Clinical Accuracy of Customized Stereotactic Fixtures for Stereoelectroencephalography

Stereoelectroencephalograpy (SEEG) is a diagnostic method involving 3-dimensional exploration of brain structures using depth electrodes for locating epileptogenic foci in patients with drug-resistant epilepsy. A variety of frame-based, frameless, and robotic stereotactic systems have been designed for the accurate placement of depth electrodes.

Using the FHC microTargeting platform as a model, we introduce a fully customized design that has all the constructive elements positioned by a computer algorithm, according to the planned trajectories, anchoring points, and anatomic constraints. All the constructive elements form a single-body fixture, which allows for the efficient implantation of multiple depth electrodes following trajectories having a wide range of orientations. We aim at evaluating the safety and accuracy of this stereotactic system in a clinical setting.

A total of 173 depth electrodes were implanted in 21 patients with drug-resistant epilepsy. Matlab and DEETO software packages were used to postoperatively evaluate the targeting accuracy. Automatic detection of electrode locations eliminated any subjectivity in calculating the targeting errors.

As a result of using custom geometry of the stereotactic platform, the new design is optimized for each patient and streamlines the surgical procedures. The most important results characterizing the platform's accuracy are the values of 1.22 mm for the median lateral target point localization error and 1.17 mm for the median lateral entry point localization error.

The patient-customized platforms are comparable in terms of safety, accuracy, and simplicity of use to the existing robotic devices for implantation of depth electrodes in patients undergoing SEEG investigations.