Sphenopalatine Ganglion Block: Indications, Technique, and Safety
Primary Indications
Sphenopalatine ganglion (SPG) block is most strongly indicated for the short-term treatment of acute migraine headaches and cluster headaches, though evidence for chronic migraine prevention remains insufficient. 1
Established Uses:
- Acute migraine treatment – SPG block provides rapid pain relief, with 70.9% of patients becoming headache-free at 15 minutes and 78.2% at 2 hours following transnasal lidocaine administration 2
- Episodic cluster headache – Effective for acute attacks, though implantable SPG stimulators are not recommended 1
- Status migrainosus – Suprazygomatic SPG block produces a 67.2% reduction in pain severity at 30 minutes when traditional abortive medications fail 3
- Other facial pain syndromes – Including sphenopalatine neuralgia, trigeminal neuralgia, and atypical facial pain 4, 5
Evidence Limitations:
- Insufficient evidence exists for chronic migraine prevention with SPG block, despite its utility in acute treatment 1
- The optimal technique and pharmacologic agents remain undefined, as studies show variable success rates depending on approach 5
Technique Options
Transnasal Approaches (Most Common):
1. Simple Topical Application:
- Apply topical anesthetic (typically 2% lidocaine) to nasal mucosa between middle and inferior turbinates 6
- Limitation: Unpredictable diffusion to the ganglion and non-durable blockade 6
2. Transnasal Injection (Enhanced Technique):
- Topical anesthesia to nasal mucosa from nares to nasopharynx 6
- Needle insertion guided by plastic cover-sheath along the same tract 6
- Needle tip positioned near medial pterygoid plate at middle concha level under fluoroscopy 6
- Advantage: Prolongs pain relief from 1 day (topical) to 4 weeks (injection) 6
3. Device-Assisted Transnasal Block:
- Using specialized devices (e.g., Sphenocath®) to deliver 2 ml of 2% lidocaine per nostril 2
- Well-tolerated with few adverse events 2
Suprazygomatic Injection Approach:
- Regional anesthetic technique targeting SPG via suprazygomatic route 3
- Advantage: More consistent results than transnasal topical application, with 67.2% pain reduction at 30 minutes 3
- Simple to perform with minimal risk 3
Critical Technical Requirements:
- Ultrasound guidance is mandatory for all nerve blocks to reduce local anesthetic systemic toxicity risk 7
- Experienced operator required for safe execution 7
- Calculate safe dose based on patient weight to prevent systemic toxicity 7
- Immediate resuscitation equipment must be available 7
Absolute Contraindications
Active infection at injection site – Prevents safe needle insertion 7
Patient refusal – Respected as absolute contraindication 7
Coagulopathy or uncorrectable bleeding disorders – Increases hemorrhage risk 7
Active P2Y12 inhibitor therapy (clopidogrel, prasugrel, ticagrelor) without appropriate discontinuation:
- Clopidogrel requires 5-day discontinuation 7
- Prasugrel requires 7-day discontinuation 7
- Ticagrelor requires 5-day discontinuation 7
Therapeutic anticoagulation unless dabigatran concentration ≤30 ng/mL or appropriate reversal (idarucizumab) administered 7
Very short life expectancy – Not appropriate for interventional procedures 7
Relative Contraindications
COVID-19 infection – Nasal SPG blocks pose aerosol generation risk 7
Aspirin monotherapy – Relative contraindication for deep/high-risk blocks; proceed only if benefit/risk ratio favorable 7
Dual antiplatelet therapy – May be acceptable for superficial/low-risk blocks with favorable benefit/risk assessment 7
Respiratory compromise risk – Avoid blocks that may impair respiratory function 7
Potential Complications and Safety Monitoring
Common Adverse Events:
- Generally well-tolerated with few adverse events reported in clinical studies 2
- Transnasal approaches may cause temporary nasal discomfort or epistaxis 6
Critical Safety Measures:
- Monitor blood pressure and electrocardiogram, especially in high cardiovascular risk patients 8
- Have resuscitation equipment immediately available for all procedures 7
- Use standard aseptic technique similar to neuraxial procedures 8
- Test block success thoroughly before declaring procedure complete 8
Local Anesthetic Systemic Toxicity Prevention:
- Ultrasound guidance reduces toxicity risk 7
- Calculate maximum safe dose based on patient weight 7
- Avoid vascular uptake by confirming needle position 6
Clinical Pitfalls to Avoid
Do not rely solely on topical transnasal application when durable blockade is needed – injection techniques provide more predictable and prolonged relief 6
Do not perform SPG blocks in patients with active COVID-19 due to aerosol generation risk from nasal procedures 7
Do not proceed without proper anticoagulation assessment – verify P2Y12 inhibitor discontinuation periods and anticoagulant levels before deep blocks 7
Do not use implantable SPG stimulators for cluster headache – current guidelines recommend against this intervention 1