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STN-DBS electrode placement accuracy and motor improvement in Parkinson’s disease: systematic review and individual patient meta-analysis
  1. Naomi I Kremer1,
  2. Teus van Laar2,
  3. Stèfan F Lange1,
  4. Sijmen Statius Muller1,
  5. Sacha la Bastide-van Gemert3,
  6. DL Marinus Oterdoom1,
  7. Gea Drost1,2,
  8. J Marc C van Dijk1
  1. 1 Neurosurgery, University of Groningen, University Medical Centre Groningen, Groningen, The Netherlands
  2. 2 Neurology, University of Groningen, University Medical Centre Groningen, Groningen, The Netherlands
  3. 3 Epidemiology, University of Groningen, University Medical Centre Groningen, Groningen, The Netherlands
  1. Correspondence to Dr Gea Drost, Neurosurgery, University Medical Centre Groningen, Hanzeplein 1, 9713 GZ, Groningen, The Netherlands; G.Drost{at}


Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is an effective neurosurgical treatment for Parkinson’s disease. Surgical accuracy is a critical determinant to achieve an adequate DBS effect on motor performance. A two-millimetre surgical accuracy is commonly accepted, but scientific evidence is lacking. A systematic review and meta-analysis of study-level and individual patient data (IPD) was performed by a comprehensive search in MEDLINE, EMBASE and Cochrane Library. Primary outcome measures were (1) radial error between the implanted electrode and target; (2) DBS motor improvement on the Unified Parkinson’s Disease Rating Scale part III (motor examination). On a study level, meta-regression analysis was performed. Also, publication bias was assessed. For IPD meta-analysis, a linear mixed effects model was used. Forty studies (1391 patients) were included, reporting radial errors of 0.45–1.86 mm. Errors within this range did not significantly influence the DBS effect on motor improvement. Additional IPD analysis (206 patients) revealed that a mean radial error of 1.13±0.75 mm did not significantly change the extent of DBS motor improvement. Our meta-analysis showed a huge publication bias on accuracy data in DBS. Therefore, the current literature does not provide an unequivocal upper threshold for acceptable accuracy of STN-DBS surgery. Based on the current literature, DBS-electrodes placed within a 2 mm range of the intended target do not have to be repositioned to enhance motor improvement after STN-DBS for Parkinson’s disease. However, an indisputable upper cut-off value for surgical accuracy remains to be established. PROSPERO registration number is CRD42018089539.


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  • Contributors NIK, TvL, SSM, GD and JMCvD conceptualised the study. NIK, SFL, SSM and SlB-vG conducted the study, including data collection and data analysis. NIK prepared the initial manuscript draft with important intellectual input from TvL, SlBvG, DLMO, GD and JMCvD. All authors approved the final version of the manuscript.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.