Cutaneous nociceptive sensitization affects the directional discrimination – but not the 2-point discrimination

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Resumé

Several pain conditions have been shown to reduce the discriminative abilities of external stimuli. The aim of this study was to investigate how cutaneous sensitization affects the tempo-spatial discrimination for both painful laser stimulation and mechanical stimulation. Fifteen healthy subjects were presented with two different stimulation paradigms, a continuous line stimulation and a 2-point stimulation. Line stimulations were delivered in two different directions in lengths of 25, 50, 75, and 100 mm. Two-point distances from 0 to 100 mm were tested. The subjects reported the perceived intensity, and either direction (line stimulations) or number of perceived points (2-point stimulations). All stimuli were tested both before and after topical capsaicin (8% concentration) sensitization (30 min). All mechanical line stimulations were reported correctly before capsaicin and 3 stimulations (out of 240) were reported incorrectly after capsaicin. For the laser line stimulation, the directional discrimination threshold (DDT) was 69.5 mm before capsaicin and 76.3 mm after capsaicin. The 2-point discrimination threshold for laser stimulation was 70.3 mm before capsaicin and 68.0 mm after, for the mechanical stimuli it was 31.5 mm before capsaicin and 31.0 mm after capsaicin. The perceived intensities were increased for the laser line stimulations after capsaicin (linear mixed model (LMM), p < 0.001) and increased with stimulation length (LMM, p < 0.001). For mechanical stimuli, NRS was increased following capsaicin (LMM, p < 0.001). The intensities for both mechanical and laser 2-point stimuli increased after capsaicin and increased with distance between points (LMM, p < 0.01). The findings show how cutaneous sensitization appears to affect directional discrimination to a larger extent than the 2-point discrimination. This study is the first to investigate how directional discrimination is altered during sensitization. If such measures can be optimized they may provide a new method to probe the neural mechanisms in pain patients.

OriginalsprogEngelsk
TidsskriftScandinavian Journal of Pain
Vol/bind19
Udgave nummer3
Sider (fra-til)605-613
ISSN1877-8860
DOI
StatusUdgivet - jul. 2019

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Capsaicin
Skin
Lasers
Linear Models
Pain
Aptitude
Healthy Volunteers

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    title = "Cutaneous nociceptive sensitization affects the directional discrimination – but not the 2-point discrimination",
    abstract = "Several pain conditions have been shown to reduce the discriminative abilities of external stimuli. The aim of this study was to investigate how cutaneous sensitization affects the tempo-spatial discrimination for both painful laser stimulation and mechanical stimulation. Fifteen healthy subjects were presented with two different stimulation paradigms, a continuous line stimulation and a 2-point stimulation. Line stimulations were delivered in two different directions in lengths of 25, 50, 75, and 100 mm. Two-point distances from 0 to 100 mm were tested. The subjects reported the perceived intensity, and either direction (line stimulations) or number of perceived points (2-point stimulations). All stimuli were tested both before and after topical capsaicin (8{\%} concentration) sensitization (30 min). All mechanical line stimulations were reported correctly before capsaicin and 3 stimulations (out of 240) were reported incorrectly after capsaicin. For the laser line stimulation, the directional discrimination threshold (DDT) was 69.5 mm before capsaicin and 76.3 mm after capsaicin. The 2-point discrimination threshold for laser stimulation was 70.3 mm before capsaicin and 68.0 mm after, for the mechanical stimuli it was 31.5 mm before capsaicin and 31.0 mm after capsaicin. The perceived intensities were increased for the laser line stimulations after capsaicin (linear mixed model (LMM), p < 0.001) and increased with stimulation length (LMM, p < 0.001). For mechanical stimuli, NRS was increased following capsaicin (LMM, p < 0.001). The intensities for both mechanical and laser 2-point stimuli increased after capsaicin and increased with distance between points (LMM, p < 0.01). The findings show how cutaneous sensitization appears to affect directional discrimination to a larger extent than the 2-point discrimination. This study is the first to investigate how directional discrimination is altered during sensitization. If such measures can be optimized they may provide a new method to probe the neural mechanisms in pain patients.",
    keywords = "2-point discrimination, capsaicin, directional discrimination, laser stimulation",
    author = "Steffen Frahm and M{\o}rch, {Carsten Dahl} and Andersen, {Ole K{\ae}seler}",
    year = "2019",
    month = "7",
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    pages = "605--613",
    journal = "Scandinavian Journal of Pain",
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    TY - JOUR

    T1 - Cutaneous nociceptive sensitization affects the directional discrimination – but not the 2-point discrimination

    AU - Frahm, Steffen

    AU - Mørch, Carsten Dahl

    AU - Andersen, Ole Kæseler

    PY - 2019/7

    Y1 - 2019/7

    N2 - Several pain conditions have been shown to reduce the discriminative abilities of external stimuli. The aim of this study was to investigate how cutaneous sensitization affects the tempo-spatial discrimination for both painful laser stimulation and mechanical stimulation. Fifteen healthy subjects were presented with two different stimulation paradigms, a continuous line stimulation and a 2-point stimulation. Line stimulations were delivered in two different directions in lengths of 25, 50, 75, and 100 mm. Two-point distances from 0 to 100 mm were tested. The subjects reported the perceived intensity, and either direction (line stimulations) or number of perceived points (2-point stimulations). All stimuli were tested both before and after topical capsaicin (8% concentration) sensitization (30 min). All mechanical line stimulations were reported correctly before capsaicin and 3 stimulations (out of 240) were reported incorrectly after capsaicin. For the laser line stimulation, the directional discrimination threshold (DDT) was 69.5 mm before capsaicin and 76.3 mm after capsaicin. The 2-point discrimination threshold for laser stimulation was 70.3 mm before capsaicin and 68.0 mm after, for the mechanical stimuli it was 31.5 mm before capsaicin and 31.0 mm after capsaicin. The perceived intensities were increased for the laser line stimulations after capsaicin (linear mixed model (LMM), p < 0.001) and increased with stimulation length (LMM, p < 0.001). For mechanical stimuli, NRS was increased following capsaicin (LMM, p < 0.001). The intensities for both mechanical and laser 2-point stimuli increased after capsaicin and increased with distance between points (LMM, p < 0.01). The findings show how cutaneous sensitization appears to affect directional discrimination to a larger extent than the 2-point discrimination. This study is the first to investigate how directional discrimination is altered during sensitization. If such measures can be optimized they may provide a new method to probe the neural mechanisms in pain patients.

    AB - Several pain conditions have been shown to reduce the discriminative abilities of external stimuli. The aim of this study was to investigate how cutaneous sensitization affects the tempo-spatial discrimination for both painful laser stimulation and mechanical stimulation. Fifteen healthy subjects were presented with two different stimulation paradigms, a continuous line stimulation and a 2-point stimulation. Line stimulations were delivered in two different directions in lengths of 25, 50, 75, and 100 mm. Two-point distances from 0 to 100 mm were tested. The subjects reported the perceived intensity, and either direction (line stimulations) or number of perceived points (2-point stimulations). All stimuli were tested both before and after topical capsaicin (8% concentration) sensitization (30 min). All mechanical line stimulations were reported correctly before capsaicin and 3 stimulations (out of 240) were reported incorrectly after capsaicin. For the laser line stimulation, the directional discrimination threshold (DDT) was 69.5 mm before capsaicin and 76.3 mm after capsaicin. The 2-point discrimination threshold for laser stimulation was 70.3 mm before capsaicin and 68.0 mm after, for the mechanical stimuli it was 31.5 mm before capsaicin and 31.0 mm after capsaicin. The perceived intensities were increased for the laser line stimulations after capsaicin (linear mixed model (LMM), p < 0.001) and increased with stimulation length (LMM, p < 0.001). For mechanical stimuli, NRS was increased following capsaicin (LMM, p < 0.001). The intensities for both mechanical and laser 2-point stimuli increased after capsaicin and increased with distance between points (LMM, p < 0.01). The findings show how cutaneous sensitization appears to affect directional discrimination to a larger extent than the 2-point discrimination. This study is the first to investigate how directional discrimination is altered during sensitization. If such measures can be optimized they may provide a new method to probe the neural mechanisms in pain patients.

    KW - 2-point discrimination

    KW - capsaicin

    KW - directional discrimination

    KW - laser stimulation

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    U2 - 10.1515/sjpain-2018-0344

    DO - 10.1515/sjpain-2018-0344

    M3 - Journal article

    VL - 19

    SP - 605

    EP - 613

    JO - Scandinavian Journal of Pain

    JF - Scandinavian Journal of Pain

    SN - 1877-8860

    IS - 3

    ER -