A surgical system configured to allow a medical professional to define an alert zone relative to a critical structure on a patient in a known coordinate system to assist the medical professional in performing surgery on a patient, said surgical system comprising: a navigation system; a control console comprising a control processor in communication with the navigation system; and a high-speed surgical instrument (220, 320, 420) including a bur, said high-speed surgical instrument (220, 320, 420) comprising a variable speed motor (245, 345, 445) in communication with said control processor, said variable speed motor (245, 345, 445) configured to rotate said bur; wherein the navigation system is configured to actively determine a position of said bur relative to the alert zone in the known coordinate system; wherein the navigation system is configured to send a signal to said control processor to manipulate said variable speed motor (245, 345, 445) of said high-speed surgical instrument (220, 320, 420) to transition the rotation of said bur from a first cutting speed to a second cutting speed when the navigation system determines said bur enters the alert zone; and wherein the transition of said bur from said first cutting speed to said second cutting speed creates a change as the bur transitions from said first cutting speed to said second cutting speed, said change created by the transition of the bur from said first cutting speed to said second cutting speed being perceptible so as to notify the medical professional that said bur has entered said alert zone, characterized in that: said first cutting speed is greater than 70,000 rotations per minute and said second cutting speed is below 70,000 rotations per minute and above 60,000 rotations per minute; and the surgical system further comprises a footswitch (250, 350, 450) movable by a medical professional in order to control operation of said variable speed motor (245, 345, 445) of said high-speed surgical instrument (220, 320, 420), the footswitch (250, 350, 450) in communication with said control processor. a navigation system; a control console comprising a control processor in communication with the navigation system; and a high-speed surgical instrument (220, 320, 420) including a bur, said high-speed surgical instrument (220, 320, 420) comprising a variable speed motor (245, 345, 445) in communication with said control processor, said variable speed motor (245, 345, 445) configured to rotate said bur; wherein the navigation system is configured to actively determine a position of said bur relative to the alert zone in the known coordinate system; wherein the navigation system is configured to send a signal to said control processor to manipulate said variable speed motor (245, 345, 445) of said high-speed surgical instrument (220, 320, 420) to transition the rotation of said bur from a first cutting speed to a second cutting speed when the navigation system determines said bur enters the alert zone; and wherein the transition of said bur from said first cutting speed to said second cutting speed creates a change as the bur transitions from said first cutting speed to said second cutting speed, said change created by the transition of the bur from said first cutting speed to said second cutting speed being perceptible so as to notify the medical professional that said bur has entered said alert zone, said first cutting speed is greater than 70,000 rotations per minute and said second cutting speed is below 70,000 rotations per minute and above 60,000 rotations per minute; and the surgical system further comprises a footswitch (250, 350, 450) movable by a medical professional in order to control operation of said variable speed motor (245, 345, 445) of said high-speed surgical instrument (220, 320, 420), the footswitch (250, 350, 450) in communication with said control processor.