title: Modeling Laterality of the Globus Pallidus Internus in Patients With Parkinson's Disease.
abstract: OBJECTIVE
  Neurosurgical interventions such as deep brain stimulation surgery of the globus pallidus internus (GPi) play an important role in the treatment of medically refractory Parkinson's disease (PD), and require high targeting accuracy. Variability in the laterality of the GPi across patients with PD has not been well characterized. The aim of this report is to identify factors that may contribute to differences in position of the motor region of GPi.
  
  
  METHODS
  The charts and operative reports of 101 PD patients following deep brain stimulation surgery (70 males, aged 11-78 years) representing 201 GPi were retrospectively reviewed. Data extracted for each subject include age, gender, anterior and posterior commissures (AC-PC) distance, and third ventricular width. Multiple linear regression, stepwise regression, and relative importance of regressors analysis were performed to assess the predictive ability of these variables on GPi laterality.
  
  
  RESULTS
  Multiple linear regression for target vs. third ventricular width, gender, AC-PC distance, and age were significant for normalized linear regression coefficients of 0.333 (p < 0.0001), 0.206 (p = 0.00219), 0.168 (p = 0.0119), and 0.159 (p = 0.0136), respectively. Third ventricular width, gender, AC-PC distance, and age each account for 44.06% (21.38-65.69%, 95% CI), 20.82% (10.51-35.88%), 21.46% (8.28-37.05%), and 13.66% (2.62-28.64%) of the R2value, respectively. Effect size calculation was significant for a change in the GPi laterality of 0.19 mm per mm of ventricular width, 0.11 mm per mm of AC-PC distance, 0.017 mm per year in age, and 0.54 mm increase for male gender.
  
  
  CONCLUSIONS
  This variability highlights the limitations of indirect targeting alone, and argues for the continued use of MRI as well as intraoperative physiological testing to account for such factors that contribute to patient-specific variability in GPi localization.
authors.affiliation: Department of Neurosurgery, David Geffen School of Medicine, University of California, Los Angeles, CA, USA.
authors.forename: Justin
authors.initials: J
authors.lastname: Sharim
authors.affiliation: Department of Neurosurgery, David Geffen School of Medicine, University of California, Los Angeles, CA, USA.
authors.forename: Daniel
authors.initials: D
authors.lastname: Yazdi
authors.affiliation: Department of Neurosurgery, David Geffen School of Medicine, University of California, Los Angeles, CA, USA.
authors.forename: Amy
authors.initials: A
authors.lastname: Baohan
authors.affiliation: Department of Neurosurgery, David Geffen School of Medicine, University of California, Los Angeles, CA, USA.
authors.forename: Eric
authors.initials: E
authors.lastname: Behnke
authors.affiliation: Department of Neurosurgery, David Geffen School of Medicine, University of California, Los Angeles, CA, USA.|Department of Bioengineering, David Geffen School of Medicine, University of California, Los Angeles, CA, USA.|Neuroscience Interdepartmental Program, David Geffen School of Medicine, University of California, Los Angeles, CA, USA.|Brain Research Institute, David Geffen School of Medicine, University of California, Los Angeles, CA, USA.
authors.forename: Nader
authors.initials: N
authors.lastname: Pouratian
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D046690:Deep Brain Stimulation / Q000379:methods*; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D005917:Globus Pallidus / Q000000981:diagnostic imaging / Q000502:physiology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000000981:diagnostic imaging / Q000628:therapy*; D012044:Regression Analysis; D012189:Retrospective Studies; D012720:Severity of Illness Index; D015898:Tomography Scanners, X-Ray Computed; D016896:Treatment Outcome; D055815:Young Adult
keywords: Basal ganglia; Parkinson disease; deep brain stimulation; globus pallidus internus; imaging