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Background: We aimed at evaluating the differential involvement of large myelinated Aβ‐, small myelinated Aδ‐, and unmyelinated C‐fibers in patients with diabetic polyneuropathy and how they contribute to neuropathic pain. Methods: We collected clinical and diagnostic test variables in 133 consecutive patients with diabetic polyneuropathy. All patients underwent Aβ‐fiber mediated nerve conduction study, Aδ‐fiber mediated laser‐evoked potentials and skin biopsy mainly assessing unmyelinated C‐fibers. Results: Pure large‐fiber and small‐fiber polyneuropathy were relatively uncommon; conversely mixed‐fiber polyneuropathy was the most common type of diabetic polyneuropathy (74%). The frequency of neuropathic pain was similar in the three different polyneuropathies. Ongoing burning pain and dynamic mechanical allodynia were similarly associated with specific small‐fiber related variables. Conclusions: Diabetic polyneuropathy mainly manifests as a mixed‐fiber polyneuropathy, simultaneously involving Aβ‐, Aδ‐, and C‐fibers. In most patients, neuropathic pain is distinctly associated with small‐fiber damage. The evidence that the frequency of neuropathic pain does not differ across pure large‐, pure small‐, and mixed‐fiber polyneuropathy, raises the possibility that in patients with pure large‐fiber polyneuropathy nociceptive nerve terminal involvement might be undetected by standard diagnostic techniques. [ABSTRACT FROM AUTHOR]

Objectives: We aimed to investigate the conduction velocity of the cold spinal pathway in healthy humans. Methods: Using a cold stimulator consisting of micro‐Peltier elements that was able to produce steep cooling ramps up to −300°C/s, we recorded cold‐evoked potentials after stimulation of the dorsal midline at C5, T2, T6 and T10 vertebral levels and calculated the conduction velocity of the cold spinal pathway. In all participants, we used laser stimulation to deliver painful heat (Aδ‐fibres–mediated) and warm (C‐fibres–mediated) stimuli to the same sites in order to compare the conduction velocity of the cold spinal pathway with that of the nociceptive and warm spinal pathways. Results: Cold stimulation evoked large‐amplitude vertex potentials from all stimulation sites. The mean conduction velocity of the cold spinal pathway was 12.0 m/s, which did not differ from that of the nociceptive spinal pathway (10.5 m/s). The mean conduction velocity of the warm spinal pathway was 2.0 m/s. Discussion: This study provides previously unreported findings regarding cold spinal pathway conduction velocity in humans that may be useful in the assessment of spinal cord lesions as well as in intraoperative monitoring during spinal surgery. Significance: This neurophysiological study provides previously unreported findings on cold spinal pathway conduction velocity in healthy humans. Cold‐evoked potentials may represent an alternative to laser‐evoked potential recording, useful to assess spinothalamic tract in patients with spinal cord lesions and monitor patients during spinal surgery. [ABSTRACT FROM AUTHOR]

Background: In this neurophysiological study, we aimed at verifying the nociceptive selectivity of the new, micropatterned electrode (150IDE), recently designed to generate an electric field limited to the intraepidermal free nerve endings.Methods: Using the new 150IDE, we recorded evoked potentials after stimulation of the face and hand dorsum in 22 healthy participants and in patients with exemplary conditions selectively affecting the nociceptive system. We also measured the peripheral conduction velocity at the upper arm and verified the nociceptive selectivity of 150IDE assessing the effect of a selective block of nociceptive nerve fibres of radial nerve with local anaesthetic infiltration. In healthy participants and in patients, we have also compared the 150IDE-evoked potentials with laser-evoked potentials.Results: In healthy participants, the 150IDE-evoked pinprick sensation and reproducible scalp potentials, with latency similar to laser-evoked potentials. The mean peripheral conduction velocity, estimated at the upper arm, was 12 m/s. The selective nociceptive fibre block of the radial nerve abolished the scalp potentials elicited by the 150IDE stimulation. In patients, the 150IDE-evoked potentials reliably detected the selective damage of the nociceptive system.Conclusions: Our neurophysiological study shows that this new 150IDE provides selective information on nociceptive system.Significance: 150IDE is a promising new tool for investigating nociceptive system in patients with neuropathic pain. [ABSTRACT FROM AUTHOR]