title: Analysis of stereotactic accuracy of the cosman-robert-wells frame and nexframe frameless systems in deep brain stimulation surgery.
abstract: BACKGROUND
  The primary goal of stereotactic systems in deep brain stimulation (DBS) surgery is accurate delivery of a DBS lead to a target identified on imaging. Thus, it is critical to understand the accuracy of the stereotactic systems and the factors which may be associated with a decrease in accuracy.
  
  
  METHODS
  Ninety patients underwent microelectrode recording-guided placement of 139 DBS leads by a single surgeon using the Cosman-Roberts-Wells (CRW) frame (n = 70) or a frameless skull-mounted trajectory guide (Nexframe; n = 69). The final DBS location was identified on a postoperative CT fused to the preoperative CT and MRI scans. The difference between this final location and the expected location was calculated.
  
  
  RESULTS
  The vector error was 2.65 mm (standard error, 0.22) for the frame and 2.78 mm (standard error, 0.25) for the frameless methods (p = 0.69). There was a gradual decline in error for both systems over time, as the vector error of the last 20 implants was 1.99 for the CRW frame and 2.04 for the Nexframe (p = 0.86).
  
  
  CONCLUSIONS
  This study shows that the CRW frame and Nexframe frameless systems have equivalent accuracy. Furthermore, the accuracy of both techniques improved over time, from 3 mm initially to 2 mm with current techniques.
authors.affiliation: Department of Neurosurgery, Medical College of Virginia Hospitals, Virginia Commonwealth University, Richmond, VA 980631, USA.
authors.forename: Craig
authors.initials: C
authors.lastname: Kelman
authors.forename: V
authors.initials: V
authors.lastname: Ramakrishnan
authors.forename: Alex
authors.initials: A
authors.lastname: Davies
authors.forename: Kathryn
authors.initials: K
authors.lastname: Holloway
mesh_terms: D000704:Analysis of Variance; D016009:Chi-Square Distribution; D046690:Deep Brain Stimulation / Q000295:instrumentation; D005917:Globus Pallidus / Q000601:surgery*; D006801:Humans; D058542:Implantable Neurostimulators; D008297:Male; D010300:Parkinson Disease / Q000601:surgery*; D013238:Stereotaxic Techniques / Q000295:instrumentation*; D020531:Subthalamic Nucleus / Q000601:surgery*; D016896:Treatment Outcome