Surgery Optimizing Radiosurgery: The Neoadjvant Role in Cavernous Sinus Meningioma
The Cavernous Sinus Meningiomás initial management was microsurgery with total or near total resection resulting in good tumor control. However, there was a poor result in ocular motility cranial nerves preservation. Considering this results, radiosurgery rose and became important due to good outcomes. In most of cases, It is possible tumor control rate, sometimes higher than 90%, which is similar to Simpson Grade I extend of surgical resection, with ocular motility preservation.
Nevertheless, it is achievable when a high radiation dose (>= 13 Gy) is delivery in all tumor volume, and the recurrence is associated à lower doses – some series, for instance, showing a 100% recurrence rate when some tumor area are not covered by correct isodose curve. That situation mostly happens when the tumor is near to optic nerve during the radiations shots are planned – it is know that a 10Gy dose in optic nerve causes impairment. In this setting, the microsurgical resection of this lesions returns in a neoadjuvant role, aiming optimize radiosurgical planning athwart maximal tumor resection without Oculomotor nerve damage and decompressing optic nerve, keeping it away from tumor. To demonstrate this neoadjuvant concept, it́s is shown a cavernous sinus meningioma case, whose microsurgical goal were optimize radiosurgical treatment, through a maximal tumor resection with Oculomotor nerves preservation and keeping the optic nerve far from the tumor with a fat graft. As soon, the radiological preoperative image were submitted to Gamma-Knife radiosurgery planning - with aid of the software Leksell GammaPlan® 10.1.1, Leksell Gamma-Knife ® Perfextion™, to simulate how would the treatment be without microsurgery resection. Then, the patient were submitted to tumor resection aiming optimize radiosurgery with optic nerver decompression and kept far from cavernous sinus tumor with a fat graft. The extracavernous component was resected without ocular motility impairment. After all, the patient was submitted to Leksell Gamma-Knife ® Perfextion™ Radiosurgical treatment. The delivered dose to the optic nerve, to the optic chiasm and to the tumor in preoperative and postoperative planning were compared. In the preoperative planning, aiming deliver a 14 Gy dose to the tumor, a 11,4 Gy dose is given to the Optic nerve and 11,9 Gy in Optic chiasm, which is toxic and inadequate. In the postoperative planning, aiming the same 14 Gy dose delivery, a 9,1 Gy dose is given to the Optic nerve and 10,5 Gy in Optic chiasm, which is suitable and secure. Considering inappropriate a 10Gy dose to the optic nerve, it would not be possible treat the tumor with 14Gy – thus, the neoadjuvant microsurgery enabled a high dose covered in hole tumor volume without optic nerve radiation impairment. Therefore, in cavernous sinus meningioma, microsurgery current role is optimize radiosurgery.