Trigeminal neuralgia (TG) has been described as the most excruciating pain known to humanity. Intense, stabbing, electric shock-like pain in the lower face and jaw or the area around the nose and above the eye is caused by irritation of the trigeminal nerve, which has branches to the forehead, cheek and lower jaw. TG usually is limited to one side of the face, and the cause of the pain usually is due to contact between a normal artery or vein and the trigeminal nerve at the base of the brain. Other causes include multiple sclerosis or pressure from a tumor.
The trigeminal nerve, which provides sensation to the face, is the fifth of 12 pairs of cranial nerves in the head. One trigeminal nerve runs to the right side of the head and the other to the left. It divides into three smaller branches. The first branch controls sensation in your eye, upper eyelid and forehead. The second branch controls sensation in your lower eyelid, cheek, nostril, upper lip and gum. The third branch controls sensations in your jaw, lower lip and some of the muscles you use for chewing.
Risk factors for TG include advanced age, hypertension and multiple sclerosis. The disorder is relatively rare, occurring more commonly in women than in men and rarely affecting anyone younger than 50.
Facial pain may appear spontaneously out of nowhere, or following a car accident, blow to the face or dental surgery. Often, pain is first experienced along the upper or lower jaw, causing many patients to assume they have a dental abscess.
- Intensely sharp, throbbing, shock-like pain
- Periods of remission
- A constant burning sensation affecting a larger area of the face
TG tends to run in cycles. Patients may suffer long periods of frequent attacks, followed by weeks or years of little or no pain. The usual pattern is one of attacks that worsen over time with shorter pain-free periods. The pain often leaves patients with uncontrollable facial twitching, which is why the disorder is also known as tic douloureux.
Magnetic resonance imaging (MRI) can determine whether a tumor or multiple sclerosis is irritating the trigeminal nerve. Otherwise, brain imaging seldom reveals the cause of nerve irritation. TG is usually diagnosed based on your description of the symptoms and tests that help rule out other facial disorders.
Medication is the first line of treatment for TG.
- Carbamazepine, an anticonvulsant drug
- Baclofen, a muscle relaxant
- Phenytoin, an anticonvulsant medication
- Oxcarbazepine, similar to carbamazepine but with fewer side effects
- Sodium valporate
Drawbacks to treatment with medication include side effects. Some patients may need relatively high doses to alleviate pain – with more pronounced side effects. Anticonvulsants may become less effective over time, and the use of more than one medication may cause a drug reaction.
If medications aren’t effective, surgical procedures are available to help control the pain. Procedures are either percutaneous (through the skin) or open (with an incision). Percutaneous approaches are preferred in older or frail patients; the open approach is recommended for younger, healthier patients.
Microvascular decompression involves microsurgical exposure of the trigeminal nerve root, identification of a blood vessel compressing the nerve and gentle movement of the nerve away from the point of compression. Generally the most effective surgery, it is also the most invasive because it requires opening the skull through a craniotomy.
Percutaneous stereotactic rhizotomy uses electrocoagulation (heat) to treat TG. The surgeon passes a hollow needle through the skin of your cheek into the trigeminal nerve. A heating current passed through the needle destroys some of the nerve fibers, relieving pain.
Percutaneous balloon compression uses a needle passed through the cheek to the trigeminal nerve. A balloon passed through a catheter is inflated, which compresses the nerve, injuring the pain-causing fibers. The balloon and catheter are removed after several minutes.
Stereotactic radiosurgery delivers a single highly concentrated dose of ionizing radiation to a small, precise target on the trigeminal nerve root. A noninvasive procedure, it avoids many of the risks and complications of open surgery. The formation over time of a lesion in the nerve interrupts transmission of pain signals to the brain.
The benefits of surgery should always be weighed carefully against its risks. Although a large percentage of patients report pain relief after surgery, there is no guarantee that surgery for trigeminal neuralgia will help every individual.
Source: American Association of Neurological Surgeons