Glossopharyngeal neuralgia, also known as vagal glossopharyngeal neuralgia, is an episode of severe pain confined to one side of the glossopharyngeal nerve or to the posterior tongue and throat of the Eustachian branch of the vagus nerve, which may radiate to the oropharynx or external ear.
Etiology
1.Primary glossopharyngeal neuralgia. The etiology of primary glossopharyngeal neuralgia is not clear, but microvascular compression of the glossopharyngeal nerve may be the main cause. The compression of the linguopharyngeal and vagus nerves by the posterior inferior cerebellar artery and other vessels causes demyelination of the linguopharyngeal and vagus nerves, resulting in a “short circuit” between the afferent impulses of the linguopharyngeal nerve and the vagus nerve, causing pain. The onset of the disease is over 40 years of age and is more common in men than women.
The clinical features of the disease are:
(1) The clinical manifestations and pain sites are different from those of primary trigeminal neuralgia, with pain occurring at the root of the tongue, pharynx, tonsils, deep ear and the posterior part of the jaw. Sometimes the pain in the deep part of the ear is the main manifestation.
(2) The attack and the nature of pain are the same as trigeminal neuralgia, the pain often comes on suddenly and stops suddenly, the duration of each attack is a few seconds or tens of seconds, usually not more than 2 minutes. The pain can also be severe like cutting, stabbing, tearing, burning, or electric shock.
(3) Triggering factors often trigger pain when swallowing, chewing, talking, coughing, or yawning.
(4) Trigger point. Trigger points are often present, mostly at the posterior pharyngeal wall, tonsils, tongue root, etc., and rarely in the external auditory canal.
(5) Other symptoms because swallowing movements often trigger painful episodes, although there is no pain between episodes, but the fear of triggering pain and afraid to eat, patients often show wasting, dehydration. Patients often show weight loss, dehydration, laryngeal spasm, cardiac rhythm disturbance and hypotensive syncope, etc.
(6) No positive signs in neurological examination.
2, secondary lingual-pharyngeal neuralgia. Some pontocerebellar horn tumors, arachnoiditis, vascular diseases, pharyngeal tumors or hypertelorism can provoke pain in the distribution area of the glossopharyngeal nerve, which is called secondary glossopharyngeal neuralgia.
Its clinical manifestations:
(1) Pain in the distribution area of the linguopharyngeal nerve: the pain attacks are long or persistent, and the triggering factors and trigger points may not be obvious, but are more severe at night.
The symptoms of linguopharyngeal nerve damage include: palatal arch paralysis, loss of sensation in the soft palate and pharynx, loss of taste and general sensation in the posterior 1/3 of the tongue, loss of gag reflex, and disturbance of parotid gland secretion.
(3) Adjacent cerebral nerve damage: often jugular foramen syndrome (Vernet’s syndrome): damage to the Ⅸ, Ⅹ, and Ⅺ cerebral nerves on one side; posterior pharyngeal syndrome (Villaret’s syndrome): damage to the Ⅸ, Ⅹ, Ⅺ, and Ⅻ and Horner’s syndrome; pontocerebellar horn syndrome may also be present.
In the case of nasopharyngeal cancer, a mass in the nasopharynx and enlarged lymph nodes in the neck may be found.
Clinical symptoms
1.More common in males than females, and the onset of disease is mostly after 35 years of age;
2. The pain is limited to the area innervated by the glossopharyngeal nerve and the auricular and pharyngeal branches of the vagus nerve, i.e., the posterior pharyngeal wall, tonsillar fossa, tongue root and deep external auditory canal, etc. It may radiate to the external ear, mandible and gingiva. The pain is usually unilateral, and only 2% of cases are bilateral. The pain is like cutting, stabbing or electrocution, sudden and intense, lasting from a few seconds to a minute, with several to dozens of attacks per day;
3, . In most cases, the pain has distinct periods of onset and quiescence, sometimes up to 1 year or more, but does not heal on its own;
4. There may be painful “trigger points” at the root of the tongue, tonsil fossa and throat, often triggered by eating, swallowing and talking;
5. There is no abnormality on physical examination and cranial CT or MRI.
Clinical classification
There are two different clinical classifications of glossopharyngeal neuralgia. In the first method, there are three types of neuralgia: typical neuralgia, atypical neuralgia, and secondary neuralgia. Typical glossopharyngeal neuralgia is usually caused by severe pain in the oropharynx and ears due to vascular compression of the 9th and 10th cranial nerve roots that enter the lateral medulla oblongata.
Atypical glossopharyngeal neuralgia is not limited to these areas, but can radiate to the forehead, external auditory canal, and auricle. Secondary glossopharyngeal neuralgia is caused by a tumor in the neck or skull base that damages the glossopharyngeal nerve. Glossopharyngeal neuralgia has also been associated with multiple sclerosis, but the onset is rare.
In contrast, Olese et al. classified two types of glossopharyngeal neuralgia: classic and symptomatic.
The diagnostic criteria for classic glossopharyngeal neuralgia are as follows:
1. Sudden facial pain lasting from a few seconds to no more than 2 min
2. At least 4 of the following conditions are met: pain unilaterally distributed in the posterior part of the tongue, tonsillar fossa, laryngopharynx, lower part of the inferior collar angle or in the ear; sudden, sharp, pins and needles or burning-like pain; severe pain; chewing, swallowing, coughing, talking or yawning can induce pain.
3.No neurological abnormalities.
4.Exclude other causes of pain by medical history, physical examination and special examination.
5.The duration of pain episodes is basically the same.
Symptomatic GPN meets the first 2 diagnostic criteria above, but also has the following conditions: the pain may persist between episodes; hyperalgesia in the distribution area of the linguopharyngeal nerve. In addition, the diagnosis requires a special examination or intraoperative clarification of the cause of the injury.
Site typing
The site of glossopharyngeal neuralgia is generally divided into two types.
(1) The area begins in the pharyngeal wall, tonsillar fossa, soft palate and the posterior third of the tongue, and then radiates to the ear; this type is the most common;
The painful area starts in the outer ear, deep part of the ear canal and the parotid area, or between the angle of the mandible and the mastoid, and rarely radiates to the pharyngeal side, which is rare. Occasionally, the pain is limited to the deep part of the outer ear canal, which only affects the tympanic branch of the linguopharyngeal nerve. The pain is sudden, with paroxysmal electric shocks, cuts, needles, burns, and severe tearing pains, and is brief.
The general tendency is to have more and more frequent episodes and longer and longer durations, often with intervals of varying duration, during which the patient is as usual. The patient may also experience increased blood pressure, laryngeal spasm, vertigo, and occasionally cardiac arrhythmias such as tachycardia, bradycardia, or even transient arrest, and hypotensive syncope.
There may be “trigger points” in the external ear, tongue root, posterior pharynx and tonsillar fossa, which can develop when stimulated, so the patient is afraid to swallow, chew, speak and do head and neck rotation, etc. The pain may also radiate to the neck or shoulder, but bilateral glossopharyngeal neuralgia is extremely rare.
Neurological examination
There are often no abnormal findings, which is a characteristic of this disease.
1. Episodes of severe pain lasting from a few seconds to a few minutes.
2. The pain involves the tonsils, the posterior pharyngeal wall, the back of the tongue, the larynx, the middle ear, and may radiate to the neck.
3. There may be painful trigger points at the root of the tongue, tonsil fossa, and throat, so it often affects swallowing, conversation, and chewing without other objective neurological signs. Patients with chronic prolonged disease may have a deviation of the uvula.
4. Painful episodes are occasionally accompanied by cardiac arrest, syncope, and convulsions.
5. Spraying 1% bupivacaine on the posterior pharyngeal wall or tonsillar area can reduce the attack to differentiate it from trigeminal mandibular branch pain.
6. Tympanic neuralgia, or otolaryngopharyngeal neuralgia, is caused by the involvement of the tympanic nerve of the linguopharyngeal nerve. The pain is paroxysmal and transient, limited to the deep part of one side of the ear and the posterior part of the ear, and radiates to the mandibular angle of the pharynx and the neck in severe cases. The pain may be spontaneous or triggered by touching the ear canal, but there is no trigger point in the linguopharynx, so swallowing is not triggered.
Diagnosis
The diagnosis is usually clear based on the clinical features of the disease, and CT and MRI examinations help to exclude secondary lesions.
Differential diagnosis
1. trigeminal neuralgia: the third branch is easily confused with glossopharyngeal neuralgia. If the pain is relieved by spraying the posterior pharyngeal wall or tonsillar area with 4% cocaine or 1% pontocaine, it can be differentiated from the pain of the mandibular branch of the trigeminal nerve;
2. Supraglottic neuralgia: The supraglottic nerve is a branch of the vagus nerve, and the neuralgia can exist alone or be accompanied by linguopharyngeal neuralgia. If local anesthesia is performed in this area, the pain is often temporarily relieved, which can be distinguished;
3. Intermediate neuralgia: It is a severe pain in one side of the ear, with a long attack time, often accompanied by herpes in the external auditory canal or auricle, and sometimes can cause peripheral facial paralysis. Individuals with atypical otalgia only are not easily distinguished from glossopharyngeal neuralgia, which is a simple otalgia. In this case, in addition to removal of the glossopharyngeal nerve, the intermediate nerve also needs to be removed during surgery;
4.Secondary linguopharyngeal neuralgia: the pain is persistent, with paroxysmal aggravation and no trigger point, and some linguopharyngeal nerve dysfunction (such as hypoesthesia of linguopharyngeal sensation and posterior tongue taste, dull pharyngeal reflex, soft jaw motor weakness, etc.) or other positive neurological signs can be seen on the affected side during examination. Localized lesions may be found on cranial CT or MRI.
Treatment
The initial treatment of glossopharyngeal neuralgia is medication. In case of ineffective medication or with serious complications, surgical treatment should be actively used.
1. Drugs: Any drug used to treat primary trigeminal neuralgia can also be applied to glossopharyngeal neuralgia. Commonly used drugs include carbamazepine, phenytoinamide, heptaerythrone and baclofen, etc.
2.Chinese medicine: Chinese medicine, acupuncture, etc.
3.Surgery: Since 1977, Laha and Jannetta thought that vascular compression was the cause of pain, more scholars have found that the vertebral artery or the posterior inferior cerebellar artery rides across the linguopharynx and vagus nerve root into the brainstem section (root entry zone). At present, microvascular decompression has become the surgical method of choice for linguopharyngeal neuralgia. Its cure rate can reach 99%.