Skull base surgery may be done to remove both benign and cancerous growths, and abnormalities on the underside of the brain, the skull base, or the top few vertebrae of the spinal column. Because this is such a difficult area to see and reach, skull base surgery may be done by a minimally invasive endoscopic procedure in which instruments are inserted through The natural openings in the skull—the nose or mouth—or by making a small hole just above the eyebrow. This type of surgery requires a team of specialists that may include ENT (ear, nose, and throat) surgeons, neurosurgeons, and radiologists. Endoscopic skull base surgery requires retooling” on the part of the skull base surgeon. For otolaryngologists or head and neck surgeons training in the era of endoscopic sinus surgery, acquisition of endoscopic skills occurs in conjunction with training in external approaches to the cranial base.