At a glance......
- 1 Types of Trigeminal Neuralgia
- 2 What causes trigeminal neuralgia?
- 3 What are the symptoms of trigeminal neuralgia?
- 4 Diagnosis of Child Trigeminal Neuralgia
- 5 Treatment of Child Trigeminal Neuralgia
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Trigeminal Neuralgia Type 2 (TN2)/Trigeminal neuralgia (TN), also called tic douloureux, is a chronic pain condition that affects the trigeminal or 5th cranial nerve, one of the most widely distributed nerves in the head. TN is a form of neuropathic pain (pain associated with nerve injury or nerve lesion.) The typical or “classic” form of the disorder (called “Type 1” or TN1) causes extreme, sporadic, sudden burning, or shock-like facial pain that lasts anywhere from a few seconds to as long as two minutes per episode. These attacks can occur in quick succession, in volleys lasting as long as two hours. The “atypical” form of the disorder (called “Type 2” or TN2), is characterized by constant aching, burning, stabbing pain of somewhat lower intensity than Type 1. Both forms of pain may occur in the same person, sometimes at the same time. The intensity of pain can be physically and mentally incapacitating.
TRIGEMINAL NEURALGIA is an extremely severe unilateral episodic facial pain that tends to come and go unpredictably in sudden shock-like attacks. The pain is normally triggered, for example by light touch, and is described as stabbing, shooting, excruciating or burning. It usually lasts for a few seconds but there can be many bursts of pain in quick succession. There can be slight variations of trigeminal neuralgia which require different treatments.
Synonyms of Trigeminal Neuralgia
- Fothergill Disease
- Tic Douloureux
- Trifacial Neuralgia
Subdivisions of Trigeminal Neuralgia
- Trigeminal neuralgia type 1 (TN1)
- Trigeminal neuralgia type 2 (TN2)
Types of Trigeminal Neuralgia
The typical or “classic” form of the disorder (called TN1) causes extreme, sporadic, sudden burning or shock-like facial pain in the areas of the face where the branches of the nerve are distributed – lips, eyes, nose, scalp, forehead, upper jaw, and lower jaw. Trigeminal neuralgia can progress and cause longer, more frequent bouts of searing pain. You may feel as though your pain came out of nowhere. Some people initially think their pain is a toothache or migraine headache.
The “atypical” form of the disorder (called TN2), is characterized by constant aching, burning, stabbing pain of somewhat lower intensity than TN1. Both forms of pain may occur in the same person, sometimes at the same time
Primary trigeminal neuralgia
- Evidence suggests that in up to 95% of cases, trigeminal neuralgia is caused by pressure on the trigeminal nerve close to where it enters the brain stem, the lowest part of the brain that merges with the spinal cord.\
- This type of trigeminal neuralgia is known as primary trigeminal neuralgia. In most cases, the pressure is caused by an artery or vein squashing (compressing) the trigeminal nerve. These are normal blood vessels that happen to come into contact with the nerve at a, particularly sensitive point.
- It’s not clear why this pressure can cause painful attacks in some people but not others, as not everyone with a compressed trigeminal nerve will experience pain.
- It may be that, in some people, the pressure on the nerve wears away its protective outer layer (myelin sheath), which may cause pain signals to travel along the nerve. However, this does not fully explain why some people have periods without symptoms (remission), or why pain relief is immediately after a successful operation to move the blood vessels away from the nerve.
Secondary trigeminal neuralgia
Secondary trigeminal neuralgia is the term used when trigeminal neuralgia is caused by another medical condition or problem, including:
- a tumor
- a cyst – a fluid-filled sac
- arteriovenous malformation – an abnormal tangle of arteries and veins
- multiple sclerosis (MS) – a long-term condition that affects the nervous system
- facial injury
- damage caused by surgery including dental surgery
The subtypes of TN are defined by ICHD-3 as follows[rx]
- Classic TN: This is secondary to neuromuscular compression and fulfilling the criteria above. This requires demonstration of the compression on an MRI or during the surgery for neuromuscular compression, with associated morphological changes in the trigeminal nerve root.
- Secondary TN: This is defined as TN secondary to an underlying disease. Some of the reported causes are multiple sclerosis, arteriovenous malformation, and cerebellopontine angle tumor.
- Idiopathic TN: This is defined as TN with no abnormalities seen on MRI or electrophysiological tests.
The trigeminal nerve is one of 12 pairs of nerves that are attached to the brain. The nerve has three branches that conduct sensations from the upper, middle, and lower portions of the face, as well as the oral cavity, to the brain. The ophthalmic, or upper, branch supplies sensation to most of the scalp, forehead, and front of the head. The maxillary, or middle, branch stimulates the cheek, upper jaw, top lip, teeth, and gums, and to the side of the nose. The mandibular, or lower, branch supplies nerves to the lower jaw, teeth and gums, and bottom lip. More than one nerve branch can be affected by the disorder. Rarely, both sides of the face may be affected at different times in an individual, or even more rarely at the same time (called bilateral TN).
What causes trigeminal neuralgia?
TN is associated with a variety of conditions. TN can be caused by a blood vessel pressing on the trigeminal nerve as it exits the brain stem. This compression causes the wearing away or damage to the protective coating around the nerve (the myelin sheath). TN symptoms can also occur in people with multiple sclerosis, a disease that causes deterioration of the trigeminal nerve’s myelin sheath. Rarely, symptoms of TN may be caused by nerve compression from a tumor, or a tangle of arteries and veins called an arteriovenous malformation. Injury to the trigeminal nerve (perhaps the result of sinus surgery, oral surgery, stroke, or facial trauma) may also produce neuropathic facial pain.
The exact cause of trigeminal neuralgia remains unknown.[rx] The majority of cases are referred to as idiopathic, although many are associated with vascular compression of the trigeminal nerve close to its exit from the brainstem by an aberrant loop of an artery or vein. A minority of cases are due to conditions like multiple sclerosis or nerve compression by a tumor.[rx] Some rare causes of trigeminal neuralgia include focal arachnoid thickening, adhesion, traction, tethering or torsion, fibrous ring around the root, cerebellopontine angle tumors, brain stem infarction, aneurysm, and arteriovenous malformation.[rx][rx][rx][rx]
The trigeminal nerve starts at the pons. Most cases of trigeminal neuralgia are due to the compression of the trigeminal nerve root, within a few millimeters of its entry into the pons. Between 80% and 90% of the cases of TN are caused by compression by an adjacent artery or a vein.[rx] The blood vessel, which has been mostly implicated in about 75% to 80% of the cases, is the superior cerebellar artery. Other blood vessels that are known to cause TN include the anterior inferior cerebellar artery, the vertebral artery, and the petrosal vein.
Generally, it has been assumed that vascular contact at the root entry zone causes trigeminal neuralgia; however, TN also may be caused by contact at a transition zone between the central and peripheral myelin. Reportedly, the most common artery involved in this condition is the superior cerebellar artery, as seen in 75% to 80% of TN cases. Persistent primitive trigeminal artery variant, an anomaly that occurs between the carotid and basilar arteries or aneurysms of the persistent primitive trigeminal artery, vertebrobasilar dolichoectasia can cause TN. Sharper trigeminal-pontine angle cisterns and smaller cerebellopontine angle cisterns may facilitate neurovascular compression (NVC).[rx][rx][rx][rx][rx]
The most common extracranial cause of trigeminal neuralgia is a perineural spread of head and neck malignancies, commonly squamous cell carcinoma, adenoid cystic carcinoma, lymphoma, melanoma, and sarcoma.[rx][rx][rx][rx][rx]
What are the symptoms of trigeminal neuralgia?
Pain varies, depending on the type of TN, and may range from sudden, severe, and stabbing to a more constant, aching, burning sensation. The intense flashes of pain can be triggered by vibration or contact with the cheek (such as when shaving, washing the face, or applying makeup), brushing teeth, eating, drinking, talking, or being exposed to the wind. The pain may affect a small area of the face or may spread. Bouts of pain rarely occur at night, when the affected individual is sleeping.
TN is typified by attacks that stop for a period of time and then return, but the condition can be progressive. The attacks often worsen over time, with fewer and shorter pain-free periods before they recur. Eventually, the pain-free intervals disappear and medication to control the pain becomes less effective. The disorder is not fatal but can be debilitating. Due to the intensity of the pain, some individuals may avoid daily activities or social contacts because they fear an impending attack.
The trigeminal nerve is the fifth cranial nerve. It is responsible for the sensory supply of the face and the motor and sensory supply to the muscles of mastication. The trigeminal nerve starts at the pons and divides into three branches[rx]:
Ophthalmic (V1): Supplies the eye, upper eyelid, and the forehead
Maxillary (V2): Supplies lower eyelid, cheek, nostril, upper lip, and upper gum
Mandibular (V3): Supplies the lower lip, lower gum, jaw and muscles of mastication
Trigeminal neuralgia symptoms may include one or more of these patterns:
- Episodes of severe, shooting or jabbing pain that may feel like an electric shock
- Spontaneous attacks of pain or attacks triggered by things such as touching the face, chewing, speaking or brushing teeth
- Bouts of pain lasting from a few seconds to several minutes
- Episodes of several attacks lasting days, weeks, months, or longer — some people have periods when they experience no pain
- Constant aching, burning feeling that may occur before it evolves into the spasm-like pain of trigeminal neuralgia
- Pain in areas supplied by the trigeminal nerve, including the cheek, jaw, teeth, gums, lips, or less often the eye and forehead
- Pain affecting one side of the face at a time though may rarely affect both sides of the face
- Pain focused in one spot or spread in a wider pattern
- Attacks that become more frequent and intense over time
- The attacks happen several times a day or a week, followed by periods during which you have none at all. These pain-free periods are known as remission.
- The pain usually affects only one side of the face.
- The attacks happen more often over time, and the pain can worsen.
- You feel the pain mostly in your cheek, jaw, teeth, gums, and lips. The eyes and forehead are affected less often.
Attacks of trigeminal neuralgia can be triggered by certain actions or movements, such as:
- brushing your teeth
- washing your face
- a light touch
- shaving or putting on make-up
- a cool breeze or air conditioning
- head movements
- vibrations, such as walking or traveling in a car
However, pain can happen spontaneously with no trigger whatsoever.
The symptoms of several pain disorders are similar to those of trigeminal neuralgia. The most common mimicker of TN is trigeminal neuropathic pain (TNP). TNP results from an injury or damage to the trigeminal nerve. TNP pain is generally described as being constant, dull and burning. Attacks of sharp pain can also occur, commonly triggered by touch. Additional mimickers include:
- Temporal tendinitis
- Ernest syndrome (injury of the stylomandibular ligament
- Occipital neuralgia
- Cluster headaches/ migraines
- Giant cell arteritis
- Dental pain
- Post-herpetic neuralgia
- Glossopharyngeal neuralgia
- Sinus infection
- Ear infection
- Temporomandibular joint syndrome (TMJ)
Diagnosis of Child Trigeminal Neuralgia
TN diagnosis is based primarily on the person’s history and description of symptoms, along with results from physical and neurological examinations. Other disorders that cause facial pain should be ruled out before TN is diagnosed. Some disorders that cause facial pain include post-herpetic neuralgia (nerve pain following an outbreak of shingles), cluster headaches, and temporomandibular joint disorder (TMJ, which causes pain and dysfunction in the jaw joint and muscles that control jaw movement). Because of overlapping symptoms and the large number of conditions that can cause facial pain, obtaining a correct diagnosis is difficult, but finding the cause of the pain is important as the treatments for different types of pain may differ.
Most people with TN eventually will undergo a magnetic resonance imaging (MRI) scan to rule out a tumor or multiple sclerosis as the cause of their pain. This scan may or may not clearly show a blood vessel compressing the nerve. Special MRI imaging procedures can reveal the presence and severity of compression of the nerve by a blood vessel.
A diagnosis of classic trigeminal neuralgia may be supported by an individual’s positive response to a short course of antiseizure medication. Diagnosis of TN2 is more complex and difficult but tends to be supported by a positive response to low doses of tricyclic antidepressant medications (such as amitriptyline and nortriptyline), similar to other neuropathic pain diagnoses.
Your doctor may conduct many tests to diagnose trigeminal neuralgia and determine underlying causes for your condition, including:
- A neurological examination. Touching and examining parts of your face can help your doctor determine exactly where the pain is occurring and — if you appear to have trigeminal neuralgia — which branches of the trigeminal nerve may be affected. Reflex tests also can help your doctor determine if your symptoms are caused by a compressed nerve or another condition.
- Magnetic resonance imaging (MRI). Your doctor may order an MRI scan of your head to determine if multiple sclerosis or a tumor is causing trigeminal neuralgia. In some cases, your doctor may inject a dye into a blood vessel to view the arteries and veins and highlight blood flow (magnetic resonance angiogram).
One published a set of guidelines for diagnosing TN is from the International Headache Society.
For classical TN
- Paroxysmal attacks of pain lasting from a fraction of a second to two minutes, affecting one or more divisions of the trigeminal nerve, and fulfilling criteria 2 and 3.
- Pain has at least one of the following characteristics:
- Intense, sharp, superficial or stabbing
- Precipitated from trigger zones or by trigger factors
- Attacks are stereotyped in the individuals patient
- There is no clinically evident neurologic deficit
- Not attributed to another disorder
For symptomatic TN
- Paroxysmal attacks of pain lasting from a fraction of a second to two minutes, with or without persistence of aching between paroxysms, affecting one or more divisions of the trigeminal nerve, and fulfilling criteria 2 and 3.
- Pain has at least one of the following characteristics
- Intense, sharp, superficial or stabbing
- Precipitated from trigger zones or by trigger factors.
- Attacks are stereotyped in the individual patient
- A causative lesion, other than vascular compression, has been demonstrated by special investigations and/or posterior fossa exploration.
Treatment of Child Trigeminal Neuralgia
Treatment options include medicines, surgery, and complementary approaches.
The first-line treatment – for patients with classic TN and idiopathic TN is pharmacologic therapy. The most commonly used medication is the anticonvulsant drug, carbamazepine.[rx] It is usually started at a low dose, and the dose is gradually increased until it controls the pain. It controls pain for most people in the early stages of the disease. However, in some patients, the effectiveness of carbamazepine decreases over time. Possible side effects of carbamazepine include drowsiness, dizziness, double vision, and nausea. In patients with Asian ancestry, before starting carbamazepine, testing for the HLA-B allele is recommended, as its presence increases the risk of development of toxic epidermal necrolysis or Stevens-Johnson syndrome.[rx]
Oxcarbazepine – is a newer drug and is being increasingly used as first-line therapy for TN in patients who do not respond to or who cannot tolerate carbamazepine (200 to 1200 mg/day) and oxcarbazepine (600 to 1800 mg/day). Possible side effects include double vision and dizziness. It can also cause hyponatremia. It should also be avoided in patients with the HLA-B 15:02 allele.
Muscle relaxant – Baclofen is a muscle relaxant that can be used to treat TN. Baclofen, lamotrigine, clonazepam, topiramate, phenytoin, gabapentin, pregabalin, and sodium valproate can be used. Side effects include dizziness, sedation, and dyspepsia.
Seizures, anticonvulsant medication – used to treat epilepsy and to delay or prevent the recurrence of depressive episodes in bipolar disorder. For epilepsy, this includes focal seizures, tonic-clonic seizures, and seizures in Lennox-Gastaut syndrome and medication lamotrigine, phenytoin, gabapentin, clonazepam, and valproic acid. Lamotrigine (200 to 400 mg/day), pregabalin (150 to 600 mg/day), gabapentin (1800 to 4200 mg/day), or topiramate (100 to 400 mg/day) may be considered. If the combination therapy fails, a switch to baclofen (40 to 80 mg/day) may be considered.[rx]
Eslicarbazepine – an active metabolite of oxcarbazepine, and the new Nav1.7 blocker, vixotrigine, are being explored for pain relief in TN.[rx]
Anticonvulsant medicines—used to block nerve firing—are generally effective in treating TN1 but often less effective in TN2. These drugs include carbamazepine, oxcarbazepine, topiramate, gabapentin, pregabalin, clonazepam, phenytoin, lamotrigine, and valproic acid.
Tricyclic antidepressants – such as amitriptyline or nortriptyline can be used to treat pain. Common analgesics and opioids are not usually helpful in treating the sharp, recurring pain caused by TN1, although some individuals with TN2 do respond to opioids. Eventually, if medication fails to relieve pain or produces intolerable side effects such as cognitive disturbances, memory loss, excess fatigue, bone marrow suppression, or allergy, then surgical treatment may be indicated. Since TN is a progressive disorder that often becomes resistant to medication over time, individuals often seek surgical treatment.
Botulinum Toxin Injections – This can be beneficial for some patients, particularly the middle-aged and the elderly, who are refractory to medical therapy or who cannot tolerate medical therapy due to their side effects.[rx]
Tetracaine nerve block – may be used as an additional treatment after carbamazepine, as can acupuncture and/or peripheral nerve stimulation.[rx] Patients with secondary TN also can respond well to pharmacotherapy. However, it is recommended to treat the underlying lesion or disease.
There is controversy around opiate use such as morphine and oxycodone for treatment of TN, with varying evidence on its effectiveness for neuropathic pain. Generally, opioids are considered ineffective against TN and thus should not be prescribed.[rx]
Microvascular decompression – This is one of the most common procedures used to treat trigeminal neuralgia. This is beneficial for patients with TN, where compression of the nerve root is the cause. [rx]This involves craniotomy and posterior fossa exploration for identifying and moving the blood vessel that is compressing the trigeminal nerve. A soft cushion is then inserted between the nerve and the vessel, to allow the nerve to recover, which eventually relieves the pain. In some patients, this procedure can result in sustained pain relief for greater than 10 years. Though this is the most effective procedure, it is also the most invasive one. Some of the complications associated with it are decreased hearing, cerebellar hematoma, CSF leaks, infarction, and facial weakness. It is believed to be the most effective long-term surgical treatment available currently for patients with TN.[rx]
Ablative procedures include rhizotomy– with thermocoagulation, chemical injection, or mechanical balloon compression. These procedures involve damaging the trigeminal nerve root, thereby interrupting the pain transmission signals to the brain. Rhizotomy with thermocoagulation uses an electrode to apply heat to damage the nerve fibers. Chemical rhizotomy involves injecting the chemical, glycerol to the trigeminal nerve, thereby damaging it. Balloon compression involves inserting a tiny balloon to the point of location of nerve fibers.[rx][rx] This balloon, on inflation, damages the nerve fibers. Some of the associated complications are postoperative dysesthesia, corneal numbness, sensory loss in trigeminal nerve distribution, and anesthesia Dolorosa.
Radiosurgery – This procedure involves using radiosurgery instrumentation.[rx][rx][rx] This is a non-invasive procedure, wherein, a highly concentrated dose of ionizing radiation is delivered to a precise target at the trigeminal nerve root. The radiation creates a lesion near the nerve root, thereby interrupting the pain signals from transmission to the brain. The formation of the lesion can be slow, and hence the pain relief using this procedure is delayed by up to several weeks or months. As this is one of the least invasive procedures, it can be repeated in patients who have a recurrence of pain. Some of the associated complications can be facial sensory loss and paresthesias.
Peripheral neurectomy and nerve block – The neurectomy can be performed on peripheral branches of the trigeminal nerve like the supraorbital, infraorbital, lingual, and alveolar nerves.[rx] This can be accomplished by alcohol injection, incision, cryotherapy, or radiofrequency lesioning. Peripheral neurectomy can be safe in elderly patients in remote and rural areas, where neurosurgical facilities are not readily available.[rx] However, the evidence regarding these peripheral techniques for trigeminal neuralgia is inconclusive.
A rhizotomy (rhizolysis)– is a procedure in which nerve fibers are damaged to block pain. A rhizotomy for TN always causes some degree of sensory loss and facial numbness. Several forms of rhizotomy are available to treat trigeminal neuralgia:
Balloon compression – works by injuring the insulation on nerves that are involved with the sensation of light touch on the face. The procedure is performed in an operating room under general anesthesia. A tube called a cannula is inserted through the cheek and guided to where one branch of the trigeminal nerve passes through the base of the skull. A soft catheter with a balloon tip is threaded through the cannula and the balloon is inflated to squeeze part of the nerve against the hard edge of the brain covering (the dura) and the skull. After about a minute the balloon is deflated and removed, along with the catheter and cannula. Balloon compression is generally an outpatient procedure, although sometimes the patient may be kept in the hospital overnight. Pain relief usually lasts one to two years.
Glycerol injection – is also generally an outpatient procedure in which the individual is sedated with intravenous medication. A thin needle is passed through the cheek, next to the mouth, and guided through the opening in the base of the skull where the third division of the trigeminal nerve (mandibular) exits. The needle is moved into the pocket of spinal fluid (cistern) that surrounds the trigeminal nerve center (or ganglion, the central part of the nerve from which the nerve impulses are transmitted to the brain). The procedure is performed with the person sitting up, since glycerol is heavier than spinal fluid and will then remain in the spinal fluid around the ganglion. The glycerol injection bathes the ganglion and damages the insulation of trigeminal nerve fibers. This form of rhizotomy is likely to result in the recurrence of pain within a year to two years. However, the procedure can be repeated multiple times.
Radiofrequency thermal lesioning – (also known as “RF Ablation” or “RF Lesion”) is most often performed on an outpatient basis. The individual is anesthetized and a hollow needle is passed through the cheek through the same opening at the base of the skull where the balloon compression and glycerol injections are performed. The individual is briefly awakened and a small electrical current is passed through the needle, causing tingling in the area of the nerve where the needle tips rest. When the needle is positioned so that the tingling occurs in the area of TN pain, the person is then sedated and the nerve area is gradually heated with an electrode, injuring the nerve fibers. The electrode and needle are then removed and the person is awakened. The procedure can be repeated until the desired amount of sensory loss is obtained; usually a blunting of sharp sensation, with preservation of touch. Approximately half of the people have symptoms that reoccur three to four years following RF lesioning. Production of more numbness can extend the pain relief even longer, but the risks of anesthesia dolorosa also increase.
Stereotactic radiosurgery – (Gamma Knife, CyberKnife) uses computer imaging to direct highly focused beams of radiation at the site where the trigeminal nerve exits the brain stem. This causes the slow formation of a lesion on the nerve that disrupts the transmission of sensory signals to the brain. People usually leave the hospital the same day or the next day following treatment but won’t typically experience relief from pain for several weeks (or sometimes several months) following the procedure. The International Radiosurgery Association reports that between 50 and 78 percent of people with TN who are treated with Gamma Knife radiosurgery experience “excellent” pain relief within a few weeks following the procedure. For individuals who were treated successfully, almost half have a recurrence of pain within three years.
Decompression Surgery – is the most invasive of all surgeries for TN, but also offers the lowest probability that pain will return. About half of individuals undergoing MVD for TN will experience recurrent pain within 12 to 15 years. This inpatient procedure, which is performed under general anesthesia, requires that a small opening be made through the mastoid bone behind the ear. While viewing the trigeminal nerve through a microscope or endoscope, the surgeon moves away from the vessel (usually an artery) that is compressing the nerve and places a soft cushion between the nerve and the vessel. Unlike rhizotomies, the goal is not to produce numbness in the face after this surgery. Individuals generally recuperate for several days in the hospital following the procedure, and will generally need to recover for several weeks after the procedure.
A neurectomy (also called partial nerve section) – which involves cutting part of the nerve, may be performed near the entrance point of the nerve at the brain stem during an attempted microvascular decompression if no vessel is found to be pressing on the trigeminal nerve. Neurectomies also may be performed by cutting superficial branches of the trigeminal nerve in the face. When done during microvascular decompression, a neurectomy will cause more long-lasting numbness in the area of the face that is supplied by the nerve or nerve branch that is cut. However, when the operation is performed in the face, the nerve may grow back and in time sensation may return. With neurectomy, there is risk of creating anesthesia Dolorosa.
Surgical treatment for TN2 is usually more problematic than for TN1, particularly where vascular compression is not detected in brain imaging prior to a proposed procedure. Many neurosurgeons advise against the use of MVD or rhizotomy in individuals for whom TN2 symptoms predominate over TN1, unless vascular compression has been confirmed. MVD for TN2 is also less successful than for TN1.
Some individuals manage trigeminal neuralgia using complementary techniques, usually in combination with drug treatment. These therapies offer varying degrees of success. Some people find that low-impact exercise, yoga, creative visualization, aromatherapy, or meditation may be useful in promoting well-being. Other options include acupuncture, upper cervical chiropractic, biofeedback, vitamin therapy, and nutritional therapy. Some people report modest pain relief after injections of botulinum toxin to block the activity of sensory nerves.
Chronic pain from TN is frequently very isolating and depressing for the individual. Conversely, depression and sleep disturbance may render individuals more vulnerable to pain and suffering. Some individuals benefit from supportive counseling or therapy by a psychiatrist or psychologist. However, there is no evidence that TN is psychogenic in origin or caused by depression, and persons with TN require effective medical or surgical treatment for their pain.