Overview of Stellate Ganglion Blocks
A Stellate Ganglion Block (SGB) is a medical procedure used to help treat conditions like complex regional pain syndrome, a chronic pain condition that affects one of the limbs, and peripheral vascular disease, a blood circulation disorder. In simple terms, it’s a type of nerve block where an anesthetic (a drug that numbs part of your body) is injected into a bunch of nerves located in your neck.
Traditionally, doctors perform this procedure around the area of your neck that matches with C6 or C7 on your spine. They use nearby body landmarks for guidance – such as a small lump on your neck known as Chassignac’s tubercle, the firm ring around your windpipe known as the cricoid cartilage, and the major artery in your neck, the carotid artery.
However, this method might lead to risks such as puncturing a lung (called pneumothorax) or a blood vessel. Hence, doctors now strongly recommend using imaging technology, like an ultrasound, to guide the injection, even when they use the comparatively safer C6 approach. This helps them to see where the needle is going, making the procedure safer and more effective.
Anatomy and Physiology of Stellate Ganglion Blocks
The nerve fibers that control the head, neck, heart, and upper arms start from the first segments of the thoracic spine (the area between your neck and abdomen), go upward through a network of nerves known as the sympathetic chain, and connect within clusters of nerve cells called cervical ganglions located in the neck. The stellate ganglion is a specific grouping of these nerve cells present in 80% of people. It is found at the junction of the lowermost cervical ganglion and the first thoracic ganglion. It is typically found at the front of the first rib and extends down to a bony projection on the seventh neck vertebra (C7).
In cases where the lowermost cervical ganglion and first thoracic ganglion are not fused, the term “stellate ganglion” refers to the lower cervical ganglion located near the projection at the front of the C7 vertebra.
The incoming nerves of the stellate ganglion travel through the cervical sympathetic chain (the nerve pathway in your neck), and outgoing nerves direct the responses of the upper limbs. Local anesthetics (numbing medications) used for stellate ganglion block (a procedure for managing pain) target both incoming and outgoing nerve fibers.
Why do People Need Stellate Ganglion Blocks
Sometimes, a certain type of pain relief treatment known as a sympathetic block can be used to manage a condition called sympathetically mediated pain (SMP). SMP is when there are unusual connections between your sympathetic and sensory nervous systems – the parts of your body responsible for controlling involuntary actions and feeling sensations.
A sympathetic block works by interrupting these abnormal connections in specific areas, enhancing blood flow to that area, and lowering the levels of certain hormones in your blood that come from a gland known as the adrenal gland. This can lead to an overall relief from pain.
One of these blocks, known as a Stellate Ganglion Block (SGB), can be used to treat various conditions. This includes post-traumatic stress disorder and a type of severe headache known as a cluster headache. SGB is not only significant for treatment, but it also works well to help confirm an SMP diagnosis – that is, to be sure if someone is indeed experiencing SMP.
SGB is useful in treating the following conditions:
- Complex regional pain syndrome affecting the head and upper limbs (a chronic pain condition that usually affects a limb)
- Peripheral vascular disease (a disease that affects the blood vessels outside the heart and brain)
- Upper extremity embolism (blockage of blood flow in an artery in the arm)
- Postherpetic neuralgia (pain that continues long after a shingles rash has healed)
- Long-lasting pain after surgery
- Hyperhidrosis (excessive sweating)
- Raynaud disease (a rare disorder of the blood vessels)
- Scleroderma (hardening and tightening of the skin and connective tissues)
- Orofacial pain (pain in the mouth, jaw, or face)
- Phantom limb (pain that feels like it’s coming from a body part that’s no longer there)
- Unusual chest pain
- Cluster headaches or vascular headaches
- Post-traumatic stress disorder
- Meniere syndrome (a disorder of the inner ear)
- Intractable angina (chronic chest pain)
- Refractory cardiac arrhythmias (heart rhythm problems that are hard to treat)
When a Person Should Avoid Stellate Ganglion Blocks
If a person recently had a heart attack, it may not be safe for them to have an appendectomy.
People who are on blood-thinners or have coagulopathy, a condition which affects the blood’s ability to clot, also need to be evaluated for the risk and benefits of the surgery.
People with glaucoma, a condition that damages the eye’s optic nerve, could be at risk during this surgery too.
If there’s already damage to the nerves on the patient’s other side or if they have severe emphysema, a long-term, progressive disease of the lungs, it may not be advisable to have this procedure.
Lastly, patients with a condition known as cardiac conduction block, which disturbs the heart’s electrical system, need to be assessed because it could affect the surgery’s safety.
Equipment used for Stellate Ganglion Blocks
In both fluoroscopic and ultrasound-guided techniques, doctors use sophisticated tools to accurately visualize and perform medical procedures.
For the fluoroscopic technique, doctors use a device known as a C-arm image intensifier. This tool allows them to see an enhanced view of a specific area of the body using X-rays. Contrast media is a special kind of dye that is used to highlight specific areas inside the body, making them clearly visible on X-ray images. A 22-gauge spinal needle, which is about 9 cm long, is used to administer local anesthesia which is a numbing medication that causes loss of feeling in a small part of the body. Non-particulate steroids are also given; these are anti-inflammatory medicines that can reduce swelling and relieve pain.
With ultrasound-guided techniques, doctors use a high-frequency linear transducer. This medical device is capable of converting electrical energy into sound waves and vice versa, which helps to create a live image on a monitor. An echo-enhanced needle, which makes it visible on ultrasound, is used to administer local anesthesia. Like the fluoroscopic technique, non-particulate steroids are also used to reduce inflammation and alleviate discomfort.
Who is needed to perform Stellate Ganglion Blocks?
The Stellate Ganglion Block (SGB) is a medical process that requires a doctor specifically trained in pain management, because it’s a moderately challenging procedure. A nurse will also be there to help you get in the right position for the injection. If the doctor decides to use a technique called “fluoroscopy,” which uses X-rays to get a better view inside your body, a radiology technician (a medical professional who’s skilled in using X-ray machines) will assist.
Preparing for Stellate Ganglion Blocks
Before and after the procedure, it’s crucial to check the patient’s key health measurements like heart rate, blood pressure etc. This is known as monitoring the patient’s vital signs. Additionally, a tube should be inserted into the patient’s vein for giving fluids or medications. It’s also very critical to learn about the patient’s health history before starting the procedure. This helps to make sure we aren’t overlooking any reasons that could make the procedure unsafe for the patient and allow us to weigh the benefits of the procedure against any potential risks.
How is Stellate Ganglion Blocks performed
Before we start the ultrasound-guided technique, the patient is asked to lie down on their back, with the neck slightly tilted backwards and the head gently turned to the side opposite to the area we’re examining. We clean and drape the area, then put the ultrasound transducer (the part that touches the body) on the throat at the level of the cricoid cartilage (a small circular piece of cartilage near the top of the voice box) and slowly move it down until we can see the upper part of the thyroid gland on the monitor. We then adjust it to the side to better view the front side of the Chassaignac’s tubercle (a prominent bump on the neck bone). While doing this, we can identify important nearby structures like the carotid artery, internal jugular vein, thyroid gland, trachea, Longus colli, and Longus capitis muscles, prevertebral fascia (a layer of tissue around the spine), the root of C6 spinal nerve, and the transverse process of C6 (parts of the neck bone).
Using color Doppler in the ultrasound, we can detect the location of vessels. The needle is positioned beside the windpipe with a path moving from the side of the neck towards the center. The needle reaches the prevertebral fascia of the Longus colli muscle, which is located between the back of the artery and the tip of the C6 bone. It’s important to avoid causing injury to vessels and nerves. Before injecting, we make sure by pulling back on the plunger that we’re not in a blood vessel or the spinal fluid. Then we inject the local anesthetic and can see it spreading throughout the tissue area on the ultrasound screen in real time. It’s highly recommended to not inject below the C6 level, to avoid hitting the vertebral artery, which doesn’t have the same protection at the C7 level. In the end, we inject about 5 ml of a local anesthetic like lidocaine 2% until it covers the entire area around the nerves.
For the fluoroscopic-guided technique, the patient is also placed in a supine (lying down on their back) position. We use a special device, called a C-arm, to take an x-ray from the front to identify the C6 level by counting up from T1 (vertebrae in the spine). We tilt and rotate the C-arm to clearly see the C6 level, starting from the top of the bone and ending at an oblique angle. Our target is the junction of the vertebral body and the uncinate process (the part of the bone that forms the joint). In an oblique view, we insert the needle laterally (from the side to the center), taking care to stay over the bone or slightly more to the center to avoid injuring blood vessels, nerves and discs. By taking both front and side views, we can confirm the needle’s correct placement. We can also inject a small amount of contrast dye under x-ray guidance to better see the needle’s position. Once confirmed, we give a small test dose of local anesthetic, followed by the full 10 ml of the lidocaine 1% injection. This procedure can be repeated at the C7 level if needed, but doctors must be cautious due to the increased risk of hitting a blood vessel.
Possible Complications of Stellate Ganglion Blocks
During certain medical procedures, accidental puncture or harm to blood vessels such as the carotid artery (major blood vessel in the neck), internal jugular vein, inferior thyroid artery, or vertebral artery can occur. Nerves, like the vagus nerve (nerve that runs from the brain to the abdomen) and brachial plexus roots (nerve group that sends signals from the spinal cord to the arms and hands) can also get damaged.
One potential risk is pneumothorax, where air enters the space between the lung and the chest wall, potentially causing a collapsed lung. There’s also a risk of injuring the thyroid – a small gland at the front of your neck that produces hormones.
In some cases, there can be accidental punctures of the esophagus (food pipe) and trachea (windpipe), causing discomfort and other complications. Horner’s syndrome, a condition that affects the facial muscles, may occur briefly as a side effect.
Intravascular injection, where a substance is injected directly into a blood vessel, can occur accidentally. There might also be an unintended spread of local anesthetic to the neuraxial region (nerves of the spinal cord), phrenic nerve (nerve that works the diaphragm for breathing), or the brachial plexus.
Lastly, infections are potential complications of these procedures. While healthcare providers will do all they can to minimize these risks, it’s important to understand that they exist and to discuss any concerns with your doctor.
What Else Should I Know About Stellate Ganglion Blocks?
A sympathetic block, also known as SGB, is a medical procedure that can be helpful in figuring out and treating certain types of pain related to the nerves, specifically in the arm, head, and neck areas. It can also be implemented to manage certain health issues like post-traumatic stress disorder (a mental health disorder developed after a traumatic event), cluster headaches (severe headache episodes that happen in periods), or intractable angina (severe chest pain due to lack of blood flow to the heart that can’t be controlled with usual treatments).
