Improved Understanding of Venous Drainage at the Cranio-cervical Junction : Study of Postoperative Venous Remodeling Following Surgical Treatment of Lesions of the Posterior Fossa or Posterior Approach of the Upper Cervical Spine.

In the literature, a dichotomous view of cerebral venous drainage is most commonly found. Thus, two drainage pathways are most often considered: the jugular vein network and the vertebral artery plexus. However, several clinical observations seem to indicate a much more complex situation. The following hypothesis is therefore put forward: there are alternative drainage pathways to these main pathways, which are physiologically present and capable of draining a significant volume of blood. A set of alternative pathways, which can be described as "deep," has been described: in particular, drainage pathways surrounding the vertebral artery (vertebral artery venous plexus), epidural plexuses, and deep cervical veins. However, the so-called "superficial" systems (subcutaneous and muscular) do not appear to have been studied. There appears to be a change in venous drainage of the craniocervical junction postoperatively (posterior cranial fossa surgery and posterior approach to the upper cervical spine). These modifications would vary depending on the venous drainage configuration present in each patient. If this hypothesis is confirmed, it could have an impact on the management of each patient. Thus, if venous remodeling models are established, this could enable personalized perioperative patient management: better optimization of body position during installation in the operating room, more effective anticipation of potential intraoperative venous bleeding, and explanation of persistent headaches in the postoperative period due to insufficient compensation of venous drainage. Confirmation of this hypothesis would also improve the understanding of certain pathologies for which the venous hypothesis has been raised (chronic hydrocephalus in adults, idiopathic intracranial hypertension, etc.).