Skull base surgery is usually performed to remove a tumor or an abnormal growth in the base of the skull. It may be performed as an open surgery or by minimally invasive techniques using an endoscope. During an open skull base surgery, an incision is made in the skull and a portion of the base of the skull is removed to reveal the abnormality. Endoscopic skull base surgery is a minimally invasive technique where a thin tube, with a small light and camera, is introduced through the nose and miniature instruments are used to remove the abnormal growth or tumor.