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Conditioned Pain Modulation Is Not Impaired in Individuals with Frozen Shoulder: A Case-Control Study
Marta Aguilar-Rodríguez1, Lirios Dueñas1,2, Mercè Balasch I Bernat1,2
1Department of Physiotherapy, Faculty of Physiotherapy, University of Valencia, 46010 Valencia, Spain.
International Journal of Environmental Research and Public Health
|December 10, 2021
Summary
Frozen shoulder (FS) involves significant pain and limited mobility. This study found that the body's natural pain inhibition system, conditioned pain modulation (CPM), functions normally in individuals with FS, suggesting central pain processing is not altered.
Area of Science:
- Pain research
- Neuroscience
- Musculoskeletal disorders
Background:
- Frozen shoulder (FS) causes debilitating shoulder pain and restricted movement.
- The underlying mechanisms of FS are not fully understood.
- Central pain mechanisms may contribute to persistent pain in FS.
Purpose of the Study:
- To investigate conditioned pain modulation (CPM) in individuals with FS.
- To compare CPM in FS patients with healthy pain-free controls.
- To explore potential alterations in central pain processing in FS.
Main Methods:
- Cross-sectional study involving 64 individuals with FS and 64 healthy controls.
- Conditioned pain modulation (CPM) assessed using pressure pain threshold (PPT) and a tourniquet test.
- Calculated absolute and percentage change in PPT (CPM effect) and pain profiles.
Main Results:
- No significant differences in absolute PPT change or CPM effect were found between FS patients and controls.
- No differences in the proportion of pro-nociceptive versus anti-nociceptive pain profiles were observed between groups.
- Endogenous pain inhibition appears to function normally in individuals with FS.
Conclusions:
- Normal functioning of endogenous pain inhibition suggests CPM is not impaired in frozen shoulder.
- Altered central pain processing mechanisms may not be a defining characteristic of frozen shoulder.
- Further research is needed to understand the specific mechanisms driving pain and mobility deficits in FS.
