Trigeminal Neuralgia

Who Gets Trigeminal Neuralgia?
What are the Symptoms of Trigeminal Neuralgia?
How Does Trigeminal Neuralgia Occur?
The Diagnosis and Treatment of Trigeminal Neuralgia

Who Gets Trigeminal Neuralgia?

Trigeminal neuralgia is among the most common facial pain syndromes and has also been called "tic duloreaux." While it may be caused by compressive blood vessels, tumors and vascular malformations, its basic pathophysiology (or pain mechanism) remains unknown. What is known is the sudden, stabbing, excruciating pain that it produces, which lasts only a few seconds and affects the face.

Trigeminal neuralgia is typically diagnosed in adults. Women are affected more than men at a rate of 60%, and those suffering from multiple sclerosis are at increased risk for developing it (although the vast majority of sufferers do not have multiple sclerosis).

What are the Symptoms of Trigeminal Neuralgia?

The primary symptom of trigeminal neuralgia is the sudden onset of severe, sharp facial pain, usually without warning. The quick bursts of pain are described as "lightning bolt-like" or "machine gun-like." It can build in strength, decrease and begin again, and then abruptly end. It can be triggered by stimuli as light as a breeze or a touch on the face, or by such acts as shaving, teeth brushing, talking, chewing and swallowing. It also can disrupt sleep, awakening people from deep slumber. As a result, some sufferers may become both physically and mentally incapacitated from the pain of trigeminal neuralgia. They may be fearful of eating and avoid activities of self-care. In addition, when the pain is especially unrelenting and prolonged, they may become prone to depression and even suicidal tendencies. It is not uncommon for people to visit their dentist, believing that their jaw pain is due to a problem with their teeth, and have unnecessary extractions.

During a pain period, attacks can occur hundreds of times a day. The interval between attacks can range from minutes to months or even years, and pain is completely absent during these times. Recurrences of the pain are almost always in the same area of the face, but tend to spread.

How Does Trigeminal Neuralgia Occur?

The trigeminal nerve is the fifth and largest of the brain's twelve nerves, carrying both motor and sensory messages from the face to the brain. The most common cause of trigeminal neuralgia is idiopathic -- that is, unknown. However, the current theory is that disease or irritation of the nerve increases the firing of sensory impulses, so much so that trigger points for pain develop on the face and in the mouth as a result of this overload. Trigeminal neuralgia also can be activated by such conditions as multiple sclerosis, tumors and abnormal blood vessels. Stress is less often a contributing factor.

The Diagnosis and Treatment of Trigeminal Neuralgia

A diagnosis is made by considering the patient's medical history and description of his or her pain. While no specific diagnostic tests are available to confirm the presence of trigeminal neuralgia, diagnostic-imaging technologies, including CT scans and MRIs, are often used to assess the patient and make sure that a tumor or other abnormality is not causing the pain. Additionally, a comprehensive medical history is taken and a thorough physical exam is performed to determine triggering stimuli, tender zones, and the exact location(s) of the pain. The exam includes inspection of the corneas, nostrils, gums, tongue and insides of the cheeks to see how these areas respond to touch and changes in temperature (heat and cold).

In most cases, treatment for trigeminal neuralgia begins with anticonvulsant drug therapy that seeks to suppress the transmission of impulses by the trigeminal nerve. Carbamazepine is the first drug of choice. It should be started at low doses and titrated, and taken with food or fluid. Patients may experience gastric irritation, a lower white cell count and central nervous system side effects, such as dizziness and walking off balance; fever, sore throat and bruises should be reported to their physician immediately. While most patients experience some relief, they may eventually develop a tolerance to carbamazepine and stop responding after months or years. Other possibly effective anticonvulsant drugs include phenytoin, gabapentin and lamotrigine. A small number of patients do not respond well or at all to anticonvulsants and should be put on a drug called baclofen. Although baclofen has fewer and less serious side effects than carbamazepine, it too can lose its effectiveness over time. Additionally, it can cause drowsiness, dizziness and fatigue. Baclofen may provide enhanced relief when used in combination with an anticonvulsant. Other less frequently used drugs to treat trigeminal neuralgia include valproate, corticosteroids and mexiletine. Luckily, most patients obtain relief with one or a combination of drugs.

Unlike other neuropathic pains, trigeminal neuralgia only responds to anticonvulsants and does not respond to antidepressants or opioids. When drug therapy is unsuccessful, invasive procedures are tried. Nerve blocks using local anesthetics can be injected into the trigger area or pain site for temporary relief. Glycerol injections, which can be done under general anesthesia or following intravenous sedation, can destroy the fibers that conduct triggering impulses, with less sensory loss. While glycerol injections have a high initial success rate, the incidence of pain recurrence is great -- after five years. The most commonly used surgical technique is microvascular decompression, an inpatient procedure requiring general anesthesia that allows surgeons to reposition arteries or veins pressing on the trigeminal nerve. Upwards of 80% of patients experience long-term pain relief and retain normal sensation in the face with a lower chance of recurrence, although recurrences do occur.

Radiofrequency gangliolysis (RFG) involves wounding the gasserian ganglion, the large, flat root of the trigeminal nerve. Guided by x-ray technology, the surgeon inserts a needle through the cheek and into the rootlets behind the gasserian ganglion to inject a radiofrequency current. This current heats and destroys selected portions of the gasserian ganglion thought to be responsible for the pain. A percutaneous procedure, RFG provides relief in almost all patients; however, the recurrence rate following RFG is 20 to 30%. RFG is used especially to treat debilitated or elderly patients who would be at risk from major surgery.

In cases where microvascular decompression cannot be tolerated or RFG has failed, peripheral neurectomy or neurolysis may be performed. This surgical and chemical destruction of the peripheral branches of the trigeminal nerve produces dense numbness to alleviate pain. Relief rarely lasts more than one year, necessitating repeat procedures.