It seems safe to say that if you are currently working with patients who have pelvic pain, you are familiar with the phrase "trigger point." Yet, what is a trigger point? This question has proved elusive for quite some time, given that there is not always a palpable structure or a visible change in the tissue that produces the pain.
Travell and Simons, in their 2 volume classic work on myofascial paindescribe the concepts of active and latent trigger points, with an active trigger point being a location in the tissue that when palpated, reproduces the patient's symptoms, often at a site distant to the one being palpated.
In a very interesting article, Hong-You Ge, MD, PhD, and colleagues describe a possible mechanism for a local pain site (trigger point) creating more global and chronic pain via central sensitization. The authors explain the concepts of spontaneous electrical activity (SEA) at the myofascial trigger point (MTP) via research over the last decade. Some of the article (which you can read full-text thanks to PubMed Central access) will bring you back to physiology class as you do your best to recall gamma motor units within the muscle spindles or extrafusal motor endplate potential (yeesh).
While the authors admit that the "how" in formation of a taut band in a muscle is still under debate, the evidence they cite as explanation to many of the tissue responses is very enlightening and interesting. Dr. Ge also describes how motor control strategies are impaired by active trigger points. We may observe this in the clinic through the patient who reports that her urinary leakage control improves following muscle tension release techniques to the pelvic floor that were administered due to pelvic pain.
As the scientific community continues to give attention to the physiology behind connective tissue dysfunction, we should hope to better explain why some of our interventions are helpful in alleviating impairments. If you feel like nerding out and catching up on some of the interesting research related to trigger points, read this article. And then, be sure to use the phrase "membrane depolarization" in your next conversation.