Robotic three-dimensional positioning of a stimulation electrode in the brain.

Functional stereotactic cerebral operations are currently performed with straight electrodes. After physiological exploration, correction of the initial target is frequently necessary and requires multiple penetrations of the brain. This paper describes a robotic three-dimensional electrode probe that can reach targets located within a cylindrical volume from a single approach trajectory. It has been mounted on the neurosurgical robot Minerva, and includes a string electrode, which can protrude out of the side window of a straight cannula and offers a high intrinsic accuracy of 0.25 mm. A simple man-machine interface allows the surgeon to select reference and target points and to activate the probe from a graphics workstation. This paper also analyzes the accuracy of the probe as well as of the whole operating system, food gelatin being used to simulate brain matter.