Histology of the vertebral artery–dural junction: relevance to posterolateral approaches to the skull base

OBJECTIVE The far-lateral and extreme-lateral infrajugular transcondylar–transtubercular exposure (ELITE) and extreme-lateral transcondylar transodontoid (ELTO) approaches provide access to lesions of the foramen magnum, inferolateral to mid-clivus, and ventral pons and medulla. A subset of pathologies in this region require manipulation of the vertebral artery (VA)–dural interface. Although a cuff of dura is commonly left on the VA to avoid vessel injury during these approaches, there are varying descriptions of the degree of VA-dural separation that is safely achievable. In this paper the authors provide a detailed histological analysis of the VA-dural junction to guide microsurgical technique for posterolateral skull base approaches. METHODS An ELITE approach was performed on 6 preserved adult cadaveric specimens. The VA-dural entry site was resected, processed for histological analysis, and qualitatively assessed by a neuropathologist. RESULTS Histological analysis demonstrated a clear delineation between the intima and media of the VA in all specimens. No clear plane was identified between the connective tissue of the dura and the connective tissue of the VA adventitia. CONCLUSIONS The VA forms a contiguous plane with the connective tissue of the dura at its dural entry site. When performing posterolateral skull base approaches requiring manipulation of the VA-dural interface, maintenance of a dural cuff on the VA is critical to minimize the risk of vascular injury.