Pain hypersensitivity in congenital blindness is associated with faster central processing of C-fibre input
(2016) European Journal of Pain — Vol. 20, n° 9, p. 1519-1529 (2016)
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- (en) Background: We have recently shown that visual deprivation from birth exacerbates responses to painful thermal stimuli. However, the mechanisms underlying pain hypersensitivity in congenital blindness are unclear. Methods: To study the contribution of Ad- and C-fibres in pain perception, we measured thresholds and response times to selective C- and Ad-fibre activation in congenitally blind, late blind and normally sighted participants. Ultrafast constant-temperature heat pulses were delivered to the hand with a CO2 laser using an interleaved adaptive double staircase procedure. Participants were instructed to respond as quickly as possible when detecting a laser-induced sensation. We used a 650 ms cut-off criterion to distinguish fast Ad- from slow C-fibre–mediated sensations. Results: Congenitally blind participants showed significantly faster reaction times to C- but not to Ad-fibre–mediated sensations. In contrast, thresholds for Ad- and C-fibre stimulation did not differ between groups. Late blind individuals did not differ from sighted controls in any aspect. A follow-up experiment using only suprathreshold stimuli for Ad- and C- fibre activation confirmed these findings and further showed that congenitally blind individuals detected significantly more C-fibre– mediated stimuli than sighted controls. A decomposition of the reaction times analysis indicated that the faster response times in the congenitally blind are due to more efficient central processing of C-fibre–mediated sensations. Conclusion: The increased sensitivity to painful thermal stimulation in congenital blindness may be due to more efficient central processing of C-fibre–mediated input, which may help to avoid impending dangerous encounters with stimuli that threaten the bodily integrity. WHAT DOES THIS STUDY ADD?: Hypersensitivity to heat pain in congenital blindness is associated with faster responses to C-fibre activation, likely caused by more efficient central processing of C-fibre-mediated input.
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Slimani, H., Plaghki, L., Ptito, M., & Kupers, R. (2016). Pain hypersensitivity in congenital blindness is associated with faster central processing of C-fibre input. European Journal of Pain, 20(9), 1519-1529. https://doi.org/10.1002/ejp.876 (Original work published 2016)