Glossopharyngeal Neuralgia (GPN)

What is glossopharyngeal neuralgia (GPN)?

Glossopharyngeal neuralgia (GPN) is a rare condition that can cause sharp, stabbing, or shooting pain in the throat area near the tonsils, the back of the tongue or the middle ear.

The pain occurs along the pathway of the glossopharyngeal nerve, which is located deep in the neck. It serves the back of the tongue, throat and the parotid gland (one of the salivary glands), the middle ear and eustachian tube.

Painful episodes are usually intermittent, lasting from a few seconds to a few minutes. The pain might recur several times in a day. In other cases it might not come back for several weeks or months.

Certain activities may trigger painful episodes, including:

• Drinking cold liquids
• Chewing
• Swallowing
• Sneezing or coughing
• Clearing the throat
• Touching the gums

Sometimes people with this condition may avoid eating, drinking or chewing because they fear that these activities may trigger a painful attack. Over time, this can result in weight loss.

Generally, only one side of the head is affected by GPN. The glossopharyngeal nerve has several branches, including the tympanic branch that receives sensations from the middle ear and mastoid.

Another important branch is the carotid sinus nerve that serves the carotid body and carotid sinus (widening of a carotid artery at the main branch point). Painful attacks may result in life-threatening symptoms, such as fainting (syncope), slow heartbeat (bradycardia) or arrhythmia (irregular heartbeat). In very rare cases, cardiac arrest may occur with no painful episodes.

How common is glossopharyngeal neuralgia (GPN)?

The disorder is rare, with less than 1 case reported per year among 100,000 people in the United States. It tends to occur more often in adults over age 40, but it may be present at any age. It appears to affect men more than women.

What causes glossopharyngeal neuralgia (GPN)?

Often there is no apparent cause for the condition. Compression of the glossopharyngeal nerve by a blood vessel near the brainstem may irritate the nerve and cause pain. In other cases, an elongated styloid process (a bone in the neck near the nerve) can cause pain. This condition is called Eagle syndrome.

Trauma due to an injury or a surgical procedure may also result in glossopharyngeal neuralgia. Other possible causes include infections, tumors and vascular abnormalities. Patients with multiple sclerosismay experience glossopharyngeal neuralgia as a result of the breakdown of the myelin sheath, the fatty membrane that surrounds and insulates the nerve.

How is glossopharyngeal neuralgia (GPN) diagnosed?

The location of the pain is important in the diagnosis of glossopharyngeal neuralgia, since other conditions, such as trigeminal neuralgia, may produce similar symptoms. There is no single diagnostic test that can confirm that GPN is present. An ear, nose and throat physician will perform an examination to rule out other disorders. The physician may stimulate certain areas, such as the tonsils or back of the tongue, to see if pain occurs.

The doctor will ask whether certain activities, such as talking or chewing, trigger pain. An MRI (magnetic resonance imaging) or CT (computed tomography) scan may be ordered to determine whether a tumor or blood vessel is compressing the nerve.

How is glossopharyngeal neuralgia (GPN) treated?

In most situations, anticonvulsant drugs are the first line of treatment. If drug therapy is not effective or if a patient has troublesome side effects from the medication, surgery is considered.

Medications

• Anticonvulsants: Carbamazepine, oxcarbazepine, phenytoin, gabapentin, pregabalin, and other antiseizure medications are often prescribed for GPN.
• Antidepressants: Amitriptyline and other antidepressant drugs are sometimes prescribed for use along with anticonvulsants to treat individuals who become depressed due to debilitating pain.
• Anesthetics: Local anesthetics may be injected to block the nerve or applied topically to areas where pain occurs (for example, the back of the throat).

Surgery

Several surgical procedures may be options in alleviating the pain associated with GPN. The most common of these is microvascular decompression as explained below. If a tumor is found compressing the nerve or if Eagle syndrome is diagnosed (elongated styloid compressing the nerve), then a different type of surgery may be warranted.

• Microvascular decompression: This procedure is the most common surgical technique for treating glossopharyngeal neuralgia. It is performed under general anesthesia. The surgeon will make an incision and a small opening in the bone behind the ear on the side of the head where pain occurs. He or she will use a microscope and/or an endoscope to view the nerve and search for any blood vessels compressing the nerve. The nerve and artery are separated and a small permanent Teflon sponge will be placed between the nerve and the vessel that is compressing the nerve. After the procedure is performed, the surgeon will replace the bone and close the incision. Microvascular decompression has the highest initial and long-term success rate. It is effective in about 90% of cases and yields a lower rate of pain recurrence. However, if a patient cannot have microvascular decompression surgery due to other medical conditions, a less invasive procedure may be used.
• Gamma Knife Radiosurgery (GK or SRS): While this has been used much more commonly in trigeminal neuralgia (similar disorder of a different nerve), it has been used in a small number of cases of difficult-to-treat glossopharyngeal neuralgia. A frame is placed on the head and MRI/CT pictures are taken. The treatment is performed by a neurosurgeon and radiation oncologist working together. The glossopharyngeal nerve is targeted using highly precise software and a high dose of focused radiation is delivered onto the nerve to cause partial injury. While this can provide pain relief, it can cause partial numbness in the back of the throat.