title: Implantation of Responsive Neurostimulation for Epilepsy Using Intraoperative Computed Tomography: Technical Nuances and Accuracy Assessment.
abstract: BACKGROUND
  Implantation of responsive neurostimulation (RNS) system has been previously discussed in the literature but there is a paucity of data on target accuracy and the use of intraoperative imaging. We describe our experience with 8 patients using intraoperative computed tomography (iCT) during implantation of the NeuroPace RNS system.
  
  
  METHODS
  A frame-based system was used. CT images were obtained and merged with preoperative magnetic resonance imaging and metabolic imaging studies to calculate target coordinates. An occipital entry point with a trajectory parallel to the hippocampus was planned. The leads were placed in the parahippocampal white matter circuitry. iCT images were obtained for immediate confirmation of lead accuracy. Images were computationally merged and superimposed on the magnetic resonance images and final coordinates of the distal contact were compared with the intended target. Targeting error was calculated in each axis as well as Euclidean distance. Preoperative and postoperative seizure frequency per month was used to evaluate outcomes.
  
  
  RESULTS
  Fifteen occipitotemporal leads were placed in 8 patients. The vector error means in the x, y, and z planes were 0.57 mm ± 0.44 mm, 0.71 mm ± 0.84 mm, and 2.23 mm ± 1.43 mm, respectively. The mean Euclidean distance error was 2.63 mm ± 1.32 mm. The z axis was found to have a significantly higher error [F2,42= 12.955; P = 0.001] when compared with the x or y axes. The median preoperative and postoperative seizure frequency per month was 3.4 and 0.78 seizures, respectively.
  
  
  CONCLUSIONS
  Frame-based stereotactic implantation of the NeuroPace RNS system using iCT is feasible and allows for intraoperative target accuracy confirmation and correction.
authors.affiliation: Department of Neurosurgery, Rush University Medical Center, Chicago, Illinois, USA.
authors.forename: Mena G
authors.initials: MG
authors.lastname: Kerolus
authors.affiliation: Department of Neurosurgery, Rush University Medical Center, Chicago, Illinois, USA.
authors.forename: Ryan B
authors.initials: RB
authors.lastname: Kochanski
authors.affiliation: Department of Neurology, Rush University Medical Center, Chicago, Illinois, USA.
authors.forename: Marvin
authors.initials: M
authors.lastname: Rossi
authors.affiliation: Department of Neurology, Rush University Medical Center, Chicago, Illinois, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Stein
authors.affiliation: Department of Neurosurgery, Rush University Medical Center, Chicago, Illinois, USA.
authors.forename: Richard W
authors.initials: RW
authors.lastname: Byrne
authors.affiliation: Department of Neurosurgery, Rush University Medical Center, Chicago, Illinois, USA. Electronic address: Sepehr_Sani@rush.edu.
authors.forename: Sepehr
authors.initials: S
authors.lastname: Sani
mesh_terms: D000328:Adult; D001921:Brain / Q000000981:diagnostic imaging* / Q000601:surgery; D017029:Epilepsy, Complex Partial / Q000628:therapy*; D005260:Female; D006801:Humans; D058542:Implantable Neurostimulators; D007430:Intraoperative Care; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D038361:Neuronavigation; D019635:Neurosurgical Procedures; D011300:Preoperative Care; D019919:Prosthesis Implantation / Q000379:methods*; D013238:Stereotaxic Techniques; D025321:Surgery, Computer-Assisted; D014057:Tomography, X-Ray Computed
keywords: Depth electrodes; Image fusion; Intraoperative CT; NeuroPace; Neuromodulation; Neuronavigation; Responsive neurostimulation; Stereotactic techniques; Targeting accuracy