New Insights into Cutaneous Laser Stimulation – Dependency on Skin and Laser Type

Frahm, Ken Steffen; Gervasio, Sabata; Arguissain, Federico; Mouraux, André

doi:10.1016/j.neuroscience.2020.09.021

Cited by 9 publications

(21 citation statements)

References 35 publications

(62 reference statements)

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“…These differences in latency might be partially attributed to different ways of heat delivery for the two stimulation methods. Whereas the heat delivered by the thermode has to travel through the skin, the laser actually penetrates the skin 61 . Consequently, even a contact heat stimulation of 300 °C/s does not stimulate the nociceptors as fast and synchronous as a laser would.…”

Section: Discussionmentioning

confidence: 99%

Improved acquisition of contact heat evoked potentials with increased heating ramp

Schoenmacker

Archibald

Kramer

et al. 2022

Sci Rep

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Contact heat evoked potentials (CHEPs) represent an objective and non-invasive measure to investigate the integrity of the nociceptive neuraxis. The clinical value of CHEPs is mostly reflected in improved diagnosis of peripheral neuropathies and spinal lesions. One of the limitations of conventional contact heat stimulation is the relatively slow heating ramp (70 °C/s). This is thought to create a problem of desynchronized evoked responses in the brain, particularly after stimulation in the feet. Recent technological advancements allow for an increased heating ramp of contact heat stimulation, however, to what extent these improve the acquisition of evoked potentials is still unknown. In the current study, 30 healthy subjects were stimulated with contact heat at the hand and foot with four different heating ramps (i.e., 150 °C/s, 200 °C/s, 250 °C/s, and 300 °C/s) to a peak temperature of 60 °C. We examined changes in amplitude, latency, and signal-to-noise ratio (SNR) of the vertex (N2-P2) waveforms. Faster heating ramps decreased CHEP latency for hand and foot stimulation (hand: F = 18.41, p < 0.001; foot: F = 4.19, p = 0.009). Following stimulation of the foot only, faster heating ramps increased SNR (F = 3.32, p = 0.024) and N2 amplitude (F = 4.38, p = 0.007). Our findings suggest that clinical applications of CHEPs should consider adopting faster heating ramps up to 250 °C/s. The improved acquisition of CHEPs might consequently reduce false negative results in clinical cohorts. From a physiological perspective, our results demonstrate the importance of peripherally synchronizing afferents recruitment to satisfactorily acquire CHEPs.

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Section: Discussionmentioning

confidence: 99%

Improved acquisition of contact heat evoked potentials with increased heating ramp

Schoenmacker

Archibald

Kramer

et al. 2022

Sci Rep

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“…After pushing the button, the subjects had to indicate the perceived intensity on a numerical rating scale (NRS) anchored as 0: no perception, 3: pain threshold, 10: maximum imaginable pain. This scale was used as it was expected that the perceived intensities would be both below and above the pain threshold (Frahm et al, 2020; Madden et al, 2019).…”

Section: Methodsmentioning

confidence: 99%

“…The computational model developed and validated in our previous study (Frahm et al, 2020) was used in this study to investigate how the experimental results (primarily the LEPs) depended on the combination of laser type and skin type. The model was based on the Finite Element Method and implemented in COMSOL Multiphysics 5.4 (COMSOLA/S), using a 2D‐axial symmetry.…”

Section: Methodsmentioning

confidence: 99%

“…It is, therefore, possible to investigate how different stimulus combinations can activate skin afferents and do so without placing temperature probes which inherently affect the thermodynamic properties of the tissue and likely the activation of the sensory afferents. Recently, we have investigated how the perception of laser stimulation depends on the combination of laser type and skin location (Frahm et al, 2020). In that study, we developed and experimentally validated a computational model, which allows investigating laser stimuli applied to different skin locations and with different laser types.…”

Section: Introductionmentioning

confidence: 99%

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Influence of skin type and laser wavelength on laser‐evoked potentials

Frahm

Gervasio

Arguissain

et al. 2023

European Journal of Pain

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BackgroundInfrared laser stimulation is a valuable tool in pain research, its primary application being the recording of laser‐evoked brain potentials (LEPs). Different types of laser stimulators, varying in their skin penetrance, are likely to have a large influence on the LEPs, when stimulating different skin types. The aim of this study was to investigate how LEPs depend on laser type and skin location.MethodsTwo different laser stimulators (CO2 and Nd:YAP) were used to compare LEPs in healthy subjects. Stimuli were delivered to the hand dorsum and palm to investigate the effects of skin type on the evoked responses. Stimulus‐evoked brain responses were recorded using EEG and perceived intensity ratings were recorded. Computational modelling was used to investigate the observed differences.ResultsLEPs evoked by stimulation of the hairy skin were similar between CO2 and Nd:YAP stimulation. In contrast, LEPs elicited from the palm were markedly different and barely present for CO2 stimulation. There was a significant interaction between laser type and skin type (RM‐ANOVA, p < 0.05) likely due to smaller CO2 LEPs in the palm. CO2 stimuli to the palm also elicited significantly lower perceived intensities. The computational model showed that the observed differences were explainable by the laser absorption characteristics and skin thickness affecting the temperature profile at the dermo‐epidermal junction (DEJ).ConclusionsThis study shows that LEP elicitation depends on the combination of laser penetrance and skin type. Low penetrance stimuli, from a CO2 laser, elicited significantly lower LEPs and perceived intensities in the palm.SignificanceThis study showed that the elicitation of laser‐evoked potentials in healthy humans greatly depends on the combination of laser stimulator type and skin type. It was shown that high penetrance laser stimuli are capable of eliciting responses in both hairy and glabrous skin, whereas low penetrance stimuli barely elicited responses from the glabrous skin. Computational modelling was used to demonstrate that the results could be fully explained by the combination of laser type and skin thickness.

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“…These temperatures can vary based on different body regions stimulated, gender and method of stimulation [102][103][104][105] . Heat stimuli can be applied to the skin using various methods: radiation (infrared, microwave, laser, etc) 74,102,106 , convection (through a fluid, i.e. air and liquid) 107,108 and conduction (by putting the skin in contact with a hot object) 73,97,[109][110][111] or a combination of these.…”

Section: Heat Perceptionmentioning

confidence: 99%

Heat stimulation as a modulatory tool for the histaminergic and non-histaminergic itch

Riccio¹

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New Insights into Cutaneous Laser Stimulation – Dependency on Skin and Laser Type

Cited by 9 publications

References 35 publications

Improved acquisition of contact heat evoked potentials with increased heating ramp

Improved acquisition of contact heat evoked potentials with increased heating ramp

Influence of skin type and laser wavelength on laser‐evoked potentials

Heat stimulation as a modulatory tool for the histaminergic and non-histaminergic itch

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