Abstract
In spite of its well-documented usefulness for the resection of invaginated odontoid process, the transoral approach has an inherent drawback in that the operative field is deep, narrow, and contaminated. To circumvent these problems, the present authors employed the lateral approach for resection of the invaginated odontoid in two cases of basilar impression and in one case of cranial settling due to rheumatoid arthritis. With the patient in a lateral position, a U-shaped skin incision encompassing the posterior margin of the sternocleidomastoid (SCM), the inion, and the posterior midline was made. The SCM and the posterior cervical muscles were reflected anteriorly and inferiorly, respectively. After securing the vertebral artery, the lateral and posterior margin of the foramen magnum was widely resected to decompress the brain stem. Craniectomy was then enlarged anteriorly, drilling off the supero-posterior portion of the occipital condyle. Continuous resection of the jugular tuberculum anterior and superior to the hypoglossal canal with unroofing of the sigmoid sinus provided an ample working space, through which the invaginated odontoid could be well visualized and easily removed. Fixation between the occipit-C1 was carried out in none of the cases because the atlanto-axial sublaxation was irreducible preoperatively. In the case with cranial settling, since the patient had marked cord compression due to subluxation at C4-C5, posterior decompression of C4-C5 followed by the fixation from C1-C7 using an implantable titanium device was carried out. In every patient, the postoperative course was uneventful and the neurological deficit was markedly improved. The above experience indicates the feasibility of the lateral approach for the resection of invaginated odontoid. Furthermore, the lateral appoach is thought to have advantages over the transoral approach in that the operative field is clean and wide, the posterior fixation procedures can be simultaneously performed, and the patient's postoperative discomfort is much reduced. The operative technique for this lateral approach is described in detail and its merits and demerits as compared to the transoral approach are discussed.
