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NCT Number: NCT06197529

Is Nociceptive Processing Evoked by Heat Homeostatically Regulated: A Contact-heat Evoked Potentials Study

Homeostatic plasticity is a mechanism that stabilizes neuronal activity to prevent excessive nervous system excitability. This mechanism can be investigated in humans by applying two blocks of non-invasive brain stimulation, such as transcranial direct current stimulation (tDCS).

In healthy subjects, homeostatic plasticity induction over the primary motor cortex increases the amplitude of motor-evoked potentials after the first block of excitatory tDCS, which then decreases after the second block of excitatory tDCS. However, this mechanism is impaired in chronic and experimental pain, demonstrated by an increase in excitability instead of a reversal.

The role of homeostatic plasticity mechanisms in pain is yet to be unraveled, but homeostatic plasticity may hold an important role in pain development or persistence.

Thus, the aim of this study is to investigate if the cortical nociceptive response reflected by contact heat stimulation (CHEPs) is regulated by homeostatic mechanisms. For this, homeostatic plasticity will be induced in both the primary motor (M1) and sensory cortices (S1). The first research question will explore if the contact heat evoked potentials are homeostatically regulated and if this regulation is occurring locally or globally in the cortex. Additionally, it will be investigated if and how capsaicin-induced nociception interacts and effects the homeostatic response as reflected by CHEPs.

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Key information

Conditions

Healthy

Age range

18 year–60 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Aalborg University / Center for Neuroplasticity and Pain

Gistrup, 9260, Denmark

About this study

Randomized, cross-over study of four sessions

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Healthy right-handed men and women aged 18-60 years
  • Speak, read, and understand English or Danish

Exclusion criteria

  • Pregnant, breastfeeding, or women in childbearing age not using contraceptive methods
  • Regular use of cannabis, opioids or other drugs (except contraceptives)
  • Current or previous neurologic, musculoskeletal, mental, or other illnesses (e.g. brain or spinal cord injuries, degenerative neurological disorders, epilepsy, major depression, cardiovascular disease, chronic lung disease, etc.)
  • Current or previous chronic or recurrent pain condition (other than low back pain in patients recruited for sub-project 6, and this item does not apply to sub-project 8)
  • Current regular use of analgesic medication or other medication which may affect the trial (including paracetamol and NSAIDs) For subproject 8, chronic low back pain patients may take analgesic medication provided the dosage is stable
  • Open wounds, eczema, scars, or tattoos in the area of the heat stimulation (sub-project 1)
  • Lack of ability to cooperate
  • Recent history of acute pain particularly in the lower limbs (unless related to low back pain in patients included in sub-project 6 or 8)
  • Abnormally disrupted sleep in 24 hours preceding experiment
  • Any medical or other condition (i.e. musculoskeletal, cardiorespiratory, neurological, etc.)
  • Contraindications to TMS application (history of epilepsy, metal implants in head or jaw, etc.)
  • Unable to answer to the "Transcranial Magnetic Stimulation Adult Safety Screen" or tDCS screening questionnaire (see Bilag_v1_06092021)

Treatment and study plan

Homeostatic Plasticity

Other

Anodal tDCS S1/M1

Topical alone (Capsaicin 8% Patch)

Drug

4x4 patch

Other names: Qutenza Capsaicin (8%)

Placebo patch

Other

4x4 patch

Homeostatic Plasticity (Sham)

Other

sham Homeostatic Plasticity protocol over S1

Primary outcomes

  1. Contact Heat Evoked Potentials

    Time frame: Pre-patch application

    Baseline (Evoked Potentials after stimulus onset from electroencephalographic channels)

  2. Contact Heat Evoked Potentials

    Time frame: 30 minutes after patch application

    Post-Patch (Evoked Potentials after stimulus onset from electroencephalographic channels)

  3. Contact Heat Evoked Potentials

    Time frame: During the homeostatic plasticity protocol - 0 minutes after the first block of anodal tDCS

    Post-Priming (Evoked Potentials after stimulus onset from electroencephalographic channels)

  4. Contact Heat Evoked Potentials

    Time frame: 0 minutes after homeostatic plasticity induction

    Post-HP (Evoked Potentials after stimulus onset from electroencephalographic channels)

  5. Contact Heat Evoked Potentials

    Time frame: 10 minutes after the homeostatic plasticity protocol

    Post-HP+10 minutes (Evoked Potentials after stimulus onset from electroencephalographic channels)

Secondary outcomes

  1. Pain Intensity After Stimulation Blocks (0-10)

    Time frame: 0 minutes after the first block of CHEP stimulation

    Pain intensity measured using an 11-point numeric rating scale where 0= no pain and 10 = worst imaginable pain

  2. Pain Intensity After Stimulation Blocks (0-10)

    Time frame: 0 minutes after the second block of CHEP stimulation

    Pain intensity measured using an 11-point numeric rating scale where 0= no pain and 10 = worst imaginable pain

  3. Pain Intensity After Stimulation Blocks

    Time frame: 0 minutes after the third block of CHEP stimulation

    Pain intensity measured using an 11-point numeric rating scale where 0= no pain and 10 = worst imaginable pain

  4. Pain Intensity After Stimulation Blocks

    Time frame: 0 minutes after the fourth block of CHEP stimulation

    Pain intensity measured using an 11-point numeric rating scale where 0= no pain and 10 = worst imaginable pain

  5. Pain Intensity After Stimulation Blocks

    Time frame: 0 minutes after the fifth block of CHEP stimulation

    Pain intensity measured using an 11-point numeric rating scale where 0= no pain and 10 = worst imaginable pain

  6. Presence of Allodynia After Stimulation Blocks

    Time frame: 0 minutes after the first block of CHEP stimulation

    Measured with a calibrated brush for the study of dynamic mechanical allodynia (Brush-05®, Somedic SenseLab AB, Sösdala, Sweden)

  7. Presence of Allodynia After Stimulation Blocks

    Time frame: 0 minutes after the second block of CHEP stimulation

    Measured with a calibrated brush for the study of dynamic mechanical allodynia (Brush-05®, Somedic SenseLab AB, Sösdala, Sweden)

  8. Presence of Allodynia After Stimulation Blocks

    Time frame: 0 minutes after the third block of CHEP stimulation

    Measured with a calibrated brush for the study of dynamic mechanical allodynia (Brush-05®, Somedic SenseLab AB, Sösdala, Sweden)

  9. Presence of Allodynia After Stimulation Blocks

    Time frame: 0 minutes after the fourth block of CHEP stimulation

    Measured with a calibrated brush for the study of dynamic mechanical allodynia (Brush-05®, Somedic SenseLab AB, Sösdala, Sweden)

  10. Presence of Allodynia After Stimulation Blocks

    Time frame: 0 minutes after the fifth block of CHEP stimulation

    Measured with a calibrated brush for the study of dynamic mechanical allodynia (Brush-05®, Somedic SenseLab AB, Sösdala, Sweden)

  11. Pittsburg Sleeping Quality Index

    Time frame: Pre-intervention and pre-patch application

    The global PSQI score ranges from 0 to 21, calculated by adding seven component scores. A global score above 5 (PSQI > 5) indicates relevant sleep disturbances or poor sleep quality (Buysse et al., 1989).

  12. BECKS Depression Inventory

    Time frame: Pre-intervention and pre-patch application

    The questionnaire includes 21 items which are rated on a 4-point scale (0 to 3). The total score is calculated by adding all items. Total score values from 0-13 indicate "normal ups and downs", and scores between 14-19, 20-28, and 29-63, are interpreted as mild, moderate, and severe symptoms (Beck et al., 1996; Goldstein et al., 2013; Wang and Gorenstein, 2013).

  13. Positive and Negative Affective Schedule - Short Form

    Time frame: Pre-intervention and pre-patch application

    Scores can range from 10 - 50, with higher scores representing higher levels of positive/negative affect.

  14. State-Trait Anxiety Inventory

    Time frame: Pre-intervention and pre-patch application

    A 40-item questionnaire that assesses state and trait anxiety with 20 items each (Skapinakis, 2014; Spielberger et al., 1983). Each subscale (S-Anxiety and T-Anxiety) uses a 4-point Linkert scale ranging from 1 ("not at all" for S- or "almost never" for T-Anxiety) to 4 ("very much so" for S- and "almost always" for T-Anxiety). A higher scole indicates more severe anxiety with a range from 20-80.

  15. Pain Catastrophizing Scale

    Time frame: Pre-intervention and pre-patch application

    This questionnaire assesses 13 items describing different thoughts and feelings which may be associated with pain. They are rated on a 5-point scale (0-5) indicating the degree to which these thoughts and feelings are present when having pain. The total score is 0-52, with a higher score indicating a higher pain catastrophizing. (Sullivan M J L, Bishop S, Pivik J. 1995)

  16. Pain intensity (Induced by Capsaicin)

    Time frame: Throughout the experimental session, every 5 minutes and up to 55 minutes after patch application

    Pain intensity measured using an 11-point numeric rating scale where 0= no pain and 10 = worst imaginable pain

Sponsors and collaborators

Lead sponsor

Aalborg University

Other

Registry information

Important dates

Study start
2023
Primary completion
2024
Study completion
2024
First posted
Jan 9, 2024
Registry last updated
May 16, 2024

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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