What are the side effects of a stellate ganglion block?

Stellate Ganglion Block Side Effects

Stellate ganglion block carries a 1.7 per 1000 risk of severe complications, predominantly CNS toxicity including convulsions, with additional risks of pneumothorax, high neuraxial blockade, and cardiovascular effects, though most adverse events are transient and self-limited. 1

Severe Complications (Rare but Life-Threatening)

Central Nervous System Toxicity

• CNS complications are the most common severe adverse events, presenting as confusion, agitation, seizures/convulsions, CNS depression, respiratory depression, or respiratory arrest 2, 3, 1
• These occur from inadvertent intra-arterial injection with retrograde flow to cerebral circulation, despite the proximity to major cerebral vessels making this block uniquely risky 2, 3
• Incidence of severe CNS complications is approximately 1.7 per 1000 blockades 2, 1

Neuraxial Complications

• High subarachnoid block (6 cases per 45,000 blocks in survey data) from inadvertent dural puncture 1
• High epidural blockade (3 cases per 45,000 blocks) 1
• One case of quadriplegia secondary to pyogenic cervical epidural abscess and discitis has been reported 4

Respiratory Complications

• Pneumothorax (9 cases per 45,000 blocks) requiring proper technique and imaging guidance 5, 1
• Respiratory arrest has been reported, particularly when blocks are performed in the head and neck area 3

Cardiovascular Effects

• Cardiovascular stimulation or depression can occur 3
• One reported death from massive hematoma leading to airway obstruction 4

Allergic Reactions

• Rare allergic reactions (2 cases per 45,000 blocks) 1

Common Side Effects (Transient and Self-Limited)

Medication-Related/Systemic Effects

• 68.4% of reported adverse events are medication-related or systemic side effects 4
• Early warning signs of local anesthetic toxicity include: restlessness, anxiety, incoherent speech, lightheadedness, numbness and tingling of mouth and lips, metallic taste, tinnitus, dizziness, blurred vision, tremors, twitching, depression, or drowsiness 3

Procedure-Related/Local Effects

• 31.5% of adverse events are procedure-related or local side effects 4
• Horner's syndrome (expected finding indicating successful sympathetic blockade) 6
• Temporary loss of sensation in the blocked distribution 3

Critical Safety Precautions

Mandatory Monitoring and Equipment

• ECG monitoring should be used (though only 28% of surveyed departments use it routinely) 1
• Intravenous line placement before the procedure (72% of departments follow this) 1
• Immediate availability of resuscitation equipment, oxygen, ventilating devices, anticonvulsant drugs, and intubation equipment 1, 4
• An assistant should be present (73% of departments require this) 1
• American Society of Anesthesiologists standard monitors for conscious sedation are vital 4

Technical Safeguards

• Image guidance (fluoroscopy or ultrasound) should be used to reduce complications, though adverse events still occur with imaging 5, 4
• Aspiration test before injection (performed by 82% of departments, though this does not guarantee proper administration) 1
• Test dose of 0.5-2 ml local anesthetic (used by 53% of departments) 1
• Calculate safe dose based on patient weight to prevent local anesthetic systemic toxicity 5

Management of Toxicity

• Intravenous lipid emulsion (ILE) therapy should be administered for severe local anesthetic systemic toxicity or cardiac arrest, as it sequesters lipophilic medications and reduces tissue concentration 2

Important Clinical Context

Most adverse events occur during or shortly after the procedure, emphasizing the need for vigilance during the immediate post-procedure period 4. Despite aspiration tests and test doses, inadvertent subarachnoid or intra-arterial injection remains the primary mechanism for life-threatening complications 1. The use of bupivacaine (preferred by 82% of departments) carries specific risks of CNS and cardiovascular toxicity that require heightened awareness 3, 1.