A new method for measuring the conduction velocities of Aβ-, Aδ- and C-fibers following electric and CO2 laser stimulation in humans

Tran, Tuan Diep; Lam, Khanh; Hoshiyama, Minoru; Kakigi, Ryusuke

doi:10.1016/s0304-3940(01)01639-1

Cited by 76 publications

(46 citation statements)

References 15 publications

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“…In previous studies using a laser beam to a tiny area of skin [4,9,10,27], which is known to selectively activate C fibers, the mean P1 latency for stimulation of the hand was 930-1144 ms, which is very similar to the present results. The estimated CV of 1.5 m/s in this study was also consistent with previous studies showing a value of 0.8 -2.8 m/s by averaged EEG [4,27,28] and 0.4 -1.8 m/s [29] by microneurography. In terms of the precise measurement of CV, microneurography is superior to EEG.…”

Section: Discussionsupporting

confidence: 91%

Selective Stimulation of C Fibers by an Intra-Epidermal Needle Electrode in Humans

Otsuru

Inui²,

Yamashiro³

et al. 2009

TOPAINJ

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Abstract:We recorded evoked potentials (EPs) induced by intra-epidermal electrical stimulation using a needle electrode with specific parameters. We identified the fibers activated by this specific stimulation by assessing the conduction velocity (CV) of the peripheral nerve. The EPs were recorded from the Cz electrode (vertex) of the International 10-20 system in ten healthy male subjects. The dorsum of the left hand and forearm were stimulated with an intensity of 0.01 mA above the sensory threshold. The mean P1 latency of EPs for the hand and forearm were 1007 ± 88 and 783 ± 80 ms, respectively, and the CV estimated from the latency of P1 was 1.5 ± 0.7 m/s. The CV indicated that the fibers activated by the stimulation were C fibers. Since the method of stimulation is convenient and non-invasive, it should be useful for investigating the functions of small fibers.

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Section: Discussionsupporting

confidence: 91%

Selective Stimulation of C Fibers by an Intra-Epidermal Needle Electrode in Humans

Otsuru

Inui²,

Yamashiro³

et al. 2009

TOPAINJ

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“…For the C fiber stimulation, we used a method that has been shown to be C fiber-mediated by conduction velocity measurements and that evokes only the sensation of warmth without a tactile or pin prick component when applied to glabrous skin (Granovsky et al, 2005). The shorter latency of this response, compared to C fiber-mediated potentials evoked by infrared laser stimulation (Tran et al, 2001;Opsommer et al, 2001), is probably due to several factors, including a longer stimulus duration (approximately 10 to 300 times longer) and a much larger stimulation area (30 to 3000 times greater). We could not detect electrophysiological evidence for the activation of Aδ fibers with this stimulus.…”

Section: Selectivity Of the Stimulationmentioning

confidence: 99%

An inhibitory interaction of human cortical responses to stimuli preferentially exciting Aδ or C fibers

2008

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Finely myelinated (type Aδ) and unmyelinated (type C) fibers are the major afferent inputs to spinothalamic tract neurons mediating sensory and reflex responses to noxious and thermal stimuli. These two fiber types differ in their sensory and biophysical properties, raising questions about the interaction of their supraspinal responses. Therefore, we investigated the interaction of cortical responses to stimuli that preferentially excite these fibers in human subjects using evoked potential recordings in a paired conditioning stimulation (CS) and test stimulation (TS) paradigm. There were two experiments, one with Aδ as CS and C as TS (Aδ-C) and another with these stimuli reversed (C-Aδ). We used intra-epidermal electrical pulses applied to the dorsal left hand at 2 and 1 × pinprick threshold (pp) for the preferential stimulation of Aδ fibers and 37 -50°C contact heat pulses applied to the left or right thenar and left hypothenar eminences for the preferential stimulation of C fibers. We found that the cortical response to preferential Aδ or C fiber stimulation was attenuated whenever either cortical response preceded the other. Standardized values of peak and integrated amplitudes were < 1 in all paring conditions and in all subjects in both experiments. The suppressive effect varied in magnitude with the intensity of the conditioning stimulus in both Aδ-C and C-Aδ experiments. Furthermore, intra-segmental interaction was differentially effective for Aδ conditioning, (peak amplitude, p < 0.008; ANOVA). Our experiments provide the first neurophysiological evidence for a somatotopically distributed, mutually suppressive interaction between cortical responses to preferentially activated Aδ and C afferents in humans. This suppressive interaction of cortical responses suggests contrasting and possibly mutually exclusive sensori-motor functions mediated through the Aδ and C fiber afferent channels. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. NIH Public Access Author ManuscriptNeuroscience. Author manuscript; available in PMC 2008 June 20. Published in final edited form as:Neuroscience. 2008 March 27; 152(3): 798-808. NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author ManuscriptAs a population, spinothalamic neurons receive direct synaptic input from a variety of somatic and visceral afferent fibers. The cutaneous afferent inputs include large diameter myelinated (Aβ) fibers that are activated only by tactile stimuli and small diameter, finely myelinated (Aδ) and unmyelinated (C) fibers innervating receptors responding to innocuous and noxious mechanical...

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“…This process can be implemented by interposing a thin plate, drilled with one or more small holes, between the stimulus probe and the skin surface in order to act as a spatial filter for the laser beam 15,16,17 . The principle of this method is based on higher innervation density of C-fiber terminals on the skin (three or four times more numerous than Aδ-fibers in humans), resulting in a higher probability of stimulating the terminals of C-fibers than those of Aδ-fibers 18 .…”

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confidence: 99%

Activation of C-fiber nociceptors by low-power diode laser

Azevêdo

Silva

Martins

et al. 2016

Arq. Neuro-Psiquiatr.

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The criteria for diagnosis of definite neuropathic pain depend on a plausible neuroanatomic distribution of the pain, a history suggestive of somatosensory lesion or disease and at least one objective confirmatory test of the existence of such relevant somatosensory lesion or disease 1 . Somatosensory evoked potentials (SEPs) and laser evoked potentials (LEPs) are becoming "standards" to document possible involvement of the neural systems in patients with neuropathic pain: the sensitivity of LEP to small lesions on the involved pathways are conferring to it medical legal value in some European countries 2 . Although exquisitely sensitive to spinothalamic impairments, LEPs are considered as a supportive tool to diagnose small fiber neuropathies (given their poor localization value) 3. These observations suggest that the search for alternative stimulus sources to obtain LEPs, aiming to reduce the risks of complications (e.g. skin burns) and the costs of the procedure, are important to increase the availability of these exams; further, the stimulus should be able to allow separate evaluations of Aδ and C fibers.Laser heat stimulators have been extensively used to study time-locked nociception responses, as they provide a near-ideal method to selectively activate cutaneous Aδ-fiber and C-fiber nociceptors. The high power outputs of lasers, which allow fast heat ramps, concomitantly activate these two systems and produce a dual perception compatible with conduction in small myelinated Aδ and unmyelinated C fibers 4 . Cortical responses to high intensity stimulation, however, do not reflect such dual activation. Scalp recordings of LEP show a major negative-positive wave (N2-P2) in the latency range of 200-400 ms when stimulating the hand dorsum. These results have been associated with Aδ-fiber activity, AbstrACtObjective: The evaluation of selective activation of C-fibers to record evoked potentials using the association of low-power diode laser (810 nm), tiny-area stimulation and skin-blackening. Method: Laser-evoked potentials (LEPs) were obtained from 20 healthy young subjects. An aluminum plate with one thin hole was attached to the laser probe to provide tiny-area stimulation of the hand dorsum and the stimulated area was covered with black ink. Results: The mean intensity used for eliciting the ultra-late laser-evoked potential (ULEP) was 70 ± 32 mW. All subjects showed a clear biphasic potential that comprised a negative peak (806 ± 61 ms) and a positive deflection (1033 ± 60 ms), corresponding to the ULEP related to C-fiber activation. Conclusion: C-fiber-evoked responses can be obtained using a very low-power diode laser when stimulation is applied to tiny areas of darkened skin. This strategy offers a non-invasive and easy methodology that minimizes damage to the tissue.Keywords: laser-evoked potentials, C-fibers, nociception, pain perception. resumo Objetivo: Avaliação da ativação de fibras C para o registro de potenciais evocados utilizando-se laser de baixa potência, áreas pequenas de estimulação e escu...

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A new method for measuring the conduction velocities of Aβ-, Aδ- and C-fibers following electric and CO2 laser stimulation in humans

Cited by 76 publications

References 15 publications

Selective Stimulation of C Fibers by an Intra-Epidermal Needle Electrode in Humans

Selective Stimulation of C Fibers by an Intra-Epidermal Needle Electrode in Humans

An inhibitory interaction of human cortical responses to stimuli preferentially exciting Aδ or C fibers

Activation of C-fiber nociceptors by low-power diode laser

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