Reaction to topical capsaicin in spinal cord injury patients with and without central pain.

Full Abstract

Central neuropathic pain is a debilitating and frequent complication to spinal cord injury (SCI). Excitatory input from hyperexcitable cells around the injured grey matter zone is suggested to play a role for central neuropathic pain felt below the level of a spinal cord injury. Direct evidence for this hypothesis is difficult to obtain. Capsaicin, activating TRPV1 receptors on small sensory afferents, induces enhanced cellular activity in dorsal horn neurons and produces a central mediated area of secondary hyperalgesia. We hypothesized that sensory stimuli and capsaicin applied at and just above the level of a spinal cord injury which already is hyperexcitable, would cause enhanced responses in patients with central pain at the level of injury compared to patients without neuropathic pain and healthy controls. Touch, punctuate stimuli, cold stimuli and topical capsaicin was applied above, at, and below injury level in 10 SCI patients with central pain below a thoracic injury, in 10 SCI patients with a thoracic injury but without neuropathic pain, and in corresponding areas in 10 healthy control subjects. The study found increased responses to touch at injury level compared to controls (p=0.033) and repetitive punctuate stimuli above and at injury level compared to controls and pain-free SCI patients (p<0.04) but not an increased response to capsaicin in patients with central pain. These results suggest that SCI patients with below-level pain have increased responses to some but not all sensory input at the level of injury.

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Author information

Author/s: Finnerup, Nanna B (NB); Pedersen, Louise H (LH); Terkelsen, Astrid J (AJ); Johannesen, Inger L (IL); Jensen, Troels S (TS);

Affiliation: Danish Pain Research Center and Department of Neurology, Aarhus University Hospital, Norrebrogade 44, DK-8000 Aarhus, Denmark. finnerup(-atsign-)ki.au.dk <finnerup(-atsign-)ki.au.dk>

Journal and publication information

Publication Type: Journal Article; Randomized Controlled Trial; Research Support, Non-U.S. Gov't

Journal: Experimental neurology (Exp Neurol), published in United States. (Language: eng)

Reference: 2007-May; vol 205 (issue 1) : pp 190-200

Dates: Created 2007/04/30; Completed 2007/06/18; Revised 2008/11/21;

PMID: 17346705, status: MEDLINE (last retrieval date: 12/26/2008)

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

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MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Administration, Topical
Adult
Aged
Analgesics, Non-Narcotic - administration & dosage; pharmacology
Autonomic Nervous System - physiopathology
Capsaicin - administration & dosage; pharmacology
Cold Temperature
Female

Humans
Hyperalgesia - chemically induced
Male
Middle Aged
Neuralgia - etiology; physiopathology
Physical Stimulation
Spinal Cord Injuries - complications
Thoracic Vertebrae

Associated Chemicals: Analgesics, Non-Narcotic (0) ; Capsaicin (404-86-4)

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