The trigger point is a tension knot that can cause symptoms of pain and neuropathy in patients. It can trap or irritate surrounding nerves and cause referred pain, which is felt elsewhere in the body. Over time, scar tissue, loss of range of motion, and weakness may also develop. We now know that myofascial trigger points (MTRPs) can cause deep pain and radiate numbness, tingling, sensation or pain similar to that of neuralgia or nerve pain.
Low back pain caused by a herniated disc produces postural compensations that may result in trigger points. An amputation due to trauma or diabetes will cause an alteration in biomechanics due to a compensatory gait pattern; the new walking pattern will cause excessive use of muscles, which may lead to activation points. A trigger point may appear in a similar way in patients who have suffered a stroke or spinal cord injury, due to the resulting postural changes. Whether the injury is muscular or nerve, the end result is the perpetuation of muscle spasms in the muscle. Muscle spasms are usually felt as tender muscle knots or tender regions in a tight muscle band that hurt when pressed.
This muscle knot is called a trigger point. When the trigger point is examined microscopically, there are multiple individual muscle fibers that have knots. When there are trigger points, muscles shorten, tendons stretch, blood vessels contract, and nerves that cross the area are compressed. This causes local pain and sometimes far from the site and sensory symptoms such as numbness and tingling.
Sometimes, a restricted range of motion occurs. The general consensus is that the formation and maintenance of muscle activation points is the reason why patients experience pain and sensory symptoms. Trigger points can form quickly after trauma or slowly over time when pressure is gradually applied to the muscle; such is the case with common injuries due to poor posture or repetitive movements. The research study, Etiology of Myofascial Trigger Points, supports the theory that trigger points are victims of muscle overuse. A common misdiagnosis is trigeminal neuralgia, which may be caused by trigger points in the sternocleido-mastoid muscle. Not only can myofascial trigger points hide an underlying health problem, but they can also mimic other known pain patterns.
Chances are you're experiencing a trigger point reading this, or you've experienced one at some point in your life. These trigger points don't allow the inner thighs on that side to lengthen the same as the one on the left side, making the knee higher. Patients will feel musculoskeletal pain in an area of the body when a trigger point has been irritated, and they may even feel the knot that is causing the pain. I have treated people with scalenes (trigger points) who thought they were having a heart attack because their chests started to hurt and they started to feel tingling in their arms and getting sleepy. A proper understanding of the triggers and the influence of manual therapy is necessary to honestly educate patients. The authors concluded that, despite the lack of well-designed studies, the best available evidence supports that trigger points develop after excessive use of muscles.