Introduction: Traditionally, transoccipital implantation of hippocampal depth electrodes requires a the patient to be in a sitting or upright position and commonly requires a stereotactic head frame. The disadvantage of this approach is that the positioning can be cumbersome and uncomfortable for the surgeon. Robotic systems such as the ROSA have enabled frameless stereotactic cannulation of the hippocampus. Here we describe robotic-assisted placement of bilateral hippocampal depth electrodes with the patient’s head in the lateral position.

Methods: Two cadaveric heads were used. Planned trajectories were registered with the Rosa navigation system, and the Rosa identified the appropriate entry points and trajectories needed to reach the targets. After drilling of the skull, the electrodes were passed into the brain parenchyma, and placement was confirmed using computed tomography (CT).

Results: Lateral positioning of the head and use of the Rosa for frameless stereotactic placement of depth electrodes allowed for accurate cannulation of the long-axis of the hippocampus. The procedure time was comparable to frame-based stereotactic methods, and operating conditions for the surgeon were superior.

Conclusions: The ROSA robotic system allows for accurate placement of bilateral hippocampal electrodes. With the patient’s head placed in the lateral position, operating conditions are optimal and more comfortable for the surgeon compared to frame-based stereotactic methods. With the use of the ROSA system, we have created an advantageous technique for placing bilateral hippocampal depth electrodes.

Patient Care: In the future, robotic stereotatic navigation systems may improve procedural efficiency and lead to further innovations in minimally invasive surgical techniques.

Learning Objectives: By the end of this session, participants should be able to 1) describe the importance of hippocampal depth electrodes for monitoring of temporal lobe epilepsy, 2) Be able to discuss the advantages and disadvantages of the current techniques used for placing hippocampal depth electrodes, and 3) identify ways in which use of robotic-assisted navigation systems may be used to help improve these techniques.

References: Bahuleyan B, Omodon M, Robinson S, and Cohen A. Frameless stereotactic endoscope-assisted transoccipital hippocampal depth electrode placement: cadaveric demonstration of a new approach. Childs Nerv Syst. 2011: 27: 1317-1320. Spire WJ, Jobst BC, Thadani VM et al. Robotic image-guided depth electrode implantation in the evaluation of medically intractable epilepsy. Neurosurg focus. 2008. 25(3): E19. Gonzalez-Martinez J, Vadera S, Enatsu R et al. Robotic-assisted sterotactic laser ablation in Medically intractable epilepsy: Operative Technique. Operative Neurosurgery. 2014. 10(2): 167-173. Wu C, LaRiviere MJ, and Laxpati N et al. Extraventricular Long-Axis Cannulation of the hippocampus: Technical considerations. Operative Neurosurgery. 2014: 10(2): 325-333. Willie JT, Laxpati NG, Drane DL et al. Real-time Magnetic Resonance-guided stereotactic laser Amygdalohippocampotomy for mesial temporal lobe epilepsy. Neurosurgery. 2014. 74(2): 569-585.