Surgical removal of cavernous sinus tumors and preservation of the cranial nerves

Abstract

In the cavernous sinus or cavernous sinus portion, various tumors arise. However, the most common tumors are trigeminal neurinomas, meningiomas, and pituitary tumors extending into the cavernous sinus. We surgically removed those tumors via a modified Dolenc approach. Under a usual frontotemporal curvelinear skin incision, craniotomy is performed. Thereafter, orbitotomy, the opening of the superior orbital fissure and optic canal, and anterior clinoidectomy are extradullary performed. The space between the superficial and inner layers constituting the lateral wall of the cavernous sinus is dissected, and the 3rd, 4th and 5th nerves are exposed. The dissection is continued until the exposure of the main trunk of the 5th nerve and Meckel's cave. The Dolenc approach is the best approach for the removal of trigeminal neurinomas. Regardless the direction of the tumor extension, the tumor can be removed by the Dolenc approach with minimal cranial nerve injury. Surgery for trigeminal neurinomas is done by basically only an extradural procedure. In meninigioma surgery in and around the cavernous sinus, most meningiomas involve the cranial nerves, intradural major cerebral arteries, and perforators. In the surgery for such meningiomas, we remove the extracavernous part of the tumor, and leave the intracavernous part to avoid injury of cranial nerves. In the follow-up period, stereotactic radiosurgery is adopted for the residual part of the tumor if the size of the residual part increases. For pituitary tumors extending into the cavernous sinus, the tumor can be removed through the pericarotid space and the anterior loop of the carotid artery after anterior clinoidectomy. In the surgery for tumors in and around the cavernous sinus, precise anatomical knowledge is most important, and cadaver dissection study is most helpful to understand the complex anatomy of the cavernous sinus. The characteristic points of each cavernous sinus tumor such as location, anatomical relation between the tumor and cranial nerves, and extension of the tumor have to be understood in order to avoid serious complications like injuries of the cranial nerves, major cerebral arteries, and perforators.