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Neck News

Trigger Points as Pain Generators in Chronic Whiplash

One way to break the pain-spasm cycle of chronic whiplash known as whiplash-associated disorders (WAD) is to treat the trigger points in the muscles. This is the finding of a new study from the University of Granada Department of Physical Therapy in Spain.

Trigger points (TrPs) are hyperirritable spots in the muscle caused by muscle immobilization (e.g., in a cast or splint or in response to pain after an accident) or overuse (repetitive motion). When active, these points create painful muscles and limited range-of-motion. Trigger points develop along with whiplash-associated disorder as a result of something called central sensitization.

Central sensitization is a hyperexcitability of the central nervous system. In other words, when present, TrPs "revv" up the engine of the nervous system and it doesn't slow down when the foot is taken off the accelerator. But there may be more to it than that as some research has shown a bidirectional mechanism. Input from TrPs to the nervous system increase pain sensitivity and vice versa. Increased sensitivity of the nervous system to stimuli may actually create the TrPs.

To understand more about the role of TrPs in whiplash-associated disorder (WAD), this group of physical therapists compared two groups of patients. Group one had a high level of whiplash-associated disability from a car accident that occurred in the last 30 days. Group two were sex- and age-matched controls who did not have a whiplash injury.

Everyone was tested for TrPs in the neck, face, and upper shoulder areas. Active neck motion was recorded and the participants rated their pain and disability. Pressure pain threshold (PPT) was also measured on both sides of the neck at C56, the second finger, and the tibialis anterior muscle of the lower leg/ankle. Pressure pain threshold is a measure of how much pressure it takes to create a painful response. Small amounts of pressure that result in high levels of pain is referred to as pressure pain hypersensitivity.

They found four major discoveries: 1) People with higher levels of neck pain were more likely to have trigger points and more of them. 2) The number of days from the accident was a factor. 3) Decreased neck motion was linked with TrPs. But which came first (the altered neck motion and then the TrPs or the TrPs and then the decreased neck motion) remains unclear. 4) Higher pressure pain sensitivity over the cervical spine (neck) is linked with more trigger points.

These findings support the idea that active TrPs generate pain in people with neck pain from a whiplash injury. The natural conclusion is that treating TrPs may be one way to reduce pain for individuals with whiplash-associated disorder. Future studies are needed to test out this theory.

Not all face, neck, and shoulder muscles were tested in this study so further studies are also advised to search for all likely TrP areas. Other factors that must be studied in relation to whiplash-associated disorders and trigger points (TrPs) include the influence of the joints, psychologic effects from the accident, and posttraumatic stress.


Antonio Manuel Fernández-Pérez, PT, MSc, et al. Muscle Trigger Points, Pressure Pain Threshold, and Cervical Range of Motion in Patients with High Level of Disability Related to Acute Whiplash Injury. In Journal of Orthopaedic & Sports Therapy. July 2012. Vol. 42. No. 7. Pp. 634-641.


07/25/2012

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