An ethmoidectomy is performed, the dura is then cut, and the tumor is removed. These types of tumors are separated into two types:  When there is a tumor, injury, or some type of defect at the skull base whether the surgeon used an endoscopic or open surgical method, the problem still arises of providing separation of the cranial cavity and cavity between the sinuses and nose to prevent cerebrospinal fluid leakage through the opening referred to as a defect. For this procedure, there are two ways to start: with a free graft repair or with a vascularized flap repair. The free grafts use secondary material like cadaver flaps or titanium mesh to repair the skull base defects, which is very successful (95% without CSF leaks) with small CSF fistulas or small defects. The local or regional vascularized flaps are pieces of tissue relatively close to the surgery site that have been mostly freed up but are still attached to the original tissue. These flaps are then stretched or maneuvered onto the desired location. When technology advanced and larger defects could be fixed endoscopically, more and more failures and leaks started to occur with the free graft technique. The larger defects are associated with a wider dural removal and an exposure to high flow CSF, which could be the reason for failure among the free graft. This surgery is turned from a very serious surgery into a minimally invasive one through the nose with the use of the endoscope. For instance craniopharyngiomas (CRAs) are starting to be removed via this method. Paolo Cappabianca described the perfect CRA for this surgery to be a median lesion with a solid parasellar component (beside the sellar) or encasement of the main neuromuscular structures that are localized in the subchiasmatic (below the optic chiasm) and retrochiasmatic (behind the optic chiasm) regions. He also says that when these conditions are met, endoscopic endonasal surgery is a valid surgical option. For a case study on large adenomas, the doctors showed that out of 50 patients, 19 had complete tumor removal, 9 had near complete removal, and 22 had partial removal. The partial removal came from the tumors extending into more dangerous areas. They concluded that endoscopic endonasal surgery was a valid option for surgery if the patients used pharmacological therapy after surgery. Another study showed that with endoscopic endonasal surgery 90% of microadenomas could be removed, and that 2/3 of normal macroadenomas could be removed if they did not go into the cavernous sinus, which means fragile blood vessel triangles would have to be dealt with so only 1/3 of those patients recovered.