Alternating-pulse iontophoresis for targeted cutaneous anesthesia

J Neurosci Methods. 2003 May 30;125(1-2):209-14. doi: 10.1016/s0165-0270(03)00054-2.

Abstract

In studies of sensory contributions to motor control, it may be advantageous to temporarily reduce the sensitivity of specific sensory systems. This article details a method for non-invasively inducing cutaneous anesthesia, leaving proprioceptive and motor functions intact. This method, called alternating-pulse iontophoresis, differs from conventional direct-current (DC) iontophoretic drug delivery in that adjacent drug delivery electrodes are stimulated out-of-phase. The total current delivered at any instant is then less than that produced during a comparable DC application, while the uniformity of drug delivery is expected to improve. Effective delivery of local anesthetics to the cutaneous foot soles by alternating-pulse iontophoresis was demonstrated using cutaneous pressure sensory threshold levels (STL's) assessed with Semmes-Weinstein monofilaments (arbitrary units of perceived force, or a.u.). Thirteen of 16 healthy subjects achieved a level of anesthesia greater than or equal to that normally associated with clinical peripheral sensory neuropathy. Average STL's measured prior to the anesthesia procedure were 4.00 a.u. ( approximately 10 mN). Immediately following the procedure, STL's were elevated to an average of 5.40 a.u. ( approximately 246 mN) and averaged 4.97 a.u. ( approximately 92 mN) after 50 min of standing. A number of research and clinical applications for this technique are suggested.

Publication types

  • Clinical Trial
  • Comparative Study
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Administration, Cutaneous
  • Adult
  • Anesthesia
  • Anesthetics, Local / administration & dosage*
  • Bronchodilator Agents / pharmacology
  • Drug Delivery Systems*
  • Electric Stimulation
  • Epinephrine / administration & dosage
  • Epinephrine / pharmacology
  • Female
  • Foot Diseases / therapy
  • Humans
  • Iontophoresis / methods*
  • Lidocaine / administration & dosage*
  • Male
  • Middle Aged
  • Sensory Thresholds / drug effects
  • Skin / drug effects
  • Time Factors

Substances

  • Anesthetics, Local
  • Bronchodilator Agents
  • Lidocaine
  • Epinephrine