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TRIGEMINAL NEURALGIA Trigeminal Neuralgia (or Tic Douloureux) is a very severe stabbing facial pain involving one or more of three divisions (or branches) of the Trigeminal Nerve (the Fifth Cranial Nerve), which supplies sensation to the face. Because of some important relatively recent developments, there is a better understanding concerning the cause of this painful condition. Different medications have been used with varying success for many years. Surgical treatments in the past involved either cutting the nerve or its branches or injecting alcohol to deaden the nerve. The ideal surgical method of management would offer complete relief of the pain without producing any numbness.What Causes Trigeminal Neuralgia? There are essentially three causes that are now recognized. The most common cause is a compression phenomenon exerted on the Trigeminal Nerve as it enters the Brain Stem. This region is inside the skull near its base. The "compression" actually causes an injury to the normal insulating material, called MYELIN, which surrounds the nerve (and acts in a manner similar to rubber that insulates electrical wires.) Usually this compression is exerted by a tortuous artery (and/or a vein), which has come to rest upon the nerve in an unusual position.The same compression-distortion injury to the nerve is seen in 10% of Trigeminal Neuralgia patients resulting from an Aneurysm (a dilated portion of an artery) or a tumor. The majority of these rare tumors are completely benign. The other important, although unusual cause of Trigeminal Neuralgia is Multiple Sclerosis, a disease, which attacks myelin. The least common cause of Trigeminal Neuralgia is arteriosclerosis ("hardening of the arteries") which may produce a small stroke in this region resulting in this dreadful pain. All three of these "causes" have in common the fact that they injure the critical insulating structure, myelin, at a very precise location, the Brainstem's nerve root entry zone of the Trigeminal Nerve in order to produce the pain of Trigeminal Neuralgia. Multiple Sclerosis, aneurysms, tumors, and atherosclerosis obviously involve other areas of the brain more frequently. It is only when one of these problems involves this very special "nerve root entry zone" that the problem of the Trigeminal Neuralgia is produced. As a general principle, it is important to understand the cause of a medical problem in order to design the specific treatment aimed at relieving the causative agent, if possible. It is only in relatively recent years that the cause of Trigeminal Neuralgia was identified. As a result, more effective modern treatments were developed. DIAGNOSIS The diagnosis of Trigeminal Neuralgia is made, primarily, on the basis of the characteristic pain experienced by the patient. Sharp, stabbing, electric shock-like short duration pain is the most common experience. The pain is usually initiated by touching the face, facial muscle contraction, brushing the teeth, bending the head or neck in extreme forward or backward positions or during eating.It is unusual for there to be any abnormal or objective findings on physical examination of either the motor or sensory portion of the Trigeminal Nerve during the neurological examination. A small percentage of patients may exhibit minor diminished sensation in one of the three divisions of the Trigeminal Nerve. Investigation MRI (including the newer "Thin Slice" technology) and MRA (Angiography) are the two neuroimaging tests that are considered to be imperative prior to any consideration for surgical therapies. It is vitally important to identify the presence or absence of a tumor or aneurysm as the cause of compression of the Trigeminal Nerve at its junction with the Brainstem (up to 10% of Trigeminal Neuralgia patients have either an aneurysm or tumor as the cause of their Trigeminal Nerve "compression".) It is our firm policy to make certain that these studies are done for ANY patient with this syndrome even if medical (non-surgical) management is contemplated.
TREATMENT Medical Therapies Once the Neuroimaging studies (described above) have ruled out the presence of a potentially life-threatening problem (aneurysm and or tumor), treatment considerations usually involve a vigorous trial of Medical (non-surgical) therapy. The use of anti-convulsant medications has proven to be effective for most patients. There are several among this drug class that have reliably controlled this pain in most patients for many years. The most effective has been TEGRETOL. Other newer agents have also had considerable success. Drug treatment failure is fairly common for several reasons including the intolerance of the unpleasant side effects for many patients. Others find the cost of long term medication to be prohibitive. Still others do not obtain adequate relief.Unconventional treatments such as acupuncture, cranio-spinal manipulation, and chiropractic maneuvers are often tried by these patients who seek alternative medicine approaches. These "therapies" are unreliable for those who really do have Trigeminal Neuralgia. Surgical Therapies There are three primary surgical procedures currently being employed to treat this problem. Previous surgical procedures were "destructive." Pain was relieved by cutting the nerve, which resulted in dense numbness in the specific distribution of the Trigeminal Nerve.Microvascular Decompression (MVD) The more modern approach to this problem was developed by Dr. Peter Jannetta. This involves an operation performed under general anesthesia in which a small (keyhole) opening is made in the back of the head behind the ear (See Figure 2.) Through this opening we are able to expose the Trigeminal Nerve as it enters the BRAINSTEM.
The abnormality causing Trigeminal Neuralgia at the place where the nerve enters the Brainstem is usually a compressive loop of artery. It is known that, as the aging process occurs, arteries throughout our body become longer. In this tight, confined area of the skull an elongating arterial loop may come to lie against the nerve as it enters the brainstem. It is able (by compression) to cause damage to the MYELIN sheath, which insulates the nerve. This results in the pain of Trigeminal Neuralgia. (See figure 3A) At surgery, the arterial loop can be repositioned to a better place using special Microsurgical (Microvascular) techniques (See Figure 3B). It is prevented from resuming its previous position by inserting a small, permanent prosthesis usually made of an inert plastic sponge material. The operation, called "Microvascular Decompression (MVD)" is highly reliable in achieving total relief of pain without causing any numbness to the face. It is also probable that this offers a greater chance of preventing any further recurrence of the pain. This procedure, while not new, has been utilized extensively for over 25 years. In scientific terms this is now a period of time that is long enough to be sure of some prolonged results. Microvascular Decompression (MVD) appears to be the most exciting and promising method for treating this problem and offers a high probability of complete long term cure. Follow-up information is becoming available from other countries and surgical groups for periods up to 25 or more years. OUR EXPERIENCE WITH MVD PROCEDURES FOR TRIGEMINAL NEURALGIA Dr. Lazar has performed over 300 MVD procedures after having been chosen by Dr. Peter Jannetta, in 1976, as one of ten American surgeons to validate his theory of the cause and the operation (MVD) used to definitively treat Trigeminal Neuralgia.Our personal experience with the long-term results of Microvascular Decompression (MVD) is similar to those from other centers (over 85% complete long term relief) and very encouraging while the risks to MVD have proven to be quite small. Our Treatment Philosophy It is our philosophy that no operation should be undertaken lightly.As with any operation and the use of general anesthetic, there is a certain (fortunately extremely small) element of risk to life. The Neuroanesthesiologist will review the special anesthetic techniques used for this procedure and answer any questions, which you might have. In making a decision about a surgical procedure, a patient must carefully weigh the risks against the potential benefits of affording relief without producing facial or corneal (eye) anesthesia (numbness) or other complications associated with other procedures that involve injury to or destruction of the Trigeminal Nerve. This procedure is usually reserved for patients who are otherwise in good health and young enough to undergo an operative procedure. Under most conditions we restrict this procedure to patients under the age of 70. However, we cannot draw a hard-and-fast rule in this regard. There have been patients under the age of 65 who may not qualify for this procedure. On the other hand, there have been patients up to the age of 74 who have tolerated the procedure quite well in my experience. Patients selected for this procedure are usually hospitalized one to five days following the performance of the operation. The first one to three postoperative days are spent in the Neurological Intensive Care Unit. Surgical Risks There are a number of vital blood vessels and nervous system structures in the operative region, which could conceivably be at risk to injury. There are several nerves, which control the movement of the muscles of the eye, which, if damaged, could produce double vision. The nerve which controls hearing, the 8th Cranial (Auditory) Nerve, is very near the Trigeminal Nerve as is the 7th Cranial (Facial) Nerve which controls movement of the face. Injuries to these nerves could result in deafness on this side and/or paralysis of this side of the face. In my experience, no Trigeminal Neuralgia patient has had any facial nerve paralysis. We seem to have been successful in reducing the risk to impairment of hearing to a very low level, partly due to our ability to monitor hearing function while surgery is being conducted. In the event that this monitoring test indicates that hearing function seems to be at risk during surgery, then the operation may be altered in some way to reduce the risk to injury. The risk to injury to a vital blood vessel which could produce a stroke (resulting in paralysis of face/extremities/bowel/bladder) or hemorrhage is exceptionally small.Success Rate for Treatment The chance to achieve satisfactory pain relief, using this "Jannetta" (or MVD) procedure is almost 85%. Some patients do not experience relief of pain for some days (or up to several weeks or months) postoperatively. More than likely, this is the result of the already present injury to the MYELIN insulation material of the nerve root, which may take some time to recover. There is another small group of patients who experience initial relief of pain and suffer a short-lived recurrence several days or weeks after surgery. In these cases, pain is usually relieved using Tegretol and/or Dilantin (or some of the newer anticonvulsant drugs) in doses which were formerly not as effective (prior to surgery). These medications are progressively withdrawn once the pain is well controlled. Fortunately, most patients who undergo this operation are relieved of the pain and do not take any of these medications again.There are three (3) other small groups of patients to be mentioned. One group will not achieve pain relief and will remain on medication. Most of these patients will experience satisfactory pain relief from lower doses of medications that were not effective in higher doses prior to surgery. The smallest group consists of patients who may experience no pain relief at all. In this case, another operation (through the same site) would be indicated. Some surgeons have found, at re-operation that the sponge had slipped. In the few patients that I have had with this problem, no sponge has slipped; and I have found it necessary to cut the nerve in order to achieve pain relief. The last category comprises those few patients in whom the anatomical problems of nerve root compression cannot be relieved, either because the risk to moving the artery or vein or dividing the vein would result in a stroke. In this case, the nerve must be divided in order to relieve the pain. The consequence of this surgical division of the nerve is a dense numbness in the face on the side that is cut. It is a satisfactory alternative for 98% of those patients who require relief of the Trigeminal Neuralgia pain where the nerve cannot be decompressed (Jannetta procedure). In two percent (2%) of patients where the nerve is cut, a disagreeable, painful, anesthetic problem may develop (anesthesia dolorosa) in the face on the side of operation. Other potential complications to this operation include postoperative leaking of Cerebrospinal Fluid (the fluid that bathes the Brain and Spinal Cord) through the incision or into the ear. Should this occur, it would require an operation to seal the leak since the problem could result in a serious infection. Infection and hemorrhage are risks to any operation but like all of those reviewed above, are exceptionally uncommon. Similarly, the risks for postoperative Brain swelling, problems with balance and coordination or paralysis of swallowing or extremities are exceptionally low. Nevertheless, the reader must recognize that operations are chosen only after medical treatment fails. Alternative Procedures Other therapeutic interventions include Percutaneous Glycerol Rhizotomy, Percutaneous Gasserian Ganglion Balloon Micro-compression, Percutaneous Radiofrequency Thermocoagulation and Stereotactic Radiosurgery.
Comprehensive Review A comprehensive review of the entire subject of Trigeminal Neuralgia and these therapeutic alternatives is available on this website.Video Files: The reader is also invited to review our video files on MVD Procedures.
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All content ©2024 by Neurosurgical Consultants, P.A. Author, Martin L. Lazar, MD, FACS All Rights Reserved. See Usage Notices. |