title: Brain penetration effects of microelectrodes and DBS leads in STN or GPi.
abstract: OBJECTIVE
  To determine how intraoperative microelectrode recordings (MER) and intraoperative lead placement acutely influence tremor, rigidity, and bradykinesia. Secondarily, to evaluate whether the longevity of the MER and lead placement effects were influenced by target location (subthalamic nucleus (STN) or globus pallidus interna (GPi)).
  
  
  BACKGROUND
  Currently most groups who perform deep brain stimulation (DBS) for Parkinson disease (PD) use MER, as well as macrostimulation (test stimulation), to refine DBS lead position. Following MER and/or test stimulation, however, there may be a resultant "collision/implantation" or "microlesion" effect, thought to result from disruption of cells and/or fibres within the penetrated region. These effects have not been carefully quantified.
  
  
  METHODS
  47 consecutive patients with PD undergoing unilateral DBS for PD (STN or GPi DBS) were evaluated. Motor function was measured at six time points with a modified motor Unified Parkinson Disease Rating Scale (UPDRS): (1) preoperatively, (2) immediately after MER, (3) immediately after lead implantation/collision, (4) 4 months following surgery-off medications, on DBS (12 h medication washout), (5) 6 months postoperatively-off medication and off DBS (12 h washout) and (6) 6 months-on medication and off DBS (12 h washout).
  
  
  RESULTS
  Significant improvements in motor scores (p<0.05) (tremor, rigidity, bradykinesia) were observed as a result of MER and lead placement. The improvements were similar in magnitude to what was observed at 4 and 6 months post-DBS following programming and medication optimisation. When washed out (medications and DBS) for 12 h, UPDRS motor scores were still improved compared with preoperative testing. There was a larger improvement in STN compared with GPi following MER (p<0.05) and a trend for significance following lead placement (p<0.08) but long term outcome was similar.
  
  
  CONCLUSIONS
  This study demonstrated significant acute intraoperative penetration effects resulting from MER and lead placement/collision in PD. Clinicians rating patients in the operating suite should be aware of these effects, and should consider pre- and post-lead placement rating scales prior to activating DBS. The collision/implantation effects were greater intraoperatively with STN compared with GPi, and with greater disease duration there was a larger effect.
authors.affiliation: Department of Neurology, University of Florida College of Medicine/Shands Hospital, Movement Disorders Center, McKnight Brain Institute, Gainesville, Florida 32610, USA.
authors.forename: J M
authors.initials: JM
authors.lastname: Mann
authors.forename: K D
authors.initials: KD
authors.lastname: Foote
authors.forename: C W
authors.initials: CW
authors.lastname: Garvan
authors.forename: H H
authors.initials: HH
authors.lastname: Fernandez
authors.forename: C E
authors.initials: CE
authors.lastname: Jacobson
authors.forename: R L
authors.initials: RL
authors.lastname: Rodriguez
authors.forename: I U
authors.initials: IU
authors.lastname: Haq
authors.forename: M S
authors.initials: MS
authors.lastname: Siddiqui
authors.forename: I A
authors.initials: IA
authors.lastname: Malaty
authors.forename: T
authors.initials: T
authors.lastname: Morishita
authors.forename: C J
authors.initials: CJ
authors.lastname: Hass
authors.forename: M S
authors.initials: MS
authors.lastname: Okun
mesh_terms: D000368:Aged; D000978:Antiparkinson Agents / Q000627:therapeutic use; D003131:Combined Modality Therapy; D046690:Deep Brain Stimulation / Q000379:methods*; D004567:Electrodes, Implanted / Q000706:statistics & numerical data; D005260:Female; D005500:Follow-Up Studies; D005917:Globus Pallidus / Q000503:physiopathology / Q000601:surgery*; D006801:Humans; D018476:Hypokinesia / Q000188:drug therapy / Q000503:physiopathology / Q000601:surgery; D007980:Levodopa / Q000627:therapeutic use; D008297:Male; D008839:Microelectrodes / Q000706:statistics & numerical data; D008875:Middle Aged; D009068:Movement / Q000187:drug effects; D009127:Muscle Rigidity / Q000188:drug therapy / Q000503:physiopathology / Q000601:surgery; D019635:Neurosurgical Procedures / Q000379:methods; D010300:Parkinson Disease / Q000175:diagnosis / Q000188:drug therapy / Q000503:physiopathology / Q000601:surgery*; D020531:Subthalamic Nucleus / Q000503:physiopathology / Q000601:surgery*; D016896:Treatment Outcome; D014202:Tremor / Q000188:drug therapy / Q000503:physiopathology / Q000601:surgery
chemical_list: D000978:Antiparkinson Agents; D007980:Levodopa