From the FDA Drug Label
Use in the Head and Neck Area Small doses of local anesthetics injected into the head and neck area, including retrobulbar, dental and stellate ganglion blocks, may produce adverse reactions similar to systemic toxicity seen with unintentional intravascular injections of larger doses Confusion, convulsions, respiratory depression and/or respiratory arrest, and cardiovascular stimulation or depression have been reported. These reactions may be due to intra-arterial injection of the local anesthetic with retrograde flow to the cerebral circulation.
Small doses of local anesthetics injected into the head and neck area, including retrobulbar, dental, and stellate ganglion blocks, may produce adverse reactions similar to systemic toxicity seen with unintentional intravascular injections of larger doses. The injection procedures require the utmost care Confusion, convulsions, respiratory depression, and/or respiratory arrest, and cardiovascular stimulation or depression have been reported.
The risks for stellate ganglion block include:
- Systemic toxicity: similar to that seen with unintentional intravascular injections of larger doses
- Confusion
- Convulsions
- Respiratory depression
- Respiratory arrest
- Cardiovascular stimulation
- Cardiovascular depression These reactions may be due to intra-arterial injection of the local anesthetic with retrograde flow to the cerebral circulation 1 2.
From the Research
Stellate ganglion block carries several important risks that patients should be aware of before undergoing the procedure, including pneumothorax, inadvertent injection into blood vessels, spinal or epidural injection, and damage to surrounding structures like the recurrent laryngeal nerve, as reported in a recent study 3. The most serious complications of stellate ganglion block include:
- Pneumothorax (collapsed lung)
- Inadvertent injection into blood vessels causing seizures or cardiac arrest
- Spinal or epidural injection leading to respiratory paralysis
- Damage to surrounding structures like the recurrent laryngeal nerve causing hoarseness More common side effects include:
- Temporary Horner's syndrome (droopy eyelid, constricted pupil, and reduced sweating on the affected side)
- Temporary hoarseness
- Difficulty swallowing
- Bruising at the injection site There's also a risk of:
- Infection
- Bleeding (especially in patients on blood thinners)
- Allergic reactions to the medications used The procedure can occasionally cause a temporary increase in pain before relief occurs, as noted in a study on the treatment of stellate ganglion block in diseases 4. These risks vary based on the patient's anatomy, medical history, and the experience of the physician performing the block, with a systematic review of complications associated with stellate ganglion nerve block highlighting the importance of image guidance and vigilance 5. The overall complication rate is relatively low when performed by experienced practitioners using image guidance such as ultrasound or fluoroscopy, which has significantly improved the safety profile of stellate ganglion blocks by allowing precise needle placement and reducing the risk of inadvertent injury to adjacent structures, as supported by a review article on optimizing clinical outcomes with stellate ganglion block and trauma-informed care 3.