Researchers have observed a phenomenon called “central sensitization” (CS) that 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? Well, if we can find a way to raise the pain threshold in patients with CS, then this could reduce the intensity and frequency of their sometimes intense and debilitating chronic pain.
Researchers have found that pain thresholds improve after an anesthetic agent is injected into myofascial trigger points (MTrP)—those tight, sore “knots” commonly found in muscles after injuries such as whiplash trauma. It has been proposed that these MTrP may act as “thermostats” controlling the manner in which the brain perceives and relays pain.
To test this theory, a 2017 double-blind study randomly assigned chronic pain whiplash patients to either a group receiving the “real” anesthetic agent or a “sham” or fake injection of the MTrP. The researchers measured pain (on a 0-10 scale), pressure perception, grip strength, and the range of motion (ROM) of the jaw in subjects from both groups before and after each intervention.
As postulated, 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. This study concluded that the pain threshold associated with CS can be modulated 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 utilized by chiropractic, 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 as well as other injuries. 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.