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Introduction to Sphenopalatine Ganglion Block
Sphenopalatine ganglion block is an effective and widely used treatment modality in the management of acute migraine headaches, cluster headaches, trigeminal neuralgia and various other craniofacial conditions. The sphenopalatine ganglion is a large cluster of neural connections that are autonomic, sensory and motor in nature. It is located deep in the pterygopalatine fossa located behind the maxillary sinus. This structure contains parasympathetic nervous fibers which provide secretory and motor functionalities to the mucous membranes of the nose, oral cavity, throat and tear-glands, as well as to the membranes which cover the brain (meninges) and cerebral blood vessels. Sympathetic fibres also pass through the ganglion and innervate the palate, nasal cavity and throat.
Migraine and Other Primary Headache Disorders
Acute migraine and other primary headache disorders such as cluster headaches or secondary headache disorders such as post-dural puncture headache, are sometimes accompanied by parasympathetic activation, which manifests in the following symptoms – tearing, nasal congestion and swollen conjunctivae. Even during optimal analgesic (pain-relief) control, patients with migraines may continue to experience these parasympathetic symptoms despite having bearable or no pain. Blocking the sphenopalatine ganglion has been theorized and shown to impede the parasympathetic outflow to various cranial and facial structures. This results in an amelioration of the aforementioned symptoms.
Sphenopalatine Ganglion Block
Sphenopalatine ganglion blocks are performed by board-certified interventional pain physicians or neurologists. Prior to the intervention, the nasal cavity is inspected for any existing obstructions which must first be cleared. 0.05% xylometazoline nasal drops are used to open the nasal passages. The facial temperature is recorded using skin sensor probes placed on both cheeks.
2% lidocaine jelly is placed in each nostril for comfort. The patient is placed in the supine position, with the head extended. The trans-nasal sphenopalatine ganglion block is delivered to the patient in the form of 2cc of 2% lidocaine (numbing agent) using a spheno-catheter device or plain cotton nasal swabs. The spheno-catheter device comprises of a small flexible sheath with a curved tip. It is inserted through the nasal passage parallel to the nasal septum (the cartilage which separates the nasal cavity in the midline). After the block, there is an expected increase in facial temperature by 1 to 2 degrees Celsius and some tearing of the eyes is expected. The patient should continue lying down for approximately 10 minutes.
The sphenopalatine ganglion block is an extremely safe procedure that can result in rapid (within 15 minutes) relief of an acute headache and a significant relief observed at 24 hours. It is extremely well tolerated and very few adverse events have been recorded. Common side effects reported have included numbness when swallowing, bitter taste of the anaesthetic agent, and slight bleeding from the nose.
References for Further Reading
- Binfalah M, Alghawi E, Shosha E, Alhilly A, Bakhiet M. Sphenopalatine Ganglion Block for the Treatment of Acute Migraine Headache. Pain Res Treat. 2018;2018:2516953. Published 2018 May 7. doi:10.1155/2018/2516953 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5971252/
- Nair AS, Rayani BK. Sphenopalatine ganglion block for relieving postdural puncture headache: technique and mechanism of action of block with a narrative review of efficacy. Korean J Pain. 2017;30(2):93–97. doi:10.3344/kjp.2017.30.2.93 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5392662/