Functional image-guided neurosurgical simulation system using computerized three-dimensional graphics and dipole tracing

This report describes a preoperative simulation and intraoperative localization system for use with three-dimensional functional images in intracranial surgery. The system, which produces three-dimensional functional images by superimposition of the generators of somatosensory evoked potentials derived from dipole tracing, was applied in the preoperative 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 potentials in three patients. In six patients, three-dimensional computer graphics were reconstructed from magnetic resonance images and allowed visualization of the lesions through the semitransparent views of the scalp surface and the brain. The three-dimensional functional images were created by superimposing the generators of somatosensory evoked potentials on three-dimensional computer graphics. This combined technique provided preoperative data regarding the three-dimensional relationship 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 preoperative simulation into the surgical field. Intraoperative localization can be performed in real time on the three-dimensional computer graphics in combination with the functional images created from dipole tracing. 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 safety of the surgery by affording preoperative simulation and intraoperative localization with the three-dimensional functional images. Two illustrative case reports are presented.