Trigeminal neuralgia

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Trigeminal neuralgia (TN) is a neuropathic disorder of the trigeminal nerve that causes episodes of intense pain in the eyes, lips, nose, scalp, forehead, and jaw.^[1]It is also known as Tic Douloureux or Fothergill’s disease (named after John Fothergill). Trigeminal nerve is one of the largest and widely distributed cranial nerve with three branches ophthalmic nerve (V1), maxillary nerve (V2) and mandibular nerve (V3). Ophthalmic and maxillary are purely sensory, while mandibular nerve has both sensory and motor functions. Pain of trigeminal neuralgia affects sensory distributions and typically radiates to maxillary and mandibular divisions in 35% of affected individuals. International Association of Study of Pain (IASP) defined TN as “sudden usually unilateral severe brief stabbing recurrent pain in the distribution of one or more branches of 5th cranial nerve”. Similarly, International Headache society (IHS) defined it as “painful unilateral affliction of face characterized by brief electric shock like pain limited to the distribution of one or more divisions of trigeminal nerve“. TN is usually characterized by paroxysmic episodes of sudden, severe, shock like pain that lasts for seconds to a few minutes. It is almost always unilateral, but is bilateral in rare cases, and right side is affected more often than the left side. These episodes can occur spontaneously or can be triggered by a mild cutaneous stimuli like chewing, shaving, touching, brushing teeth or even air currents can trigger an episode. The pain tends to occur in cycles with remissions lasting months or even years. These episodic attacks are known to worsen in frequency or severity overtime and can have a significant impact on a person’s quality of life, resulting in problems such as weightloss, depression and, in severe cases, suicide. Attacks may provoke patients to grimace, wince or make an aversive head movement, known as tic, hence the term ‘tic douloureux”. Data is not consistent, but some studies have shown that migraine and hypertension can act as a risk factor for trigeminal neuralgia. According to etiology, IHS has classified TN into three main categories classical, secondary and idiopathic TN. Although majority of the cases of TN are idiopathic but other causes may include systemic diseases like multiple sclerosis, diabetes mellitus, infectious conditions caused by Mycobacterium leprae, Secondary syphilis, Leptospirosis etc, injuries to trigeminal nerve both centrally and peripherally caused by trauma, ENT pathologies, intracranial tumors, cysts, arteriovenous malformations, tuberculomas and allergic reactions. Pathology of TN is related to demyelination and dystrophy of nerve caused by above mentioned etiological factors. Allergic reaction and its frequent manifestations such as cold, chronic rhinitis, maxillary sinusitis, tonsillitis and chronic inflammation can trigger immune response which in turn results in accumulation of immunoglobulins and histamine in trigeminal nerve region and play role in TN pathogenesis. Diagnosis of TN is mainly clinical, based primarily on history, physical examination and neurological examination, but other causes of facial pain should be ruled out. Common differentials include glossopharyngeal neuralgia, cracked tooth syndrome, cluster headaches and postherpetic neuralgia. Treatment of TN depends upon severity and underlying cause of disease and include medicines mainly anti epileptics, surgery and complimentary approaches. Carbamazepine is the first line drug used for initial management. However, as it is a long term condition, some people overtime may stop responding to medications, or they may experience unpleasant side effects. For those people surgical options can be considered. Psychosocial support also plays an important role in improving quality of life.

Trigeminal neuralgia is considered by many to be among the most painful of conditions and once was labeled the suicide disease because of the significant numbers of people taking their own lives before effective treatments were discovered. In 1773, John Fothergill presented his detailed description of TN ” a painful affection of the face” to the Medical Society to London, hence the name Fothergill’s disease.

The annual incidence of TN is 4 to 13 per 100,000 people. Despite its low incidence, numbers may be significantly higher due to frequent misdiagnosis. TN is one of the more frequently seen neuralgias in the older adult population. The incidence increases gradually with age; most idiopathic cases begin after age 50, although onset may occur in the second and third decades or, rarely, in children.

Signs of trigeminal neuralgia can be seen in males who may deliberately miss an area of their face when shaving, in order to avoid triggering an episode. Although trigeminal neuralgia is not fatal, successive recurrences may be incapacitating, and the fear of provoking an attack may make sufferers reluctant to engage in normal activities.

There is no cure for trigeminal neuralgia, but most people find relief from medication or sometimes from one of the many so-called complementary or alternative therapies. Atypical trigeminal neuralgia, which involves a more constant and burning pain, is more difficult to treat, both with medications and surgery. During a TN attack, some patients may get quick relief by applying an ice pack or a readily available source of cold temperature to the area of pain.

There is no cure for trigeminal neuralgia but most people find relief from one of the five surgical options. Surgery may result in varying degrees of numbness to the patient and lead occasionally to “anesthesia dolorosa,” which is numbness with intense pain. However, many people do find dramatic relief with minimal side effects from the various surgeries that are now available.^[2]

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Trigeminal neuralgia is considered by many to be among the most painful of conditions and once was labeled the suicide disease because of the significant numbers of people taking their own lives before effective treatments were discovered.

Historically trigeminal neuralgia has been called “suicide disease” by Harvey Cushing, who did a series of studies involving 123 cases of TN during 1896 and 1912.^[1]

• First full and accurate description of trigeminal neuralgia was given by John Fothergill in 1773, but early descriptions of TN can be inferred from the writings of Galen, Aretaeus of Cappadocia and in the 11th century by Avicenna(“tortura Orgs”).^[2]
• The most convincing early description was of a German physician, Johannes Laurentius Bausch. In 1671, he suffered from a lightening like pain in the right face and became unable to speak or eat properly and apparently succumbed to malnutrition.^[3]
• In 1677, John Locke, a physician and well known philosopher described the condition in a series of letters to Dr John Mapletoft. His account tells of his unfortunate patient, the Countess of Northumberland, wife of Ambassador to France.^[2]
• In 1756, Nicolas Andre conceptualized TN in terms of convulsive behavior and invented the term tic Douloureux to reflect both the pain his patients described as well as the facial spasms he documented.^[4]

• In 1773, John Fothergill’s description of “a painful affection of the face” was presented to Medical Society to London.^[5]

• Four-time British Prime Minister William Gladstone is believed to have had the disease.^[6]
• In 2009, the entrepreneur and author Melissa Seymour was diagnosed with TN and underwent microvascular decompression surgery. Her case was covered by magazines and newspapers which helped to raise public awareness of the illness in Australia. Seymour was subsequently made a Patron of the Trigeminal Neuralgia Association of Australia.^[7]
• In 2011, Salman Khan, one of India’s most successful film stars, was diagnosed with TN, resulting in tremendous media coverage in the country and abroad. He underwent surgery in the US.^[7]
• In 2013 All-Ireland winning Gaelic footballer Christy Toye was diagnosed with the condition.^[7]
• Jim Fitzpatrick – Member of Parliament for Poplar and Limehouse – disclosed he suffered from trigeminal neuralgia before undergoing neurosurgery. He has openly discussed his condition at parliamentary meetings and is a prominent figure in the TNA UK charity.^[7]
• Andrea Jenkyns – Member of Parliament for Morley and Outwood – diagnosis with TN came to light during her television debate on Prime Minister’s Questions where she struggled to get her words out.^[7]
• Jefferson Davis – President of the Confederate States of America.^[7]
• Charles Sanders Peirce – American philosopher, scientist and father of pragmatism.^[7]
• Gloria Steinem – American feminist, journalist, and social and political activist.^[7]
• Anneli van Rooyen, Afrikaans singer-songwriter popular during the 1980s and 1990s, was diagnosed with atypical trigeminal neuralgia in 2004.^[7]
• H.R., singer of hardcore punk band Bad Brains.^[7]

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The pain of trigeminal neuralgia is often falsely attributed to a pathology of dental origin. Rarely do patients come to the surgeon without having had removed many, and not infrequently all, teeth on the affected side or both sides.^[1] Extractions do not help for the pain is originating in the trigeminal nerve and not in an individual nerve of a tooth. Because of this difficulty, many patients may go untreated for long periods of time before a correct diagnosis is made. The trigeminal nerve is the fifth cranial nerve, a mixed cranial nerve responsible for sensory data such as tactition (pressure), thermoception (temperature), and nociception (pain) originating from the face above the jawline; it is also responsible for the motor function of the muscles of mastication, the muscles involved in chewing but not facial expression. Presence of refractory periods after a triggered episode, trains of painful sensations after a single stimulus, and latency from the time of stimulation to the onset of pain shows the role of central pain mechanisms involved in the pathogenesis of the pain of trigeminal neuralgia.^[2] Several theories exist to explain the possible causes of this pain syndrome. The leading explanation is that a blood vessel is likely to be compressing the trigeminal nerve near its connection with the pons. The superior cerebellar artery is the most-cited culprit. Such a compression can injure the nerve’s protective myelin sheath and cause erratic and hyperactive functioning of the nerve. This can lead to pain attacks at the slightest stimulation of any area served by the nerve as well as hinder the nerve’s ability to shut off the pain signals after the stimulation ends. This type of injury also may be caused by an aneurysm (an outpouching of a blood vessel); by a tumor; by an arachnoid cyst in the cerebellopontine angle,^[3] or by a traumatic event such as a car accident or even a tongue piercing. Two to four percent of patients with TN, usually younger, have evidence of multiple sclerosis, which may damage either the trigeminal nerve or other related parts of the brain. When there is no structural cause, the syndrome is called idiopathic. Postherpetic neuralgia, which occurs after shingles, may cause similar symptoms if the trigeminal nerve is affected.

Evidence for a role of central pain mechanisms includes the presence of refractory periods after a triggered episode, trains of painful sensations after a single stimulus, and latency from the time of stimulation to the onset of pain 

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Hardik Patel, M.D. Luke Rusowicz-Orazem, B.S.

Common causes of trigeminal neuralgia include sources of nerve compression from cardiovascular obstruction, tumor pressure, infectious disease, and facial trauma.

According to International Headache Society(IHS), in the International Classification of Headache Disorders, Third Edition (ICHD-3),TN is divided into classic (or classical) TN, secondary TN, and idiopathic TN.^[1]

Trigeminal neuralgia developing without apparent cause other than neurovascular compression.^[1] The common site of neurovascular compression is at the root entry zone, with compression by an artery more clearly associated with symptoms than compression by a vein. The artery involves is mainly superior cerebellar artery in classic TN and the atrophic changes may include demyelination, neuronal loss, changes in microvasculature and other morphological changes.^[2] MRI can demonstrate nerve root atrophy and/or displacement due to neurovascular compression as shown in image.^[3]

Classical trigeminal neuralgia usually appears in the second or third divisions and the pain rarely occurs bilaterally (sequentially rather than concomitantly). It may be preceded by a period of atypical continuous pain termed pre-trigeminal neuralgia and most patients remain asymptomatic between the paroxysms.^[2]

Trigeminal neuralgia caused by an underlying disease other than neuromuscular compression such as multiple sclerosis or a tumor along the trigeminal nerve.

Trigeminal neuralgia without an identifiable cause is termed as Idiopathic TN.

All these three categories can present with either purely paroxysmal pain or with additional continuous pain. TN with continuous pain, previously known as atypical TN can best be described as:

It can be defined as facial pain in the distribution(s) of one or more branches of the trigeminal nerve that is caused by another disorder and is indicative of neural damage. Unlike TN, the pain is predominantly continuous or near continuous, and is described most often as burning or squeezing, or a pins and needles sensation. Brief paroxysms of pain may occur but are not predominant. Examples include:^[1][3][4]

• Painful trigeminal neuropathy attributed to acute herpes zoster
• Trigeminal postherpetic neuropathy
• Painful post-traumatic trigeminal neuropathy
• Painful trigeminal neuropathy attributed to other disorder
• Idiopathic painful trigeminal neuropathy

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The differential diagnosis of TN includes the conditions that cause classic TN and secondary TN, mainly compression of the trigeminal nerve by a vascular loop or a nonvascular space-occupying lesion, and demyelination from multiple sclerosis in the pons or root entry zone of the trigeminal nerve. Although less likely to be confused with TN, the differential diagnosis also includes various causes of painful trigeminal neuropathy, such as acute herpes zoster, postherpetic neuralgia, and trauma to the trigeminal nerve. In most cases, painful trigeminal neuropathy can be distinguished from TN by a thorough history and examination.^[1] A history of persistent pain or pain that occurs episodically in attacks lasting longer than two minutes eliminates classical trigeminal neuralgia and should lead to a search for other diagnoses. The pain of glossopharyngeal neuralgia, which may be triggered by talking or swallowing, is located in the tongue and pharynx.^[2]. Some differentials are listed in the table below:

SUNCT: short lasting, unilateral, neuralgiform headache attacks with conjunctival injection and tearing

SUNA: short lasting, unilateral, neuralgiform headache attacks with autonomic symptoms

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TN is a rare condition that affects women more than men. The annual incidence of TN is 4 to 13 per 100,000 people.^[1][2]Despite its low incidence, numbers may be significantly higher due to frequent misdiagnosis. TN is one of the more frequently seen neuralgias in the older adult population. The incidence increases gradually with age; most idiopathic cases begin after age 50, although onset may occur in the second and third decades or, rarely, in children.^[3]

The male-to-female prevalence ratio of TN ranges from 1:1.5 to 1:1.7.^[4] This female predominance may be related to the increased longevity of women compared with men. Rare familial cases have been reported, but the vast majority of patients have sporadic disease.^[5]

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Data is not consistent about identifiable risk factors for development of trigeminal neuralgia, but some studies have shown that hypertension and migraine can act as a risk factors for development of TN.^[1][2]

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