Glossopharyngeal Neuralgia

What is Glossopharyngeal Neuralgia?

Glossopharyngeal neuralgia (GPN), also known as cranial mononeuropathy or vagoglossopharyngeal neuralgia, first coined in 1921 by Harris, constitutes a rare pain syndrome resulted due to irritation of the glossopharyngeal nerve (the 9th of the 12 pairs of cranial nerves).

Signs and Symptoms

Areas that are connected to the 9th cranial nerve experience severe, electric shock-like pain that according to the International Headache Society, can be episodic (Classical GPN) or constant (Symptomatic GPN).

Pain Triggering Factors

• Chewing
• Coughing
• Drinking chilled liquids
• Laughing
• Talking
• Swallowing
• Yawning
• Feeling the gums
• Sneezing
• Clearing the throat

Glossopharyngeal Neuralgia

Characteristics of the Pain

• Lasts for a few seconds to a few minutes
• Affects one side of the throat (may be bilateral in rare cases)
• Occurs at random throughout the day
• Frequency increases over time, leading to certain disabilities
• Severe enough to rouse one from sleep

Areas Where Pain is Felt

• Back of nose and throat (nasopharynx)
• Back of tongue
• Middle ear
• Jaw
• Tonsil area
• Neck

Rare Features of GPN

• Tinnitus
• Vomiting
• Vertigo
• Swelling sensation
• Involuntary movements

Causes

Although it is not known what causes the irritation, it is believed that damage of the protective sheath of the 9th cranial nerve results in sending abnormal messages that disrupt the normal signals of the nerve, causing pain. There may be various causes:

Compression of the glossopharyngeal nerve by:

• Arteries and veins
• Abnormal growths at the base of the skull
• Tumors
• Swelling of glands
• Problems of the spinal cord such as multiple sclerosis
• Abnormally large styloid process

Irritation of the glossopharyngeal nerve by:

• Mouth infections such as tooth abscess, tooth extraction, and other dental issues
• Viral infections caused by the herpes virus and other infections such as mums, common cold
• Inflammations of the nose, ear or throat

Risk Factors

• Being over 40 years of age
• Direct blow over the neck or ear regions during sports
• An injury to the nerve and neck due to any serious accident
• Medical conditions like diabetes
• Rheumatoid conditions and musculoskeletal problems
• Elongated styloid process
• Hypertension

Complications

• Slow pulse rate
• Sudden fall in blood pressure
• Fainting (syncope)
• Seizures
• Bradycardia
• Cardiac syncope

Diagnosis and Tests

After a careful physical examination of the patient’s symptoms, if GPN is suspected, the back portion of the patient’s throat is touched with a cotton-tipped applicator to arouse pain. If pain occurs, a local anesthetic is applied to the same region and again the pain stimulus is performed. An absence of pain when the area is numb suggests GPN.

Imaging tests to detect the presence of tumors or an elongated styloid process

• CT scan of the head
• MRI of the head
• X-rays of the head or neck

Imaging tests to look for arterial or vascular compression

• MRA of the head
• CT angiogram
• X- rays of the arteries

Other imaging and blood tests

• Blood tests (sugar level) to determine the cause of nerve damage
• Electromyogram (EMG) to record muscle contractions or changes caused due to nerve stimulation
• Nerve conduction study (NCS) to record changes in nerve signals

Differential Diagnosis

• Trigeminal neuralgia
• Eagle syndrome
• Geniculate neuralgia

Treatment and Management

Treatment that is mainly directed towards reducing pain involves:

Medication

Anticonvulsants such as carbamazepine (Tegretol), oxcarbazepine (Trileptal), gabapentin (Neurontin), phenytoin (Dilantin), baclofen (Lioresal), and pregabalin (Lyrica) may be administered to block the pain and abnormal signals.

Some antidepressants and relaxants like amitriptyline or nortriptyline may also prove effective in lessening pain.

Application of a Local Anesthetic

By applying a local anesthetic called lidocaine at the back of the throat, numbness may be formed in the area, and temporary relief from swallowing difficulty can be obtained.

Sometimes pain may be relieved by injecting sterile glycerol at the nerve root.

Surgery

Surgical procedures are sought only when the patient does not respond to drug therapy.

Microvascular Decompression (MVD): MVD, the commonest treatment, providing relief to nearly 85% of patients involves a procedure called craniotomy by which a 1-inch opening is made and the blood vessel pressing the nerve is either lifted or removed.

This surgery, requiring 1 to 2 days of hospital stay includes a 5% risk of death as blood pressure and heart rate problems may emerge owing to the manipulation of the nearby vagus nerve.

Nerve Rhizotomy: If the blood vessel compressing the nerve cannot be traced or is difficult to remove, then this procedure is carried out. To detect the root fibers of the vagus nerve causing pain, a small incision is made at the back of the skull using a stimulation probe and finally the concerned fibers are severed.

Both these operations may provide 96% long-term relief, but there may be side effects such as hoarseness, swallowing difficulty (dysphagia), and loss of taste sensation.

Percutaneous Stereotactic Radiofrequency Rhizotomy (PSR): This is a minimally invasive outpatient procedure that uses an electrode with current to damage some of the pain-causing nerves.

Radiation

Gamma Knife Radiosurgery or Stereotactic Radiosurgery: Aiming to destroy the affected nerve root to block the transmission of pain signals to the brain, it is done by delivering highly focused radiation beams at the root of the nerve. This noninvasive outpatient procedure, usually done on aged patients who are incapable of tolerating surgeries, provides relief from pain gradually. Consequently, patients remain on medication for some time to handle the pain as the radiation takes effect.

Other Modes of Management
Lifestyle changes like avoiding repeated late night sitting, limitless use of electronic gadgets, heedless consumption of caffeinated beverages or smoking

• Homeopathy, Ayurveda, acupuncture, and yoga practiced under efficient guidance
• Message therapy (for muscle stress and spasms)
• Psychotherapy and counseling to overcome stress

How to Prevent GPN

Although there are no known ways to prevent the syndrome, following a low-salt and low-fat diet, along with natural supplements such as magnesium, iron, and other important nutrients, may help in keeping the protective covering of the nerve intact, reducing the chances of damage.

Incidence and Prevalence

The incidence of GPN is estimated to be between 0.2- 0.7 per 1000,000 people per year. Amidst this, around 10% of individuals are misdiagnosed as trigeminal neuralgia.

Prognosis

With some patients, the pain syndrome goes away after proper treatment following an initial attack. In more serious cases, the attacks recur and are followed by short or long remission periods. The recovery depends on the underlying ailment that causes pain and the effectiveness of the initial treatment.

Glossopharyngeal Neuralgia vs. Trigeminal Neuralgia

Though GPN is often misdiagnosed with trigeminal neuralgia due to both being facial pain syndromes, they can be distinguished on the basis of the location of pain. While the pain of GPN typically concerns ear and throat, trigeminal Neuralgia causes pain in lips, eyes, nose, scalp, and forehead.

GPN ICD-9-CM Code and ICD-10-CM Code

The ICD-9-CM code of GPN is 352.1, and ICD 10 CM is G52.1.