Figure 1. Closed-Loop Responsive Neurostimulation (RNS) Implantation and Data Processing Method.

A, Preoperative magnetic resonance image and postimplantation computed tomography fused image (EpiNav software²⁷) aligned in the axial plane across the trajectory of the implanted RNS lead in the left hippocampus of patient 6. B, The 2 distal anterior hippocampal contacts provide bipolar channel 1, and the 2 proximal posterior hippocampal contacts form bipolar channel 2 (top), which record a unilateral electrographic seizure pattern (ESP) in the left hippocampus during the baseline period. For channel 2, a time-frequency plot shows the spectral evolution of the ESP aligned to onset (red vertical line). C, During stimulation, the amplifier is disconnected (time intervals in green), thereby generating a rectangular pulse artifact in the time domain (top) that is often followed by a considerable amplifier saturation direct current shift. In the frequency domain, stimulation appears as a low-frequency artifact accompanied by broadband cancellation (middle) that is often followed by a wideband artifact corresponding to amplifier saturation. Ch indicates channel; w, week of stimulation.