High anterior cervical approach to the clivus and foramen magnum: a microsurgical anatomy study.

BACKGROUND

Surgical exposure of lesions located along the ventral foramen magnum (FM) and clivus poses a unique set of challenges to neurosurgeons. Several approaches have been developed to access these regions with varying degrees of exposure and approach-related morbidity.

OBJECTIVE

To describe the microsurgical anatomy of the high anterior cervical approach to the clivus and foramen magnum, and describe novel skull base extensions of the approach.

METHODS

Eight adult cadaveric specimens were included in this study. The high anterior cervical approach includes a minimal anterior clivectomy and its lateral skull base extensions: the extended anterior far-lateral clivectomy and the inferior petrosectomy. The microsurgical anatomy and exposure of the various extensions of the approach were analyzed. In addition, the capability of complementary endoscopy was evaluated.

RESULTS

With proper positioning, the minimal anterior clivectomy exposed the vertebrobasilar junction, proximal basilar artery, anteroinferior cerebellar arteries, and 6th cranial nerve. The lateral skull base extensions provided access to the anterior FM, mid-lower clivus, and petroclival region, up to the Meckel cave, contralateral to the side of the surgical approach.

CONCLUSION

The high anterior cervical approach with skull base extensions is an alternative to the classic approaches to the ventral FM and mid-lower clivus. A minimal anterior clivectomy provides access to the midline mid-lower clivus. The addition of an extended anterior far-lateral clivectomy and an inferior petrosectomy extends the exposure to the anterior FM and cerebellopontine angle lying anterior to the cranial nerves. The approach is also ideally suited for endoscopic-assisted techniques.