Face Pain Info Pages - Part 9

Treatments for Typical and Atypical Trigeminal Neuralgia

Surgical Procedures

When medications are unsuccessful in managing facial pain or when the side effects of medications become toxic or disabling for the patient, surgery may be considered. Many physicians are disposed to recommend against surgery for ATN (Type 2 TN), because rates of surgical success are lower than for Type 1 TN. Likewise, some physicians may actively resist surgery if they do not find evidence of nerve compression by blood vessels in MRI imagery. However, vascular compressions are often found during the exploratory phase of Micro-vascular Decompression where none was previously detected in medical imaging.

Several surgical procedures are available to patients considering this option. Selection of a particular procedure needs to be based upon the general state of patient health (particularly clotting problems, high blood pressure, or previous stroke or cardiac problems) as well as on the likelihood of success, length of probable pain relief, and risk of bad side effects in patients who present with your specific patterns of pain. As noted elsewhere in this article, general observations about surgical procedures are helpful as information but not definitive as advice or guidance for you as an individual.

Also important is the experience of the prospective surgical team. You are more likely to get a positive outcome from a team that does your chosen procedure five times each week than from a surgeon who does five procedures per year. Likewise -- in my personal view -- the absolute LOUSIEST reason for choosing a type of procedure is because your doctor does it and recommends it. The doctor should be required to demonstrate both his or her experience and the long-term outcomes in a large group of previous patients tracked over time. If a doctor isn't doing follow-up surveys on pain recurrence, then I would have very strong reservations concerning his or her suitability to work for someone in my own family.

There is nothing wrong with having a young doctor do your surgery, especially if the procedure is one of the less complicated. But if a doctor has done your procedure only a few times, you should ask what more experienced surgeon (by name) will be in the operating theater with him or her, looking over his or her shoulder. Then go read (or have an expert read) both doctors' Curriculum Vitae. The last thing you need is to be on the bottom end of somebody's learning curve, without adequate senior oversight. Likewise, this type of surgery is no job for a general practitioner or even for a neurosurgeon who lacks highly focused and specific training for intracranial procedures.

Six surgical procedures are commonly used against facial neuropathy and neuralgia. I have listed them below. The ones that I assess from readings in the medical literature and from patient reports to be the most effective and long-lasting are listed first. Based on their own clinical experience, some physicians might contest my judgment on this priority order. If asked to advise a close family member or friend on how to figure out who is "right" in such a discussion, I would suggest that he or she ask how the doctor knows what he or she claims to know about success rates.

"Please don't offer your clinical judgment alone. I want to see your numbers and/or your published papers based on procedures you have actually performed yourself or supported as a member of surgical teams." This is admittedly a tough standard to meet. But you're dealing with an extremely tough condition, and things that a doctor may do while you are under anesthesia can sometimes make matters worse if he or she screws up. Remember that the doctor is being paid a great deal to work as your employee. He or she is not a high priest in some esoteric religion, immune from questioning and requiring your blind faith.

Microvascular Decompression is often regarded as the "gold standard" against which all other procedures are compared. It is the only surgery that attempts to remove a basic cause of pain rather than blocking or suppressing pain by creating lesions on the trigeminal nerve farther along the nerve distribution. MVD involves opening a nickel- to quarter-sized hole in the skull behind your ear, visually examining the area around the brainstem with a microscope or endoscope, finding places where a vein or artery touches the trigeminal nerve, and then inserting surgical padding between the vessel and the nerve. After separating the nerve, the doctor closes the incision, sometimes with a titanium plate screwed into the skull bone.

For an experienced surgical team treating patients with Typical TN, the initial rates of successful pain relief can be in the 90-95% range for Type I (Typical) TN pain.  Stats for Type II (Atypical) pain are not as good (see below). Many patients wake up from surgery pain-free, although pain from the procedure itself may linger for a few days to a few weeks. About 70% of all Type I MVD patients are still pain-free after ten years. More than half continue to be pain-free past 15 years. Among Type II patients, pain is fully or significantly (partly) relieved in about 50% of MVD patients for at least five years.

[See  "Predictors of outcome in surgically managed patients with typical and atypical trigeminal neuralgia: comparison of results following microvascular decompression.",   Tyler-Kabara EC, Kassam AB, Horowitz MH, Urgo L, Hadjipanayis C, Levy EI, Chang YF.  Department of Neurosurgery, Center for Cranial Nerve Disorders, University of Pittsburgh Medical Center, Pennsylvania 15213-2582, USA.]

Mortality for MVD is very low -- less than 1% (and never in my research a direct outcome of the surgery itself). Serious and lasting side effects can occur in about 10-15% of MVD patients. The most severe of these effects is Anesthesia Dolorosa (AD), a form of facial pain that combines deep burning and aching with a loss of surface sensation. AD is very difficult to treat with anything other than opioid drugs. It can occur in other procedures as well. I am uncertain whether any of the procedures has a markedly lower incidence of this lasting side effect

One note, derived in part from an inquiry received here at Living with TN: as reported in a few medical literature references, it appears that the chances of a pain recurrence after MVD are higher when the offending vessel is a vein than when it is an artery. Possibly reflecting this reality, some surgeons choose to divide and cauterize veins that are touching the nerve but not growing into it. There is a balance to be struck between addressing a known source of pain versus possibly damaging the nerve by excess handling during surgery.

Also of concern is that some neurosurgeons advise against MVD for Atypical TN patients, even when a nerve compression is detected in MRI imagery.  However, in addition to the reference above at least one more recent paper on the subject indicates that for patients whose pain starts out as Typical TN with its stabs of electric-shock pain, MVD can be almost as effective when 50% of present pain is constant.

See: “Effect of Microvascular Decompression in Trigeminal Neuralgia Patients with or without Constant Pain.”

Another useful article in the Knowledge Base of the TN Association is: "Microvascular Decompression in Patients with Isolated Maxillary Division Trigeminal Neuralgia, with Particular Attention to Venous Pathology"  The authors found that surgical outcomes of MVD for Atypical TN Patients with this type of isolated pain were about the same as for Typical TN patients. 

Some doctors offer an alternative to MVD in what is called "partial nerve section," for patients in whom no compressions are identified during surgical exploration. The intent of partial nerve section is to cause a lesion on the nerve, downstream from its emergence from the brainstem, reducing the efficiency of nerve firing that causes cascades of pain. Nerve section has a higher risk of disabling side effects and pain recurrence in what is called “Differentiation Pain" -- originating in the central nervous system due to interruption of nerve paths to the peripheral nerves and sensing. For this reason, the procedure is considered by some neurosurgeons to be a desperation measure.

Another reference was provided by our Living with TN user "Emmy."  Dr. Hugh B. Coakham of the Neurosurgical Clinic at BUPA Hospital, Redland Hill, Bristol, UK, is highly authoritative in this field. Elements of the outcomes analysis in his article were performed independently by Dr. Joanna Zakrzewska, a serving member of the Trigeminal Neuralgia Association Medical Advisory Board.  See: Hugh B. Coakham. M.D., "The Surgical Treatment of Trigeminal Neuralgia." Advances in Clinical Neuroscience and Rehabilitation 7(2) (May-June, 2007).

In a sampling of 359 patients who underwent MVD, 96% of those for whom the procedure was a first surgery declared their satisfaction with the surgical outcome. For patients where MVD was a second procedure following previous Glycerol or Radio Frequency (RF) Rhizotomy, or nerve block, 76% were satisfied.

The great majority of all patients declared that they would have preferred to have the surgery earlier than they had been permitted to, probably related to the fact that all had failed medical therapy before being offered surgery. Unusually, Dr. Coakham’s study is one of the few papers to report results of annual follow-up patient surveys for a period up to 12 years.

   One note of caution:  some patients are allergic to metals commonly used in plates which cover the incision made during an MVD -- particularly titanium or the nickle used in hardening titanium. If you know that you have allergies to metals, then tell your doctor in advance of MVD, or your dentist in advance of any facial surgery to correct for bite or TMJ issues. [Discovery Credit:  Carol Harmer and Tinkerbell, members of Living With TN]

Radio Frequency Rhizotomy (also known as RF Lesioning) has initial success statistics comparable to those of MVD. It is a less expensive office procedure that involves inserting a surgical probe through the cheek and threading it into one of the spaces in the skull through which the trigeminal nerve passes. The end of the probe is then heated while in contact with the nerve, to cause a controlled lesion  on the nerve. This lesion is intended to interrupt or moderate surges of nerve activity that cause the volleys of electric-shock pain experienced by Typical TN patients.

The paper by Dr. Coakham indicates that long-term outcomes of RF Rhizotomy are highly comparable with MVD, although a somewhat lower percentage of surveyed patients declared satisfaction with their current situation, Success rates for a second or subsequent procedure are lower than for the initial surgery. For a second MVD, 76% were satisfied versus 96% on a first MVD. 64% of second-time patients versus 60-80% of first-time patients in other types of surgery declared that they would have the procedure that they received, again.

Balloon Compression is a variation on RF Rhizotomy in which the desired lesion on the trigeminal nerve is created by inflating a small surgical balloon that has been threaded through a probe inserted into the patient's cheek. Inflation occurs while the probe is in contact with the surface of the nerve, and the lesion is a result of crushing the myelin layer of the nerve in a limited region. The procedure has not been as widely used as RF Rhizotomy. In sources I have read, the success statistics and persistence of relief appear to be somewhat lower than those with RF Rhizotomy or MVD.

Gamma Knife Stereotactic Radiosurgery (GK) is advertised and advocated as a "noninvasive" surgery that requires no opening of the skull or use of physical probes. The patient's head is immobilized in a rigid frame, while a pattern of collimated beams of gamma radiation is delivered to a target area on the trigeminal nerve. By dividing up the total dose in multiple beams from different directions, the radiation exposure of tissues surrounding the target zone is reduced, while irradiating a small zone of the surface of the nerve with sufficient energy to cause a lesion.

In January, 2009, the International Radiosurgery Association (IRSA) updated its practice guidelines for the use of Stereotactic Radiosurgery in Trigeminal Neuralgia. From that source, the reported results with Gamma Knife vary widely between reports, with full pain relief observed in 50-75% of patients and relief kicking in over periods of weeks to months following the procedure. Bothersome facial numbness was observed in about 15% of the cases. Recurrence of pain within a few months up to five years appears to be a significant concern. About half of patients in some trials had recurrence within three years after surgery.

Not acknowledged in the IRSA practice standard are side effects of Gamma Knife outside the target zone of the procedure. At least two neurosurgeons who perform MVD surgery have reported to me that when they have performed MVD as a second procedure for recurring pain following Gamma Knife, they frequently found "a real mess," with multiple lesions and adhesions of the nerve to surrounding tissues. Such conditions can significantly reduce the likelihood of a successful outcome during a re-operation by MVD or other procedures.

In my opinion, the most supportable role for Gamma Knife Radiosurgery is with patients for whom MVD is not an option having acceptable risk. This would largely be older patients whose cardiac health may be compromised by general anesthesia and those who suffer from high blood pressure or stroke. I do not accept that the term "noninvasive" is an accurate description for the total impact of this procedure on the patient.

I also note that some of the physicians who contributed to the IRSA practice standard were affiliated with hospitals that have invested in expensive radiosurgery treatment centers. Thus there is an implied financial self-interest in lending the best possible interpretation of reported outcome statistics. This self-interest is not acknowledged in the published standard.

Glycerol Rhizotomy is also a peripheral surgery involving a probe through the cheek. It is performed as a medical office procedure. The lesion is created by exposing the trigeminal nerve to a solution containing a form of alcohol. Rates of initial success with this procedure are not as good as observed with RF Rhizotomy or MVD, and recurrence rates are much higher. About half of all Glycerol patients have recurring pain within two years. However, doctors who use this procedure point out that Glycerol Rhizotomy can be repeated multiple times, whereas there is a lifetime limit on the amount of gamma radiation exposure considered safe.

Cyber Knife (CK) is another variant on Stereotactic Radiosurgery. It is newer than Gamma Knife and employs an accelerated beam of photons rather than beams of gamma radiation. The procedure was originally developed as a real-time treatment for tumors throughout the body. Direction of the photon beam is controlled with the aid of X-ray imaging. In the IRSA practice standard, it is acknowledged that the accuracy of targeting with Cyber Knife is somewhat less precise than with Gamma Knife. From two to six times as much radiation energy is deposited in tissues immediately surrounding a nominal target zone of 1-mm diameter.

Not as much information is available on success statistics with Cyber Knife as for Gamma Knife. As with GK, there are certainly patients who report being pain-free within a few weeks after surgery. In the patient reports I have read in various on-line forums, I have also seen a lot of reports that the procedure apparently made no difference at all. But we cannot generalize such an impression as scientific evidence. Thus I would have to say that the jury is still out concerning how effective either GK or CK is for Trigeminal Neuralgia patients.

For readers interested in deciding between surgeries, there is an excellent if somewhat dated article written by Drs. Taha and Tew of the Mayfield Clinic in Cincinnati, Ohio. Dr. Tew is a past member of the TN Association Medical Advisory Board. You should be able to find this article via interlibrary loan at any large University Medical School library.  See: Taha, J. M., Tew, J. M., Jr.: “Comparison of Surgical Treatments for Trigeminal Neuralgia: Reevaluation of Radiofrequency Rhizotomy.” ,” Neurosurgery 38(5):865-871 (May, 1996).

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Face Pain Info Pages - Part 10

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