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Correspondence  |   December 2000
Capsaicin-induced Pain and Tourniquet Constriction
Author Affiliations & Notes
  • Holger Holthusen, M., D.
    *
  • *Heinrich-Heine-University, Duesseldorf, Germany. Holthusen@med.uni-duesseldorf.de
Article Information
Correspondence
Correspondence   |   December 2000
Capsaicin-induced Pain and Tourniquet Constriction
Anesthesiology 12 2000, Vol.93, 1551. doi:
Anesthesiology 12 2000, Vol.93, 1551. doi:
To the Editor:—
Recently, Byas-Smith et al.  1 reported that tourniquet constriction expands and exacerbates pain during intradermal injection of capsaicin in humans. The underlying mechanism was unclear. It is suggested herein that excitation of paravascular nociceptors is involved in expansion of pain.
Capsaicin has been shown to evoke pain from skin, 2 muscle, 3 and paravascular tissue, but not from veins. 4 In the latter study, one of the authors had a disconcerting experience. Capsaicin was perfused through a vascularly isolated hand vein segment to test capsaicin for its property to excite vascular nociceptors. It definitively did not, but strong pain occurred distant from the perfusion site and spread to the entire forearm. In fear of spreading pain to the entire body, a tourniquet was installed quickly to the upper arm, which, however, increased pain further, up to an unbearable intensity. It was determined that capsaicin solution had drained via  a previously unnoticed side branch of the isolated vein segment into the venous system. From there, capsaicin apparently had gained access to the paravascular space (capsaicin does not evoke pain in veins). The substantial increase in capsaicin-induced pain during tourniquet inflation is unknown. A recruitment of myelinated fibers during ischemia has been discussed;5 however, fostering by venous congestion of transendothelial crossing of capsaicin to the paravascular tissue also may play a role. Thus, the spread of capsaicin from the site of application to the paravascular space may have contributed, at least in part, to the observations made by Byas-Smith et al.  1 
References
Byas-Smith MG, Bennett GJ, Gracely RH, Max MB, Robinovitz E, Dubner R: Tourniquet constriction exacerbates hyperalgesia-related pain induced by intradermal capsaicin injection. A nesthesiology 1999; 91: 617–25Byas-Smith, MG Bennett, GJ Gracely, RH Max, MB Robinovitz, E Dubner, R
Simone DA, Baumann TK, LaMotte RH: Dose-dependent pain and mechanical hyperalgesia in humans after intradermal injection of capsaicin. Pain 1989; 67: 99–107Simone, DA Baumann, TK LaMotte, RH
Marchettini P, Simone DA, Caputi G, Ochoa JL: Pain from excitation of identified muscle nociceptors in humans. Brain Res 1996; 740: 109–16Marchettini, P Simone, DA Caputi, G Ochoa, JL
Arndt JO, Kindgen-Milles D, Klement W: Capsaicin did not evoke pain from human hand vein segments but did so after injections into the paravascular tissue. J Physiol 1993; 463: 491–9Arndt, JO Kindgen-Milles, D Klement, W
Handwerker HO, Ringkamp M, Schmelz M: Neurophysiological Basis for Chemogenic Pain and Itch, Touch, Temperature and Pain in Health and Disease: Mechanisms and Assessments, vol 3, Progress in Pain Research and Management. Edited by Boivie J, Hansson P, Lindblom U. Seattle, IASP Press, 1994, pp 195–206