Trigger Point Injections in St. Louis

A trigger point is a small, tight band in a muscle that will not let go. It hurts when you press on it. It also sends pain to other places. A trigger point in the upper trapezius (the muscle on top of the shoulder) often sends pain into the head and neck. Left alone, the muscle around it tenses up to guard the pain. That pulls the band even tighter.

A fine needle goes right into the tight band. Then a small volume of local anesthetic is injected. The needle working together with the anesthetic breaks the cycle of spasm and pain. That lets the muscle stretch out again. We use ultrasound to guide the needle when the target sits near a nerve, a blood vessel or the chest wall.

Muscle pain of the neck, shoulders, upper back and the low back muscles along the spine responds best. We also use trigger point injections with other treatments when tense, guarding muscles are holding back your rehab. That includes rehab after a motor vehicle injury.

The injection takes only a few minutes. Several points can be treated in one visit. Soreness at the injection site is normal for a day or two. Stretch the treated muscle gently afterward. The goal is to give the muscle back its length, not just to numb it.

The leading explanation is the integrated hypothesis. It puts the problem at the motor endplate, where the nerve meets the muscle. Too much acetylcholine (the nerve’s signal chemical) is released. That keeps a small cluster of sarcomeres (the tiny units that make muscle contract) locked tight. Because those units cannot relax, they squeeze the tiny blood vessels that feed them. That cuts off the oxygen and ATP (the cell’s fuel) the muscle needs to let go. The squeeze starves the muscle, and the starved muscle keeps squeezing.

In that low-oxygen pocket, bradykinin, substance P, CGRP and hydrogen ions build up. All of them make the local pain nerves more touchy. That is why an active trigger point is so tender for its size. It is also why pressing it brings back your own familiar pain, not just a new hurt.

Trigger points send pain in patterns that do not follow dermatomes (the skin areas each spinal nerve serves). That often confuses the diagnosis. The spread starts in the spinal cord. Steady pain signals from the muscle wind up dorsal horn neurons (pain relay cells in the spinal cord). Those same cells also get signals from other body areas. So the brain gets the source wrong. The wiring is the same from person to person. So the pain maps repeat between people, and that makes them useful in the clinic.

It also explains why treating only the spot that hurts often fails. The upper trapezius sends pain into the temple. The gluteus minimus (a deep hip muscle) sends pain down the leg, much like sciatica. Treating where you feel the pain instead of where the trigger point sits is a common reason these problems last for years.