title: Finite-difference modeling of the anisotropic electric fields generated by stimulating needles used for catheter placement.
abstract: The use of peripheral nerve blocks to control pain is an increasing practice. Many techniques include the use of stimulating needles to locate the nerve of interest. Though success rates are generally high, difficulties still exist. In certain deeper nerve blocks, two needles of different geometries are used in the procedure. A smaller needle first locates a nerve bundle, and then is withdrawn in favor of a second, larger needle used for injection. The distinct geometries of these needles are shown to generate different electric field distributions, and these differences may be responsible for failures of the second needle to elicit nerve stimulation when placed in the same location as the first. A 3-D finite-difference method has been employed to numerically calculate the electric field distributions for a commercial set of stimulating needles.
authors.affiliation: Department of Physics, University of Florida, Gainesville, FL 32611-8440, USA. lorentztrans@yahoo.com
authors.forename: James C
authors.initials: JC
authors.lastname: Davis
authors.forename: Norman E
authors.initials: NE
authors.lastname: Anderson
authors.forename: Jason G
authors.initials: JG
authors.lastname: Ramirez
authors.forename: F Kayser
authors.initials: FK
authors.lastname: Enneking
authors.forename: Mark W
authors.initials: MW
authors.lastname: Meisel
mesh_terms: D016880:Anisotropy; D002404:Catheterization / Q000379:methods*; D003198:Computer Simulation; D004558:Electric Stimulation / Q000295:instrumentation* / Q000379:methods*; D004567:Electrodes, Implanted; D004574:Electromagnetic Fields; D020342:Finite Element Analysis; D006801:Humans; D007267:Injections / Q000379:methods; D008959:Models, Neurological; D009339:Needles; D009407:Nerve Block / Q000379:methods*; D010525:Peripheral Nerves / Q000502:physiology*