title: Subthalamus stimulation in Parkinson disease: Accounting for the bilaterality of contacts.
abstract: BACKGROUND
  Deep brain stimulation (DBS) in Parkinson's disease uses bi-hemispheric high-frequency stimulation within the subthalamus, however, the specific impacts of bilaterality of DBS are still not clear. Thus, we aimed to study the individual-level clinical impact of locations of right-left contact pair-up accounting for each subthalamic nucleus (STN) anatomy.
  
  
  METHODS
  Contact locations and effects at 1 year were studied retrospectively in an unselected series of 53 patients operated between 2004 and 2010. Location of contacts was defined relatively to the main axis of STN used to map longitudinal and transversal positions, and STN membership (out meaning out-of-STN). Contact pairings were described via three methods: (i) Unified contact location (UCL) collapsing DBS into an all-in-one contact; (ii) balance of contact pair-up (BCPU), defined as symmetric or asymmetric regardless of laterality; (iii) hemisphere-wise most frequent contact pair-up (MFCP) regardless of BCPU. Clinical data were: mean levodopa equivalent dose, Unified Parkinson's Disease Rating Scale (UPDRS) motor score III without medication, UPDRS II and III speech sub-scores, UPDRS II freezing sub-score, 1 year versus preoperative values, with and without levodopa. Ad-hoc two-sided tests were used for statistical analysis.
  
  
  RESULTS
  Worsening speech, was more frequent for UCL_out patients and when the left MFCP contact was rear and/or superolateral, however, it less frequent for BCPU-asymmetric patients. Worsening freezing was more frequent when the right MFCP contact was rear and superolateral.
  
  
  CONCLUSIONS
  These results point to strategies for minimizing dysarthria and freezing as adverse effects of DBS.
authors.affiliation: Service of Neurosurgery, Gabriel Montpied Hospital, University Hospital of Clermont-Ferrand, Clermont-Ferrand, France; Image-Guided Clinical Neuroscience and Connectomics, Research Team, Auvergne University, Auvergne, France.
authors.forename: Jean-Jacques
authors.initials: JJ
authors.lastname: Lemaire
authors.affiliation: Image-Guided Clinical Neuroscience and Connectomics, Research Team, Auvergne University, Auvergne, France; Biostatistics, Clinical Research Direction, Gabriel Montpied Hospital, University Hospital of Clermont-Ferrand, Clermont-Ferrand, France.
authors.forename: Bruno
authors.initials: B
authors.lastname: Pereira
authors.affiliation: Service of Neurology, Gabriel Montpied Hospital, University Hospital of Clermont-Ferrand, Clermont-Ferrand, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Derost
authors.affiliation: Image-Guided Clinical Neuroscience and Connectomics, Research Team, Auvergne University, Auvergne, France.
authors.forename: François
authors.initials: F
authors.lastname: Vassal
authors.affiliation: Service of Neurology, Gabriel Montpied Hospital, University Hospital of Clermont-Ferrand, Clermont-Ferrand, France.
authors.forename: Miguel
authors.initials: M
authors.lastname: Ulla
authors.affiliation: Biostatistics, Clinical Research Direction, Gabriel Montpied Hospital, University Hospital of Clermont-Ferrand, Clermont-Ferrand, France.
authors.forename: Dominique
authors.initials: D
authors.lastname: Morand
authors.affiliation: Service of Neurosurgery, Gabriel Montpied Hospital, University Hospital of Clermont-Ferrand, Clermont-Ferrand, France; Image-Guided Clinical Neuroscience and Connectomics, Research Team, Auvergne University, Auvergne, France.
authors.forename: Guillaume
authors.initials: G
authors.lastname: Coll
authors.affiliation: Service of Neurosurgery, Gabriel Montpied Hospital, University Hospital of Clermont-Ferrand, Clermont-Ferrand, France; Service of Radiology, Neuroradiology Unit, Gabriel Montpied Hospital, University Hospital of Clermont-Ferrand, Clermont-Ferrand, France.
authors.forename: Jean
authors.initials: J
authors.lastname: Gabrillargues
authors.affiliation: Service of Neurology, Gabriel Montpied Hospital, University Hospital of Clermont-Ferrand, Clermont-Ferrand, France.
authors.forename: Ana
authors.initials: A
authors.lastname: Marques
authors.affiliation: Service of Neurology, Gabriel Montpied Hospital, University Hospital of Clermont-Ferrand, Clermont-Ferrand, France.
authors.forename: Bérangère
authors.initials: B
authors.lastname: Debilly
authors.affiliation: Service of Neurosurgery, Gabriel Montpied Hospital, University Hospital of Clermont-Ferrand, Clermont-Ferrand, France; Image-Guided Clinical Neuroscience and Connectomics, Research Team, Auvergne University, Auvergne, France.
authors.forename: Jérôme
authors.initials: J
authors.lastname: Coste
authors.affiliation: Service of Neurology, Gabriel Montpied Hospital, University Hospital of Clermont-Ferrand, Clermont-Ferrand, France.
authors.forename: Franck
authors.initials: F
authors.lastname: Durif
keywords: Bilateral; Parkinson's disease; Subthalamic nucleus; deep brain stimulation