title: Cognitive outcome 5 years after bilateral chronic stimulation of subthalamic nucleus in patients with Parkinson's disease.
abstract: OBJECTIVE
  To assess the long-term cognitive and behavioural outcome after bilateral deep brain stimulation (DBS) of the subthalamic nucleus (STN) in patients affected by Parkinson's disease, with a 5-year follow-up after surgery.
  
  
  METHODS
  11 patients with Parkinson's disease treated by bilateral DBS of STN underwent cognitive and behavioural assessments before implantation, and 1 and 5 years after surgery. Postoperative cognitive assessments were carried out with stimulators turned on.
  
  
  RESULTS
  A year after surgery, there was a marginally significant decline on a letter verbal fluency task (p = 0.045) and a significant improvement on Mini-Mental State Examination (p = 0.009). 5 years after surgery, a significant decline was observed on a letter verbal fluency task (p = 0.007) and an abstract reasoning task (p = 0.009), namely Raven's Progressive Matrices 1947. No significant postoperative change was observed on other cognitive variables. No patient developed dementia 5 years after surgery. A few days after the implantation, two patients developed transient manic symptoms with hypersexuality and one patient developed persistent apathy.
  
  
  CONCLUSIONS
  The decline of verbal fluency observed 5 years after implantation for DBS in STN did not have a clinically meaningful effect on daily living activities in our patients with Parkinson's disease. As no patient developed global cognitive deterioration in our sample, these findings suggest that DBS of STN is associated with a low cognitive and behavioural morbidity over a 5-year follow-up, when selection criteria for neurosurgery are strict.
authors.affiliation: Istituto di Neurologia, Università Cattolica del Sacro Cuore-Largo Gemelli, 8, I-00168 Rome, Italy.
authors.forename: M F
authors.initials: MF
authors.lastname: Contarino
authors.forename: A
authors.initials: A
authors.lastname: Daniele
authors.forename: A H
authors.initials: AH
authors.lastname: Sibilia
authors.forename: L M A
authors.initials: LM
authors.lastname: Romito
authors.forename: A R
authors.initials: AR
authors.lastname: Bentivoglio
authors.forename: G
authors.initials: G
authors.lastname: Gainotti
authors.forename: A
authors.initials: A
authors.lastname: Albanese
mesh_terms: D000368:Aged; D001714:Bipolar Disorder / Q000209:etiology; D003072:Cognition Disorders; D046690:Deep Brain Stimulation / Q000009:adverse effects; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008609:Mental Status Schedule; D008875:Middle Aged; D019964:Mood Disorders / Q000209:etiology; D010300:Parkinson Disease / Q000628:therapy*; D018579:Patient Selection; D020531:Subthalamic Nucleus / Q000502:physiology*