title: A personalized stereotactic fixture for implantation of depth electrodes in stereoelectroencephalography.
abstract: BACKGROUND
  The stereoelectroencephalographic (SEEG) implantation procedures still represent a challenge due to the intrinsic complexity of the method and the number of depth electrodes required.
  
  
  OBJECTIVE
  We aim at designing and evaluating the accuracy of a custom stereotactic fixture based on the StarFix™ technology (FHC Inc., Bowdoin, ME) that significantly simplifies and optimizes the implantation of depth electrodes used in presurgical evaluation of patients with drug-resistant epilepsy.
  
  
  METHODS
  Fiducial markers that also serve as anchors for the fixture are implanted into the patient's skull prior to surgery. A 3D fixture model is designed within the surgical planning software, with the planned trajectories incorporated in its design, aligned with the patient's anatomy. The stereotactic fixture is built using 3D laser sintering technology based on the computer-generated model. Bilateral rectangular grids of guide holes orthogonal to the midsagittal plane and centered on the midcommissural point are incorporated in the fixture design, allowing a wide selection of orthogonal trajectories. Up to two additional grids can be accommodated for targeting structures where oblique trajectories are required. The frame has no adjustable parts, this feature reducing the risk of inaccurate coordinate settings while simultaneously reducing procedure time significantly.
  
  
  RESULTS
  We have used the fixture for the implantation of depth electrodes for presurgical evaluation of 4 patients with drug-resistant focal epilepsy, with nearly 2-fold reduction in the duration of the implantation procedure. We have obtained a high accuracy with a submillimetric mean positioning error of 0.68 mm for the anchor bolts placed at the trajectory entry point and 1.64 mm at target.
  
  
  CONCLUSIONS
  The custom stereotactic fixture design greatly simplifies the planning procedure and significantly reduces the time in the operating room, while maintaining a high accuracy.
authors.affiliation: Department of Physics, Bucharest University, Bucharest, Romania.
authors.forename: Bogdan
authors.initials: B
authors.lastname: Balanescu
authors.forename: Ronald
authors.initials: R
authors.lastname: Franklin
authors.forename: Jean
authors.initials: J
authors.lastname: Ciurea
authors.forename: Ioana
authors.initials: I
authors.lastname: Mindruta
authors.forename: Alin
authors.initials: A
authors.lastname: Rasina
authors.forename: Razvan C
authors.initials: RC
authors.lastname: Bobulescu
authors.forename: Cristian
authors.initials: C
authors.lastname: Donos
authors.forename: Andrei
authors.initials: A
authors.lastname: Barborica
mesh_terms: D000328:Adult; D001931:Brain Mapping / Q000379:methods; D004567:Electrodes, Implanted; D004569:Electroencephalography / Q000379:methods*; D004827:Epilepsy / Q000601:surgery*; D006801:Humans; D008875:Middle Aged; D013238:Stereotaxic Techniques / Q000295:instrumentation*