An observational study in Myalgia, Muscle Pain and Orofacial Pain, sponsored by Wroclaw Medical University. Enrolling by invitation at 1 site in Poland. Open to participants aged 18 Years to 80 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-03-06.
Sponsored by Wroclaw Medical University · Observational
The main aim of the presented project will be to examine the concentration of selected receptors (CB1, CB2, TRPV-1) showing affinity for binding to cannabidol (CBD) and cannabinol (CBN) in blood samples collected from people with chronic pain in the masticatory muscles and from people without this pain. Moreover, study participants will be examined by a qualified doctor, according to the validated and standardized international DC/TMD protocol (Diagnostic Criteria for Temporomandibular Disorders) and the criteria included in ICOP-1 (International Classification of Orofacial Pain, 1st edition). The nature and duration of pain, psychoemotional state and central sensitization (the phenomenon of increased reactivity of the nervous system to stimuli) will be determined using validated questionnaires. The obtained results will be subjected to statistical analysis in order to check the relationships between the examined parameters.
Background: Orofacial pain is a common phenomenon in adult patients in Poland. According to available scientific research, it occurs in over half of the population, i.e. 55.9% In its chronic form, orofacial pain may lead to reduced sleep quality, reduced life satisfaction and psychoemotional disorders, including depressive disorders. A popular trend among patients suffering from chronic orofacial pain is the abuse of non-steroidal anti-inflammatory drugs, which in most cases demonstrate low, short-term effectiveness and disproportionate to the side effects. There are scientific reports suggesting that substances such as cannabidol (CBD) and cannabinol (CBN) may be effective in the treatment of chronic nociceptive and neuropathic pain, but there is a clear lack of research on the importance of the concentration of receptors on which they can potentially affect exogenous cannabinoids in the risk of occurrence and development of chronic pain. Of the many receptors to which cannabinoids have affinity, the present study selected those that are involved in neurotransmission related to pain, in particular orofacial pain. The concentrations of CB1, CB2, TRPV-1 receptors will be examined, below is a brief description of each of them to explain their selection.
CB1 and CB2 receptors are G protein-coupled metabotropic receptors and belong to the 7-transmembrane receptor family. CB1 has been detected in central nervous system synapses and sensory neurons. The effect of high CB1 expression in areas closely related to the regulation of pain sensation is the relief of migraine and neuropathic pain. However, CB2 receptors can be found in T and B lymphocytes, spleen, pancreas and tonsils. They work to modulate the release of cytokines and the migration of immune cells in a way that appears to reduce inflammation and some types of pain.
The TRPV-1 receptor is the so-called transient potential 1 vanilloid receptor. They occur primarily at the peripheral endings of nerve fibers, where, as a result of the stimuli that stimulate them, they may participate in the development and conduction of pain. The receptor mediates peripheral pain sensation, able to lower the activation threshold and delay the response of nociceptors. Secondary analgesia following ligand-dependent activation is used in the treatment of some difficult-to-control types of pain, e.g. neuropathic pain. TRPV1 can be activated by endogenous substances, e.g. anandamide, or exogenous substances, e.g. cannabinoids contained in cannabis. It is also worth adding that CBD has the property of blocking FAAH (the enzyme fatty acid amide hydrolase), protecting anandamide against degradation, which means that CBD is also an agonist towards TRPV-1 and protects the natural agonist against degradation by FAAH.
Aim: The aim of this study is to answer how the concentration of the above receptors may influence the occurrence of chronic pain in the masticatory muscles in the study population.
It should be mentioned that CB1, CB2 and TRPV-1 receptors have not yet been included in this research perspective and there are no publications or scientific reports on this subject.
Material and methods:
The study included a study group of 51 people suffering from chronic pain in the masticatory muscles and a control group of 51 healthy people, without pain in the masticatory muscles. Patients will be seen at the Clinic of the University Dental Center in Wrocław. The patient will be qualified based on the standardized and validated international DC/TMD protocol (Diagnostic Criteria for Temporomandibular Disorders) and the criteria included in ICOP-1 (International Classification of Orofacial Pain, 1st edition). The patient's examination will be performed by a qualified dentist.
The control group will include people without chronic pain in the masticatory muscles. The exclusion criteria remain the same as for the study group.
As mentioned above, each study participant will initially undergo an extraoral and intraoral examination based on the validated international DC/TMD (Diagnostic Criteria for Temporomandibular Disorders) protocol. The examinations will be performed by trained dentists.
Patients from both groups will be asked to complete the following validated questionnaires:
The last stage includes collecting a venous blood sample from patients in the study and control groups and determining the concentration of CB1, CB2 and TRPV-1 receptors. The receptors will be determined using specialized ELISA kits.
The collected data will then be subjected to statistical analysis in order to verify the research hypothesis and capture statistically significant relationships.
256 studies on the registry are indexed under Myalgia; 46 are open to participants now.
This study's planned enrollment of 102 is below the median of 196 across 35 observational studies indexed under Myalgia.
Browse Myalgia studies →Wroclaw Medical University is the lead sponsor of 99 studies on the registry; 29 are open to participants now.
Counted across the registry records on this site, refreshed daily.
Patients with suspicion of Chronic Orofacial Pain of Muscle Origin referred to the Wroclaw Medical University. Healthy controls.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Participants with chronic pain in the masticatory muscles
Diagnostic Test: Blood CB1, CB2, TRPV-1 concentration measurement
Participants without chronic pain in the masticatory muscles
Diagnostic Test: Blood CB1, CB2, TRPV-1 concentration measurement
In each of the patients blood CB1, CB2, TRPV-1 concentration will be measure
Relationship between the concentration of receptors with affinity for Cannabidol and Cannabinol and the risk of occurrence and severity of chronic orofacial pain of muscle origin
Each participant will undergo blood test focusing on CB1, CB2, TRPV-1 concentration
Time frame: May 5, 2024 - December 31, 2024
Assessment of the occurrence of chronic orofacial pain of muscular origin assessed using the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) protocol.
Each patient will undergo DC/TMD protocol-based clinical examination using DC/TMD examination form assessing incidence of pain of masticatory muscles and surrounding structures.
Time frame: May 5, 2024 - December 31, 2024
Assessment of the occurrence of chronic orofacial pain of muscular origin assessed using the Gradual Chronic Pain Scale.
Each participant will fill in Graded Chronic Pain Scale. Scoring Criteria for Grading Chronic Pain Severity: Characteristic Pain Intensity is a 0 to 100 score derived from Questions 1 through 3:Mean (Pain Right Now, Worst Pain, Average Pain) X 10. Disability Score is 0 to 100score derived from Questions 4 through 6:Mean (Daily Activities, Social Activities, Work Activities) X 10. Disability Points: Add the indicated points for Disability Days (Question 7)and for Disability Score. Classification: GRADE 0- No TMD pain in prior 6 months. GRADE I-Low Intensity Characteristic Pain Intensity\<50, Low Disability\<3 Disability Point. GRADE II -High Intensity Characteristic Pain Intensity \>50, LowDisability\<3 Disability Points. GRADE III- High Disability3 to 4 Disability Points, Moderately Limiting (Regardless of Characteristic Pain Intensity). GRADE IV- High Disability 5 to 6 Disability Points, Severely Limiting (Regardless of Characteristic Pain Intensity).
Time frame: May 5, 2024 - December 31, 2024
Assessment of the occurrence of chronic orofacial pain of muscular origin assessed using the McGill Pain Questionnaire.
Each participant will fill in McGill questionnaire that is composed of 78 words. Respondents choose those that best describe their experience of pain. Scores are tabulated by summing values associated with each word; scores range from 0 (no pain) to 78 (severe pain).
Time frame: May 5, 2024 - December 31, 2024
Assessment of the occurrence of chronic orofacial pain of muscular origin assessed using the Migraine Disability Assessment Test (MIDAS)
The Migraine Disability Assessment Test (MIDAS) is a test used by doctors to determine how severely migraines affect a patient's life. Patients are asked questions about the frequency and duration of their headaches, as well as how often these headaches limited their ability to participate in activities at work, at school, or at home.
Time frame: May 5, 2024 - December 31, 2024
Assessment of the occurrence of chronic orofacial pain of muscular origin assessed using the Perceived Stress Scale -10
Each participant will fill in Perceived Stress Scale -10. Scores are obtained by reversing the scores on the four positive items, e.g., 0=4, 1=3, 2=2, etc. and then summing across all 10 items. Items 4,5, 7, and 8 are the positively stated items. It can range from 0 to 40. Scores ranging from 0-13 would be considered low stress,14-26 would be considered moderate stress, 27-40 would be considered high perceived stress.
Time frame: May 5, 2024 - December 31, 2024
Assessment of the occurrence of chronic orofacial pain of muscular origin assessed using the Generalized Anxiety Disorder -7
Each participant will fill in Generalized Anxiety Disorder -7 that consists of 7 items. Total score ranges 0-21 points. Scores of 5, 10, and 15 are taken as the cut-off points for mild, moderate and severe anxiety, respectively.
Time frame: May 5, 2024 - December 31, 2024
Assessment of the occurrence of chronic orofacial pain of muscular origin assessed using the Somatic Symptom Scale - 8
Each participant will fill in the Somatic Symptom Scale - 8 (SSS-8) which is a brief self-report questionnaire used to assess somatic symptom burden. It measures the perceived burden of common somatic symptoms. These symptoms were originally chosen to reflect common symptoms in primary care but they are relevant for a large number of diseases and mental disorders. Scoring: 0-3: no to minimal, 4-7: low, 8-11: medium,12-15: high,16-32: very high.
Time frame: May 5, 2024 - December 31, 2024
Assessment of the occurrence of chronic orofacial pain of muscular origin assessed using the Central Sensitizatin Inventory
Each participant will fill in Central Sensitizatin Inventory. This questionnaire consist of two parts. First part includes 25 questions regarding common central sensitivity symptoms. It allows to categorize participant into one of five categories: subclinical (0-29), mild (30-39), moderate (40-49), severe (50-59), and extreme (60-100) Second part is not scored, but it determines if the participant has been diagnosed with certain CSS disorders or related disorders.
Time frame: May 5, 2024 - December 31, 2024
Assessment of the occurrence of chronic orofacial pain of muscular origin assessed using the Pain Catastrophizing Scale
Each participant will fill in the Pain Catastrophizing Scale.The Pain Catastrophizing Scale (PCS) will be used to assess pain-related catastrophizing, taking into account items such as exaggeration, hopelessness, and rumination. The PCS consists of 13 items rated on a scale from 0 to 4. The scale can score a maximum of 52 points, with higher scores indicating greater pain-related catastrophic thinking.
Time frame: May 5, 2024 - December 31, 2024
Plan to share: Undecided
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Wroclaw Medical University