Trigeminal neuralgia (TN) is a chronic pain condition caused by disrupted function of the fifth cranial nerve (the trigeminal nerve), which is responsible for sensation in the face. In most cases, TN results from a healthy artery or vein pressing on the trigeminal nerve at the base of the brain, causing the nerve to malfunction. People with multiple sclerosis—a disease that causes deterioration of myelin sheaths (nerves’ protective coatings) in the brain and brainstem—may develop TN symptoms as the trigeminal nerve’s myelin sheath weakens. In rarer cases, pressure from a tumor or an arteriovenous malformation (AVM) may cause the disruption. TN occurs more commonly in people over 50.
The symptoms of trigeminal neuralgia are usually limited to one side of the face. The classic form of the disorder, TN1, is typified by sporadic bursts of extreme shooting, throbbing, electric-shock-like pain that causes uncontrollable facial twitching. Episodes can last anywhere from a few seconds to as long as two minutes and are often triggered by facial contact or vibration resulting from eating, drinking, washing, shaving, applying makeup, tooth brushing or even a light breeze.
TN1 is usually classified by periods of remission (lasting weeks, months or even years) between spates of pain episodes, but over time attacks may become more frequent and intense until pain-free periods have disappeared entirely. TN2, the atypical form, is characterized by an aching, burning pain that is less intense but more widespread and ever-present. People with TN can experience both forms of pain, even at the same time.
Most people start experiencing symptoms spontaneously, unrelated to a specific incident. Most causes of TN are not life-threatening, though after initial diagnosis your doctor may order a magnetic resonance imaging (MRI) scan to rule out an AVM, a tumor or multiple sclerosis. Diagnosis may be difficult because of the large number of conditions that can cause facial pain, but by carefully evaluating the type, location and triggers of a person’s pain and conducting a neurological examination, doctors can begin prescribing appropriate treatment.
The treatment of trigeminal neuralgia starts with medication. Doctors may prescribe anticonvulsants (to block nerve firing), antispasmodics (to relax muscles) or tricyclic antidepressants (to relieve pain). Unfortunately, due to the progressive nature of TN, medications may lose their effectiveness over time and people may find the side effects (memory loss, confusion, drowsiness, dizziness or nausea) of higher dosages intolerable.
If medication is no longer effective, surgical procedures may help control the pain. To avoid many of the risks of traditional surgery, doctors at the Boston Gamma Knife Center at Tufts Medical Center use Gamma Knife radiosurgery to treat TN. This noninvasive treatment uses state-of-the-art technology to focus 192 beamlets of gamma radiation on the trigeminal nerve where it exits the brainstem. The radiation eventually causes the disruption of the transmission of pain signals to the brain, alleviating the symptoms of trigeminal neuralgia.
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