Stellate Ganglion Block Side Effects and Complications

The Stellate Ganglion Block (SGB) is a powerful tool for reducing symptoms of anxiety, irritability, PTSD, hot flashes, pain, heart rhythm problems, and long COVID symptoms. While SGB is a safe procedure, you should always be aware of potential side effects and risks.

Understanding the Side Effects of Stellate Ganglion Block

There are two sets of side effects of the Stellate Ganglion block:

1. Expected (normal) side effects: these are expected and resolve within several hours
2. Adverse side effects: these are rare and typically resolve but can potentially last longer

The overall rate of serious complications is under 1%. The rate continues to come lower with the use of ultrasound in performing the SGB.

Expected and Normal SGB Side Effects

Blocking the nerves of your stellate ganglion causes a "sympathectomy," or a reduction in your fight-flight nervous system response. This causes several (expected) effects that typically last a few hours:

• Drooping Eyelid (Ptosis): This is a temporary effect due to nerve blockage in the sympathetic nervous system.‍
• Pupil Constriction: Also known as Horner's syndrome, this includes drooping eyelid, pupil constriction, and lack of sweating on one side of the face.
• Nasal Congestion: The nerves affected by the block can lead to congestion by dilating the blood vessels behind your nose.
• Arm Warmth: This is caused by relaxation of blood vessels in the arm, causing the arm to warm up.
• Facial Flushing: The injection may cause temporary redness and warmth in the face.

The combination of drooping eyelid, facial flushing, and pupillary constriction is called the Horner's syndrome.

Other Common (Temporary) SGB Side Effects

Nearby nerves also get numbed during the SGB. This includes nerves that go to your vocal cords, your vagus nerve, and the nerves to your arm. This can cause other side effects that may last several hours:

• Difficulty Swallowing: Some patients may experience mild difficulty swallowing.
• Temporary Hoarseness: The anesthetic can affect the vocal cords, causing a hoarse voice.
• High heart rate and/or high blood pressure: If the vagus nerve gets anesthetized during the block. This is uncommon.
• Low heart rate and/or low blood pressure: From reducing the fight-flight response and inducing a sense of relaxation.
• Dizziness
• Temporary arm weakness and/or numbness: From local anesthetic numbing the nerves of your arm.

These side effects are temporary, and we have several precautions for our patients:

• All patients need an IV to provide heart rate or blood pressure medications, if needed.
• We ask that patients not eat or drink while their voice is hoarse to avoid the risk of food going into the lungs.
• Ultrasound is used to inject the lowest dose (and volume) of medication to minimize these risks.

Rare but Serious Risks of SGB

• Infection: SGB injection carries a risk of infection at the injection site or, very rarely, near the spine. We carefully disinfect the skin to minimize this risk. High risk patients may need to take antibiotics before the procedure.
• Nerve Damage: Although rare, there is a potential risk of nerve injury with any injection near nerves.
• Bleeding: Patients, especially if on blood thinners, may have a higher risk of bleeding complications. Sometimes this can lead to a hematoma.
• Seizure: Resulting from local anesthetic reaching the brain too fast.
• Allergic reaction: Rarely a patient is allergic to the local anesthetic medication.

Managing SGB Side Effects

It is important that you understand the side effects associated with SGB before the procedure. While SGB is considered a very safe procedure, especially with ultrasound guidance, your vigilance in monitoring for possible side effects is very important for your safety.

Most side effects are temporary and resolve on their own. However, if you experience severe, persistent, or worrisome symptoms, it’s important to contact your healthcare provider. They can offer guidance and support to manage any adverse effects effectively.