title: Skin biopsy and quantitative sensory testing do not predict response to lidocaine patch in painful neuropathies.
abstract: Predictors of response to neuropathic pain treatment in patients with painful distal sensory neuropathies are lacking. The 5% lidocaine patch is believed to exert its effects on neuropathic pain via a local stabilizing effect on cutaneous sensory afferents. As such, it provides a model to assess whether the status of epidermal innervation as determined by skin biopsy or quantitative sensory testing (QST) of small- and large-diameter sensory afferents might serve as predictors of response to topical, locally active treatment. In this study we assessed associations between epidermal nerve fiber (ENF) densities, sensory nerve conduction studies (NCS), QST, and response to a 5% lidocaine patch in patients with painful distal sensory neuropathies. We observed no association between distal leg epidermal and subepidermal innervation and response to the lidocaine patch. Several patients with complete loss of distal leg ENF showed a response to the lidocaine patch. Similarly we observed no consistent association between treatment response and QST for vibration, cooling, warm, heat-pain, and cold-pain thresholds, or distal sensory NCS. Thus, distal-leg skin biopsy, QST, and sensory NCS cannot be used to identify patients with painful polyneuropathy likely to respond to a lidocaine patch in clinical practice. Further studies are required to clarify precisely the mechanism and site of action of the lidocaine patch in patients with peripheral neuropathic pain.
authors.affiliation: Department of Neurology, University of Rochester Medical Center, 601 Elmwood Ave, Box 673, Rochester, NY 14642, USA.
authors.forename: David N
authors.initials: DN
authors.lastname: Herrmann
authors.forename: Valerie
authors.initials: V
authors.lastname: Pannoni
authors.forename: Richard L
authors.initials: RL
authors.lastname: Barbano
authors.forename: Janet
authors.initials: J
authors.lastname: Pennella-Vaughan
authors.forename: Robert H
authors.initials: RH
authors.lastname: Dworkin
mesh_terms: D000368:Aged; D000779:Anesthetics, Local / Q000008:administration & dosage / Q000627:therapeutic use*; D001706:Biopsy; D015331:Cohort Studies; D004817:Epidermis / Q000294:innervation / Q000473:pathology; D005260:Female; D006801:Humans; D007866:Leg / Q000294:innervation; D008012:Lidocaine / Q000008:administration & dosage / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D009431:Neural Conduction / Q000187:drug effects; D009437:Neuralgia / Q000188:drug therapy* / Q000209:etiology; D010147:Pain Measurement / Q000379:methods*; D011115:Polyneuropathies / Q000150:complications / Q000188:drug therapy* / Q000503:physiopathology; D011379:Prognosis; D012867:Skin / Q000294:innervation / Q000473:pathology*; D016896:Treatment Outcome
chemical_list: D000779:Anesthetics, Local; D008012:Lidocaine