TREATMENT OPTIONS FOR THE ACUTE FACIAL PAIN OF TRIGEMINAL NEURALGIA
From Washington University Physicians, posted February 28, 2009, written by Mary Jo Blackwood, RN, MPH
People who have this type of facial pain describe it as intermittent electrical shock that affects a specific area of the face. The pain can be triggered by eating, drinking, touching the face, or even a breeze wafting by.
At first, the duration of the jolt is very brief and intermittent, but if untreated, the duration of each pain increases, and the frequency turns to constant pain It is such an intense pain that before the advent of effective treatment, many sufferers committed suicide.
There is no single test that identifies trigeminal neuralgia (TN), also referred to as tic douloureux. The condition is diagnosed through patient history and examination. “There are other causes of facial pain that must be ruled out because treatments effective for TN won’t work for them', says Washington University neurosurgeon at Barnes-Jewish Hospital, Joshua Dowling, MD. "It is important that people be seen early in the condition. The quality of the pain changes over time and becomes less clearly defined as TN.” Dowling says these patients have many more options for relief than ever before.
The trigeminal nerve is one of the eight cranial nerves, and two branches of the trigeminal nerve go to the teeth and jaws. Patients might first seek pain relief from a dentist or endodontist and end up with a tooth extraction or root canal. This actually increases the pain by aggravating an existing inflammation. Because TN is so uncommon, it is frequently misdiagnosed; the differential diagnosis usually is made by a neurologist.
Treatment depends of several factors, including the nerve branch affected. MRI or CT scans of the brain identify some causes of TN, such as tumors (usually benign), vascular malformations, and multiple sclerosis (MS). Imaging, particularly MRI, is also helpful in identifying the location of the blood vessel or any other anatomical abnormalities that could affect surgery.
“Patients with MS can develop similar symptoms. Rarely, TN can be the first symptom of MS. If a new TN patient is young, we have to consider MS as a cause," says Dowling. "The majority of cases, which typically occur in people over 50 and more often in women than men, are caused by compression of the nerve by a blood vessel bundle.”
There are no medications specifically approved for the treatment of TN, although Dowling has seen success in some patients with oral anticonvulsants. When pain cannot be kept under control with medications, the neurosurgeon has a variety of treatment optionss with which to personalize treatment. Depending on the situation and age of the patient, approaches may include surgery, needle procedures, and targeted radiation. All techniques have some amount of recurrence.
“The only approach that doesn’t involve injuring the nerve is microvascular decompression (MVD). However, it is major brain surgery. In this procedure, we cut out a circle of bone about the size of a quarter or half-dollar to expose the identified area of compression under the skull. Then we slip in a Teflon cushion between the nerve and the blood vessel bundle pressing on it, relieving the pressure. That gets at the root of the problem without damaging the nerve and works immediately. It has a greater than 90% initial success rate, and the lowest recurrence rate of any procedure, 35% at ten years. This procedure is best for the younger, healthier patients.”
Needle procedures are done percutaneously, or through the skin. A needle goes through the cheek and up under the cheek bone to get to the nerve bundle. Three different needle procedures are performed with good success, and all involve damaging part of the nerve to relieve pain while limiting the degree of numbness. The effect can be caused mechanically, by heat, or chemically:
1. Balloon compression: A balloon inserted through the needle is inflated with enough pressure to compress the nerve, blocking the pain signals.
2. Radiofrequency (RF) thermal partial sensory rhizotomy: This uses heat to damage part of the nerve fiber. Dowling uses this one the most. “It tends to work right away and may wear off after several years, but it can be repeated. While it causes a mild degree of facial numbness, patients get used to it, and it’s a good alternative for MS patients.”
3. Glycerol injection: Injected through the needle under guided imagery, glycerol causes a chemical injury to the nerve, numbing the pain.
Gamma Knife Option
Stereotactic Radiosurgery (Gamma knife®): This is a radiation delivery device that focuses about 200 separate beams of radiation on a tiny area of the nerve root. It allows a high dose of radiation to be delivered deep into the head without affecting the surrounding structures, and injuring the nerve enough to treat the pain while limiting the amount of numbing.
“The treatment is ultimately effective in most patients, but it can take up to two months for the pain to subside. If people are in real crisis with their pain, it’s not the best urgent procedure. It is, however, very safe; I have treated one patient who was 100-years old.”
The main message for patients with TN is that no one size or treatment fits all. Dowling and his colleagues have a spectrum of procedures to meet individual needs. “If there is any doubt as to the cause of the facial pain, it should be checked by a competent neurologist or neurosurgeon, and early before it becomes chronic.”