In an adult with acute moderate‑to‑severe migraine refractory to a non‑steroidal anti‑inflammatory drug (NSAID) and a triptan, and limited by nausea or vomiting, how should a sphenopalatine (pterygopalatine) ganglion block be performed, including technique, anesthetic dose, contraindications, monitoring, and expected efficacy?

Sphenopalatine Ganglion Block for Refractory Acute Migraine

In adults with acute moderate-to-severe migraine refractory to NSAIDs and triptans, a sphenopalatine ganglion (SPG) block using 0.5% bupivacaine via transnasal applicator (Tx360 or SphenoCath) can provide complete pain relief within 15 minutes and should be considered before resorting to opioids or prolonged ED observation. 1, 2

Indications and Patient Selection

• SPG block is most appropriate when first-line therapy (NSAID + triptan combination) has failed after adequate dosing and the patient presents with severe, disabling migraine accompanied by nausea or vomiting that limits oral medication absorption. 1, 2
• Chronic migraine is the headache subtype most likely to respond to SPG block, though it demonstrates efficacy across primary headache disorders including acute severe migraine attacks. 3
• The procedure is particularly valuable when rapid discharge from the emergency department is desired, as door-to-discharge time can be reduced to under one hour compared to 2–3 hours with traditional IV "migraine cocktail" protocols. 2

Technique and Equipment

Preferred Application Method

• The Tx360 device and SphenoCath are the two most commonly used commercial applicators, selected primarily for ease of use by experienced clinicians. 3
• A standard transnasal approach is employed: the patient is positioned supine with neck extended, and the applicator is advanced along the superior aspect of the middle turbinate until the tip reaches the posterior nasopharynx at the level of the pterygopalatine fossa. 3, 2
• The transnasal route is preferred over the percutaneous infrazygomatic approach (which requires fluoroscopic guidance) because it can be performed rapidly at the bedside without imaging. 4, 3

Anesthetic Selection and Dosing

• 0.5% bupivacaine 3 mL is the most commonly used local anesthetic, delivered via the transnasal applicator to bathe the SPG in the pterygopalatine fossa. 3, 2
• Alternative agents include 2% lidocaine or 4% lidocaine, though bupivacaine is favored for its longer duration of action (4–6 hours versus 1–2 hours for lidocaine). 3
• The anesthetic is instilled slowly over 30–60 seconds to ensure adequate contact with the ganglion and minimize patient discomfort from rapid infusion. 2

Contraindications

• Absolute contraindications include known allergy to local anesthetics (amide class), active epistaxis, severe coagulopathy, and anatomic obstruction of the nasal passage preventing applicator advancement. 3
• Relative contraindications include uncontrolled hypertension (systolic >180 mmHg), recent nasal or sinus surgery, and pregnancy (due to limited safety data, though the procedure itself poses minimal systemic risk). 5, 3
• Patients with a history of recurrent severe epistaxis or nasal polyps should be evaluated for anatomic suitability before attempting the block. 3

Monitoring and Safety

• No specialized monitoring beyond standard vital signs is required during or after the procedure, as systemic absorption of 3 mL of 0.5% bupivacaine (15 mg total dose) is negligible and well below toxic thresholds. 2
• Patients should remain supine for 5 minutes after instillation to prevent anesthetic drainage into the oropharynx, which can cause transient throat numbness and an unpleasant taste. 2
• The most common adverse effect is transient nasal discomfort or burning during instillation, reported in approximately 20–30% of patients; this resolves within 2–3 minutes. 3, 2
• Serious complications (e.g., intravascular injection, seizure, cardiovascular collapse) are exceedingly rare with the transnasal approach and have not been reported in case series using commercial applicators. 3, 2

Expected Efficacy and Outcomes

• Complete resolution of headache occurs in approximately 60% of patients within 15 minutes of SPG block, with an additional 15–20% achieving partial relief (>50% pain reduction). 4, 2
• Associated autonomic features (lacrimation, rhinorrhea, conjunctival injection) resolve in nearly all responders, often before headache pain subsides. 4
• Pain relief onset is typically noted within 5–10 minutes, with maximal effect by 15 minutes, allowing rapid reassessment and potential discharge. 4, 2
• Approximately 20–25% of patients experience minimal or no benefit; these non-responders should receive standard IV therapy (metoclopramide 10 mg + ketorolac 30 mg) rather than repeated SPG blocks during the same visit. 1, 4, 2

Treatment Protocols and Frequency

• SPG block is most commonly performed as a one-time, as-needed procedure during an acute severe attack in the emergency department or urgent care setting. 3
• When used as a scheduled protocol for chronic or frequent migraine, the most common regimen is twice weekly for 6 weeks, though evidence for this approach is limited and based primarily on expert opinion rather than controlled trials. 3
• Acute medication frequency limits still apply: if a patient requires SPG blocks or any other acute migraine treatment more than 2 days per week, preventive therapy must be initiated immediately to avoid medication-overuse headache and chronic progression. 1, 6

Integration into the Treatment Algorithm

• SPG block should be positioned after failure of combination therapy (triptan + NSAID) but before resorting to opioids, which are contraindicated for migraine due to limited efficacy, high dependence risk, and propensity for rebound headaches. 1
• The procedure is particularly valuable for patients with contraindications to triptans (ischemic heart disease, uncontrolled hypertension, cerebrovascular disease) or NSAIDs (renal impairment, active GI bleeding), as it provides a non-systemic alternative. 1, 3
• If SPG block fails, escalate to IV dihydroergotamine (DHE) 0.5–1.0 mg or the standard IV combination of metoclopramide 10 mg + ketorolac 30 mg, rather than repeating the block. 1

Common Pitfalls and How to Avoid Them

• Inadequate applicator positioning is the most common cause of block failure; ensure the tip reaches the posterior nasopharynx by advancing until slight resistance is felt, then inject slowly while maintaining position. 2
• Premature patient discharge before the 15-minute assessment window can result in missed treatment failures; always reassess pain and autonomic symptoms at 15 minutes before deciding on disposition. 2
• Overuse of SPG blocks as a substitute for preventive therapy perpetuates the cycle of frequent attacks; any patient requiring blocks more than twice weekly must be transitioned to daily preventive medication (propranolol, topiramate, or CGRP monoclonal antibodies). 1, 6, 3
• Failure to counsel on medication-overuse headache when SPG block is used in conjunction with other acute treatments; the 2-day-per-week limit applies to the total use of all acute therapies, not each individual modality. 1, 6

Evidence Quality and Limitations

• The evidence supporting SPG block for acute migraine consists primarily of case series and uncontrolled observational studies rather than large randomized controlled trials, limiting the strength of recommendations. 4, 3, 2
• A 2020 survey of American Headache Society members revealed wide variation in practice patterns, with no consensus on optimal protocols, suggesting that clinicians have developed individualized approaches based on clinical experience rather than standardized guidelines. 3
• The lack of head-to-head comparisons with standard IV therapy (metoclopramide + ketorolac) means the relative efficacy of SPG block versus traditional approaches remains uncertain. 3, 2
• Despite these limitations, the rapid onset, favorable safety profile, and potential for expedited discharge make SPG block a reasonable option for refractory cases when performed by trained clinicians. 3, 2