Overview of Trigger Point Injection
Myofascial trigger points, first identified by Dr. Janet Travell in 1942, are like “knots” that can form in your muscles. They are particular spots in your muscles that are tense and when touched they can cause pain at another part of the body, not just the area that’s being pressed on. They can sometimes also cause a small jerky movement known as a twitch response. These trigger points can lead to stiffness, limit the movement of the joint, and potentially be linked to chronic conditions that affect your muscles and bones.
These points can develop after an injury or as a result of ongoing strain on your muscles. However, it’s important to know that trigger points are not the same as tender points. The main difference between them is that tender points are specific spots that hurt where they are pressed and do not cause pain anywhere else.
People can have one or many of these trigger points in their body. There are several ways to treat them, such as using ultrasound, manipulation therapy which involves moving and massaging the muscles, a method called Spray and Stretch which uses a cooling spray to numb the area and then stretches the muscle, and injections. Each of these methods works in a different way to help relieve the tension from these points.
Anatomy and Physiology of Trigger Point Injection
The development of trigger points, or sore spots in muscles, is believed to be connected to irregularities at the junctions within a muscle where motor nerves, which control muscle movement, and pain nerves co-exist. This is likely tied to an increased sensitivity in the spinal cord. According to electromyography (EMG) studies, which measure muscle response or electrical activity, trigger points show spontaneous electrical activity. This suggests improper electrical signal generation in these areas.
This theory is supported by histological evidence, which is microscopic study of tissues, from muscle biopsies that show signs of muscle hyper-contracture. This is consistent with continuous calcium release from the sarcoplasmic reticulum (a structure in our muscle cells) because of neural activation and generation of electrical signals. Because of this, patients may feel localized pain, muscle tension, and have a decreased range of motion in affected areas.
Trigger point injections, a treatment method for these sore spots, are most commonly used for muscle groups such as the masseter (major muscle in the jaw), levator scapulae (muscle along the neck to shoulder), gluteus medius (muscle in the buttock), quadratus lumborum (muscle in the lower back), trapezius (muscle in the back and neck), sternocleidomastoid (muscle in the neck), and temporalis muscles (muscle on the side of the head).
Trigger points affecting the trapezius muscle can result in tension headaches or pain in the neck, shoulders, and upper arms. Trigger points in the iliopsoas muscle (a muscle that connects the spine to the leg) are commonly responsible for causing groin pain.
Why do People Need Trigger Point Injection
Trigger point injections (TrPi) are a type of treatment used to help with myofascial trigger points, which are essentially knots in your muscles that can cause pain. These injections have been shown to be effective in treating these painful muscle knots, especially in people who are experiencing symptoms. How do they work? When these injections are given, they relax the tight knot of muscle, which helps to improve blood flow to the area and allows the muscle to extend to its proper length. This also helps to remove any waste or byproducts that have built up in the muscle. This combination of benefits helps to break the cycle of pain and tension.
Trigger point injections are usually used when there’s a particular spot in the muscle that can be felt, and produces pain when it is touched or pressure is applied. This treatment is commonly used for various conditions including chronic or occasional headaches, pain in the jaw joint, back pain, reduced movement due to muscle knots, and pain in the groin area.
When a Person Should Avoid Trigger Point Injection
There are several reasons why a doctor might not perform a treatment called a trigger point injection. These reasons can be categorized as absolute, which means the procedure cannot be done safely, or relative, which means the procedure will need additional care or considerations.
Absolute reasons are:
- If the patient doesn’t want the procedure
- If the patient has a serious skin infection where the trigger point is located
- If the patient has a defect in their skull near the trigger point
- If the trigger point is in a spot that isn’t safe to reach with a needle
The relative reasons, which mean the doctor will need to be extra careful, are:
- If the patient is taking blood thinners, is pregnant, or if it’s difficult to identify where the trigger point is
- If the person has a known allergy to local anesthetics, which are medicines used to numb a specific area
- If the patient has severe fibromyalgia, which is a disease that causes pain and tenderness throughout the body
- If the patient has a history of forming keloids, which are thick, raised scars
- If the patient has a psychiatric disorder that’s not well-managed
- If the patient is very anxious or has a big fear of needles
Equipment used for Trigger Point Injection
If a doctor decides to perform a treatment known as a trigger point injection, they’ll need several different tools and substances. This could include:
A short, thin needle (27-30 gauge, 1.5 inches), or even acupuncture needles if a technique called “dry needling” is being used. This needle will be attached to a small tube called a syringe, which can hold 3, 5, or 10-mL of liquid. The doctor will wear non-sterile gloves during the procedure.
Sometimes, an anesthetic, or numbing agent, like lidocaine or bupivacaine without epinephrine, might be used to help make the procedure more comfortable. Sodium bicarbonate, a type of salt, might also be added to reduce discomfort.
The doctor might also decide to include a corticosteroid, or anti-inflammatory medicine, such as triamcinolone, or an alternative therapy solution such as D5W or sterile saline, a type of salt water. Sometimes, a topical anesthetic spray, (optional), like ethyl chloride might be used to numb the skin where the injection will take place.
They might also consider adding steroids like triamcinolone or dexamethasone to the local anesthetic mixture.
Before the procedure, the doctor will clean the skin using alcohol pads or a chlorhexidine 2%, a skin disinfectant. They’ll also use a device called a pulse oximeter and a blood pressure monitor to check your vital signs during the procedure.
Who is needed to perform Trigger Point Injection?
Trigger point injections, which are used to relieve pain, can be done by medical professionals like doctors, physician assistants, and nurse practitioners. These healthcare providers have gone through intensive training and have developed specific skills to perform this procedure safely and effectively. It’s also advised to have a team of medical support staff on hand to get everything ready for the procedure.
Preparing for Trigger Point Injection
Before a doctor performs a trigger point injection, they will first explain to the patient what the procedure entails, including its benefits and potential risks. The patient or their legal guardian if the patient is not fully capable, must then give their permission in writing before the procedure. During this time, all the necessary equipment is prepared and checked thoroughly, and another member of the healthcare team is present to ensure everything is correct before the procedure starts.
The patient will either be seated or lying down, depending on where the trigger point is located. After this, the doctor will clean the treatment area with alcohol wipes or a 2% chlorhexidine solution, a type of antiseptic, and allow it to dry. To make the procedure easier, some doctors like to mark each trigger point with a skin marker or pen for reference.
If a type of pain relief spray is used, the doctor will apply it onto the trigger points before the procedure in order to numb the area. This helps to make the patient more comfortable during the procedure.
How is Trigger Point Injection performed
Once a specific tight or tender area in a muscle (known as a “trigger point”) has been found, the skin above it is cleaned. The doctor then uses the fingers of one hand to pinch and hold the trigger point in place. Meanwhile, using their other hand, the doctor inserts a small needle attached to a syringe into this tight area at a slight angle. The needle is moved in and out of the muscle without being fully removed, in a rhythmic fashion. This process is repeated from different angles until the muscle starts to twitch or finally feels less tense. The doctor may feel a “crunching” or “pulling” sensation as the needle moves within the tightened muscle, but this feeling should lessen as the treatment continues.
If the treatment involves just using the needle without any medication (referred to as “dry-needling”), the process is completed when the trigger point becomes relaxed. If the treatment involves injecting medication, the doctor will then make sure that the needle is not inside a blood vessel by pulling back on the plunger of the syringe (this is called aspirating). If it’s all clear, they will then inject a small amount of the chosen medication into the trigger point. They may inject the medication straight in or in a ‘fanning’ pattern.
This technique will then be repeated if there are more trigger points to be treated. Both dry needling and injecting a numbing medicine called lidocaine have similar results, but numbing the area with lidocaine can result in less soreness after the procedure. If it’s possible, and provided the provider has been trained to do so, ultrasound can be used for guidance during the injection to confirm that the needle is in the right place and avoid hitting nerves or blood vessels.
Possible Complications of Trigger Point Injection
Trigger point injections are a type of treatment often used to help manage pain. Like all treatments, there can be potential side effects or complications. Some people might experience pain, bleeding, or an infection after a trigger point injection. It’s also possible to have an allergic reaction to the medications used during the injection, or a physical reaction to the injection itself causing a bruise (hematoma), or an injury to a blood vessel.
Rarely, these injections can cause more serious complications, such as pneumothorax, a condition where air gets trapped between your lungs and chest wall. This is especially true when the injections are used to treat pain in the upper back and neck region. To lower the risk of this complication, doctors will take special measures, like using a certain grip and angle during the injection when treating areas around the ribs.
Very rarely, some people might have severe muscle weakness due to low potassium levels in the blood, a condition known as severe hypokalemic paralysis. There can also be other side effects related to the injection technique, such as soreness after treatment, a sudden drop in heart rate and blood pressure leading to fainting (vasovagal and syncopal response), bleeding at the treatment site, or a blood-filled swelling in the neck region (acute cervical epidural hematoma).
What Else Should I Know About Trigger Point Injection?
Pain in our muscles and bones can often lead to a visit to your doctor or a pain specialist. It’s a common problem that these healthcare providers deal with regularly. To handle this pain successfully, various treatments are often used together. This multi-pronged approach usually offers safer and more effective results.
One treatment option they might suggest is trigger point injections. These injections are aimed at reducing pain in the muscles and bones. The injections target specific pain points in your muscles. By doing this, healthcare providers can directly treat the troubled area, address the source of your pain, and disrupt ongoing pain cycles. Best of all, this treatment usually has few, if any, side effects.
Patients often notice a significant improvement in movement range and overall physical function. Additionally, they can achieve this without needing to take pain medication. Trigger point injections are known to yield meaningful outcomes, so it’s worth considering this treatment in the right circumstances.
