By Jeffrey Brown, MD, FACS, FAANS
Glossopharyngeal Neuralgia (GPN) was first described by the one of the first modern neurosurgeons, Walter Dandy, as “paroxysmal pain frequently brought on by eating and swallowing with involvement of the root of the tongue and pharynx, with radiation to the throat and/or the deep ear structures.” The description is still accurate.
What is the glossopharyngeal nerve?
This is the ninth of twelve cranial nerves, meaning nerves that directly enter or exit the brain not the spinal cord, and is anatomically closely related to the tenth cranial nerve, the vagus nerve. As the above definition notes, the glossopharyngeal nerve provides sensation to the throat and base of the tongue, the deep middle ear, but also the parotid gland. The parotid gland is at the base of the jaw. Injury to it will cause a dry mouth. The ninth nerve provides taste sensation to the base of the tongue and some motor function to a swallowing muscle of the throat.
Dandy’s definition was used by Peter Jannetta to select patients in which he first performed vascular decompression of the vago-glossopharyngeal complex as the most appropriate treatment for
this entity. Note- He spoke of decompressing two nerves-the vagus and the glossopharyngeal.
The glossopharyngeal and vagus nerves, compose a web of fascicles such that a vessel in contact with the ninth nerve will also be in contact with the lower fibers of the tenth nerve. These also are sensory to the throat.
Distinguished trigeminal and glossopharyngeal neurosurgeons believe that glossopharyngeal neuralgia is an inaccurate description of this entity leading to neuropathic (stabbing) ear and throat pain. Glossopharyngeal neuralgia is more appropriately categorized as vago-glossopharyngeal neuralgia when caused by a vascular compression because of the close relationship of the fibrous web that enters the jugular foramen at the skull base. This is the opening in the skull that also allows exit from the brain of the large jugular vein, which drains blood from one side of the brain. For this reason, efforts to treat GPN by a rhizotomy, a heat injury to the nerve done with a special needle, is a concern. The vein can be punctured. Surgeons who choose to section the GPN rather than decompress it have learned that they must also section these vagus fibers to achieve adequate pain relief. Of course, this leads to permanent, and sometimes uncomfortable, numbness in the throat. There thus remains controversy if GPN is better treated by sectioning the GPN and adjacent sensory fibers of vagus nerve or by attempting to decompress.
What happens to the body with injury to the vagus nerve near the base of the skull?
If the motor fibers of the nerve are injured there can be weakness of the palate, giving the voice a nasal element. Trouble with swallowing follows weakness of the pharyngeal (throat) muscles. There may be weakness or even paralysis of the vocal cord causing hoarseness.
One of the lesser-known issues with vago-glossopharyngeal neuralgia is that when the vagus nerve is involved there can be speech difficulty-lowered volume of speech or hoarseness with ongoing effort, perhaps a chronic cough.
The good news is that GPN is surgically treatable.
In Jannetta’s series, 79% of 39 patients treated over the course of 24 years had immediate pain relief and 76% had continuing complete relief with follow-up of 6 months to 14 years with a mean of 4 years. Many more series of patients by other centers have confirmed the benefits of glossopharyngeal nerve decompression for glossopharyngeal neuralgia.2-4 There has also been a small study of decompression surgery of the “lower cranial nerves” specific for “dysphonia-” speech quality issues including chronic cough, breathing irregularity and hoarseness.
Finally, it may be possible for one to have both trigeminal and glossopharyngeal neuralgia. It may not be clear when there is ear pain whether it is from trigeminal or from glossopharyngeal neuralgia.
Choose your physician with care to find one that understands the nuances of your care and you should do well.