Brain tumors are abnormal growths that occur in the cranium or in the central spinal canal. There are more than 120 types of brain tumors. They can be classified as either benign or malignant. Malignant brain tumors contain cancer cells and are typically more serious and life-threatening. Benign brain tumors are not cancerous, yet they can still be deadly. One type of brain tumor, known as juvenile nasopharyngeal angiofibroma (JNA), typically occurs in teenage boys. Although it is usually benign, JNA tends to bleed and occurs in the nasopharynx. Although tumors of the pituitary gland generally are benign and do not spread to the rest of the body, they can create multiple functional problems, including blindness and pressure on the brain. Previously, neurosurgeons had to perform the operation by splitting the facial skeleton or peeling back the scalp and removing the skull on the forehead. Another option for brain surgery is an endoscopic endonasal approach. This involves removing skull base brain tumors entirely through the nose and sinuses without incisions to the face. During the procedure, surgeons have a good view of surrounding tissue, which helps them to preserve important nerves. The endoscope is inserted through the nose and sinuses to directly reach the tumor. The brain and important nerves are not manipulated during this process. The tumor and surrounding area are brightly lit by the endoscope, which has a tiny camera that sends video images to a large screen. Specially-designed surgical tools are then inserted next to the endoscope to dissect and remove the tumor. Because the brain is not disturbed, the recovery time after surgery typically is days, instead of weeks or months. Patients are typically able to sail through the procedure with little discomfort and no visible scars. The procedure is also associated with reduced post–operative complications. Doctors say this operation is less invasive because the incision is made further back in the nasal passages. At the same time, the disadvantage of the endoscope is that surgeons rely on a camera to look at the image. In such a situation, some depth perception is compromised, even with improved cameras with higher definition. Surgeons therefore don't have a three-dimensional image and don't quite get three-dimensional depth. Also, endoscopic brain surgery is not available for all tumors in the brain, just for those at the base.