Surgical treatment options are available when conservative management fails. One minimally invasive surgical treatment is called radiofrequency lesioning (RFL). This outpatient procedure involves insertion of a hollow needle through the cheek into the trigeminal nerve where it exits from the skull (Fig 1). The patient is temporarily anesthetized while an electrical current is passed through the needle to burn the nerve. The patient is awakened to assess effectiveness. This procedure leaves the patient with permanent facial numbness in the area supplied by that particular branch of the nerve. If V₁ is anesthetized, the patient's vision will not be affected, but they will not feel any eye trauma. As a result, the patient's eye must be monitored daily for erythema, a possible indication of corneal abrasion or infection. Although RFL is quite effective for short-term relief of pain associated with TN, the nerve grows back in approximately 50% of cases, requiring repeat operation. In addition, some patients find the numbness very uncomfortable-this is called painful numbness or anesthesia dolorosa. Other side effects include temporary weakness of the masseter muscle on that side of the face and temporary ear fullness as a result of fluid in the eustachian tube (Kanpolat, Savas, Bekar, & Berk, 2001; Latchaw, Hardy, Forsythe, & Cook, 1983).

FIGURE 1 Radiofrequency Lesioning

The most effective surgical treatment of TN is microvascular decompression (MVD) of the trigeminal nerve. This procedure requires general anesthesia and exposure of the trigeminal nerve. Entry is made through the suboccipital area, on the affected side (Fig 2). After a small piece of bone is removed, the brain is retracted to allow exposure of the cranial nerves at the base of the skull. If an artery is found to be compressing the nerve, it is moved away from the nerve and a small spongy material is positioned to prevent friction on the nerve (Fig 3). The superior cerebellar artery is the most common cause of compression. Next is the anterior inferior cerebellar artery. Occasionally, an ectatic basilar artery is involved. Postoperative care includes management of nausea and surgical pain. The facial pain is usually relieved immediately. Most patients remain in the hospital 24-48 hours and complete their recovery at home over the course of about 2 weeks. This procedure results in the most desirable outcome without facial numbness.

FIGURE 2 Microvascular Decompression

FIGURE 3 Microvascular Decompression

Other surgical treatments include balloon compression, glycerol injection, and radiosurgery. Balloon compression is another method used to damage the trigeminal nerve. A soft catheter with a balloon tip is inserted into the area where the nerve exits the base of the brain. Although the patient is anesthetized, the balloon is inflated to compress the nerve. Glycerol injection of the nerve may also be used. During this procedure, a needle is inserted through the cheek into the cistern around the trigeminal nerve, leading to pain relief (McLeod & Patton, 2007; North, Kidd, Plantadosi, & Carson, 1990). Radiosurgery is an outpatient treatment where hundreds of small beams of radiation are focused on the trigeminal nerve, usually resulting in short-term pain relief.

Materials and Methods

All procedures were performed by two surgeons. Sixty patients, 29 women and 31 men, underwent RFL. The median age was 75 years (range = 26-92 years). The median duration of pain prior to surgery was 8.5 years. The distribution of pain is noted in Table 1. Forty-eight (80%) patients had pain relief on follow-up (without medication). Five patients experienced no postoperative pain relief. Six patients experienced recurrence of pain after initial postoperative relief. The time to recurrence was 1, 7, 9, 9, 10, and 12 months after the initial procedure. Complications included anesthesia dolorosa (painful numbness) in 3 patients, diplopia in 1 patient, corneal anesthesia in 1 patient, and subarachnoid hemorrhage in 1 patient.

TABLE 1. Pain Distribution

Of the 48 patients undergoing MVD, 33 were women and 15 were men. The median age was 58 years (range = 31-85 years). The median duration of pain was 5 years. The distribution of pain is noted in Table 1. At last follow-up, 33 patients (69%) had complete pain relief without medication. Eight patients had no postoperative pain relief. Four patients experienced recurrence after initial postoperative relief. Complications included anesthesia dolorosa in 2 patients, diplopia in 1 patient, cerebrospinal fluid leakage in 2 patients, hydrocephalus in 2 patients, and facial weakness in 3 patients (2 patients were delayed onset and were both transient). Hydrocephalus after MVD is due to blood products in the cerebrospinal fluid from surgery.

Unfortunately, the quality of data reporting for TN treatment is generally poor, often lacking critical follow-up information. Of the 175 articles reviewed by Zakrzewska and Thomas (1993), only 4 could be used to evaluate rates of complete pain relief after RFL. Those 4 studies are examined in Table 2. RFL appears to have an early success rate in the 70%-90% range. Nerve regrowth or other issues lead to a steady drop in long-term success rate to about 50%. Many RFL patients will require repeat lesioning procedures.

TABLE 2. Articles Reviewing the Actuarial Results of Radiofrequency Lesioning

Seven studies of MVD were felt worthy of further analysis because of success rates. They are listed in Table 3. Early success rates are reported in the 80%-90% range. Longer term success rates are around 70%. It appears that the MVD has a higher long-term success rate than that of RFL. It rarely causes facial numbness (which is the goal of RFL) and is associated with low complication rates. Most authors noted that finding an artery distorting the trigeminal nerve was a favorable prognostic factor. Most authors performed a partial sensory rhizotomy when an arterial compression was not evident.

TABLE 3. Articles Reviewing the Actuarial Results of Microvascular Decompression

Conclusion

Eisenberg, E., River, Y., Shifrin, A., & Krivoy, N. (2007). Antiepileptic drugs in the treatment of neuropathic pain. Drugs, 67(9), 1265-1289. [Context Link]

Kanpolat, Y., Savas, A., Bekar, A., & Berk, C. (2001). Percutaneous controlled radiofrequency trigeminal rhizotomy for the treatment of idiopathic trigeminal neuralgia: 25-Year experience with 1600 patients. Neurosurgery, 48(3), 524-542. [Context Link]

Latchaw, J. P., Hardy, R. W., Forsythe, S. D., & Cook, A. F. (1983). Trigeminal neuralgia treated by radiofrequency coagulation. Journal of Neurosurgery, 59(3), 479-484. [Context Link]

Lewis, M., Sankar, V., De Laatt, A., & Benoliel, R. (2007). Management of neuropathic orofacial pain. Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology and Endodontics, 103(1), S32.e1-S32.e24. [Context Link]

McLeod, N. M., & Patton, D. W. (2007). Peripheral alcohol injections in the management of trigeminal neuralgia. Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology and Endodontics, 104(1), 12-17. [Context Link]

North, R. B., Kidd, D. H., Plantadosi, S., & Carson, B. S. (1990). Percutaneous retrogasserian glycerol rhizotomy. Predictors of success and failure in treatment of trigeminal neuralgia. Journal of Neurosurgery, 72(6), 851-856. [Context Link]

Sarlani, E., Grace, E., Balciunas, B., & Schwarta, A. (2005). Trigeminal neuralgia in a patient with multiple sclerosis and chronic demyelinating polyneuropathy. Journal of American Dental Association, 136(4), 469-476. [Context Link]

Zakrzewska, J., & Thomas, D. (1993). Patient assessment of outcomes after three surgical procedures for the management of trigeminal neuralgia. Acta Neurochirurgica, 122(3-4), 225-230. [Context Link]