FUNCTIONAL IMAGE-GUIDED NEUROSURGICAL SIMULATION SYSTEM USING COMPUTERIZED 3-DIMENSIONAL GRAPHICS AND DIPOLE TRACING

THIS REPORT DESCRIBES a preoperative simulation and intraoperative loc alization system for use with three-dimensional functional images in i ntracranial surgery, The system, which produces three-dimensional func tional images by superimposition of the generators of somatosensory ev oked potentials derived from dipole tracing, was applied in the preope rative localization of central sulci in 12 patients with intracranial disorders. The preoperative localization of central sulci was assessed by intraoperative cortical recording of somatosensory evoked potentia ls in three patients. In six patients, three-dimensional computer grap hics were reconstructed from magnetic resonance images and allowed vis ualization of the lesions through the semitransparent views of the sca lp surface and the brain. The three-dimensional functional images were created by superimposing the generators of somatosensory evoked poten tials on three-dimensional computer graphics. This combined technique provided preoperative data regarding the three-dimensional relationshi p between the sensorimotor cortex and the lesions. We also developed a three-dimensional digitizer that incorporates a mechanical arm and a laser pointer for use in integrating information obtained in the preop erative simulation into the surgical field. Intraoperative localizatio n can be performed in real time on the three-dimensional computer grap hics in combination with the functional images created from dipole tra cing. This system was applied in five patients who underwent surgical brain tumor resections with minimal damage to the normal brain tissue. The use of this system for stereotactic craniotomy increased the safe ty of the surgery by affording preoperative simulation and intraoperat ive localization with the three-dimensional functional images. Two ill ustrative case reports are presented.