Sphenopalatine Ganglion Radiofrequency Thermocoagulation

Excerpt

Sphenopalatine ganglion (SPG) neuralgia is a complex disease characterized by chronic head and neck pain often accompanied by autonomic features. Although symptoms are highly variable, patients typically experience dull headaches associated with pain in the maxillary arch and teeth. The onset of intense pain can be accompanied by profuse sweating and vasomotor changes. The SPG has been a target for numerous procedures to ease symptoms of myofascial pain, post-herpetic neuralgia, post-traumatic headache, cluster headache, and pain originating from the temporomandibular joint (TMJ), as well as various head and neck cancers. The SPG block was first reported by Sluder in 1908, who injected 20% cocaine solution via a transnasal approach. In 1970, Ruskin studied the effects of SPG blocks for the management of headaches, facial neuralgia, low back pain, and TMJ pain. In 1981, Devoghel demonstrated its benefit for cluster headaches. Currently, cluster headaches, trigeminal neuralgia, migraine headaches, and atypical facial pain are the most common indications for performing an SPG block.

Radiofrequency thermocoagulation (RFTA), also known as radiofrequency neurotomy, is a technique that employs thermal energy to ablate target nerves involved in the pathological transmission of painful stimuli. The RFTA device uses high-frequency (300-500 kHz) electromagnetic radiation to create charged molecular oscillation, which in turn produces heat. In conventional RFTA, the needle generates a 5 to 15 mm electric field that ultimately increases the temperature of the affected tissue to greater than 45 °C. This temperature produces local tissue damage and loss of myelinated nerve fibers. When the needle tip heats to 80 °C for 60 to 90 seconds, it reliably ablates an 8 to 10 mm area. Pulsed radiofrequency ablation (PRFA) is a similar soft tissue-destroying modality. PRFA is performed with short 20 ms pulses every 0.5 seconds, allowing the tissue to cool between pulses and, therefore, not exceeding the target temperature of 42 °C. The advantage of PRFA is that there is less tissue destruction and less pain, but the disadvantages are that there is typically a shorter duration of relief, and the procedure may require more frequent repeat treatments, which may increase the cost.