CSF rhinorrhea is the drainage of the fluid which surrounds the brain into the nose. CSF rhinorrhea results from a breakdown of the dura and supporting structures of the skull base resulting in a connection between the subarachnoid space and the nose. This fluid that is draining into the nose has the important functions of cushioning the brain, maintaining pressure within the eye, and cleansing the central nervous system much like the lymphatic system serves the same function in the rest of the body. CSF rhinorrhea can be the result of trauma to head, nasal or ear surgery or occur spontaneously. CSF rhinorrhea can be treated surgically.