At a glance
- Segments
- Upper (dorsum), middle (sphenoid) and lower (nasopharyngeal) clivus
- Lateral limits
- Paraclival carotids; abducens nerves (Dorello)
- Targets
- Chordoma, chondrosarcoma, ventral meningioma, brainstem lesions
- Reconstruction
- Pedicled nasoseptal flap essential
- Main risks
- CSF leak, carotid/basilar injury, abducens palsy
Overview
Kassam and colleagues described the transclival module of the expanded endonasal approach, extending from the posterior clinoids to the foramen magnum, and divided the clivus into upper, middle and lower thirds[1]. The approach gives a direct midline view of the ventral posterior fossa and avoids traversing the cranial nerves, which lie lateral to most midline lesions. The development of the vascularised nasoseptal flap made routine intradural transclival surgery feasible by reducing the CSF-leak rate[2].
Indications
- Clival chordomas and chondrosarcomas, the principal indication.
- Ventral and midline petroclival and foramen-magnum meningiomas that displace the nerves laterally.
- Selected ventral brainstem cavernous malformations, epidermoids and vertebrobasilar aneurysms.
Surgical anatomy
The upper clivus (the dorsum sellae and posterior clinoids) is reached by transposing the pituitary gland; the middle clivus forms the posterior wall of the sphenoid sinus below the sella, bordered by the paraclival carotid arteries; the lower clivus lies behind the nasopharynx and extends to the foramen magnum, bordered by the hypoglossal canals and the occipital condyles. The abducens nerve pierces the clival dura and runs upward in Dorello's canal beneath the petrosphenoidal ligament, close to the paraclival carotid. The basilar artery and the vertebrobasilar junction lie directly behind the clival dura[1,3].
Operative steps
- Harvest the nasoseptal flap; wide bilateral sphenoidotomy and posterior septectomy.
- For the lower clivus, incise and reflect the nasopharyngeal mucosa and the longus capitis muscles.
- Drill the clival bone between the paraclival carotids, identified with Doppler and navigation; the vidian canal leads to the anterior genu of the carotid.
- For tumours, drill until healthy bone is reached.
- Open the dura in the midline, controlling the basilar venous plexus with haemostatic agents.
- Reconstruct with an inlay graft, an onlay graft and the vascularised flap.
Complications and how to avoid them
- CSF leak, the commonest complication after intradural clival surgery: multilayer reconstruction with a vascularised flap, with lumbar drainage in selected cases[2].
- Abducens nerve palsy: know the course of the nerve in Dorello's canal and avoid lateral traction.
- Injury to the internal carotid or basilar artery or perforators.
- Meningitis and craniocervical instability after extensive lower-clival and condylar resection.
Take-home
Surgical pearls
- The clival nerves lie lateral; a midline lesion that displaces them is the ideal target.
- Use Doppler and navigation to define the paraclival carotids before drilling.
- Reconstruction is part of the approach, not an afterthought.
Related
References
- 1.Kassam AB, Snyderman CH, Mintz A, Gardner P, Carrau RL. Expanded endonasal approach: the rostrocaudal axis. Part II. Posterior clinoids to the foramen magnum. Neurosurg Focus. 2005;19(1):E4.
- 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.
- 3.Rhoton AL Jr. The sellar region. Neurosurgery. 2002;51(4 Suppl):S335-S374.
General education for medical professionals. It summarises published literature and is not advice for any individual patient or a substitute for supervised surgical training.