title: Assessment of the effects of unilateral electrode dysfunction in patients with Parkinson disease undergoing bilateral subthalamic nucleus deep brain stimulation.
abstract: BACKGROUND
  Bilateral subthalamic nucleus deep brain stimulation (STN-DBS) is the gold standard surgical treatment for medically intractable Parkinson disease, and unilateral electrodes are reported to have beneficial effects. However, assessment of patients after electrode failure needs to be established.
  
  
  OBJECTIVE
  To assess the effects of the remaining unilateral electrode in Parkinson disease after bilateral STN-DBS.
  
  
  METHODS
  Between May 2000 and March 2009, 8 patients had unilateral STN-DBS after bilateral STN-DBS. We assessed clinical outcome by comparing the Unified Parkinson Disease Rating Scale (UPDRS) motor score, activities of daily living, levodopa-equivalent daily dosages, and quality of life according to the Short-Form 36 Health Survey between patients with unilateral and bilateral electrodes.
  
  
  RESULTS
  Although ipsilateral and axial UPDRS motor scores were compromised, UPDRS motor scores contralateral to the side of the implant remained unaltered after removal of 1 electrode. Although physical aspects of quality of life declined significantly with a unilateral electrode, pain and social functioning were not significantly affected. No significant changes in activities of daily living, Hoehn and Yahr stage, or levodopa-equivalent daily dosage were observed after removal of 1 electrode.
  
  
  CONCLUSIONS
  The UPDRS motor score with unilateral STN-DBS was compromised relative to bilateral STN-DBS for ipsilateral motor and axial symptoms. When 1 electrode is compromised, revision of that electrode will eventually be required, but not immediately in all patients. If a patient tolerates loss of 1 electrode according to motor score while maintaining activities of daily living and quality of life, it is possible to wait and observe the situation instead of immediately revising the electrode.
authors.affiliation: Department of Neurosurgery, Bundang CHA Hospital, CHA University School of Medicine, Seongnam, Korea.
authors.forename: Young Seok
authors.initials: YS
authors.lastname: Park
authors.forename: Joo Pyung
authors.initials: JP
authors.lastname: Kim
authors.forename: Won Seok
authors.initials: WS
authors.lastname: Chang
authors.forename: Phil Hyu
authors.initials: PH
authors.lastname: Lee
authors.forename: Young Ho
authors.initials: YH
authors.lastname: Sohn
authors.forename: Jin Woo
authors.initials: JW
authors.lastname: Chang
mesh_terms: D000328:Adult; D000368:Aged; D046690:Deep Brain Stimulation / Q000009:adverse effects* / Q000295:instrumentation* / Q000379:methods; D004567:Electrodes, Implanted / Q000009:adverse effects*; D004868:Equipment Failure; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000503:physiopathology / Q000628:therapy*; D011183:Postoperative Complications / Q000453:epidemiology* / Q000503:physiopathology; D012189:Retrospective Studies; D020531:Subthalamic Nucleus / Q000502:physiology* / Q000503:physiopathology