Trigeminal neuralgia (TN), tic douloureux (also known as prosopalgia, the Suicide Disease or Fothergill’s disease) is a neuropathic disorder characterized by episodes of intense pain in the face, originating from the trigeminal nerve. One, two, or all three branches of the nerve may be affected. It is, "one of the most painful conditions known to humans, yet remains an enigma to many health professionals."This pain may be felt in the ear, eye, lips, nose, scalp, forehead, cheeks, teeth, and/or jaw and side of the face; some patients also experience pain in their left index finger. Trigeminal neuralgia (TN) is not easily controlled but can be managed with a variety of treatment options. It is estimated that 1 in 15,000 people suffer from trigeminal neuralgia, 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.
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 shocks, 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.
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 trigeminal neuralgia called atypical trigeminal neuralgia. This variant is also called "trigeminal neuralgia, type 2", based on a recent classification of facial pain. In some cases of atypical trigeminal neuralgia 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-like pain and burning or prickling pain. It can also manifest as an unrelenting, a boring piercing pain.
CAUSE
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.
Several theories exist to explain the possible causes of this pain 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 - 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 (an outpouching of a blood vessel); by a tumor; by an arachnoid cyst in the cerebellopontine angle; or by a traumatic event such as a car accident or even a tongue piercing.
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 not everyone with TN has MS. Only 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. 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, 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.
TREATMENT
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 trigeminal neuralgia (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. 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.
MEDICATIONS
Anticonvulsants are a common treatment strategy for trigeminal neuralgia. Carbamazepine is the first line drug; second line drugs include baclofen, lamotrigine, oxcarbazepine, phenytoin, gabapentin, and sodium valproate. Uncontrolled trials have suggested that clonazepam and lidocaine may be effective.
Low doses of some antidepressants such as amytriptiline 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 due to counter acting a medication side effect.
Botox can be injected into the nerve by a physician, and has been found helpful using the "migraine" pattern adapted to the patient's facial pains or special needs.
Patients may also find relief by having their neurologist implant a neuro-stimulator.
Many patients cannot tolerate medications for years, and an alternative treatment is to take a drug such as gabapentin and apply it externally. Depending on your location this preparation is prepared extemporaneously by pharmacists. If in remission your doctor may cease your medication. Medications are usually started or ceased in a slow manner so not to cause unnecessary side effects such as seizures.
Rotating and/or a combination of medications may be needed if one becomes ineffective.
Opiates such as morphine and oxycodone can be prescribed, and there is evidence of their effectiveness on neuropathic pain, especially if combined with gabapentin.
A case report found sumatriptan effective in the management of drug-resistant Trigeminal Neuralgia
Benzodiazepines, mainly Clonazepam (Klonopin) are also prescribed off-label for this condition.
SURGERY
Surgery may be recommended, either to relieve the pressure on the nerve or to selectively damage it in such a way as to disrupt pain signals from getting through to the brain. In trained hands, surgery has been reported to have an initial success rate approaching 90 percent. However, some patients require follow-up procedures if a recurrence of the pain begins.
Of the five surgical options, the microvascular decompression, also known as the Janetta procedure, is the only one aimed at fixing the presumed cause of the pain. In this procedure, the surgeon enters the skull through a 25-millimetre (1 in) hole behind the ear. The nerve is then explored for an offending blood vessel, and when one is found, the vessel and nerve are separated or "decompressed" with a small pad, usually made from an inert surgical material such as Teflon. When successful, MVD procedures can give permanent pain relief with little to no facial numbness.
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 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 pain or have experienced recurrent pain after microvascular decompression.
Similar success rates have been reported with glycerol injections and radiofrequency rhizotomies. 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.
Stereotactic radiation therapy
The nerve can also be damaged to prevent pain signal transmission using Gamma Knife or a linear accelerator-based radiation therapy (e.g. Trilogy, Novalis, CyberKnife). No incisions are involved in this procedure. It uses very precisely targeted radiation to bombard the nerve. This option is used especially for those people who are medically unfit for a long general anaesthetic, or who are taking medications for prevention of blood clotting (e.g., warfarin, heparin, aspirin). It also may be used for those who may need to have a less invasive procedure. A prospective Phase I trial performed at Marseille, France, showed that 83% of patients were pain-free at 12 months, with 58% pain-free and off all medications. Side effects were mild, with 6% experiencing mild tingling and 4% experiencing mild numbness. However, there is no guarantee for a permanent success.
There has only been one prospective clinical trial for surgical therapy for trigeminal neuralgia. In a prospective cohort trial, microvascular decompression was found to be significantly superior to stereotactic radiosurgery in achieving and maintaining a pain-free status in patients with trigeminal neuralgia and provided similar early and superior longer-term patient satisfaction rates compared with those treated with stereotactic radiosurgery.
SOCIAL CONSEQUENCES OF TRIGEMINAL NEURALGIA
Depending on the stage of TN, many sufferers may not present with any outwardly noticeable symptoms, though some will exhibit brief facial spasms during an attack. Some physicians will seek a psychological root cause rather than a physiological abnormality. This is especially true of those suffering from atypical TN, who may not have any compression of the TN and in whom the sole criterion of the diagnosis may be the complaint of severe pain (constant electric-like shocks, constant crushing or pressure sensations, or a constant severe ache) and in this case trigeminal neuralgia still exists but is not visible to physicians because it was caused by the nerve being damaged during a dental procedure such as root canals, extractions, gum surgeries or it may be a condition secondary to multiple sclerosis. Yet others may show sharp electrical pains that are intense and somewhat brief.
Many TN sufferers are confined to their homes or are unable to work because of the frequency of their attacks and side effects from medications. It is important for friends and family to educate themselves on the intense severity of TN pain and to be understanding of limitations that TN places upon the sufferer. At the same time, the TN patient must be extremely proactive in furthering his or her rehabilitative efforts. Enrolling in a chronic pain support group, or seeking one-on-one counseling can help to teach a TN patient how to adapt to the new-found affliction.
As with any chronic pain syndrome, clinical depression has the potential to set in, especially in younger patients who often are under-treated for chronic pain. Friends and family, as well as clinicians along with physicians and neurologists, should be alert to the signs of a rapid change in behavior and should take appropriate measures when necessary. It must be constantly reinforced to the sufferer of TN that treatment options do exist.
OTHER
Cases of trigeminal neuralgia associated with tongue or facial piercing might be resolved after the jewelry was removed.
Some patients have reported a correlation between dental work and the onset of their trigeminal nerve pain.
Recently, some researchers have investigated the link between neuropathic pain, such as TN, and coeliac disease.
NOTABLE CASES
Australian author Colleen McCullough has trigeminal neuralgia and has undergone surgical treatment in Jan 2010.
High profile entrepreneur and author Melissa Seymour was diagnosed with Trigeminal Neuralgia 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, the British Member of Parliament for Poplar and Limehouse disclosed that he was a sufferer from the condition when launching a Parliamentary debate on it on 27 July 2010.
Taken from Wikipedia
http://en.wikipedia.org/wiki/Trigeminal_neuralgia
