Where have we been? Where are we going?

The field of human stereotactic and functional neurosurgery is 50 years old. It began with the pioneering work of Spiegel and Wycis, who developed an apparatus to be used in human neurosurgery designed like the Horsley-Clarke apparatus invented for animal experimentation 40 years earlier, but based on targeting by intracerebral landmarks. During the past half century, the field of stereotactic surgery has evolved from a small field involving a handful of scientists to a field dominated by a technology that is permeating all of neurosurgery. A review of the scientific programs and activities of the World Society for Stereotactic and Functional Neurosurgery reflects the changing level of activity in these fields, the waxing and waning of functional neurosurgery that is now vital and active, and the evolution of stereotactic guidance into the field of computer-assisted neurosurgery. Functional neurosurgery involves the application of human neurophysiology to the treatment of various diseases that produce malfunction of the nervous system, and remains the domain of those few neurosurgeons well versed in neurological pathophysiology. Image-based or computerized stereotactic surgery, on the other hand, is used in those procedures common to neurosurgery, and should be available to any operating neurosurgeon.