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Brain penetration effects of microelectrodes and DBS leads in STN or GPi
  1. J M Mann1,
  2. K D Foote2,
  3. C W Garvan3,
  4. H H Fernandez1,
  5. C E Jacobson IV1,
  6. R L Rodriguez1,
  7. I U Haq1,
  8. M S Siddiqui4,
  9. I A Malaty1,
  10. T Morishita1,
  11. C J Hass5,
  12. M S Okun1,2
  1. 1
    Department of Neurology, University of Florida College of Medicine/Shands Hospital, Movement Disorders Center, McKnight Brain Institute, Gainesville, Florida, USA
  2. 2
    Department of Neurosurgery, University of Florida College of Medicine/Shands Hospital, Movement Disorders Center, McKnight Brain Institute, Gainesville, Florida, USA
  3. 3
    Office of Educational Research, College of Education, University of Florida, Gainesville, Florida, USA
  4. 4
    Department of Neurology, Wake Forest University, Winston Salem, North Carolina, USA
  5. 5
    Department of Applied Physiology and Kinesiology, University of Florida, Movement Disorders Center, Gainesville, Florida, USA
  1. Dr M S Okun, Department of Neurology, McKnight Brain Institute, National Parkinson Foundation, 100 S Newell Dr, Room L3-101, Department of Neurology, Gainesville, FL 32610, USA; okun{at}


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.

Conclusion: 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.

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  • Competing interests: None.

  • Funding: We would like to acknowledge the support of the National Parkinson Foundation Center of Excellence, the McKnight Brain Institute, UF and Shands, and NIH/NINDS K23 NS044997.

  • Ethics approval: Ethics approval was obtained.