What is an spg block?
A Sphenopalatine Ganglion Block (SPG block) is a procedure that delivers an anesthetic agent (numbing medicine) to a collection of nerves in the ganglion for the purpose of stopping the transmission of pain.
This is typically done through the nose—as that is the least invasive way to access the SPG— and the medication used is a local anesthetic such as lidocaine (the same or similar medication that is injected by a dentist or used to anesthetize a laceration before stitches).
How does it work?
To understand what an SPG block is, and how and why it could help relieve your headache pain, it helps to first understand what the SPG itself is and what role it plays in migraine pathology.
What is the sphenopalatine ganglion?
The sphenopalatine ganglion (or SPG) consists of a bundle of nerve cells located just behind the bony structures of the nose. It contains autonomic nerves—specialized nerves that control organ functions—and sensory nerves.
In the SPG, autonomic nerves supply the lacrimal glands (which produce tears) and the inner lining of the nose and sinuses (which produces nasal discharge or congestion). The SPG also has connections to the brainstem (where cluster and migraine attacks may be generated) and to the meninges (coverings of the brain) by the trigeminal nerve (through the ophthalmic branch).
The trigeminal nerve is the main sensory nerve of the face, and is also the primary nerve involved in headache disorders. When activated, this nerve transmits pain signals to the brain via the ophthalmic branch to the meninges.
When activated, the blood vessels in the meninges become dilated causing a sterile inflammatory cascade. This vasodilation and inflammation signals pain signals back to the brain.
What is the role of the sphenopalatine ganglion in headache disorders?
The SPG has connections to the brainstem (where cluster and migraine attacks may be generated) and to the meninges (coverings of the brain) by the trigeminal nerve (through the ophthalmic branch). Pain receptors are activated when the blood vessels become dilated and inflamed. Pain impulses are then transmitted through the trigeminal nerve, eventually to the sensory areas of the brain, and are perceived as pain. In migraine and cluster headache, nerves carrying these pain signals pass through the SPG, with some making connections to the autonomic nerves.
This explains why in cluster headache, and sometimes in migraine, we see autonomic features including tearing of the eyes and nasal congestion or discharge.
What to expect from an spg block procedure
It is important to note that the duration of pain relief is highly variable. Some patients receive no benefit from the procedure while others report a drastic reduction in the amount of medications taken to relieve headache attacks over the 4-6 weeks following the procedure.
What are the potential side effects or risks?
The risks of the procedure are typically minimal and temporary. Discomfort during and after the procedure, a numb sensation when swallowing, bitter taste from the anesthesia, low blood pressure, nausea and/or light-headedness are the most common side effects reported. These side effects typically resolve within minutes to a few hours. There is a very small risk of nasal bleeding, seizures, infection and allergic reactions.
SPG blocks have been reported to treat the following conditions:
Will insurance cover this procedure?
Most insurance carries cover SPG block for a variety of headache disorders, but you should speak with your insurance representative to ensure it is covered if your provider performs it.
How often can I have this procedure done?
SPG block can be repeated as often as needed to reduce pain.
The Sphenopalatine Ganglion (SPG) is a group of nerve cells that is linked to the trigeminal nerve, the main nerve involved in headache.
The link between the SPG and the trigeminal nerve is important in head pain. If you apply local anesthetics (or numbing medications) to block or partially block the SPG, this can be helpful in reducing head and facial pain.
SPG block is a safe, quick, and effective way to reduce severity and frequency of various headache disorders for a period of time. Like many other procedures in headache medicine, SPG block is likely to work best when combined with a comprehensive headache treatment pla