Innovative instruments that have come into use in this country in the past few years now enable neurosurgeons routinely to remove benign or malignant CNS tumors that might once have frustrated their best efforts. Fred Epstein, MD, professor of neurosurgery, New York University School of Medicine, New York City, told the recent Congress of Neurological Surgeons meeting in Chicago that the CUSA (Cavitron Ultrasonic Surgical Aspirator), developed by Cooper Medical Corp, Santa Clara, Calif, is one of the most efficacious of these devices. The CUSA permits the neurosurgeon to remove large tumors from teh inside out, "debulking" them quickly and effectively, without traction or manipulation and with minimal transmission of movement to adjacent normal tissues. The instrument's hollow titanium tip, vibrating 23,000 times per second, rapidly fragments even firm tumors. Simultaneously, it delivers an irrigating solution that converts the fragmented tissue into an emulsion and then aspirates the particles, leaving