meningitis (2–8 percent), velopharyngeal incompetence (10–15 percent with palate split), airway compromise requiring prolonged intubation or tracheostomy, dysphagia, and the absolute requirement for posterior stabilisation.