Spatial summation of heat pain: a reassessment

Abstract

Heat pain threshold is commonly considered to be an 'absolute' value, which is not dependent on the area stimulated. In contrast, suprathreshold heat pain sensation has been shown to be highly dependent on the area stimulated, with considerable spatial summation demonstrated both within and between dermatomes. The present study sought to reevaluate two major issues: (a) Whether nociceptive thresholds are, indeed, independent of stimulation area. (b) Whether the spatial summation of suprathreshold heat pain sensation is independent of threshold changes. Using noxious heat we evaluated nociceptive thresholds and perceived pain intensity for contact areas of 0.25, 2.25, 6.25 and 15.36 cm2. Our results show that considerable spatial summation of heat pain thresholds is obtained and an apparent spatial summation of perceived intensity can also be observed. However, these apparent changes in perceived pain intensity can be accounted for completely by the changes in noxious heat thresholds. Furthermore, when using a stimulus configuration in which stimulation area was increased without changing nociceptive threshold, no spatial summation of perceived pain intensity was seen. Our results suggest that the spatial summation of perceived heat pain intensity can be attributed to reduced heat pain threshold. Furthermore, our findings stress the importance of determining pain thresholds in studies examining the psychophysics of suprathreshold noxious stimuli.

Spatial summation of mechanically evoked muscle pain and painful aftersensations in normal subjects and fibromyalgia patients

“…Spatial summation of pain (SSP) relies on central pain mechanisms (Coghill et al, 1993c;Price, 1999) and is important for pain-coding (Price et al, 1989;Douglass et al, 1992;Defrin and Urca, 1996). Whereas most research on SSP utilized thermal stimuli, the spatial summation of Corresponding author: Roland Staud, M.D., Department of Medicine, University of Florida College of Medicine, Gainesville, FL 32610-0221, Telephone: (352) Fax: (352) 392-8483, Email: staudr@ufl.edu Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication.…”

Validation of a Brazilian quantitative sensory testing (QST) device for the diagnosis of small fiber neuropathies

“…First we do not use thermodes with different ramp rates in different body sites. In the same way we only used a large thermode and this could not be sensitive enough to detect mild neuropathy because of spatial summation 29 . However, the ramp rate and body location used in this study was mainly employed by others 2 and large thermode allows sensation to be more easily discriminated in normal skin 30 and provide more reproducible thresholds 26 .…”

A multi-scale view of skin thermal pain: from nociception to pain sensation

“…Early studies reported little or no SS for painful cold and heat stimuli (Wolf & Hardy 1941;Hardy et al 1952;Green & Hardy 1958;Hardy et al 1959;Murgatroyd 1964;Kenshalo et al 1967;Stevens & Marks 1971;Stevens et al 1974), while the important role of SS for pain coding has been demonstrated in both psychophysical (Hardy et al 1940;Skouby 1951;Green & Hardy 1958;Chery-Croze & Duclaux 1980;Kojo & Pertovaara 1987;Price et al 1989;Douglass et al 1992;Coghill et al 1993a,b;Lautenbacher et al 1995;Defrin & Urca 1996;Nielsen & Arendt-Nielsen 1997;Defrin et al 2002;Marchand & Arsenault 2002) and clinical studies (Atchison et al 1991;Stohler & Kowalski 1999).…”

“…Studies show that increasing the area of noxious stimulation results in a decrease in pain threshold (Skouby 1951;Machet-Pietropaoli & Chery-Croze 1979;Kojo & Pertovaara 1987;Defrin & Urca 1996;Greenspan et al 1997;Nielsen & Arendt-Nielsen 1997;Lautenbacher et al 2001;Defrin et al 2003) or an increase in perceived pain intensity (Price et al 1989;Douglass et al 1992;Defrin & Urca 1996;Marchand & Arsenault 2002). In these studies, SS was examined by applying either a single stimulus with an increasing area (Machet-Pietropaoli & Chery -Croze 1979;Kojo & Pertovaara 1987;Defrin & Urca 1996;Defrin et al 2003), or an increasing number of stimuli (one to three) of a fixed size (Price et al 1989;Douglass et al 1992;Nielsen & Arendt-Nielsen 1997).…”

“…In these studies, SS was examined by applying either a single stimulus with an increasing area (Machet-Pietropaoli & Chery -Croze 1979;Kojo & Pertovaara 1987;Defrin & Urca 1996;Defrin et al 2003), or an increasing number of stimuli (one to three) of a fixed size (Price et al 1989;Douglass et al 1992;Nielsen & Arendt-Nielsen 1997).…”