title: Deep brain stimulation electrodes used for staged lesion within the basal ganglia: experimental studies for parameter validation. Laboratory investigation.
abstract: OBJECTIVE
  Deep brain stimulation (DBS) has been shown to be an effective treatment for various types of movement disorders. High-frequency stimulation is applied to specific brain targets through an implanted quadripolar lead connected to a pulse generator. These leads can be used for creating lesions in the brain. The experimental study reported here was designed to examine the electrical parameters that could be used to create reproducible therapeutic lesions in the brain.
  
  
  METHODS
  Egg whites were used to measure the relationship between the electrical parameters (current and voltage) applied through the DBS electrode and the size of coagulum. The authors measured current spread from the electrode contact used for lesioning to the adjacent contact. Similar studies were performed in the pallidum or the thalamus of human cadavers. Modeling of the lesion size was performed with simulation of current density and temperature. The ultrastructure of the electrodes after lesioning was verified by electron microscopy.
  
  
  RESULTS
  Coagulation size increased with time but reached a plateau after 30 seconds. For a given set of electrical parameters, reproducibility of the size of lesions was high. Using constant voltage, lesions were larger in egg whites than in cadaveric brains with a mean length of 5 +/- 0.6 mm in egg whites at 40 V, 125 mA, impedance 233 Omega; and 4.0 +/- 0.8 mm in cadavers at 40 V, 38 mA, impedance 1333 Omega. Computer modeling indicated negligible current flow to the adjacent, unused electrodes. The electrodes showed no structural alterations on scanning electron microscopy after more than 200 lesions.
  
  
  CONCLUSIONS
  Results of this study demonstrate that DBS electrodes can be used to generate lesions reproducibly in the brain. The choice of lesioning parameters must take into account differences in impedance between the test medium (egg whites) and the human brain parenchyma.
authors.affiliation: Department of Neurosurgery, Centre Hospitalier Universitaire de Nantes, France. sylvie.raoul@chu-nantes.fr
authors.forename: Sylvie
authors.initials: S
authors.lastname: Raoul
authors.forename: Dominique
authors.initials: D
authors.lastname: Leduc
authors.forename: Thomas
authors.initials: T
authors.lastname: Vegas
authors.forename: Paul
authors.initials: P
authors.lastname: Sauleau
authors.forename: Andres M
authors.initials: AM
authors.lastname: Lozano
authors.forename: Marc
authors.initials: M
authors.lastname: Vérin
authors.forename: Philippe
authors.initials: P
authors.lastname: Damier
authors.forename: Youenn
authors.initials: Y
authors.lastname: Lajat
mesh_terms: D001479:Basal Ganglia; D002102:Cadaver; D046690:Deep Brain Stimulation / Q000295:instrumentation*; D004529:Egg White; D004564:Electrocoagulation; D004567:Electrodes, Implanted; D006801:Humans