Although injections may be helpful in confirming a diagnosis, they should be used primarily after a specific presumptive diagnosis has been established. Injections should not be used in isolation, but rather in conjunction with a program stressing muscle flexibility, strengthening, and functional restoration. Proper follow-up after injections to assess the patient's treatment response and ability to progress in the rehabilitation program is essential. A limited number of injections can be tried to reduce pain, but careful monitoring of the response is required prior to a second or third injection.
These injections are an adjunct treatment, which facilitates participation in an active exercise program and may assist in avoiding the need for surgical intervention. All physiatrists who perform injections should be aware of the indications, contraindications, and complications of therapeutic injections, and fully inform patients of the potential risks.
Myofascial trigger points are felt to be hyperirritable foci in muscles and fascia associated with taut muscle bands. Trigger points are diagnosed by palpation and produce a local twitch response and a referred pain pattern distal to the site of muscle irritability. Trigger points cannot be properly diagnosed in the acute stages of low back pain when muscle spasm and inflammation are present. Initially, trigger points generally respond to a program of stretching and correction of poor postural mechanics with or without other modalities, such as superficial heat or cold. Trigger point injections should be reserved for patients who have not responded in the first four to six weeks to a properly directed program and appropriate pharmacologic intervention.
The trigger point injection should be carried out under antiseptic technique informing the patient of potential adverse effects. There is little evidence to support any beneficial effect of adding corticosteroid to the injection. In fact, a saline injection can as effective as a local anesthetic. However, for patient comfort and to assist in deciding upon therapeutic efficacy, injecting a local anesthetic such as lidocaine and/or mepivacaine is acceptable.
Injection of multiple trigger points should be avoided. Some trigger points may require more than one injection, but generally more than three injection of the same trigger point is not indicated. Repeated trigger point injections may cause local muscle damage and scarring, which may potentially lead to a poor functional outcome. They should not be performed in isolation, but rather, in conjunction with a directed exercise program. Proper follow-up after injections is necessary in order to assess the patient's response to the injection and to progress the rehabilitation program.