title: The mechanism and effect of chronic electrical stimulation of the globus pallidus for treatment of Parkinson disease.
abstract: OBJECTIVE
  Although chronic electrical stimulation of the globus pallidus (GP) has been shown to ameliorate motor disabilities in Parkinson disease (PD), the underlying mechanism remains to be clarified. In this study the authors explored the mechanism for the effects of deep brain stimulation of the GP by investigating the changes in neurotransmitter levels in the cerebrospinal fluid (CSF) during the stimulation.
  
  
  METHODS
  Thirty patients received chronic electrical stimulation of the GP internus (GPi). Clinical effects were assessed using the Unified PD Rating Scale (UPDRS) and the Hoehn and Yahr Staging Scale at 1 week before surgery and at 6 and 12 months after surgery. One day after surgery, CSF samples were collected through a ventricular tube before and 1 hour after GPi stimulation. The concentration of neurotransmitters such as gamma-aminobutyric acid (GABA), noradrenaline, dopamine, and homovanillic acid (HVA) in the CSF was measured using high-performance liquid chromatography. The treatment was effective for tremors, rigidity, and drug-induced dyskinesia. The concentration of GABA in the CSF increased significantly during stimulation, although there were no significant changes in the level of noradrenaline, dopamine, and HVA. A comparison between an increased rate of GABA concentration and a lower UPDRS score 6 months postimplantation revealed that the increase in the GABA level correlated with the stimulation-induced clinical effects.
  
  
  CONCLUSIONS
  Stimulation of the GPi substantially benefits patients with PD. The underlying mechanism of the treatment may involve activation of GABAergic afferents in the GP.
authors.affiliation: Department of Neurological Surgery, Wakayama Medical University, Wakayama, Japan. ogura@wakayama-med.ac.jp
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Ogura
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Nakao
authors.forename: Ekini
authors.initials: E
authors.lastname: Nakai
authors.forename: Yuji
authors.initials: Y
authors.lastname: Uematsu
authors.forename: Toru
authors.initials: T
authors.lastname: Itakura
mesh_terms: D000328:Adult; D000368:Aged; D004599:Electric Stimulation Therapy / Q000379:methods*; D005260:Female; D005917:Globus Pallidus / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D018377:Neurotransmitter Agents / Q000134:cerebrospinal fluid; D010300:Parkinson Disease / Q000628:therapy*; D005680:gamma-Aminobutyric Acid / Q000134:cerebrospinal fluid*
chemical_list: D018377:Neurotransmitter Agents; D005680:gamma-Aminobutyric Acid