Evolution of contemporary instrumentation for computer-assisted stereotactic surgery.

This article discusses the evolution of our stereotactic system which evolved from the commercially available Todd-Wells stereotactic instrument. The Todd-Wells frame was originally designed for radiographically based, functional neurosurgical procedures. We modified it for computed tomography compatibility and later devised localization systems for magnetic resonance imaging and digital angiography. Based on the limitations in the original design applying to our own set of requirements, including tumor stereotaxis, we totally redesigned the system around the arc-quadrant principle of the original Todd-Wells instrument. While this intermediate system was being used in our surgical practice, further limitations were noted and corrected in the system we presently use. The present stereotactic frame is completely interactive with an operating room computer system.