TRANSORAL SURGERY - AN ANATOMIC STUDY

The transoral approaches have become commonplace in modern neurosurgic al practice for treatment of ventral midline lesions of the clivus and upper cervical spine. Although the standard technique of transoral su rgery is conceptually simple, anatomic relationships are not so readil y appreciated. The present study was undertaken in an effort to define more clearly the midline anatomic relationships as they pertain to th e standard transoral and transpalatine operations. The anatomic relati onships involved in planning microsurgical transoral approaches were e xamined in 15 human cadavers. Landmarks approximating the midline of t he skull base and the upper cervical spinal canal were defined to assi st the surgeon's orientation. Measurements were made in axial, sagitta l, and parasagittal planes to various neurovascular structures in the posterior cranial fossa and upper cervical spinal canal. The study rev ealed that, for the standard transoral and transoral-transpalatine dis sections, the carotid arteries. abducens nerves, interior petrosal sin uses, hypoglossal nerves, and vertebral arteries would be a greatest r isk being 0.76, 1.06, 1.51, 1.34, and 1.52 cm from the midline at spec ified locations. The measurements and the computed tomography images p rovide a useful reference for the surgeon.