At a glance
- Routes
- Transoral, endoscopic endonasal, transcervical
- Targets
- Odontoid, C1 anterior arch, lower clivus, ventral CMJ
- Indications
- Irreducible ventral compression (BI, pannus, tumour)
- Planning line
- Nasopalatine line (endonasal reach)
- Usually with
- Posterior occipitocervical fusion
Overview
The ventral craniovertebral junction can be compressed by an irreducible odontoid in basilar invagination, by inflammatory pannus in rheumatoid arthritis, by malunited fractures and by tumours. The traditional transoral approach exposes the odontoid through the oropharynx but requires splitting of the soft palate in many patients and carries risks of infection, velopharyngeal insufficiency and swallowing problems. Kassam and colleagues reported a fully endoscopic endonasal resection of the odontoid in 2005, opening the junction from above through the nose without traversing the oral cavity[1].
Indications
- Basilar invagination with irreducible ventral brainstem compression after attempted traction.
- Rheumatoid pannus causing cervicomedullary compression when posterior fusion alone is insufficient.
- Tumours of the odontoid and lower clivus, such as chordoma.
- Chiari malformation with significant ventral compression.
Planning
The lower limit of endonasal access can be predicted on sagittal CT using the nasopalatine line, drawn from the lower edge of the nasal bones to the posterior edge of the hard palate. Lesions below this line, or patients with a low odontoid, may be better approached transorally or transcervically. Dynamic imaging determines whether the compression is reducible; reducible deformities are often treated by posterior reduction and fusion alone.
Operative steps (endonasal)
- Supine, head neutral or slightly flexed, with navigation; consider neuromonitoring.
- Incise the nasopharyngeal mucosa as an inverted U-shaped flap; reflect the longus colli and longus capitis.
- Drill the anterior arch of C1 and the odontoid from its tip downward, preserving a shell of cortical bone until the end.
- Divide the apical and alar ligaments and remove pannus to decompress the dura.
- Close the nasopharyngeal flap; reconstruct with a vascularised flap if the dura is opened[2].
- Perform posterior occipitocervical fixation at the same sitting or in a staged procedure.
Complications
- Craniocervical instability: odontoid resection removes the main stabilising structures, so posterior fusion is almost always needed.
- CSF leak if the dura is opened.
- Vertebral artery injury from lateral drilling.
- Dysphagia and velopharyngeal insufficiency, particularly after transoral surgery.
Take-home
Surgical pearls
- Try to reduce the deformity first; many can be fixed from behind alone.
- Use the nasopalatine line to decide between endonasal and transoral routes.
- Plan the posterior fusion as part of the same operation.
Related
References
- 1.Kassam AB, Snyderman C, Gardner P, Carrau R, Spiro R. The expanded endonasal approach: a fully endoscopic transnasal approach and resection of the odontoid process: technical case report. Neurosurgery. 2005;57(1 Suppl):E213.
- 2.Hadad G, Bassagasteguy L, Carrau RL, et al. A novel reconstructive technique after endoscopic expanded endonasal approaches: vascular pedicle nasoseptal flap. Laryngoscope. 2006;116(10):1882-1886.
General education for medical professionals. It summarises published literature and is not advice for any individual patient or a substitute for supervised surgical training.