High spontaneous activity of C-nociceptors in painful polyneuropathy
2012 (English)In: Pain, ISSN 0304-3959, E-ISSN 1872-6623, Vol. 153, no 10, 2040-2047 p.Article in journal (Refereed) Published
Polyneuropathy can be linked to chronic pain but also to reduced pain sensitivity. We investigated peripheral C-nociceptors in painful and painless polyneuropathy patients to identify pain-specific changes. Eleven polyneuropathy patients with persistent spontaneous pain and 8 polyneuropathy patients without spontaneous pain were investigated by routine clinical methods. For a specific examination of nociceptor function, action potentials from single C-fibres including 214 C-nociceptors were recorded by microneurography. Patients with and without pain were distinguished by the occurrence of spontaneous activity and mechanical sensitization in C-nociceptors. The mean percentage of C-nociceptors being spontaneously active or mechanically sensitized was significantly higher in patients with pain (mean 40.5% and 14.6%, respectively, P = .02). The difference was mainly due to more spontaneously active mechanoinsensitive C-nociceptors (operationally defined by their mechanical insensitivity and their axonal characteristics) in the pain patients (19 of 56 vs 6 of 43; P = .02). The percentage of sensitized mechanoinsensitive C-nociceptors correlated to the percentage of spontaneously active mechanoinsensitive C-nociceptors (Kendall's tau = .55, P = .004). Moreover, spontaneous activity of mechanoinsensitive C-nociceptors correlated to less pronounced activity-dependent slowing of conduction (Kendall's tau = -.48, P = .009), suggesting that axons were included in the sensitization process. Hyperexcitability in mechanoinsensitive C-nociceptors was significantly higher in patients with polyneuropathy and pain compared to patients with polyneuropathy without pain, while the difference was much less prominent in mechanosensitive (polymodal) C-nociceptors. This hyperexcitability may be a major underlying mechanism for the pain experienced by patients with painful peripheral neuropathy.
Place, publisher, year, edition, pages
2012. Vol. 153, no 10, 2040-2047 p.
Microneurography, Neuropathic pain, Nociceptors, Sensitization
Medical and Health Sciences
IdentifiersURN: urn:nbn:se:uu:diva-183568DOI: 10.1016/j.pain.2012.05.017ISI: 000309055500011OAI: oai:DiVA.org:uu-183568DiVA: diva2:574702