[A New Era of Brain Tumor Surgery by Exoscope]

The exoscope, proposed by Gildenberg et al. in 1994, was developed as a new surgical assistive technology that differed from conventional microscopic surgeries. However, no significant progress has been made in this regard over the past decade. In 2008, a high-definition exoscope (HDXO-SCOPE) system developed by Mamelak et al. achieved a focal length of approximately 200 mm with an accuracy comparable to that of an operating microscope. This camera, commercialized as VITOM^® (Karl Storz) was smaller than an operating microscope but had a wider field of view. Furthermore, the VITOM^® was later adapted to three-dimensional imaging, providing an experience similar to microsurgery. The ORBEYE^® (Olympus), on the other hand, was developed as an alternative to the operating microscope and provided a three-dimensional field of view with a focal length of 220 to 550 mm. The most significant advantage of the exoscope is the increased freedom of surgical positioning. Conventional microscopes restrict the surgical approach and surgeons' physical position when conducting surgery, which can be problematic. On the other hand, the exoscope reduces burden on the arms and body and allows for more precise surgery. The exoscope is especially useful in surgeries of posterior cranial fossa, and surgeries on elderly patients. The use of an exoscope also allows greater flexibility when conducting surgery of midbrain lesions. In general, exoscopes are good alternatives to microscopes for brain tumor surgery; however, the current technology should be further improved. Exoscopes are expected to ultimately surpass surgical microscopes in the future leading to their adoption in an increasing number of surgeries.