Biochemical alterations in the trapezius muscle of patients with chronic whiplash associated disorders (WAD)--a microdialysis study.
The mechanisms behind the development of chronic trapezius myalgia in patients with whiplash associated disorders (WAD) appear to involve both peripheral and central components, but the specific contribution of alterations in muscle is not clear. Female patients with WAD and involvement of trapezius (N=22) and female controls (N=20; CON) were studied during an experiment compromised of rest (baseline), 20min repetitive low-force exercise and 120min recovery. Their interstitial concentrations of serotonin (5-HT), glutamate, lactate, pyruvate, potassium, interleukin-6 (IL-6), and blood flow were determined in the trapezius muscle using a microdialysis technique. Pressure pain thresholds (PPT) over trapezius and tibialis anterior muscles were also assessed. In WAD, we found signs of generalized hypersensitivity according to PPT. The WAD group had significantly higher interstitial [IL-6] and [5-HT] in the trapezius than the CON. [Pyruvate] was overall significantly lower in WAD, and with lactate it showed another time-pattern throughout the test. In the multivariate regression analysis of pain intensity [5-HT] was the strongest regressor and positively correlated with pain intensity in WAD. In addition, blood flow, [pyruvate], and [potassium] influenced the pain intensity in a complex time dependent way. These findings may indicate that peripheral nociceptive processes are activated in WAD with generalized hypersensitivity for pressure and they are not identical with those reported in chronic work-related trapezius myalgia, which could indicate different pain mechanisms.
Gerdle
Björn
B
Division of Rehabilitation Medicine, Department of Neuroscience and Locomotion, Faculty of Health Sciences, SE 58185 Linköping, Sweden.
Lemming
Dag
D
Kristiansen
Jesper
J
Larsson
Britt
B
Peolsson
Michael
M
Rosendal
Lars
L
D000328:Adult; D002908:Chronic Disease; D015444:Exercise; D005260:Female; D018698:Glutamic Acid / Q000378:metabolism; D006801:Humans; D015850:Interleukin-6 / Q000378:metabolism; D019344:Lactic Acid / Q000378:metabolism; D017551:Microdialysis; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000098:blood supply / Q000378:metabolism*; D019547:Neck Pain / Q000209:etiology* / Q000378:metabolism* / Q000503:physiopathology; D010147:Pain Measurement; D017288:Pain Threshold; D011188:Potassium / Q000378:metabolism; D011312:Pressure; D019289:Pyruvic Acid / Q000378:metabolism; D012039:Regional Blood Flow; D012701:Serotonin / Q000378:metabolism; D012782:Shoulder; D014911:Whiplash Injuries / Q000150:complications*
D015850:Interleukin-6; D012701:Serotonin; D019344:Lactic Acid; D018698:Glutamic Acid; D019289:Pyruvic Acid; D011188:Potassium