Researchers have observed a phenomenon called “central sensitization” (CS). It is common in patients who have long-term, chronic pain following trauma such as whiplash. With CS, the patient’s ability to feel pain is abnormally high or hypersensitive. So when pain from pressure, temperature, electrical, or other sources is applied to the skin, they feel it sooner and more intensely than individuals without CS.
Why is this so important? If we can find a way to raise the pain threshold in patients with CS, then it reduces the intensity and frequency of their debilitating chronic pain.
Researchers find that pain thresholds improve after an anesthetic agent injects into a myofascial trigger point (MTrP). Myofascial trigger points are tight, sore “knots” commonly found in muscles after injuries such as whiplash trauma. These MTrP may act as “thermostats” controlling the manner in which the brain perceives and relays pain.
Pain Threshold Associated With CS
To test this theory, a 2017 double-blind study randomly assigned chronic pain whiplash patients to two groups. There is a group receiving the “real” anesthetic agent or a “sham” or fake injection of the MTrP. Researchers measured pain, pressure perception, grip strength, and range of motion (ROM) of the jaw in subjects from both groups before and after each intervention.
Only the group receiving the “real” anesthetic agent had improved pressure pain tolerance in addition to increased jaw ROM. Unexpectedly, both groups experienced similar improvements when rating their pain on a 0-10 scale. In conclusion, the study shows that the pain threshold associated with CS can alter by injecting myofascial trigger points (with or without an anesthetic agent). Although, only the anesthetized group had objective improvement (jaw ROM and pressure sensitivity improvement). Interestingly, the treatment of painful trigger points has LONG been a common form of care by chiropractors. This treatment is known as trigger point therapy or TPT. Myofascial release is another soft-tissue technique commonly utilized over MTrP by chiropractors.
This study may help explain why so many patients benefit from chiropractic care following whiplash trauma. The added benefits from spinal manipulation and modality use over trigger points are two additional ways chiropractic care can benefit those suffering from both acute and chronic pain associated with whiplash trauma.
