Local Anesthetic Injection of Trigger Points
This can be thought of as acupuncture but done with a slightly larger needle and deeper into the muscle.
This procedure is done for myofascial pain syndrome, which is a condition used to describe pain that comes from muscles and their encasings (fascia). It is characterized by myofascial trigger points, which are hard, palpable, discrete, localized nodules within taut bands of muscle which can be painful on compression.
Making the diagnosis (Rivers 2015):
1. A tender spot is found with palpation, with or without referral of pain (trigger point) and;
2. Recognition of symptoms by patient during palpation of tender spot and;
3. At least three of the following:
a. Muscle stiffness or spasm
b. Limited range of motion of an associated joint
c. Pain worsens with stress
d. Palpation of taut band and/or nodule associated with a tender spot
It is thought that physical overloading of muscles is a key factor, followed by lifestyle factors that potentiate the formation of a trigger point. Once formed, a lack of oxygen to the trigger point, in an inflammatory milieu, stimulate local nerves to be more sensitive, eventually leaving an imprint within the central nervous system as it becomes chronic in nature.
Trigger point injections are thought to interrupt this pain signaling pathway.
What are the benefits?
Pain relief is the main benefit. A recent metanalysis of 33 studies published in 2019 by Ahmed and colleagues, in the Clinical Journal of Pain, demonstrated that local anesthetic injections in the regions of taut bands or myofascial trigger points are effective at reducing pain.
With ultrasound-guidance, the specific characteristics of the taut band and/or trigger point can be observed prior to injection, as well as its response to it afterwards. Localizing the muscle under ultrasound improves accuracy, thereby necessitating less medication, and minimizing side effects.
What are the alternatives?
Conservative treatment includes aerobic exercise, strengthening and stretching of muscles, and mindfulness. Allied health professionals, such as massage, chiropractic, and physical therapy are also helpful. Oral medications can also be trialed, but side effects are possible.
For any chronic pain issue, a multi-modal approach must be used.
In terms of procedures, injections with botulinum toxin (botox) have been reported, but they have not consistency reproduced favorable results (Ahmed 2019). This may be due to methodological differences in study design, and the research is still evolving in this field.
How long will my pain be reduced?
This depends on several factors, such as how long this has been an issue, the number of areas involved, and how these injections fit into the overall treatment plan. It is not uncommon for pain to return after a few weeks, necessitating repeat injections. For some, pain relief can last much longer.
How often can I have this done?
A good response to this medication is a decrease of pain of at least 3/10 for more than 6 hours (Ahmed 2019). If this is achieved, there is evidence of therapeutic effect. Injections can be performed every few weeks if required, so long as it fits with the patient’s overall goals, lifestyle, and expectations.
Who can’t have this done?
Any patient who may appear to have:
- Infection within the body, near the site of administration, or the actual joint itself
What are the side effects?
- Pain after injection: Muscle soreness after the injection is common, like getting a flu shot. Like other injections, it usually settles within 2 days. Application of ice and Tylenol can help, if desired.
- Pain during the procedure: The skin is the most sensitive part when it comes to any injection. We minimize this by using a vapocoolant spray on the skin. Pain associated with the injection is usually brief and well-tolerated.
- Infection: When a needle is passed through the skin into the body, there is a very small chance of introducing an infection. The chance of this occurring is extremely low, less than 0.002%, or equivalent to being struck by a car as a pedestrian and experiencing a catastrophic event. To minimize this risk, we not only follow the WHO minimum best practice standards for injections, but use sterile gloves, sterile ultrasound probe covers, and sterile ultrasound gel.
- Bleeding: This is a greater risk if you have a known bleeding disorder or are taking blood thinners. By using ultrasound guidance, there is less “poking” around to get to the target tissue of interest, and thus less theoretical risk of bleeding. Pressure is maintained over the skin afterwards to reduce bleeding.
- Allergy: A swelling reaction to the local injectate can occur at the site of administration, or even rarer a whole-body reaction (case reports only). We ask all patients to remain in the clinic waiting room afterwards for a minimum of 15 minutes to observe for any adverse reactions to the medication.
Can I drive afterwards?
If you were able to drive to the appointment, most people can drive afterwards. Nonetheless, we ask all patients to remain in the clinic waiting room for a minimum of 15 minutes afterwards to observe for any adverse reactions if steroid was provided.