Trigeminal neuralgia
Overview
Trigeminal neuralgia, tic douloureux (also known as prosopalgia, the Suicide Disease or Fothergill's disease) is a neuropathic disorder characterized by episodes of intense pain
Pain
Pain is an unpleasant sensation often caused by intense or damaging stimuli such as stubbing a toe, burning a finger, putting iodine on a cut, and bumping the "funny bone."...

 in the face, originating from the trigeminal nerve
Trigeminal nerve
The trigeminal nerve contains both sensory and motor fibres. It is responsible for sensation in the face and certain motor functions such as biting, chewing, and swallowing. Sensory information from the face and body is processed by parallel pathways in the central nervous system...

. It has been described as among the most painful conditions known. It is estimated that 1 in 15,000 people suffer from TN, although the actual figure may be significantly higher due to frequent misdiagnosis.
Encyclopedia
Trigeminal neuralgia, tic douloureux (also known as prosopalgia, the Suicide Disease or Fothergill's disease) is a neuropathic disorder characterized by episodes of intense pain
Pain
Pain is an unpleasant sensation often caused by intense or damaging stimuli such as stubbing a toe, burning a finger, putting iodine on a cut, and bumping the "funny bone."...

 in the face, originating from the trigeminal nerve
Trigeminal nerve
The trigeminal nerve contains both sensory and motor fibres. It is responsible for sensation in the face and certain motor functions such as biting, chewing, and swallowing. Sensory information from the face and body is processed by parallel pathways in the central nervous system...

. It has been described as among the most painful conditions known. It is estimated that 1 in 15,000 people suffer from TN, although the actual figure may be significantly higher due to frequent misdiagnosis. In a majority of cases, TN symptoms begin appearing after the age of 50, although there have been cases with patients being as young as three years of age. It is more common in females than males.
The trigeminal nerve is a paired cranial nerve that has three major branches: the ophthalmic nerve
Ophthalmic nerve
The ophthalmic nerve is one of the three branches of the trigeminal nerve, the fifth cranial nerve. The ophthalmic nerve carries only sensory fibers.-Branches:*Nasociliary nerve**sensory root of ciliary ganglion**posterior ethmoidal nerve...

 (V1), the maxillary nerve (V2), and the mandibular nerve
Mandibular nerve
The mandibular nerve is the largest of the three branches of the trigeminal nerve.-Roots:It is made up of two roots:* a large sensory root proceeding from the inferior angle of the trigeminal ganglion....

 (V3). One, two, or all three branches of the nerve may be affected. 10-12% of cases are bilateral (occurring on both the left and right sides of the face). The pain may be felt in the ear, eye, lips, nose, scalp, forehead, cheeks, teeth, or jaw and side of the face.
TN is not easily controlled but can be managed with a variety of treatment options. As of 2010, the TN therapeutics market was estimated to be about $83 million.

Signs and symptoms

The disorder is characterized by episodes of intense facial pain that last from a few seconds to several minutes or hours. The episodes of intense pain may occur paroxysmally. To describe the pain sensation, patients may describe a trigger area on the face so sensitive that touching or even air currents can trigger an episode; however, in many patients the pain is generated spontaneously without any apparent stimulation. It affects lifestyle as it can be triggered by common activities such as eating, talking, shaving and brushing teeth. Wind, high pitched sounds, loud noises such as concerts or crowds, chewing, and talking can aggravate the condition in many patients. The attacks are said by those affected to feel like stabbing electric shock
Electric shock
Electric Shock of a body with any source of electricity that causes a sufficient current through the skin, muscles or hair. Typically, the expression is used to denote an unwanted exposure to electricity, hence the effects are considered undesirable....

s, burning, pressing, crushing, exploding or shooting pain that becomes intractable.

Individual attacks usually affect one side of the face at a time, lasting from several seconds to a few minutes and repeat up to hundreds of times throughout the day. The pain also tends to occur in cycles with remissions lasting months or even years. 10-12% of cases are bilateral, or occurring on both sides. This normally indicates problems with both trigeminal nerves since one serves strictly the left side of the face and the other serves the right side. Pain attacks are known to worsen in frequency or severity over time, in some patients. Many patients develop the pain in one branch, then over years the pain will travel through the other nerve branches. Some patients also experience pain in the index finger.

It may slowly spread to involve more extensive portions of the trigeminal nerve. The spread may even affect all divisions of the nerve, and sometimes simultaneously. Cases with bilateral involvement have not indicated simultaneous activity. The following suggest a systemic development: rapid spreading, bilateral involvement or simultaneous participation with other major nerve trunks. Examples of systemic involvement include multiple sclerosis or expanding cranial tumor. Examples of simultaneous involvement include tic convulsive (of the fifth and seventh cranial nerves) and occurrence of symptoms in the fifth and ninth cranial nerve areas.

Outwardly visible signs of TN can sometimes be seen in males who may deliberately miss an area of their face when shaving, in order to avoid triggering an episode. Successive recurrences are incapacitating and the dread of provoking an attack may make sufferers unable to engage in normal daily activities.

Some patients report continuous pain or continuous pain during waking hours; for reasons that are not yet known, TN sufferers rarely have pain attacks or are awoken due to pain while they are sleeping. In fact, most patients have a very brief window of reprieve upon awakening from sleep, though that window can sometimes last only minutes. The mechanisms as to why one feels no pain while they are asleep, or in a slumber state, even though a pillow may be in contact with a "trigger point" on one's face, remains a mystery to physicians and dentists.

There is also a variant of TN called atypical trigeminal neuralgia
Atypical trigeminal neuralgia
Atypical Trigeminal Neuralgia , or Type 2 Trigeminal Neuralgia, is a rare form of Trigeminal neuralgia, a disorder of the fifth cranial nerve. This form of neuralgia is difficult to diagnose, as it is rare and the symptoms overlap with several other disorders...

 (also referred to as "trigeminal neuralgia, type 2"), based on a recent classification of facial pain. In some cases of atypical TN the sufferer experiences a severe, relentless underlying pain similar to a migraine in addition to the stabbing shock-like pains. In other cases, the pain is stabbing and intense but may feel like burning or prickling, rather than a shock. Sometimes the pain is a combination of shock-like sensations, migraine
Migraine
Migraine is a chronic neurological disorder characterized by moderate to severe headaches, and nausea...

-like pain and burning or prickling pain. It can also manifest as an unrelenting, boring, piercing pain.

Causes

The trigeminal nerve is a mixed cranial nerve responsible for sensory data such as tactition (pressure), thermoception
Thermoception
Thermoception or thermoreception is the sense by which an organism perceives temperature. The details of how temperature receptors work are still being investigated. Ciliopathy is associated with decreased ability to sense heat, thus cilia may aid in the process...

 (temperature), and nociception
Nociception
Nociception is defined as "the neural processes of encoding and processing noxious stimuli." It is the afferent activity produced in the peripheral and central nervous system by stimuli that have the potential to damage tissue...

 (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.

Several theories exist to explain the possible causes of this pain
Pain
Pain is an unpleasant sensation often caused by intense or damaging stimuli such as stubbing a toe, burning a finger, putting iodine on a cut, and bumping the "funny bone."...

 syndrome. It was once believed that the nerve was compressed in the opening from the inside to the outside of the skull; but newer leading research indicates that it is an enlarged blood vessel - possibly the superior cerebellar artery
Superior cerebellar artery
The superior cerebellar artery arises near the termination of the basilar artery.It passes lateralward, immediately below the oculomotor nerve, which separates it from the posterior cerebral artery, winds around the cerebral peduncle, close to the trochlear nerve, and, arriving at the upper...

 - compressing or throbbing against the microvasculature of the trigeminal nerve near its connection with the pons. 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 may rarely be caused by an aneurysm
Aneurysm
An aneurysm or aneurism is a localized, blood-filled balloon-like bulge in the wall of a blood vessel. Aneurysms can commonly occur in arteries at the base of the brain and an aortic aneurysm occurs in the main artery carrying blood from the left ventricle of the heart...

 (an outpouching of a blood vessel
Blood vessel
The blood vessels are the part of the circulatory system that transports blood throughout the body. There are three major types of blood vessels: the arteries, which carry the blood away from the heart; the capillaries, which enable the actual exchange of water and chemicals between the blood and...

); by a tumor
Tumor
A tumor or tumour is commonly used as a synonym for a neoplasm that appears enlarged in size. Tumor is not synonymous with cancer...

; by an arachnoid cyst
Arachnoid cyst
Arachnoid cysts are cerebrospinal fluid covered by arachnoidal cells and collagen that may develop between the surface of the brain and the cranial base or on the arachnoid membrane, one of the three membranes that cover the brain and the spinal cord...

 in the cerebellopontine angle
Cerebellopontine angle
The cerebellopontine angle is a structure at the margin of the cerebellum and pons.Breast cancer can metastasize to the cerebellopontine angle.It can be a site for lipoma.It is where acoustic neuromas are usually found.-External links:...

; or by a traumatic event such as a car accident or even a tongue piercing
Tongue piercing
A tongue piercing is a body piercing usually done directly through the center of the tongue, and is the most popular piercing site in the western world after the ear and nostril.-History and culture:...

.

Short-term peripheral compression is often painless, with pain attacks lasting no more than a few seconds. Persistent compression results in local demyelination with no loss of axon potential continuity. Chronic nerve entrapment results in demyelination primarily, with progressive axonal degeneration subsequently. It is, "therefore widely accepted that trigeminal neuralgia is associated with demyelination of axons in the gasserion ganglion, the dorsal root, or both." It has been suggested that this compression may be related to an aberrant branch of the superior cerebellar artery that lies on the trigeminal nerve. Further causes, besides an aneurysm, multiple sclerosis or cerebellopontine angle tumor, include: a posterior fossa tumor, any other expanding lesion or even brainstem diseases from strokes.

A large portion of multiple sclerosis patients have TN, but is not a symptom of MS. Only two to four percent of patients with TN, usually younger, have evidence of multiple sclerosis
Multiple sclerosis
Multiple sclerosis is an inflammatory disease in which the fatty myelin sheaths around the axons of the brain and spinal cord are damaged, leading to demyelination and scarring as well as a broad spectrum of signs and symptoms...

, which may damage either the trigeminal nerve or other related parts of the brain. It has been theorized that this is due to damage to the spinal trigeminal complex. Trigeminal pain has a similar presentation in patients with and without MS.

Postherpetic Neuralgia
Postherpetic neuralgia
Postherpetic neuralgia is a neuralgia caused by the varicella zoster virus. Typically, the neuralgia is confined to a dermatomic area of the skin and follows an outbreak of herpes zoster in that same dermatomic area...

, which occurs after shingles, may cause similar symptoms if the trigeminal nerve is damaged.

When there is no [apparent] structural cause, the syndrome is called idiopathic
Idiopathic
Idiopathic is an adjective used primarily in medicine meaning arising spontaneously or from an obscure or unknown cause. From Greek ἴδιος, idios + πάθος, pathos , it means approximately "a disease of its own kind". It is technically a term from nosology, the classification of disease...

.

Management

As with many conditions without clear physical or laboratory diagnosis, TN is unfortunately sometimes misdiagnosed. A TN sufferer will sometimes seek the help of numerous clinicians before a firm diagnosis is made.

There is evidence that points towards the need to quickly treat and diagnose TN. It is thought that the longer a patient suffers from TN, the harder it may be to reverse the neural pathways associated with the pain.

The dentist must ensure a correct diagnosis does not mistake TN as a temporomandibular disorder
Temporomandibular joint disorder
Temporomandibular joint disorder , or TMJ syndrome, is an umbrella term covering acute or chronic inflammation of the temporomandibular joint, which connects the mandible to the skull. The disorder and resultant dysfunction can result in significant pain and impairment...

. Since triggering may be caused by movements of the tongue or facial muscles, TN must be differentiated from masticatory pain that has the clinical characteristics of deep somatic rather than neuropathic pain. Masticatory pain will not be arrested by a conventional mandibular local anesthetic block.

Dentists who suspect TN should proceed in the most conservative manner possible and should ensure that all tooth structures are "truly" compromised before performing extractions or other procedures.

Medical

  • The anticonvulsant
    Anticonvulsant
    The anticonvulsants are a diverse group of pharmaceuticals used in the treatment of epileptic seizures. Anticonvulsants are also increasingly being used in the treatment of bipolar disorder, since many seem to act as mood stabilizers, and in the treatment of neuropathic pain. The goal of an...

    s carbamazepine
    Carbamazepine
    Carbamazepine is an anticonvulsant and mood-stabilizing drug used primarily in the treatment of epilepsy and bipolar disorder, as well as trigeminal neuralgia...

     is the first line treatment; second line medications include baclofen
    Baclofen
    Baclofen is a derivative of gamma-aminobutyric acid . It is primarily used to treat spasticity and is under investigation for the treatment of alcoholism....

    , lamotrigine
    Lamotrigine
    Lamotrigine, marketed in the US and most of Europe as Lamictal by GlaxoSmithKline, is an anticonvulsant drug used in the treatment of epilepsy and bipolar disorder. It is also used as an adjunct in treating depression, though this is considered off-label usage...

    , oxcarbazepine
    Oxcarbazepine
    Oxcarbazepine is a anticholinergic anticonvulsant and mood stabilizing drug, used primarily in the treatment of epilepsy. It is also used to treat anxiety and mood disorders, and benign motor tics...

    , phenytoin
    Phenytoin
    Phenytoin sodium is a commonly used antiepileptic. Phenytoin acts to suppress the abnormal brain activity seen in seizure by reducing electrical conductance among brain cells by stabilizing the inactive state of voltage-gated sodium channels...

    , gabapentin
    Gabapentin
    Gabapentin is a pharmaceutical drug, specifically a GABA analogue. It was originally developed for the treatment of epilepsy, and currently is also used to relieve neuropathic pain...

    , and sodium valproate
    Sodium valproate
    Sodium valproate or valproate sodium is the sodium salt of valproic acid and is an anticonvulsant used in the treatment of epilepsy, anorexia nervosa, panic attack, anxiety disorder, posttraumatic stress disorder, migraine and bipolar disorder, as well as other psychiatric conditions requiring...

    . Uncontrolled trials have suggested that clonazepam
    Clonazepam
    Clonazepamis a benzodiazepine drug having anxiolytic, anticonvulsant, muscle relaxant, and hypnotic properties. It is marketed by Roche under the trade name Klonopin in the United States and Rivotril in Australia, Brazil, Canada and Europe...

     and lidocaine
    Lidocaine
    Lidocaine , Xylocaine, or lignocaine is a common local anesthetic and antiarrhythmic drug. Lidocaine is used topically to relieve itching, burning and pain from skin inflammations, injected as a dental anesthetic or as a local anesthetic for minor surgery.- History :Lidocaine, the first amino...

     may be effective.
  • Low doses of some antidepressant
    Antidepressant
    An antidepressant is a psychiatric medication used to alleviate mood disorders, such as major depression and dysthymia and anxiety disorders such as social anxiety disorder. According to Gelder, Mayou &*Geddes people with a depressive illness will experience a therapeutic effect to their mood;...

    s such as amitriptyline
    Amitriptyline
    Amitriptyline is a tricyclic antidepressant . It is the most widely used TCA and has at least equal efficacy against depression as the newer class of SSRIs...

     are thought to be effective in treating neuropathic pain, but a tremendous amount of controversy exists on this topic, and their use is often limited to treating the depression that is associated with chronic pain, rather than the actual sensation of pain from the trigeminal nerve. Antidepressants are also used to counteract a medication side effect.
  • Duloxetine
    Duloxetine
    Duloxetine is a serotonin-norepinephrine reuptake inhibitor manufactured and marketed by Eli Lilly. It is effective for major depressive disorder and has been shown to be as effective as venlafaxine for generalized anxiety disorder...

     can also be used in some cases of neuropathic pain, and as it is also an antidepressant can be particularly helpful where neuropathic pain and depression are combined.
  • Opiates such as morphine
    Morphine
    Morphine is a potent opiate analgesic medication and is considered to be the prototypical opioid. It was first isolated in 1804 by Friedrich Sertürner, first distributed by same in 1817, and first commercially sold by Merck in 1827, which at the time was a single small chemists' shop. It was more...

     and oxycodone
    Oxycodone
    Oxycodone is an opioid analgesic medication synthesized from opium-derived thebaine. It was developed in 1916 in Germany, as one of several new semi-synthetic opioids in an attempt to improve on the existing opioids: morphine, diacetylmorphine , and codeine.Oxycodone oral medications are generally...

     can be prescribed, and there is evidence of their effectiveness on neuropathic pain, especially if combined with gabapentin
    Gabapentin
    Gabapentin is a pharmaceutical drug, specifically a GABA analogue. It was originally developed for the treatment of epilepsy, and currently is also used to relieve neuropathic pain...

    .

Surgical

The evidence for surgical therapy is poor and it is thus only recommended if medical treatment is not effective. While there may be pain relief there is also frequently numbness post procedure. Microvascular decompression
Microvascular decompression
Microvascular decompression , also known as the Jannetta procedure, is a neurosurgical procedure used to treat trigeminal neuralgia, a pain syndrome characterized by severe episodes of intense facial pain and hemifacial spasm.-History:...

 appears to result in the longest pain relief. Percutaneous radiofrequency thermorhizotomy may also be effective as may gamma knife radiosurgery however the effectiveness decreases with time.

Three other procedures use needles or catheters that enter through the face into the opening where the nerve first splits into its three divisions. Some have excellent success rates using a cost-effective percutaneous
Percutaneous
In surgery, percutaneous pertains to any medical procedure where access to inner organs or other tissue is done via needle-puncture of the skin, rather than by using an "open" approach where inner organs or tissue are exposed .The percutaneous approach is commonly used in vascular procedures...

 surgical procedure known as balloon compression have been reported. This technique has been helpful in treating the elderly for whom surgery may not be an option due to coexisting health conditions. Balloon compression is also the best choice for patients who have ophthalmic nerve
Ophthalmic nerve
The ophthalmic nerve is one of the three branches of the trigeminal nerve, the fifth cranial nerve. The ophthalmic nerve carries only sensory fibers.-Branches:*Nasociliary nerve**sensory root of ciliary ganglion**posterior ethmoidal nerve...

 pain or have experienced recurrent pain after microvascular decompression
Microvascular decompression
Microvascular decompression , also known as the Jannetta procedure, is a neurosurgical procedure used to treat trigeminal neuralgia, a pain syndrome characterized by severe episodes of intense facial pain and hemifacial spasm.-History:...

.

Glycerol injections involve injecting an alcohol-like substance into the cavern that bathes the nerve near its junction. This liquid is corrosive to the nerve fibers and can mildly injure the nerve enough to hinder the errant pain signals. In a radiofrequency rhizotomy, the surgeon uses an electrode to heat the selected division or divisions of the nerve. Done well, this procedure can target the exact regions of the errant pain triggers and disable them with minimal numbness.

Notable cases

Australian author Colleen McCullough
Colleen McCullough
Colleen McCullough-Robinson, , is an internationally acclaimed Australian author.-Life:McCullough was born in Wellington, in outback central west New South Wales, in 1937 to James and Laurie McCullough. Her mother was a New Zealander of part-Māori descent. During her childhood, her family moved...

 has TN and has undergone surgical treatment in Jan 2010.

High profile entrepreneur and author Melissa Seymour was diagnosed with TN in 2009 and underwent microvascular decompression surgery in a well documented case 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.

Jim Fitzpatrick
Jim Fitzpatrick (politician)
James Fitzpatrick is a British Labour Party politician, who has been the Member of Parliament for Poplar and Limehouse since the 2010 General Election. From 1997 to the 2010 election he was the member for Poplar and Canning Town...

, the British Member of Parliament for Poplar and Limehouse
Poplar and Limehouse (UK Parliament constituency)
Poplar and Limehouse is a constituency represented in the House of Commons of the Parliament of the United Kingdom. It elects one Member of Parliament using the first past the post system of election....

 disclosed that he was a sufferer from the condition when launching a Parliamentary debate on it on 27 July 2010.

Charles Sanders Peirce, who has been called "... the greatest American thinker ever," was a sufferer for most of his life.

In August 2011, Indian actor Salman Khan
Salman Khan
Salman Khan is an Indian film actor. He has starred in more than 80 Hindi films.Khan, who made his acting debut with a minor role in the drama Biwi Ho To Aisi with Rekha in a lead role, had his first commercial success with the blockbuster Maine Pyar Kiya , for which he won a Filmfare Award for...

disclosed that he has been suffering from trigeminal neuralgia for 7 years.

External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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