Overview

Several disorders that cause facial pain can be successfully treated by neurosurgical procedures. It is important to accurately diagnose the disorder and identify the best treatment for each disorder. In the absence of randomized prospective studies, standardized methods of reporting, and standardized outcome criteria, it is difficult to compare the results of various surgical procedures and the different reported series of the same surgical procedure. Nevertheless, several important observations emerge from reviews of the literature and personal experience.

General Observations on Facial Pain

• Accurate diagnosis is required.
• The diagnosis of typical Trigeminal Neuralgia (TGN) is seldom difficult.
• In general, the length of the list of the patients symptoms is directly proportional to the likelihood of treatment failure.
• Medical treatment should be explored before surgery is contemplated.
• There is no successful surgical procedure for treatment of atypical facial pain.
• It is more difficult to treat neuropathic than neuralgic pain.
• Patients with dysesthetic pain seldom respond to ablative surgery.
• There is no single superior treatment for facial pain. The treatment should be individualized. Patients should have access to a broad spectrum of treatment options.
• The results of surgical treatment diminish as facial pain becomes more chronic.

Results for Trigeminal Neuralgia (TGN)

Generalizations regarding treatment of TGN have been presented in the literature. While some surgeons advocate one procedure for all patients, others select different surgical procedures for different patients. In the midst of this controversy, surgeons must not lose sight of the facts and observations pertaining to the treatment of TGN. Following are some of our observations: 

Recognize atypical TGN and status trigeminus
One must distinguish atypical TGN from atypical facial pain. In atypical TGN, patients report lancinating or brief episodes of sharp or burning pain that last seconds to minutes and are associated with milder constant aching pain. 

Some patients experience status or continuous repeated episodes of pain of TGN. These patients appear fatigued, often dehydrated, and in constant severe pain. They frequently report simple continuous pain rather than the typical episodic pain. Such patients usually require an urgent surgical procedure. 

There is no current cure for TGN
All current surgical procedures for TGN are associated with risk of pain recurrence (1). After successful surgery, pain of TGN can progress to involve other trigeminal nerve divisions or the contralateral side. In some patients, pain of TGN is difficult to treat, regardless of what treatment is given. Longstanding chronic TGN is more difficult to treat. Long-term pain relief is highest after microvascular decompression (MVD) and percutaneous stereotactic radiofrequency rhizotomy (PSR). 

Among the current treatment options, microvascular decompression (MVD) and percutaneous stereotactic radiofrequency (PSR) rhizotomy have comparable rates of pain relief that are highest among the available options. In a review of series of approximately 100 patients or more published in the past 10 years (2-12), the rates of pain relief calculated were 77% in 7 years for MVD and 75% in 6 years for PSR rhizotomy. 

TGN Pain Recurrence

Procedure	Follow-up	Pain-free
MVD	7 years	77%
PSR	6 years	75%
Glycerol rhizotomy	3 years	55%
Balloon compression	3 years	76%
Radiosurgery	1.5 years	55%

The timing of pain recurrence is similar for MVD and PSR. In the series of Barker et al. (6), pain recurrence occurred primarily in the first 2 years after MVD, and then dropped to 2% per year in years 3-5, 1% per year in years 6-10, and 0.7% per year thereafter. In the authors series (13), pain recurrence after PSR rhizotomy occurred in 3% of patients per year through the first 5 years, 1.4% per year in years 6-10, and 0.75% thereafter. 

Glycerol rhizotomy and radiosurgery have the highest rates of pain persistence or recurrence. Pain relief calculated 55% in 3 years for glycerol rhizotomy (2,14-21). Initial results of 129 patients from three series demonstrate a pain relief rate of 55% in 1.5 years after radiosurgery (22-24). Balloon compression has a recurrence rate that is higher than that of MVD and PSR rhizotomy, but lower than that of glycerol rhizotomy and radiosurgery. Pain relief was calculated to be 75% in 3 years for balloon compression (2,25,26). 

All percutaneous procedures are associated with dysesthesia
Glycerol rhizotomy is frequently reported to be the preferred percutaneous destructive procedure because of its rare association with dysesthesia (troublesome numbness). Our review of the literature does not support this hypothesis. In a review of the results of 1751 patients in 10 series, significant dysesthesias occurred in 4% of patients after glycerol rhizotomy, in 7% of patients after PSR rhizotomy, and in 6% of patients after balloon compression. Some surgeons relate the high incidence of dysesthesia to poor technique, such as the injection of glycerol without cisternography or injection of large volumes of glycerol during glycerol rhizotomy (21), production of anesthesia and analgesia during PSR rhizotomy (1), and prolonged balloon inflation during balloon compression (26). Supporters of glycerol rhizotomy and balloon compression estimate a lower incidence of dysesthesia in technically adequate procedures (21). Supporters of PSR rhizotomy estimate rates of dysesthesia and pain recurrence that are comparable with those of glycerol rhizotomy and balloon compression if lesions created by PSR produced hypalgesia only (1). 

Contrary to percutaneous destructive procedures, MVD rarely produces significant facial numbness or dysesthesia. In the authors experience, facial sensory loss and dysesthesia complicated cases of venous compression or excessive manipulation of the trigeminal rootlets. The initial results of radiosurgery demonstrate a rare association with sensory loss and dysesthesia, despite the fact that the nerve is deliberately injured (23).

Postoperative corneal anesthesia in patients with V-1 pain is highest after PSR

Among the percutaneous destructive procedures, PSR rhizotomy has the highest risk of postoperative loss of corneal sensations after surgery for V-1 pain. PSR rhizotomy differentially affects the small myelinated and unmyelinated fibers, which mediate the corneal reflex (2). In contrast, balloon compression differentially affects large myelinated fibers (26). Glycerol has neurolytic effects on both small and large myelinated fibers (21). In our review of the literature, the corneal reflex was lost in 6% of PSR rhizotomies, in 5% of glycerol rhizotomies, and in 1% of balloon compressions. MVD and radiosurgery have been rarely associated with corneal anesthesia. 

Postoperative trigeminal motor weakness is highest after balloon compression

Balloon compression carries the highest risk of postoperative trigeminal motor weakness. In a review of the literature, trigeminal weakness occurred transiently in 19% of patients after PSR rhizotomy, infrequently (1%) after glycerol rhizotomy, and permanently in 5% after balloon compression. Trigeminal motor weakness occurred rarely after MVD and radiosurgery. Complications such as trismus, otalgia, and hyperacusis have not been thoroughly discussed in the literature and are likely underestimated. 

Perioperative morbidity and mortality are higher after MVD
than after percutaneous destructive procedures

Literature review demonstrates that the perioperative mortality or serious morbidity (i.e., stroke, hemorrhage, venous sinus occlusion, myocardial infarction, hydrocephalus), permanent hearing loss or facial palsy, and minor perioperative complications (i.e., wound dehiscence or infection, cerebrospinal fluid leak, pseudomeningocele, bacterial and aseptic meningitis, pulmonary complications, ataxia) were higher after MVD than after percutaneous procedures. After MVD, serious morbidity or mortality occurred in 1%, permanent hearing loss occurred in 3%, and minor complications occurred in 16%. The risks are higher in patients who have an ectatic and tortuous vertebrobasilar system arterial tree (27). These results do not compare favorably with rates of 0.07% serious morbidity and mortality, 0.5% serious hearing loss, and 1.3% minor complications for percutaneous procedures.

Conclusion

MVD is highly successful in treating pain of TGN with a relatively low risk of pain recurrence, dysesthesia, corneal analgesia, and trigeminal motor weakness; however, one should not overlook the perioperative risks associated with this surgery, especially in the elderly. MVD may be best suited for healthy patients, but is not the best procedure for patients in poor medical condition. Because of the risk of hearing loss, MVD may not be suitable for patients who have contralateral hearing loss. MVD may also not be the best procedure for patients who have large, ectatic, and tortuous vertebrobasilar arterial system because of increased perioperative morbidity. 

Percutaneous destructive procedures are appropriate procedures for the elderly and for those in poor medical condition. Because of its low pain recurrence rate, PSR rhizotomy generally seems to be the most appropriate procedure. By avoiding dense lesions, adverse effects of dysesthesias are greatly reduced. PSR rhizotomy may not be the best procedure for patients with V-1 pain and patients with pain distributed over the three trigeminal divisions. 

Because glycerol rhizotomy is associated with a high recurrence rate, the procedure likely requires repetition. Multiple glycerol injections are associated with a higher risk of failure and adverse effects. During glycerol rhizotomy, surgeons and patients should be ready to convert the procedure to PSR rhizotomy if cerebrospinal fluid flow is not obtained. Because of its low risk of trigeminal motor dysfunction, glycerol rhizotomy is particularly advantageous for patients with contralateral pain, trigeminal motor weakness, and temporomandibular joint dysfunction. Glycerol rhizotomy is also appropriate for patients who have pain over V-1 or the entire face and are not candidates for a posterior fossa procedure. 

Balloon compression seems particularly advantageous for patients who have V-1 pain and are not good candidates for microvascular decompression. Alternative procedures for these patients include glycerol rhizotomy, peripheral nerve section, and radiosurgery. 

Other surgical procedures have a role in the treatment of TGN. Peripheral nerve section is appropriate for elderly patients with V-1 pain or with bilateral facial pain. Radiosurgery has a role in the treatment of patients who cannot safely undergo surgical procedures, such as patients who are receiving anticoagulants. 

In summary, the authors conclude that the discipline of treating TGN should be similar to disciplines of treating other disorders, such as aneurysms, tumors, and vascular malformations. The discipline entails a multimodality approach conducted by a team who can offer medical and surgical treatments directed to the needs of the individual patient.

next>> Recurrent Trigeminal Neuralgia

Sources

Through the Trigeminal Neuralgia Association (TNA), local support groups are available. The support group provides an opportunity for patients and their families to share experiences, receive support, and learn about advances in treatments, pain control, and medications. Additional information is available on the web at www.tna-support.org or facial-neuralgia.org

If you would like information about the Greater Cincinnati Trigeminal Neuralgia Support Group, please call the Mayfield Clinic at (513)569-5290. For support outside Greater Cincinnati, please contact the Trigeminal Neuralgia Association at 800-923-3608. 

The following journal articles and books formed the basis of our observations along with our own personal experience. Bibliography listing.

updated: 6.2004
originally published > Tew JM, Taha JM: Therapeutic Decisions in Facial Pain. Clinical Neurosurgery 46:410-431, 2000