Pittsburgh, April 24, 1998 -- Stereotactic radiosurgery, which uses intensely focused gamma radiation, can successfully treat pain associated with trigeminal neuralgia (TGN), according to a study by neurological surgeons at the University of Pittsburgh Medical Center (UPMC).

The study will be presented by principal investigator Douglas Kondziolka, MD, associate professor of neurological surgery and radiation oncology, at the American Association of Neurological Surgeons meeting on April 25 in Philadelphia.

TGN is a severe, sharp or electric-shock like pain occurring in the face typically lasting seconds to minutes. Patients often describe the pain as being triggered by laughing, chewing, brushing the teeth, talking, wind on the face or even touching the face. Patients may also experience mild numbness particularly around the corner of the mouth.

Patients are typically treated with medication or microvascular decompression, a surgical treatment pioneered at the Department of Neurological Surgery at the University of Pittsburgh.

The Gamma Knife performs precise computer-driven bloodless brain surgery. It destroys brain tumors and vascular malformations in the brain which were once considered inoperable. Gamma knife surgery is safer than many existing procedures because patients need not undergo risky open-skull procedures and adult patients do not require general anesthesia. Gamma surgery causes few side effects, and patients usually leave the hospital within 24 hours.

"Initially, Gamma Knife surgery was used for patients with recurrent pain after prior surgeries," said Dr. Kondziolka. "But recently, the Gamma Knife has been advocated as a minimally invasive surgical strategy for TGN to provide pain relief with low risk of facial sensory loss."

The Gamma Knife is targeted on the trigeminal nerve just in front of the brain stem. The dose of radiation is not enough to destroy or seriously injure the nerve, but is enough to affect its function and provide pain relief.

"The pain message is interrupted but the normal function of the nerve, feeling in the face and chewing, is maintained in virtually all patients," Dr. Kondziolka said.

Over a five-year period, 121 patients underwent Gamma Knife radiosurgery for TGN. Patients ranged in age from 32 to 92 years and the mean duration of pain before Gamma Knife treatment was 11 months.

After a follow-up of 18 months, initial improvement was noted in 88.3 percent of the patients (106 patients). Of these, total pain relief was achieved in 60 percent of patients (64 patients), 50 to 90 percent relief in 17 percent of patients (18 patients), 10 to 50 percent relief in nine percent of patients (nine patients) and no relief in 14 percent of patients (15 patients).

"In our study, significant and lasting pain relief was achieved in 77 percent of the patients," Dr. Kondziolka said. "Radiosurgery should be considered for treatment of TGN, especially in patients with other medical illnesses or in whom other surgical procedures have failed."

The Gamma Knife is housed in the Center For Image-Guided Neurosurgery at the UPMC and contains 201 sources of cobalt 60 in a heavily shielded, lead-lined room. It aims the 201 sharply focused sources of cobalt at targets of just several millimeters up to three centimeters in diameter. Because the beams focus precisely on the target tissues, effects on surrounding brain tissue are minimized.