Viser hvor stor andel av c-fibrene som har spontan aktivitet ved nevropati, og hvor stor andel av de igjen som har dobbelt eller trippelt avfyring. Nevner at spontane avfyringer skjer i en viss andel av de uten multippel avfyring også. Og at selv uten smerte er det en liten andel av fibrene som fyrer av dobbelt. De konkluderer med at det er usikkert hvordan slik spontan aktivitetet egentlig er relatert til kliniske smertenivåer.
Multiple firing of C nociceptors upon a single electrical stimulus has been suggested to be a possible mechanism contributing to neuropathic pain. Because this phenomenon maybe based on a unidirectional conduction block, it might also be related to neuropathic changes without a direct link to pain.
In 11 of 105 nociceptors, double spiking was found, with 1 fibre even showing triple spikes on electrical stimulation.
There was a significant association between spontaneous activity and multiple spiking in C nociceptors, with spontaneous activity being present in 9 of 11 fibres with multiple spiking, but only in 21 of 94 nociceptors without multiple spiking (P<.005, Fisher exact test).
Among the 75 C nociceptors without spontaneous activity, only 2 nociceptors showed multiple spiking.
In 8 neuropathy patients without pain, double spiking was found only in 4 of 90 nociceptors
Multiple spiking of nociceptors coincides with spontaneous activity in nociceptors of painful neuropathy patients. We therefore conclude that rather than being a generic sign of neuropathy, multiple spiking is linked to axonal hyperexcitability and spontaneous activity of nociceptors. It is still unclear whether it also is mechanistically related to the clinical pain level.