The operating neurosurgical microscope has been used since the 1950's when Dr. RMP Donaghy of the University of Vermont was active in the development of microsurgical technique and instrumentation. One of his prot g 's, Dr. MG Yasargil of the University of Zurich, Switzerland, further advanced the use of the operating microscope and emphasized the need for careful dissection of the pia arachnoid membranes on the surface of the brain to achieve safer retraction of normal brain and gain better access to pathological tissues. Endoscopy is the transmission of light to and visual information from the operative field through a small tube. The tube my be flexible or rigid. Endoscopy has also been available since the 1920's when Dr. Walter Dandy of the Johns Hopkins School of Medicine first peered into the cerebral ventricles of his patients.
Endoscopic surgery requires the addition of channels for dissection tools, suction, and irrigation.
Video images are quickly obscured if the operative field has even a small quantity of blood that cannot be irrigated and removed. Within the past decade endoscopes have been developed that are much smaller and have more working channels for the passage of surgical instruments. The endoscope is currently used routinely for work inside the cerebral ventricles. Hypo-vascular tumors, i.e. those with fewer blood vessels, such as colloid cysts of the third ventricle, are best approached with this technique. Vascular tumors may be better approached with conventional techniques because of the ability to stop bleeding from the tumor more quickly.