Unlike other instruments, the invention does not require any sharp blades or cumbersome power sources (such as those needed for ultrasound devices) in the operating theatre. Instead, a small paddle rotates at high speed, converting the tissue into a liquid form that can be removed by a small vacuum pump attached to the instrument. By altering the shape and speed of the paddle, doctors can alter the instrument to remove either soft or hard tissue. Rapidly growing cancerous tumours, for example, are 'softer' that normal brain tissue, while slow-growing benign tumours are 'harder' than healthy tissue. The instrument also allows the doctor to feel the consistency of the tissue, while analysis of the fluid remove can alert the surgeon if he or she starts to remove healthy tissue - improving the chances of a healthy recovery by the patient.