TRIGEMINAL NEURALGIA HEMIFACIAL SPASM GLOSSOPHARYNGEAL NEURALGIA

(A Patient Information Service)

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. Surgical treatments in the past involved either cutting the nerve or its branches or injecting alcohol to deaden the nerve. Various medications have been used with varying success for many years. The ideal surgical method of management would offer complete relief of the pain without producing any numbness. Because of recent important developments, there is a better understanding concerning the cause of this painful condition. There are essentially three causes that are now recognized. The most common cause is a compression phenomenon exerted on the fifth cranial 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 surrounding the nerve. This insulating material (which acts like rubber that insulates electrical wires) is called MYELIN. 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 has also been seen in patients with trigeminal neuralgia associated with an aneurysm (dilated portion of a blood vessel) or a tumor. Aneurysms or tumors are very unusual as causes of neuralgia. The majority of these rare tumors are completely benign. The other important cause of Trigeminal Neuralgia is multiple sclerosis. Multiple sclerosis is a disease, which attacks myelin and is extremely unusual as a cause of trigeminal neuralgia. On very rare occasions arteriosclerosis may produce a small stroke in this region resulting in facial pain. All three of these "causes" have in common the fact that they injure the critical insulating structure, myelin, at a very precise location in order to produce the problem that results in the pain of Trigeminal Neuralgia. The injury to the myelin that results in this pain is precisely at the nerve root entry zone of the trigeminal nerve as it enters the brainstem. 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.

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. 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 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. At surgery, the arterial loop can be repositioned to a better place using special microsurgical techniques. It is prevented from resuming its previous position by inserting a small, permanent prosthesis usually made of an inert plastic sponge material. In this way, it is possible to achieve 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. This Microvascular Decompression (MVD) technique appears to be the most exciting and promising method for treating this problem and offering a complete long term cure. Follow-up information is becoming available from other countries and cities for periods up to 25 or more years. Our own experience with these encouraging long-term results is similar to those from other centers. However, this treatment involves a formal operation and the general risks of any surgical procedure as well as general anesthesia.

It is my philosophy that no operation should be undertaken lightly. The risks to this operation have proven to be quite small in my experience. As with any operation and the use of general anesthetic, there is a certain (fortunately extremely small) element of risk to life. The anesthesiologist 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 destroying the 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 I restrict this procedure to patients under the age of 70. However, I 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.

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 nerve, also called the 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.

The chance to achieve satisfactory pain relief, using this "Jannetta" 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.

Another commonly used operation is Radiofrequency destruction (thermocoagulation) of the trigeminal nerve. This procedure was developed by Drs. Sweet and Wepsic of Boston. For many years this was the most widely used procedure for Trigeminal Neuralgia. The procedure involves destroying a portion of the nerve with a special needle electrode. The needle is placed in the cheek and is passed through a small opening in the base of the skull under X-ray control to contact the nerve after it has left the brainstem. Correct localization within the nerve is determined by stimulating through the needle electrode, which produces a tingling sensation in the patient's face. Once the correct localization is achieved, a Radiofrequency (electrical) current is placed through the needle electrode and a small amount of nervous tissue is destroyed. The patient is then tested and the procedure repeated until an adequate degree of nerve destruction has been achieved to relieve the pain. This entire procedure is performed under a form of anesthesia known as neuroleptanalgesia, or "twilight sleep". This method allows the patient to remain awake and cooperate without experiencing any undue discomfort. It is necessary for the patient to cooperate with the surgeon in order to achieve the desired result. The results of this procedure can be quite gratifying. Over 90 percent of patients can enjoy relief of the pain of Trigeminal Neuralgia. Most patients have the preservation of some facial sensation. The patient usually will not feel that the face is totally numb, such as might occur after the nerve is cut or an alcohol block has been performed. However, in approximately 15 percent of patients, an undesirable degree of numbness is produced. Patients must be willing to accept this 15 percent chance of disagreeable facial numbness before this procedure can be undertaken.

The major risk of this procedure, other than the recurrence of pain, is that the facial numbness can spread to involve the first part (or branch) of the Trigeminal Nerve, which supplies sensation to the forehead and cornea of the eye. Should this happen, pain sensation from the eye will be lost. This will not affect vision. However, the patient would lose the protection that the pain sensation provides. A piece of dirt or other foreign body that lodges in the eye could cause scratching and damage to the eye without the patient being aware of it. Should this more extensive sensory loss occur, very careful, lifelong attention to care of the eye is necessary in order to prevent damage to the eye. This procedure should not result in any paralysis of the facial muscles, which are ordinarily used to express emotion. However, some weakness can occur in the muscles involved in chewing. The very rare occurrence of a phenomenon known as "anesthesia dolorosa" should be mentioned. In these patients, although the trigeminal pain is relieved, a new different type of constant burning takes its place. This rare phenomenon occurs in less than one percent of patients.

This procedure is usually well tolerated in elderly patients who have significant medical illnesses such as diabetes, hypertension or heart disease. Previous surgical procedures or alcohol blocks do not prevent it from being effective. Patients are usually hospitalized overnight. There is an approximate 33 percent early recurrence rate of the Trigeminal Neuralgia. Fifty (50) percent of patients are expected to experience return of the pain within five (5) years. This can usually be relieved with a repeat procedure. Most patients do not find the procedure extremely difficult to tolerate although there is some degree of discomfort during the positioning of the needle and destroying part of the nerve with the Radiofrequency current. This discomfort is controlled to a great extent with the anesthesia utilized.

An alternate procedure (Percutaneous Retrogasserian Glycerol Rhizotomy — PRGR) was initially developed by Dr. Sten Hakanson of Sweden in 1975. In some ways it is similar to the needle thermocoagulation described above. In this case, sterile glycerol (a sugar-like substance in a clear solution) is injected just behind the Gasserian Ganglion (see diagrams 4 and 5) that is the major "relay station" for the Trigeminal Nerve. The needle placement is done in a similar fashion as for the thermocoagulation procedure. In this case we are able to avoid the unpleasant electrical stimulation as is done for thermocoagulation. Glycerol probably acts to produce a relatively minor injury to the nerve although sensory loss has been much less common and less severe compared to thermocoagulation. It has been reported that up to 65% of patients have had some form of decreased sensation for up to six months; however, less than 10% have significant permanent sensory impairment.

According to most reports, about half (1/2) of the patients obtain relief of the Trigeminal Neuralgia pain within 24 hours; the other half obtain relief within 15-20 days. The average time to pain relief is about five days after injection.

The advantages of this procedure (PRGR) when compared to radiofrequency thermal rhizotomy are that: it is less painful to the patient; it can be done with various anesthetic options ranging from relatively "light" premedication to general anesthesia; it is less likely to result in permanent sensory loss; and it is just as or a little more likely to provide long-term relief of pain. Most experienced surgeons now report 65-75% satisfactory relief of pain. Ten (10%) percent of patients have an unsatisfactory result and are considered to be technical failures. About 15% of patients will require a second injection before satisfaction is obtained. An early recurrence of pain is considered to be less than six months post-injection. (This will occur in approximately 10%.) A late recurrence of pain (after six months post-injection) may occur in 7-8%. The procedure can be repeated if recurrent pain is not adequately controlled with medications (Tegretol/Dilantin). Although 65-75% of patients have excellent (pain-free) results, another small group will be sufficiently improved so that continued use of medication (such as Tegretol and/or Dilantin) will satisfactorily relieve the pain. (These are all patients who could not achieve or maintain pain relief with these medications before the procedure.)

The procedure is not entirely without risk. Some persistent (usually minor) sensory impairment occurs in 25% of patients. Another 2% will have a persistent denser sensory loss. In 2% of patients the sensation to the cornea is impaired. Unpleasant, even painful sensory disturbances occur in about 3% of patients. There are risks to weakness of the muscle that is involved in chewing, double vision, injury to the blood vessels which supply blood to brain (stroke/hemorrhage) as well as to brain itself (which could result in paralysis of the face/arm/leg); however, these risks are very small. The risk to infection is also very small. A small number of patients have suffered an inflammatory response (of the brain coverings) as a result of the injection. This is usually accompanied by fever and stiff neck. It has been reported to resolve rapidly with steroid medication.

This procedure is usually performed on an outpatient basis. Occasionally patients are hospitalized for 24 hours. We require that the patient remain in a sitting position for at least four hours after the procedure to keep the glycerol on the nerve for an optimum time. It will slowly disappear and be diluted by the cerebrospinal fluid, which bathes the brain.

An additional procedure utilizing the same access technique (image guided placement of a needle through the base of the skull- viz. Figures 4 & 5) is available. In this case (Percutaneous Gasserian Ganglion Microcompression) a tiny catheter is threaded through the needle to a place directly adjacent to the Gasserian Ganglion. The balloon is then inflated and compresses the Gasserian Ganglion. This compression results in a small amount of trauma to the Ganglion. The "microtrauma" usually is successful in relieving the pain of Trigeminal Neuralgia. The advantage here is that very little injury is actually produced in the nerve (certainly as compared to the "Thermocoagulation" procedure). The disadvantage is related to the fact that "very little damage is actually produced". One must recognize that the "pain-free" result may not last as long as other procedures that create a little more "injury" to the nerve. Nevertheless, there are patients who will prefer this procedure and occasionally in whom this would be the most appropriate initial choice.

A word should be mentioned about Stereotactic Radiation Therapy (Radiosurgery). It is now possible using various methods of "focused-beam" radiation therapy, of which the "Cyberknife" (or Accuray) system is the newest and the "Gamma Knife" the oldest and most common, to "target" tiny areas of the brain for injury and destruction. This is another form of "destructive" therapy. This is becoming an increasingly popular treatment method which, while having merit, does not address the actual cause of the Trigeminal Neuralgia, only the symptom. Common sense should cause one to acknowledge the inherent objections to this type of treatment recognizing that the actual cause is most patients is a blood vessel in an aberrant anatomical position. We recommend this type of therapy only in the rarest of circumstances such as the very elderly or infirmed who would not tolerate the other treatments. Since radiation therapy affects small blood vessels by initiating a process of progressive inflammation and occlusion (which is, in part, why it is used for tumors and arteriovenous malformations) this may lead to delayed onset of additional neurological deficit such as increasing numbness in the Trigeminal Nerve distribution. There is not enough long term information to comment any further at this point.

HEMIFACIAL SPASM is a neurological condition, affecting the seventh (or "Facial") cranial nerve, which supplies many of the muscles of the face. The facial muscles affected are those involved in movements that express emotion. These include muscles of the forehead, eye closing mechanisms, as well as muscles around the mouth. In this bothersome condition, known as "Hemifacial Spasm" the patient experiences repetitive episodes of uncontrollable and involuntary muscle spasms in the face. It frequently begins around the eye and/or corner of the mouth and at some later date spreads to involve the rest of the face (on the one side). It is not associated with any pain. This condition is the result of a pressure injury to the "Facial Nerve" as it leaves the brainstem. Usually the cause of pressure is a blood vessel. The nerve injury phenomenon (injury to the Myelin) is similar to that seen in Trigeminal Neuralgia. The modern treatment of Hemifacial Spasm includes a similar operation to the Microvascular Decompression (MVD) procedure described above for Trigeminal Neuralgia. The Facial (or seventh cranial) nerve is located approximately one half inch below the Trigeminal (Fifth Cranial) Nerve. The MVD operation is conducted through a skull opening in a similar location as described for Trigeminal Neuralgia. In Hemifacial Spasm the ideal treatment results in the relief of the muscle spasm without resorting to destructive operations which produce paralysis of the facial muscles on the one side affected. Unfortunately, medical treatment (usually with Tegretol, Dilantin or any other anticonvulsant drug) is less effective in Hemifacial Spasm than in Trigeminal Neuralgia. Our efforts in the surgical treatment of this condition are to preserve motor function to the face while attempting to relieve the muscle spasm. It is quite successful and gratifying to the patient.

GLOSSOPHARYNGEAL NEURALGIA is a very painful condition, similar in severity to Trigeminal Neuralgia, which involves the Glossopharyngeal (or ninth cranial) nerve. In this disease, the sharp stabbing pain is experienced in the back of the throat and deep in the ear region. It may originate with the act of swallowing. Once again, the cause is a pressure injury (usually by a blood vessel) to the nerve, as it enters the brainstem. In those patients where medical treatment (usually with Tegretol and/or Dilantin) fails, Microvascualr Decompression (MVD) treatment is the recommended treatment since it allows the surgeon to "decompress" the Glossopharyngeal nerve. If decompression is not possible, then the fibers of the Glossopharyngeal (ninth) nerve and the upper two or three fibers of the adjacent Vagus (tenth cranial) nerve are cut. This would result in numbness in the back of the throat and paralysis of some of the muscles in the back of the interior of the mouth and throat on the one side. These nerves are cut only when decompression proves to be impossible since it is imperative to relieve this excruciating pain. Once again, the surgical results are quite gratifying and have proven to be reliable over long periods of time.

IMPORTANT INFORMATION: Prior to being considered for surgical treatment of these conditions, I would ask that you forward an evaluation from your personal doctor indicating your previous medical/surgical history, health and confirming the diagnosis. If you have been taking medication, such as Tegretol, Dilantin, Neurontin or any other anticonvulsant drug, this should be indicated as well as their effectiveness and the dosages taken. I would also want to know about the length of time that this medication has been taken. Information concerning previous surgical or dental attempts to relieve this pain and their effectiveness should be noted. Any other medications, allergies, or other significant medical facts should be included. I prefer to see the patient in consultation prior to hospitalization in order to examine him/her and to answer any remaining questions. However, when medical or social circumstances such as patients arriving from out of town (or from another country) make this impractical, direct admission can be arranged.

The accompanying diagrams and explanations help to illustrate some of the anatomical factors and operations. In the case of the "Jannetta Procedure," a right-sided example has been chosen to demonstrate the typical findings in Trigeminal Neuralgia. A similar procedure directed toward the appropriate involved nerve is conducted for Hemifacial Spasm (seventh cranial nerve) or Glossopharyngeal Neuralgia (ninth cranial nerve) to attempt to relieve those conditions in those patients with these specific problems. The Facial (7th) nerve lies below the Trigeminal (5th) nerve. The Glossopharyngeal (9th) nerve lies below the Facial (7th) nerve.

In the case of a Percutaneous Retrogasserian Glycerol Rhizotomy (PRGR) a right-sided procedure is also illustrated. Unfortunately thermocoagulation, Glycerol Rhizotomy, Microcompression and Focused Beam Radiation techniques are NOT applicable for Hemifacial Spasm or Glossopharyngeal Neuralgia. These techniques are available only for Trigeminal Neuralgia. It is the unique anatomy of the Trigeminal nerve that renders it relatively easily accessible through a small opening (which already exists) in the base of the skull. This allows the surgeon to accurately place a needle in a precise anatomical location with little risk.

Please do not hesitate to ask questions concerning this material. Our office will be pleased to provide other, more technical medical data concerning these clinical entities and our experience.

Some of our publications on this subject are listed below:

1. Trigeminal Neuralgia: Recent Advances in Management. Texas Medicine 74: 45-48, 1978 (Lazar, M.L.)
2. Management of Tic Douloureux. Letter to the Editor, JAMA 240: 1715, 1978 (Lazar, M.L.)
3. Treatment of Pain Syndromes in Current Treatment of Neurological Diseases, edited by Rosenberg, R., Spectrum Publications, Jamaica, NY, 1979, pp.589-604. (Bland, J.E., Lazar, M.L. and Naarden, A.L.)
4. Trigeminal Neuralgia (Abstract). Dental Abstracts, August 1979, pp. 526-527 (Lazar, M.L.)
5. Trigeminal Neuralgia and Multiple Sclerosis: Demonstration of the Plaque in an Operative Case, Neurosurgery 5:711-717, 1979 (Lazar, M.L. and Kirkpatrick, J.B.)
6. Current Treatment of Tic Douloureux, Oral Surgery, Oral Medicine, Oral Pathology 50:504-508, 1980 (Lazar, M.L.)
7. Facial Pain Mimicking Oral Pathology. Some Modern Concepts and Treatment, J. American Dental Association 100:884-888, 1980 (Lazar, M.L., Greenlee, R.G. and Naarden, A.L.)
8. Trigeminal Neuralgia: Recent Advances in Management (Abstract) Headache 19:401, 1979 (Lazar, M.L.)

LEGEND FOR FIGURE 3

Figure B: Operative View: The right petrosal vein is visualized, cauterized and divided in the anterolateral aspect of the posterior fossa.

Figure C: Operative View: Magnification view of fourth and fifth cranial nerve, superior cerebellar artery with cerebellum retracted.

Figure D: Orientation View: The redundant tortuous superior cerebellar artery impinges on the fifth cranial nerve causing trigeminal neuralgia.

Figure E: Operative View: High magnification of redundant tortuous superior cerebellar artery causing compression-distortion of the trigeminal nerve.

Figure F: Operative View: High magnification. The superior cerebellar artery has been transposed to a posterior, superior and lateral position in relation to the trigeminal nerve. The compression-distortion force has been relieved. Plastic sponge prosthesis holds the vessel in the transposed position and protects the nerve.

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This page last edited on 2/20