Overview of Suprascapular Nerve Block
The suprascapular nerve block is a helpful procedure for providing pain relief and numbing for the shoulder. The suprascapular nerve is a nerve in the shoulder that gives feeling to the acromioclavicular and glenohumeral joints, which are parts of the shoulder. This nerve also controls the supraspinatus and infraspinatus muscles, which are muscles that help move your shoulder. To help stop shoulder pain, doctors can specifically target and numb the suprascapular nerve without impacting the phrenic nerve which helps control breathing. This process is usually done as an alternate method to the interscalene brachial plexus block, which often causes one side of the diaphragm to be paralyzed due to the numbing of the phrenic nerve.
There are two main ways doctors can numb the suprascapular nerve. The first method, called the landmark-based posterior approach, was first used in 1941 by Wertheim and Rovenstein to treat severe, chronic shoulder pain. More recently, doctors use nerve stimulation and ultrasound to help find and numb the suprascapular nerve more accurately. However, this method can be tough due to the small size of the nerve and its location within the shoulder, below the trapezius and supraspinatus muscles.
In 2012, Andreas Siegenthaler and his team introduced a new, ultrasound-guided anterior approach to the suprascapular nerve block. This method uses ultrasound to guide the doctor towards the nerve from the front of the shoulder. Further details about how and when to use both the posterior and anterior approach, as well as possible complications from these procedures, will be discussed.
Anatomy and Physiology of Suprascapular Nerve Block
The suprascapular nerve is a nerve in your neck and shoulder that controls movement and feeling. It comes from the 5th and 6th spinal nerves in your neck. Sometimes, it may also get fibers from the 4th spinal nerve. This nerve initially is part of what we call the upper trunk of the brachial plexus – a network of nerves that send signals from your spine to your shoulder, arm, and hand.
This nerve moves around some muscles in your neck, goes through a notch (basically a narrow opening) in your shoulder blade, and travels under a muscle in your shoulder. It then exits this path through another notch and goes into a different area of your shoulder blade.
The suprascapular nerve helps control your shoulder muscles. Before it enters the path through your shoulder blade, the nerve powers the muscle that helps lift your arm. After it exits the path, it powers the muscle that helps roll your shoulder outward. The nerve also sends feeling signals from both of your shoulder joints, although other nerves also send feeling signals from these joints.
There are ways doctors can view this nerve. One way is to use an ultrasound, a device that uses sound waves to create pictures of the inside of your body. They place it in front of the bone in your shoulder and move it up and down. This gives them an image of the different layers of skin, fat, and muscle in your shoulder, and lets them see the spot where the nerve and a blood vessel sit on the bone in your shoulder.
A doctor can also find the suprascapular nerve near the network of nerves at the base of your neck, beside a muscle called the omohyoid. This is an alternative way to look at the anatomy of the nerve.
Why do People Need Suprascapular Nerve Block
A suprascapular nerve block is a medical procedure that doctors use to help relieve chronic (long-term), acute (sudden), and perioperative (around the time of surgery) shoulder pain. This technique was first used in 1941 to help a patient dealing with severe shoulder pain that wouldn’t go away.
This type of nerve block can help many different people, including those with chronic pain conditions. This includes things like inflammatory arthritis, rheumatoid arthritis, adhesive capsulitis (also known as frozen shoulder), rotator cuff tendonitis, bursitis, degenerative disease, and constant shoulder pain after surgery or a stroke.
A suprascapular nerve block can be especially helpful for people who have had trauma or surgery, as the shoulder pain that happens suddenly after these events can be really intense and make it hard to function.
In some cases, such as the period around a surgery, a suprascapular nerve block can be a real game-changer. In particular, it can really help control shoulder pain in people who have severe lung conditions that make a different type of nerve block (known as an interscalene brachial plexus block) not a good option. This other type of block can cause a motor blockade of the phrenic nerve, which controls the movement of the diaphragm – an important muscle for breathing.
When a Person Should Avoid Suprascapular Nerve Block
A suprascapular nerve block is an optional procedure used to help with pain. Just like any medical procedure, there are certain reasons or situations where it may not be a good idea or even possible to carry it out.
One outright reason for not going ahead with the procedure is if the patient refuses it. It’s also not recommended if the patient is unable to stay still or cooperate during the procedure. This is important because usually, the procedure is done while the patient is awake. Being awake allows the patient to give feedback that could help the doctor adjust the position of the needle. That being said, in certain cases, it’s still considered safe to do this procedure under general anesthesia, which is when a patient is put to sleep for surgery. This is true especially when the doctor uses ultrasound for guidance.
Another reason why a patient wouldn’t be able to have a peripheral nerve block is if they’re proven to be allergic to all types of local anesthetics, which are drugs used to stop pain in a specific area of the body. Though this kind of allergy is extremely rare, it does happen.
Equipment used for Suprascapular Nerve Block
When a doctor needs to numb a certain part of your body, they might use a technique known as a peripheral nerve block. They use a special machine, called a diagnostic ultrasound machine, to help guide this process. This machine uses different levels of sound waves to see different depths in the body. For structures closer to the surface, the machine uses high frequency sound waves (between 5 and 13 MHz), while for structures deeper in the body, the machine uses low frequency sound waves (between 2 and 5 MHz).
The doctor uses a special type of needle, known as an echogenic short bevel block needle, to inject the numbing medicine for single-use nerve blocks. If you need the numbing effect to last for a longer time, they may use a larger needle called a 17-gauge Touhy needle. This needle is used to place a tiny tube called a peripheral nerve catheter that can provide a continuous flow of the numbing medicine.
The specific numbing medicine the doctor uses, known as a local anesthetic, will depend on what they feel is best for your procedure. The options usually include various concentrations of medicines called bupivacaine or ropivacaine. Sometimes, they will add other medications to the numbing solution to improve its effectiveness or make it last longer.
Before the procedure, the doctor will clean your skin with either a Chlorhexidine 2% or povidone-iodine solution to prevent infections. They will use a special syringe with an extension tube to inject the numbing medicine into your body. This helps them to deliver the medicine accurately and safely.
The area around the ultrasound machine will be kept sterile with a cover and gel. While the procedure is happening, your doctor will monitor your vital signs such as blood pressure, heart rate and oxygen levels to make sure everything is going smoothly. These are typically monitored with non-invasive tools like a blood pressure cuff, EKG, and a device called a pulse oximeter which measures oxygen levels in your blood.
Who is needed to perform Suprascapular Nerve Block?
A trained medical professional, like a doctor or nurse, can perform a procedure known as a ‘suprascapular nerve block’. This is a type of treatment used to relieve shoulder pain. Sometimes, extra help might be needed to make sure you are positioned comfortably, to give you medicine that will help you relax (sedation), or to assist with injecting the local anesthetic (a medication to numb a specific area of your body).
Preparing for Suprascapular Nerve Block
The doctor will first explain to the patient all the aspects of the procedure – its benefits, potential risks and other alternatives. The patient’s understanding and agreement is crucial at this stage. Once the patient has been briefed, we’ll work on setting up. The patient’s vital signs like blood pressure, pulse, temperature, and breathing rate will be monitored through special equipment. The patient can then be moved into the right position. The best position for the “posterior approach” (a method that allows the doctor to access your shoulder blade and a notch in your shoulder blade) is to sit upright. If the “anterior approach” method is used, which requires access to the area beside your collarbone, the patient should lie down slantingly. Placing a blanket behind the patient’s shoulders can help make the collarbone area clearer for the procedure.
Before starting, the doctor will clean the skin over the injection site using chlorhexidine, a kind of disinfectant, to eliminate possible infections. The doctor will use a special cover and gel on the ultrasound device used for guidance during the procedure. The medicine for the block will be drawn into a syringe attached to a needle and any air will be removed from it.
How is Suprascapular Nerve Block performed
The suprascapular nerve block is a technique used to manage pain in the shoulder area. This procedure can be done in two ways: one from the back side of the shoulder, or another from the front, near the collarbone. Both ways can be performed with the help of ultrasound for better accuracy.
In the beginning, a device using ultrasound will be placed above your collarbone to help your doctor locate a specific nerve bundle in your neck area. They will trace this nerve bundle to find the exact location of the suprascapular nerve. They will then follow the suprascapular nerve down to where it is nearby to the brachial plexus, a network of nerves that run from the spine, through the neck and armpit and into the arm.
Your doctor will then use a needle to inject a solution, which helps to block pain, around the suprascapular nerve. They will check to make sure the needle is in the right place and not located in a blood vessel. The amount of solution is usually small, but they will keep injecting until they see that it has spread completely around the nerve.
The suprascapular nerve block can also be performed from the back side of your shoulder. The ultra sound device will be placed near your shoulder blade. Your doctor will be able to see a specific area of your shoulder blade known as the suprascapular canal. Within this area, they will be able to locate the suprascapular nerve and a blood vessel, the suprascapular artery.
A needle is then used to inject a solution to block the pain. The injection is done at about halfway along the nerve, between the suprascapular and the spinoglenoid notch – two notches in your shoulder blade. The doctor will check to make sure the needle is in the right place and not inside a blood vessel. The amount of solution is usually small, but they will keep injecting until they see that it has spread completely around the nerve.
Both these methods help block the pain signals to your brain and provide relief, and your doctor will select the best method for your individual situation.
Possible Complications of Suprascapular Nerve Block
Using ultrasound carefully during procedures, and making sure the needle tip is always visible, can reduce the risk of complications. One possible complication is a pneumothorax, or a collapsed lung, which can happen if the needle is inserted too far. This happens in about 1% of procedures.
This is why special care is needed for patients where it’s hard to see exactly where the needle is. Pneumothorax is a common cause for medical lawsuits related to chronic pain practices, making up 4% of such cases.
There are ways to lower the risk of pneumothorax. For example, avoiding putting the needle through a particular area above the shoulder blade can help. Also, positioning the patient’s hand across their body can lift the shoulder blade away from the chest wall. This makes the space between the skin and chest wall larger, helping keep the needle from going too far and reducing the risk of a collapsed lung.
Another possible complication of a suprascapular nerve block, or pain-relief procedure, is accidentally injecting into a vein or artery instead of the nerve. Nearby to the nerve, there are a vein and artery that are separate from the nerve by a thin band of tissue. If the needle accidentally goes into the vein or artery, it could cause a dangerous reaction to the local anesthetic, which could be life-threatening. To avoid this, it’s crucial to often check during the procedure that the needle isn’t in a blood vessel. You can do this by trying to draw back on the needle to see if any blood comes out. Visual checks using the ultrasound can also confirm that the needle isn’t in a vessel. If the ultrasound’s images aren’t clear, the risk of accidentally injecting into a vessel might be greater.
Other potential risks of nerve blocks in general include infections, bleeding, a bad reaction to the local anesthetic, and damage to the nerves.
What Else Should I Know About Suprascapular Nerve Block?
Using ultrasound to guide the numbing of a nerve in your shoulder (suprascapular nerve) can effectively treat both short-term and long-term shoulder pain. This nerve supplies feeling to the parts of your shoulder where the collarbone meets the shoulder blade and where the upper arm bone fits into the shoulder blade.
There are two ways to numb this nerve, and the method matters because the nerve that controls your breathing (phrenic nerve) is located near a network of nerves in your upper chest area (brachial plexus). The first method numbs the nerve from the back of your shoulder and doesn’t risk affecting your phrenic nerve. The second method numbs the nerve from the front of your shoulder, which could potentially affect your phrenic nerve depending on the amount of numbing medication used.
One study performed on a dead body looked at how much numbing medication could be used in the front shoulder method without affecting the phrenic nerve. They found that 4.2 milliliters of the medication could numb the nerve without affecting the phrenic nerve 90% of the time. More research on living people is needed, but avoiding affecting the phrenic nerve is crucial for people with serious lung diseases.
The front method of numbing the shoulder nerve may be just as effective in relieving pain as the most commonly used method of numbing the nerves in the neck (interscalene peripheral nerve block). A study compared how well three common methods of numbing nerves for shoulder surgery worked (the neck method, the front shoulder method, and the above-collarbone method) and found that all three resulted in similar levels of pain relief and no difference in the use of opioid painkillers. However, using the front shoulder method preserved lung function better than the neck method. After the shoulder nerve was numbed from the front, people were still able to take in 90% of their usual amount of air, could get 87% of their usual amount of air out in one second, and their diaphragm moved less than usual. After the neck was numbed, however, people could only take in 67% of their usual amount of air, could get 68% of their usual amount of air out in one second, and their diaphragm moved more than usual.
Another study also found that the front shoulder method is just as good at relieving pain as the neck method and is better for lung function. Therefore, both the front and back shoulder methods can be valuable tools for doctors to treat shoulder pain.
