Exploring Pain Modulation Mechanisms: A Study of TMS and Repeated Conditioned Pain Modulation
Priyanka Rana, PT, MPT, PhD
Summary
Conditioned pain modulation (CPM) is the behavioral measure of diffuse noxious inhibitory control (DNIC), an endogenous pain inhibitory pathway in which pain inhibits pain. CPM is less efficient in individuals with chronic pain conditions, and it is a predictor for the development of chronic pain. Continuous stimulation of central/cortical mechanisms through engaging CPM might alter pain processing and improve pain inhibition. Transcranial Magnetic Stimulation (TMS) is a valuable tool for assessing how effectively the brain's central and cortical mechanisms engage in pain inhibition, particularly through pathways like CPM. While alterations in cortical excitability related to analgesic-induced pain inhibition have been documented, the effects of continuous stimulation of central pain pathways, along with the mediating influence of psychosocial factors, remain underexplored. This study aims to investigate the central pain modulatory mechanisms, as assessed by CPM, and cortical excitability, as measured by TMS, in healthy participants. Additionally, the study will evaluate the impact of sociocultural factors, including ethnic identity, optimism, resilience, perceived stress, and marginalization, on the magnitude and efficiency of CPM responses. The successful completion of this research will determine how cortical excitability changes due to training and whether these changes are mediated by psychosocial factors.
Description
Background: Pain and Its Burden Pain is a prevalent and complex health condition that significantly impacts individuals, families, and society as a whole. Of the 39.4 million adults experiencing pain most days and persisting for over three months, nearly two-thirds report it as "constantly present," with over half describing it as "unbearable and excruciating" . Pain can be categorized into physiological and pathological types. Nociceptive and inflammatory pain are physiological responses that serve protective and adaptive functions, whereas pathological pain is considered non-protective and…
Eligibility
- Age range
- 18–75 years
- Sex
- All
- Healthy volunteers
- Yes
Inclusion Criteria: * pain-free * between 18-75 years old. Exclusion Criteria: Participants will not be excluded based on race or gender but will be excluded if they meet any of the following: * non-English speaking * systemic medical condition is known to affect sensation * regular use of prescription pain medication to manage pain * current or history of chronic pain condition * currently using blood thinning medication * any blood clotting disorder such as hemophilia * any contraindication to the application of ice or cold packs, such as uncontrolled hypertension, cold urticaria, cryogl…
Interventions
- BehavioralConditioned Pain Modulation (CPM)
Participants will receive a testing stimulus of pressure applied per ascending intensity at the web space of the foot until the pain reaches 40 out of 100, then discontinued. After testing the stimulus, participants will then receive a conditioning stimulus by immersing the non-dominant hand into the water-cooled by refrigeration unit with a temperature of 6 degree Celsius (males) or 8 degree Celsius (females) for 60 seconds. Subjects will be asked to rate the cold pain during the four 60-second trials. Participants completely removed their hand from the cold pressor for 30 seconds following each of the four 60-second immersions, during which time the testing stimulus will be re-applied per the sequential paradigm to the web space of the foot. Participants complete four 60-second periods of immersion.
Location
- Department of Physical Therapy and Movement Science, University of Texas at El PasoEl Paso, Texas