Stellate Ganglion Block Side Effects
Stellate ganglion block carries a low but significant risk of serious complications, with severe adverse events occurring in approximately 1.7 per 1000 procedures, most commonly CNS toxicity from inadvertent intravascular injection, though most side effects are minor and transient. 1
Common Minor Side Effects
The most frequently encountered side effects are generally mild and self-limited:
- Horner's syndrome (ptosis, miosis, anhidrosis) occurs as an expected pharmacologic effect indicating successful sympathetic blockade 2
- Hoarseness from recurrent laryngeal nerve involvement is common and typically resolves within hours 3, 2
- Arm heaviness or weakness from brachial plexus spread occurs frequently but is temporary 1
- Dysphagia (difficulty swallowing) may occur from local anesthetic spread to surrounding structures 1
Serious Complications
CNS Toxicity (Most Common Severe Complication)
- Seizures/convulsions represent the most frequent severe complication, typically from inadvertent intra-arterial injection into the vertebral artery 1, 3
- Transient locked-in syndrome has been reported from vertebral artery injection, though rare 3
- Loss of consciousness can occur from systemic local anesthetic toxicity 1
- Higher doses of intravenous lipid emulsion can improve outcomes in severe local anesthetic toxicity 4
Neuraxial Complications
- High subarachnoid block occurred in 6 cases per 45,000 procedures in one large survey 1
- High epidural blockade was reported in 3 cases per 45,000 procedures 1
- Respiratory paralysis from high neuraxial spread requires immediate airway management 3, 4
Structural Complications
- Pneumothorax occurred in 9 cases per 45,000 procedures 1
- Retropharyngeal hematoma is rare but life-threatening, potentially causing airway obstruction and requiring emergency airway management 4, 5
- One death has been reported from massive hematoma leading to airway obstruction 5
- Quadriplegia from pyogenic cervical epidural abscess and discitis has been reported in one case 5
Cardiovascular Effects
- Severe arterial hypotension can occur, particularly with inadvertent intravascular injection 3
- Cardiopulmonary arrest is a rare but recognized risk 2
Other Complications
- Allergic reactions occurred in 2 cases per 45,000 procedures 1
- Phrenic nerve block may cause temporary diaphragmatic dysfunction 3
Critical Safety Considerations
Most complications (68.4%) are medication-related or systemic, while 31.5% are procedure-related or local. 5 The majority of adverse events occur during or shortly after the procedure. 5
Essential Safety Measures
- Aspiration testing before injection does not guarantee proper needle placement and cannot prevent all complications 1
- Test doses of 0.5-2 ml are used by only 53% of practitioners but do not eliminate risk 1
- Intravenous access should be established before the procedure (72% of departments routinely do this) 1
- ECG monitoring is used routinely by only 28% of departments but is strongly recommended 1
- An assistant should be present (73% of departments follow this practice) 1
- Immediate availability of resuscitation equipment, anticonvulsant drugs, and intubation supplies is mandatory 1, 5
Image Guidance and Complication Rates
Image guidance (ultrasound or fluoroscopy) does not eliminate complications—51.5% of reported adverse events occurred despite image guidance. 5 Ultrasound was used in 24.6% of complication cases and fluoroscopy in 26.9%. 5
Clinical Context from Long COVID Literature
In the context of long COVID treatment, two patients experienced substantial alleviation of dysautonomia symptoms following stellate ganglion block, suggesting potential therapeutic benefit in select populations, though this represents very limited evidence. 6