What Is a Trigger Point Injection?
A trigger point injection is the administration of certain drugs directly into areas within muscles or fascia (the protective material surrounding many muscles of the body, which is composed of a material similar to connective tissue) that are sources of pain. This type of muscular pain may be a symptom of a variety of conditions.
The drugs included in trigger point injections may be local anesthetics such as lidocaine or procaine.
A more novel approach is to inject Botox (or botulinum toxin A) into a trigger point. This medication inhibits muscle contraction at a cellular level, which may contribute to the symptoms mentioned above. These injections are regarded as an effective treatment for pain or discomfort emanating from a trigger point.
Trigger point injections are associated with some risks, however. Common side effects include bleeding or infection in the skin or other tissue through which a needle has been inserted. These risks may be avoided by keeping the area clean and bandaged after a procedure. Patients who suffer from blood clotting disorders or who take medications to reduce clotting may not be suitable candidates for trigger point injections due to the risk of excessive blood loss. These injections may also be unsuitable for pregnant women and those with increased body mass (which may obscure or obstruct a clear injection path to certain muscles).
Local anesthetic medications are associated with adverse effects such as numbness or discomfort in the chest, temporary headache, and sensory problems. Botox is a diluted form of a bacterial neurotoxin. Therefore, side effects associated with this drug include muscle weakness, respiratory distress, or difficulty in swallowing.
How Are Trigger Point Injections Performed?A trigger point injection procedure is typically carried out in a pain clinic or similar facility.
The patient will be asked to sit or lie in a position in which the muscle(s) carrying a trigger point may be accessible to the doctor or pain specialist.
The trigger point may be located and visualized using technology such as ultrasound.
The skin above this area is cleaned, and the needle delivering the medication is inserted.
Injection can cause initial reactions such as sudden pain or spasm in the muscle(s) being treated. However, these are temporary.Optimal trigger point injections may require multiple injections of the same area. This ensures complete coverage of the affected muscle(s) by the drugs and thorough deactivation of the trigger point.
The average trigger point injection procedure lasts several minutes.
After a completed injection procedure, the patient may be advised not to strain or over-use the treated area.
The physician or specialist may also advise light exercise or stretching of the relevant muscle to contribute to the long-term remission of the trigger point while the tissue is relaxed by the injection.
Conditions Related To Trigger Point Injections
The development of trigger points is associated with conditions in which tightened bands of muscle tissue are formed by abnormal contraction, resulting in increased muscular tension. These may intensify or spread over time to form small, localized areas within the muscle, also known as a trigger point. In some cases, they may be felt under the skin as a knot or nodule. Knots may react with muscle twitches or pain when pressed on with a finger.
This disorder is also often known as myofascial pain syndrome, or pain of the muscles (‘myo-‘) or fascia. Myofascial pain syndrome can contribute to other musculoskeletal disorders such as rotator cuff disease (a condition affecting the upper arm and shoulder) by increasing the strain or pressure on a muscle or muscle group.
The exact mechanism by which myofascial pain syndrome arises and develops has not yet been established. It is thought to be due to a number of factors, rather than a singular cause. These may include damage or diseases of fascia or connective tissue. Autoimmune conditions, in which the body’s own fascia is attacked by its immune system, may also be factors in myofascial pain syndrome development.
Both cancer and its treatment (e.g. excision surgeries or chemotherapy) can result in damage to the healthy fascia or muscles in the vicinity of a tumor, leaving damaged and tightened muscle tissue as a consequence.
The formation of trigger points may also be associated with a range of factors and other conditions. These include:
- Abrupt overload or strain on the affected muscle(s)
- Decreases in the temperature of the affected muscle(s)
- Emotional distress
- Gall bladder diseases
- Lumbrosacral radiculopathy, or damage to nerve roots in the back, which may lead to excessive tension in back muscles
- Muscular fatigue
- Muscular trauma
In cases of conditions such as fibromyalgia and radiculopathy, trigger point injections may effectively relieve both muscle tension and the pain associated with these conditions.
An interesting and relatively new application of trigger point injection is in the treatment of certain types of headache. This is due to observations that trigger points in some muscles of the skull or neck may contribute to headache pain. Some studies have found that trigger point injection in some of these is a valid part of treatment for many types of headache (e.g. chronic or episodic). However, a study involving patients with episodic tension-type headaches and matched healthy controls found that, while trigger points were significantly more common in the patient group, this did not correlate with headache frequency, severity, or duration. This may indicate a need for further research to define the link between trigger point injections and improvements in headache disorders.
ConclusionTrigger point injections are injections of drugs such as procaine or Botox directly into points of muscle tissue subject to excessive tension.
These trigger points may be associated with pain, reduced mobility, and negative effects on life quality.
These procedures are relatively quick and convenient, and can effectively address trigger points associated with various conditions and syndromes.
A consultation with your pain specialist may help if you have, or suspect you may have, one or more muscular trigger points.
- CADTH Rapid Response Reports. Botulinum Toxin A for Myofascial Pain Syndrome: A Review of the Clinical Effectiveness. Ottawa (ON): Canadian Agency for Drugs and Technologies in Health. Copyright (c) 2014 Canadian Agency for Drugs and Technologies in Health.; 2014.
- Morjaria JB, Lakshminarayana UB, Liu-Shiu-Cheong P, Kastelik JA. Pneumothorax: a tale of pain or spontaneity. Therapeutic advances in chronic disease. 2014;5(6):269-273.
- Soares A, Andriolo RB, Atallah AN, da Silva EM. Botulinum toxin for myofascial pain syndromes in adults. The Cochrane database of systematic reviews. 2014;7:Cd007533.
- Robbins MS, Kuruvilla D, Blumenfeld A, et al. Trigger point injections for headache disorders: expert consensus methodology and narrative review. Headache. 2014;54(9):1441-1459.
- Suh MR, Chang WH, Choi HS, Lee SC. Ultrasound-guided myofascial trigger point injection into brachialis muscle for rotator cuff disease patients with upper arm pain: a pilot study. Annals of rehabilitation medicine. 2014;38(5):673-681.
- Cardoso LR, Rizzo CC, de Oliveira CZ, Dos Santos CR, Carvalho AL. Myofascial pain syndrome after head and neck cancer treatment: Prevalence, risk factors, and influence on quality of life. Head & neck. 2014.
- Saeidian SR, Pipelzadeh MR, Rasras S, Zeinali M. Effect of trigger point injection on lumbosacral radiculopathy source. Anesthesiology and pain medicine. 2014;4(4):e15500.
- Affaitati G, Costantini R, Fabrizio A, Lapenna D, Tafuri E, Giamberardino MA. Effects of treatment of peripheral pain generators in fibromyalgia patients. European journal of pain (London, England). 2011;15(1):61-69.
- Fernandez-de-Las-Penas C, Cuadrado ML, Pareja JA. Myofascial trigger points, neck mobility, and forward head posture in episodic tension-type headache. Headache. 2007;47(5):662-672.