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Enriquez C.1, Heir G.2, Nasri-Heir C.2, Edmond S.3
1Stockton University, Physical Therapy Program, Galloway, United States, 2Rutgers The State University of New Jersey, Diagnostic Sciences, Newark, United States, 3Rutgers The State University of New Jersey, School of Health Professions, Newark, United States
Background: Quantitative Sensory Tests (QST) are psychophysical testing paradigms used in clinical research to objectively assess individual pain processing mechanisms in patients with clinical pain1,2,3. Quantitative Sensory Tests include Temporal Summation (TS)1,3 and Conditioned Pain Modulation (CPM)1,5. Temporal Summation is administered to quantitatively assess pain sensitivity secondary to central sensitization process that results from repeated cutaneous stimulation at a painful intensity1,2,3. In contrast, CPM involves the mechanism of endogenous analgesia6, where two painful stimuli are concurrently applied over different body regions to directly assess the central nervous system´s ability to modulate pain input, which reflects the integrity of the endogenous pain modulation system1,4. Patients with orofacial pain have been found to develop chronic pain, demonstrating similar characteristics of abnormal pain sensitivity and heightened self-reported pain as those with chronic musculoskeletal pain disorders such as low back pain, tension-type headache, and fibromylagia2,6,7 Understanding the etiology of orofacial pain is an important research goal, as it is a preliminary step towards development of effective interventions and successful treatment outcomes for these individuals.
Purpose: We aimed to investigate if abnormal pain processing mechanisms such as heightened pain sensitivity1,5 is associated with inefficient endogenous pain modulation2,5 in the etiology of symptoms among patients with orofacial pain.
Methods: The study was conducted in accordance with Helsinki Declaration. A convenience sample of patients with orofacial pain (n=40) seen for initial visit in an orofacial pain clinic were sequentially recruited and assessed for individual pain processing mechanisms using QST. Temporal summation and CPM testing protocols were administered prior to the subjects receiving any intervention. The numeric pain rating scale with anchors using 0 = no pain and 10 = worst imaginable pain was used as the outcome measurement tool for pain report during TS and CPM testing. Baseline demographics, psychological variables, and self-reported disability scores were also collected. Pearson correlation analyses were conducted on TS and CPM scores, as well as self-reported psychological and disability measures to assess potential relationships between these variables.
Results: Study results found strong and positive correlation between increased pain sensitivity and inefficient endogenous pain modulation system (r = 0.69, p 0.001) assessed using TS and CPM respectively, in patients who seek treatment for orofacial pain. No significant association was found between age and gender, including psychological and disability variables (p >0.05).
Conclusion(s): Heightened pain sensitivity is directly correlated with the central nervous system´s inability to effectively modulate pain input, reflecting impairment in the endogenous pain modulation system among patients with orofacial pain. These are important considerations in the treatment of patients in this population. The higher the sensitivity to pain, the less efficient the endogenous pain modulation system.
Implications: Study results provide preliminary evidence on the etiology of symptoms in orofacial pain. Understanding these factors is important in effective prevention towards progression to a chronic pain state. Aberrant pain processing mechanisms, in addition to associated physical impairments, are significant contributing factors in persistent pain experience among orofacial pain patients. These are important considerations in creating effective treatment strategies and successful treatment outcomes in patients with orofacial pain.
Funding acknowledgements: University of Medicine and Dentistry of New Jersey (UMDNJ) - School of Health Related Professions Pre-Doctoral Fellowship Grant
Topic: Pain & pain management
Ethics approval: Participants were provided with informed consent approved by UMDNJ Institutional Review Board.
All authors, affiliations and abstracts have been published as submitted.
