The Myofascial Pain Syndrome and Trigger Point Therapy
The myofascial pain syndrome, MPS is one of the most common overlooked diagnoses in chronic pain. Up to 85% of patients with chronic pain have an underlying MPS. The terms MPS, myofascial trigger point, taut band, local twitch response and their definitions were first published in the fifties by Dr. Janet Travell. In 1983, together with Dr. David Simons, Travell published the groundbreaking Trigger Point Manuals which are now in their second edition and have been translated into 12 different languages. Today Travell and Simons can be considered as true medical pioneers.
The Foundations of Trigger Point Therapy
The goals of successful trigger point therapy are releasing local sarcomere contractions, increasing local blood flow as well as inhibiting local inflammatory processes. The more precisely trigger points are treated the better the results achieved. There is a worldwide consensus among specialists that the combination of manual trigger point therapy and dry needling are the most effective approaches in the treatment of trigger points.
The hallmark of the MPS are myofascial trigger points. Imaging techniques to diagnose trigger points and taut bands exist. However they have little value in clinical practice. The characteristic features of trigger points can be manually identified by palpation. The accepted diagnostic criteria are:
- taut band
- local tenderness within the taut band
- referred pain
- local twitch response
Many studies have shown a high interrater reliability among trained clinicians for the diagnostic criteria of trigger points. The MPS can be local or widespread. It can affect one, two or more quadrants. This is one of the reasons why the MPS is often mistaken for fibromyalgia. Trigger Points have characteristic referred pain patterns.
Pathophysiology of Myofascial Trigger Points
Muscle lesions (e.g. trauma, RSI) can cause ruptures of the sarcoplasmatic reticulum which leads to an uncontroled release of calcium ions from the sarcoplasmatic reticulum. This in turn causes persistent sarcomere contractions. Many contracted sarcomeres and muscle fibres cause the taut band. Taut bands are palpable and can be visualized by ultrasound and MRI. On the one hand prolonged contractions have an increased energy demand and on the other hand they compress vessels, which leads to a decreased energy supply. The result is an energy crisis. Due to the lack of ATP there is also a decreased reuptake of calcium ions into the sarcoplasmatic reticulum which perpetuates contractions. As a result there is a local release of bradykinin and CGRP which lower the threshold of nociceptive endings. Many studies confirm the energy crisis theory. The integrated hypothesis is an expansion of the energy crisis theory and is the most accepted model for the explanation of trigger points. It postulates that the energy crisis process takes place in the vicinity of motor endplates. This leads to an incresed release of acetylcholine and therefore perpetuates the vicious circle of prolonged contraction.