MENINGEAL ARCHITECTURE OF THE CAVERNOUS SINUS - CLINICAL AND SURGICALIMPLICATIONS

OBJECTIVE: The meningeal structure of the cavernous sinus (lateral sel lar compartment) was anatomically and histologically studied. We discu ss the clinical and surgical significance and present clinical example s of cranial base tumors. METHODS: Ten adult cadaveric heads were used for microsurgical dissection or histological studies. Specimens of th e cavernous sinus were continuously sectioned in three dimensions and stained by Masson's trichrome method. The findings are anatomically di scussed as they pertain to presented clinical cases. RESULTS: The cave rnous sinus, located in an interdural space between periosteal and men ingeal dura, is properly accessed by detachment of the periosteal brid ge between the superior orbital fissure and the middle fossa. The late ral meningeal dura is dissected under minimal hemorrhage from the sinu s, with a surgically important cleaving plane between the ''deep layer ,'' a semitransparent meningeal sheath with which the cranial nerves a re covered and protected. It has various degrees of meningeal pockets, of which Meckel's cave is the largest example. Adventitia of the caro tid artery in the sinus, uncovered with protective meninges, is consid ered to contact directly with tumors of the sinus origin. The meningea l wall of the cavernous sinus anatomically has three weak points as fa r as tumor invasion and extension are concerned: the venous plexus aro und the superior orbital fissure, the loose texture of the medial wall around the pituitary body, and dural pockets of the IIIrd and Vth cra nial nerves. The dural wall is extremely thin or missing at those poin ts. CONCLUSION: A surgical technique based on the meningeal anatomy is important for cavernous sinus surgery. The cavernous apex and Meckel' s cave, which are spaces of convergence of cranial nerves, however, ar e weak points for surgical dissection. The presence or absence of tumo r invasion into those areas may influence the microsurgical results.