A novel miniature robotic device for frameless implantation of depth electrodes in refractory epilepsy

Abstract

OBJECTIVE The authors' group recently published a novel technique for a navigation-guided frameless stereotactic approach for the placement of depth electrodes in epilepsy patients. To improve the accuracy of the trajectory and enhance the procedural workflow, the authors implemented the iSys1 miniature robotic device in the present study into this routine. METHODS As a first step, a preclinical phantom study was performed using a human skull model, and the accuracy and timing between 5 electrodes implanted with the manual technique and 5 with the aid of the robot were compared. After this phantom study showed an increased accuracy with robot-assisted electrode placement and confirmed the robot's ability to maintain stability despite the rotational forces and the leverage effect from drilling and screwing, patients were enrolled and analyzed for robot-assisted depth electrode placement at the authors' institution from January 2014 to December 2015. All procedures were performed with the S7 Surgical Navigation System with Synergy Cranial software and the iSys1 miniature robotic device. RESULTS Ninety-three electrodes were implanted in 16 patients (median age 33 years, range 3-55 years; 9 females, 7 males). The authors saw a significant increase in accuracy compared with their manual technique, with a median deviation from the planned entry and target points of 1.3 mm (range 0.1-3.4 mm) and 1.5 mm (range 0.3-6.7 mm), respectively. For the last 5 patients (31 electrodes) of this series the authors modified their technique in placing a guide for implantation of depth electrodes (GIDE) on the bone and saw a significant further increase in the accuracy at the entry point to 1.18 ± 0.5 mm (mean ± SD) compared with 1.54 ± 0.8 mm for the first 11 patients (p = 0.021). The median length of the trajectories was 45.4 mm (range 19-102.6 mm). The mean duration of depth electrode placement from the start of trajectory alignment to fixation of the electrode was 15.7 minutes (range 8.5-26.6 minutes), which was significantly faster than with the manual technique. In 12 patients, depth electrode placement was combined with subdural electrode placement. The procedure was well tolerated in all patients. The authors did not encounter any case of hemorrhage or neurological deficit related to the electrode placement. In 1 patient with a psoriasis vulgaris, a superficial wound infection was encountered. Adequate physiological recordings were obtained from all electrodes. No additional electrodes had to be implanted because of misplacement. CONCLUSIONS The iSys1 robotic device is a versatile and easy to use tool for frameless implantation of depth electrodes for the treatment of epilepsy. It increased the accuracy of the authors' manual technique by 60% at the entry point and over 30% at the target. It further enhanced and expedited the authors' procedural workflow.

Accuracy of intracranial electrode placement for stereoelectroencephalography: A systematic review and meta‐analysis

“…The frameless systems included in the analysis include the Vertek arm (Medtronic), Varioguide (BrainLab), Navigus tool (Medtronic), and the Guide Frame‐DT (Medtronic) . A single study compared the use of the iSYS1 robotic trajectory guidance system for the insertion of 93 electrodes in 16 patients with a historical cohort using the Vertek arm frameless technique . The number of patients and baseline characteristics of the historical cohort was not specified.…”

A new tool for touch-free patient registration for robot-assisted intracranial surgery: application accuracy from a phantom study and a retrospective surgical series

“…Dorfer et al 10 reported a mean entry point LE of 1.3 mm (range 0.1-3.4 mm) from 93 electrodes implanted with optical tracking registration and an iSYS1 robot. For the subset of the most recent 31 electrode implantations with optimized hardware, they reported a mean entry point LE (± SD) of 1.18 ± 0.5 mm.…”

“…The analysis was carried out in similar conditions, adding some hardware for SEEG procedure optimization. 10 Von Langsdorff et al 27 reported a mean accuracy (± SD) of 0.44 ± 0.23 mm, coupling the Fisher frame and Neuromate in a 21-trajectory study. Nevertheless, details about the planning data sets and the coregistration method were not provided.…”

Neuronavigation-guided Frameless Stereoelectroencephalography (SEEG)

“…Frameless techniques include both stereotactic robotic techniques 9) and frameless neuronavigation techniques with or without stereotactic techniques. 6,10,11) …”

“…Frame-based methods and stereotactic robotic guidance methods are certainly accurate, but carry several drawbacks 10,12) including the need for highly expensive stereotactic robotic equipment or restricted access to the surgical field in frame-based methods. As a result, these methods are not commonly used, whereas neuronavigation systems are widely used in the neurosurgical field.…”