Sphenopalatine ganglion is located in the sphenopalatine fossa, posterior to the middle turbinate, and inferior to the maxillary nerve. The sensory fibers derived from the maxillary nerve travel through the SPG to provide sensory innervation to the nasal cavity, palate, and parts of the nasopharynx and oropharynx. Anesthetic blockage of this ganglion is effective in the relief of a wide variety of facial pains and headaches.
The SPG plays a critical role in headache disorders, especially trigeminal autonomic cephalgias (TACs). The key features of TACs are unilateral headaches typically associated with autonomic dysfunction like lacrimation and rhinorrhea (due to parasympathetic activation), ptosis (due to sympathetic stimulation) and miosis (both parasympathetic and sympathetic stimulation). Cluster headaches are the most common TACs. Stimulation of SPG causes cerebral vasodilatation and increases cerebral blood flow, which results in the release of vasoactive intestinal peptide, acetylcholine, and nitric oxide. These inflammatory substances, in turn, activate trigeminal nociceptors and cause headaches.
The SPG has been a target for various procedures to ease the symptoms of myofascial pain, postherpetic neuralgia, post-traumatic headache, cluster headache and pain originating from the temporomandibular joint, as well as various head and neck cancers. The SPG block was first demonstrated by Sluder in 1908, who injected 20% cocaine solution to via transnasal approach to block the SPG. In 1970, Ruskin studied the effects of SPG block for management of headaches, facial neuralgia, low back pain, and TMJ pain. Devoghel et al. demonstrated its benefit on cluster headache. Currently, cluster headaches, trigeminal neuralgia, migraine headaches, and atypical facial pain are the most common indications for SPG block.
The simplest method of targeting the sphenopalatine ganglion is the self-introduction of an intranasal, cotton-tipped applicator coated with 4% lidocaine. Another approach is to do a nasal spray with the same concentratoin of anesthetic.
The anesthetic can be delivered using a special syringe, such as the SphenoCath or the TX360, with an extension to reach the inferior turbinate, superior turbinate and sphenopalatine foramen.
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