title: Alternating-pulse iontophoresis for targeted cutaneous anesthesia.
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.
authors.affiliation: NeuroMuscular Research Center, St. 4th Floor, 19 Deerfield Street, 02215, Boston, MA, USA.
authors.forename: Peter F
authors.initials: PF
authors.lastname: Meyer
authors.forename: Lars I E
authors.initials: LI
authors.lastname: Oddsson
mesh_terms: D000279:Administration, Cutaneous; D000328:Adult; D000758:Anesthesia; D000779:Anesthetics, Local / Q000008:administration & dosage*; D001993:Bronchodilator Agents / Q000494:pharmacology; D016503:Drug Delivery Systems; D004558:Electric Stimulation; D004837:Epinephrine / Q000008:administration & dosage / Q000494:pharmacology; D005260:Female; D005534:Foot Diseases / Q000628:therapy; D006801:Humans; D007478:Iontophoresis / Q000379:methods*; D008012:Lidocaine / Q000008:administration & dosage*; D008297:Male; D008875:Middle Aged; D012684:Sensory Thresholds / Q000187:drug effects; D012867:Skin / Q000187:drug effects; D013997:Time Factors
chemical_list: D000779:Anesthetics, Local; D001993:Bronchodilator Agents; D008012:Lidocaine; D004837:Epinephrine