Trigeminal neuralgia

Trigeminal neuralgia (TN or TGN), also called Fothergill disease, tic douloureux, or trifacial neuralgia, is a long-term pain disorder that affects the trigeminal nerve, the nerve responsible for sensation in the face and motor functions such as biting and chewing. It is a form of neuropathic pain. There are two main types: typical and atypical trigeminal neuralgia. The typical form results in episodes of severe, sudden, shock-like pain in one side of the face that lasts for seconds to a few minutes. Groups of these episodes can occur over a few hours. The atypical form results in a constant burning pain that is less severe. Episodes may be triggered by any touch to the face. Both forms may occur in the same person. Pain from the disease has been linked to mental-health issues, especially depression. The exact cause is unknown, but believed to involve loss of the myelin of the trigeminal nerve. This might occur due to nerve compression from a blood vessel as the nerve exits the brain stem, multiple sclerosis, stroke, or trauma. Less common causes include a tumor or arteriovenous malformation. It is a type of nerve pain. Diagnosis is typically based on the symptoms, after ruling out other possible causes such as postherpetic neuralgia. Treatment includes medication or surgery. The anticonvulsant carbamazepine or oxcarbazepine is usually the initial treatment, and is effective in about 90% of people. Side effects are frequently experienced that necessitate drug withdrawal in as many as 23% of patients. Other options include lamotrigine, baclofen, gabapentin, amitriptyline, and pimozide. Opioids are not usually effective in the typical form. In those who do not improve or become resistant to other measures, a number of types of surgery may be tried. Trigeminal neuralgia affects an estimated 0.03% to 0.30% of people around the world, with a 3:1 ratio between women and men. It usually begins in people over 50 years old, but can occur at any age. The condition was first described in detail in 1773 by John Fothergill.

Signs and symptoms

This disorder is characterized by episodes of severe facial pain along the trigeminal nerve divisions. The trigeminal nerve is a paired cranial nerve that has three major branches - the ophthalmic nerve (V1), the maxillary nerve (V2), and the mandibular nerve (V3). Any or all branches of the nerve may be affected. Trigeminal neuralgia most commonly involves the middle branch (the maxillary nerve or V2) and lower branch (mandibular nerve or V3) of the trigeminal nerve. An individual attack usually lasts from a few seconds to several minutes or hours, but these can repeat for hours with very short intervals between attacks. In other instances, only four to 10 attacks are experienced daily. The episodes of intense pain may occur paroxysmally. To describe the pain sensation, people often describe a trigger area on the face so sensitive that touching or even air currents can trigger an episode, but in many people, 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. The wind, chewing, and talking can aggravate the condition in many patients. The attacks are said, by those affected, to feel like stabbing electric shocks, burning, sharp, pressing, crushing, exploding, or shooting pain that becomes intractable. The pain also tends to occur in cycles with remissions lasting months or even years. Pain attacks are known to worsen in frequency or severity over time in some people. Pain may migrate to other branches over time, but in some people remains very stable. Bilateral (occurring on both sides) trigeminal neuralgia is very rare except for trigeminal neuralgia caused by multiple sclerosis (MS). This normally indicates problems with both trigeminal nerves, since one nerve serves the left side of the face and the other serves the right side. Occasional reports of bilateral trigeminal neuralgia reflect successive episodes of unilateral (only one side) pain switching the side of the face rather than pain occurring simultaneously on both sides. Rapid spreading of the pain, bilateral involvement, or simultaneous participation with other major nerve trunks (such as painful tic convulsive of nerves V and VII or occurrence of symptoms in the V and IX nerves) may suggest a systemic cause. Systemic causes could include MS or expanding cranial tumors. The severity of the pain makes washing the face, shaving, and performing good oral hygiene more difficult. The pain has a significant impact on activities of daily living, especially as those affected live in fear of when they are going to get their next attack of pain and how severe it will be. It can lead to severe depression and anxiety. Not all people, though, have the symptoms described above; several variants of TN occur, one of which is atypical trigeminal neuralgia (trigeminal neuralgia, type 2 or trigeminal neuralgia with concomitant pain), based on a recent classification of facial pain. In these instances, a more prolonged, lower-severity background pain can be present for over 50% of the time and is described more as a burning or prickling, rather than a shock. Trigeminal pain can also occur after an attack of herpes zoster. Postherpetic neuralgia has the same manifestations as in other parts of the body. Herpes zoster oticus typically presents with inability to move many facial muscles, pain in the ear, taste loss on the front of the tongue, dry eyes and mouth, and a vesicular rash. Less than 1% of varicella zoster infections involve the facial nerve and result in this occurring. Trigeminal deafferentation pain (TDP), also termed anesthesia dolorosa, or colloquially as phantom face pain, is from unintentional damage to a trigeminal nerve following attempts to fix a nerve problem surgically. TDP is usually constant with a burning sensation and numbness and is very difficult to treat, as further surgeries are usually ineffective and possibly detrimental to the person.

Causes

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