The brain is fully encased inside a lining called dura. Between this dura and the brain lies a clear and colourless liquid called the cerebrospinal fluid or CSF that acts as a cushion for the brain. The brain and the dura are positioned partly above the nose and the sinuses that are separated from them by a thin bone.
The potential risks of this surgery are similar to endoscopic sinus surgery risks wherein there is less than 1% risk of unexpected damage to the brain and the optic nerve. There is also some risk that the leakage can recur.
The benefit of the surgery is to not only stop the CSF leak but also to remove the risk of an intracranial infection. The defect which allows CSF to drain into the sinuses can also allow bacteria (commonly found within the sinuses) to infect the brain and its surrounding tissue.