Anterior Approaches to the Craniovertebral Junction

Published on 02/04/2015 by admin

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Last modified 02/04/2015

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Chapter 18 Anterior Approaches to the Craniovertebral Junction

TRANSORAL TRANSPHARYNGEAL APPROACH TO THE CRANIOVERTEBRAL JUNCTION2

This approach exposes the inferior one-third of the clivus down to the C2 vertebral body. The entrance to the oral cavity must provide a working distance of 2.5–3 cm between the upper and lower teeth.2 A tracheostomy is performed when the operation involves the high nasopharynx and the craniocervical junction. An operation at the atlas and axis levels may not require a tracheostomy. The patient is placed supine with the neck in slight extension. The mouth is kept open with a Dingman or Crockard retractor.

SOFT PALATE INCISION

The soft palate can be split at the midline to extend superior exposure (Figs. 18-2 and 18-3). The incision should be full thickness and extended to the junction of the hard and soft palates. If the lesion is located in the lower clivus, simply dividing the soft palate may be sufficient, but if the upper clivus needs to be exposed, removal of the bony plate is required.

The palatal retractors are inserted to elevate the soft palate, and they are attached to the basic ring of the self-retractors.

PHARYNGEAL WALL INCISION

The anterior C1 arch can be palpated through the posterior pharyngeal wall and verified with fluoroscopy. An initial incision is made on the midline through the mucosa of the posterior pharynx (Fig. 18-4). The anatomical landmark for the midline is the anterior tubercle of C1.

The mucosa layer is dissected separately from the prevertebral fascia investing the underlying muscle layer (Fig. 18-5). The longus capitis and longus colli muscles are subperiosteally elevated, and the arch of C1 is identified.

The longus and longus capitis muscles are originated from the basiocciput, and the origin site should be stripped off for exposure of the lower clivus (Fig. 18-6). Beneath the muscle layer, the anterior longitudinal ligament (ALL) is firmly attached to vertebral body surface. The ALL has a pointed attachment to the anterior tubercle of the atlas that widens as it descends to its insertion at the sacrum.5 The ALL is divided with electrocautery and reflected with a sharp dissect to complete the exposure of the C1 arch.

The mucoperiosteal layers are spread with a self-retaining retractor to a maximum of 1.5 cm to either side (Fig. 18-7). The anatomical landmark of the lateral limit of the exposure is the pharyngeal recess. Usually the maximal transverse exposure is provided at the level of the C1 arch, and the transverse length of exposure is lessened at the C2 level.

The vertebral artery is located 1.4 cm lateral from the midline at the C2 level, 2.2–2.4 cm at C1, and 1.1–1.4 cm at the foramen magnum level. Knowledge of the exact location of the midline minimizes vertebral artery injury.

CASE ILLUSTRATION

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