Approaches to the ClivusPatrick J. Gullane, Michael J. Odell, Peter C. Neligan, and Christine B. Novak
Recent medical and surgical advances, including radiology and the development of the multidisciplinary skull base team, have led to a more aggressive approach to treatment of clival lesions. A thorough knowledge of the variety of surgical approaches and their limitations is integral to the successful management of the patient with clival pathology.
♦ Surgical Approaches
The location and size of the lesion are major determinants in selecting the most efficacious surgical approach.
Transoral Approach
- The clivus can be approached through the oral cavity, with or without a mandibulotomy. The decision to perform a mandibulotomy is generally based on the extent and location of the lesion. Smaller lesions can be removed without a mandibulotomy and will result in less morbidity.
- Good jaw mobility is needed for a transoral approach; therefore, patients with severe limitations of jaw movement may not be appropriate for this approach.
- Some surgeons prefer to perform a tracheostomy for all transoral approaches, whereas others advocate using an orotracheal tube and a Boyle-Davis retractor to prevent the endotracheal tube from obstructing the field of view. The decision to use an orotracheal tube or to perform a tracheostomy should be based on the possible postoperative airway edema as well as the anticipated defect size and reconstructive procedures.
- To adequately expose the clivus, a palatotomy must be performed. Depending on the location of the lesion, a soft palate incision may be sufficient (for lesions in the more caudal aspects of the clivus), or excision of varying amounts of the hard palate may be necessary. Using palatal incisions, every effort should be directed toward maximizing blood supply to the “palatal mucosal flap” and minimizing cicatricial palatal shortening, which can lead to postoperative velopharyngeal insufficiency. Provided the palatal incisions heal without sequelae, the loss of varying amounts of the hard palate will result in minimal patient morbidity.
- Posterior pharyngeal wall flaps are elevated to provide access to bony structures that are either involved with disease or precluding access to it. Meticulous closure of these flaps is required to provide a barrier to colonizing microbes.
- Once adequate flaps have been raised, bony removal is performed to provide adequate surgical access or for tumor resection.
- Following tumor removal, the defect is examined, and reconstructive options are explored. Significant dural resection generally prevents adequate primary dural seal and necessitates a graft to achieve a watertight closure.
- Mandibulotomy approaches are a very effective method to obtain wide exposure of the clivus, upper cervical spine, and sphenoid sinus. Because of the postoperative edema associated with this technique, most surgeons perform a tracheostomy prior to mandibulotomy.
- The procedure begins with a lip-splitting incision. This can be accomplished by extending the incision directly down the midline or in a circumferential fashion. The location of the mental nerve is noted, and the osteotomy is performed in the parasymphyseal region. Many surgeons tend to prefer a paramedian rather than a midline osteotomy because it is hypothesized that healing is superior with a paramedian osteotomy.
- Because dental status can affect the bony fixation of the mandibulotomy, this should be assessed preoperatively. Edentulous patients with an atrophic mandible require a different plating strategy than dentulous patients who have a greater amount of bone. With the presently available plating techniques, nonlinear osteotomies have minimal advantages.
- Depending on the area to be visualized, there are two options available for exposing the posterior pharynx:
- Lesions located in the midline of the lower clivus and the craniocervical junction are ideally suited to a midline glossotomy approach. This technique provides excellent access to the clivus from the base of the sphenoid sinus to the level of C4–C6 and depends on patient factors such as the degree of jaw mobility and neck configuration. A tracheostomy is performed to minimize the risk of postoperative airway obstruction. Prior to dividing the anterior floor of the mouth and tongue, a mandibulotomy is performed as described previously. It is important to divide the tongue in the midline to avoid injury to the lingual or the hypoglossal nerves and to minimize blood loss. The incision is extended posteriorly to the epiglottis. This permits excellent exposure of the mucosa overlying the lower clivus and upper cervical spine. However, with this approach, lesions that extend superiorly into the sphenoid sinus are less well visualized, and those that extend laterally into the cavernous sinus or parasellar regions should not be approached by this method. Because of the difficulty in obtaining dural closure, lesions with extensive dural or intradural involvement are best exposed by other methods.
- For lesions extending unilaterally into the parapharynx or infratemporal fossa, an incision in the floor of the mouth will provide improved surgical exposure. The incision is extended posteriorly from the midline to the anterior tonsillar pillar on the side of the lesion. The submandibular duct and gland are preserved and left in continuity. Division of the mandibular muscular attachments allows the mandible to swing laterally. The floor of the mouth incision is then extended onto the anterior tonsillar pillar and soft palate and when retracted provides a wide exposure of the posterior pharyngeal wall and parapharyngeal space. Division of the pterygoid muscles permits access to the infratemporal fossa. This exposure provides access from the ipsilateral infratemporal fossa to the contralateral eustaschian tube and medial pterygoid plate. Removal of the posterior hard palate and maxillary tuberosity provides increased exposure by opening the pterygopalatine fossa.
Transnasal/Transfacial Approach
Lateral Rhinotomy and Medial Maxillectomy
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