title: Low-frequency Subthalamic Stimulation in Parkinson's Disease: Long-term Outcome and Predictors.
abstract: Parkinson's disease patients undergoing subthalamic nucleus deep brain stimulation (STN DBS) at standard frequency (>100 Hz) often develop gait impairment, postural instability and speech difficulties. Low frequency stimulation (<100 Hz, LFS) can improve such axial symptoms, but there are concerns that improvement may be transient.
  
  
  
  To identify long-term outcome and predictors of low-frequency subthalamic stimulation in Parkinson's disease.
  
  
  
  Through a chart review we identified 85 out of 324 STN DBS patients who received a trial of LFS and describe their characteristics and outcome predictors.
  
  
  
  Patients were switched to LFS (<100 Hz) 3.8 ± 3.3 years after surgery. Most patients (64%) attained a subjective improvement of gait, speech or balance for 2.0 ± 1.9 years. Motor scores improved within the first year after the stimulation change and showed a slower progression over time when compared to patients switched back to high frequency stimulation. UPDRS III axial score on medication before surgery and the y-axis coordinate of the active contact were independent predictors of LFS retention.
  
  
  
  This report provides evidence that the use of LFS yields an enduring benefit in a considerable percentage of patients who develop axial motor symptoms during conventional stimulation.
authors.affiliation: Department of Neuroscience "Rita Levi Montalcini", University of Torino, Torino, Italy.
authors.forename: Maurizio
authors.initials: M
authors.lastname: Zibetti
authors.affiliation: Service de Neurologie, CHU Grenoble, Joseph Fourier University, INSERM U836, Grenoble, France.
authors.forename: Elena
authors.initials: E
authors.lastname: Moro
authors.affiliation: Division of Neurosurgery, Toronto Western Hospital - UHN, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Vibhor
authors.initials: V
authors.lastname: Krishna
authors.affiliation: Division of Neurosurgery, Toronto Western Hospital - UHN, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Francesco
authors.initials: F
authors.lastname: Sammartino
authors.affiliation: Morton and Gloria Shulman Movement Disorders Clinic and the Edmond J. Safra Program in Parkinson's Disease, Toronto Western Hospital - UHN, Division of Neurology, University of Toronto, Toronto, Ontario, Canada; Centre for Neurodegenerative Diseases (CEMAND), Department of Medicine and Surgery, University of Salerno, Salerno, Italy.
authors.forename: Marina
authors.initials: M
authors.lastname: Picillo
authors.affiliation: Morton and Gloria Shulman Movement Disorders Clinic and the Edmond J. Safra Program in Parkinson's Disease, Toronto Western Hospital - UHN, Division of Neurology, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Renato P
authors.initials: RP
authors.lastname: Munhoz
authors.affiliation: Division of Neurosurgery, Toronto Western Hospital - UHN, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Andres M
authors.initials: AM
authors.lastname: Lozano
authors.affiliation: Morton and Gloria Shulman Movement Disorders Clinic and the Edmond J. Safra Program in Parkinson's Disease, Toronto Western Hospital - UHN, Division of Neurology, University of Toronto, Toronto, Ontario, Canada; Krembil Research Institute, Toronto, Ontario, Canada. Electronic address: alfonso.fasano@uhn.ca.
authors.forename: Alfonso
authors.initials: A
authors.lastname: Fasano
mesh_terms: D000368:Aged; D046690:Deep Brain Stimulation / Q000009:adverse effects / Q000379:methods*; D005260:Female; D005684:Gait / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000503:physiopathology / Q000628:therapy*; D004856:Postural Balance / Q000502:physiology; D013060:Speech / Q000502:physiology*; D020531:Subthalamic Nucleus / Q000503:physiopathology*; D016896:Treatment Outcome
keywords: Deep brain stimulation; Low-frequency stimulation; Parkinson's disease; Subthalamic nucleus; Surgery