The suboccipital cavernous sinus

Abstract

We studied the microsurgical anatomy of the suboccipital region, concentrating on the third segment of the vertebral artery (V3), which extends from the transverse foramen of the axis to the durai penetration of the vertebral artery, especially its loops, branches, supporting fibrous rings, adjacent nerves, and surrounding venous structures. Ten cadaver heads (20 sides) were formalin-fixed, and their blood vessels were perfused with colored silicone rubber; they were dissected under magnification and the anatomic structures were studied topographically, from the superficial to the deep tissues. In two additional specimens, serial histologie sections were done through the V3 and its encircling elements to elucidate their cross-sectional anatomy. Measurements of surgical and clinical importance were obtained, also under magnification. Our study reveals an astonishing anatomic resemblance between the suboccipital complex and the cavernous sinus (venous cushioning; anatomic properties of the V3 and those of the petrous-cavernous ICA, namely their loops, branches, supporting fibrous rings, and periarterial autonomie neural plexus; adjacent nerves; and skull base locations). Likewise, our review of the literature shows they have a related embryological development and functional and pathological features, as well as similar transitional patterns in the arterial walls of the V3 and the petrous-cavernous ICA. Hence, due to its analogy to the cavernous sinus, we call this suboccipital complex the suboccipital cavernous sinus. We also discuss its roles in physiologic and pathologic conditions as they pertain to various clinical and surgical implications.