Linear Accelerator Radiosurgery Provides a Noninvasive Alternative for Trigeminal Neuralgia-Related Pain

Stereotactic radiosurgery has been shown delivers a single, highly concentrated dose of ionizing radiation to a small, precise target--in the case of trigeminal neuralgia --to the site where the trigeminal nerve leaves the brainstem.

The procedure is noninvasive and avoids many of the risks and complications of open surgery and other treatments. Over a period of time and as a result of radiation exposure, the slow formation of a lesion in the nerve interrupts transmission of pain signals to the brain.

Researchers from the University of California, Los Angeles (UCLA; USA) recently evaluated the efficacy of linear accelerator radiosurgery to treat trigeminal neuralgia over a 10-year period. Zachary A, Smith, M.D. presented the findings of their study on April 17, 2007, during the 75th Annual Meeting of the American Association of Neurological Surgeons (AANS), held in Washington, DC, USA.

In patients with trigeminal neuralgia, the pain typically involves the lower face and jaw, although sometimes it affects the area around the nose and above the eye. The pain is usually limited to one side of the face. The intense, stabbing, electric shock-like pain is caused by irritation of the trigeminal nerve, which is responsible for conveying the information of sensation from the face. It is thought that the nerve can become damaged at the point where it leaves the brainstem, thereby leading to a misfiring of the nerve, and pain instead of normal sensation.

Initially, 15 patients were treated with a low-dose radiation (70 Gy) and 30% isodose-line (IDL) radiation at the brainstem. Sixty-nine patients received doses of 90 Gy, with the same percentage of brainstem radiation. In the final 23 patients, the percentage of brainstem radiation was increased to 50%, but the overall dose to the nerve remained the same. The results were based on follow-up examination and questioning of 120 patients after radiation treatment.

"During the course of 10 years of treatment at UCLA, we modified the way we treated this disorder using new parameters and doses as we learned more about patient outcomes. What we concluded is that radiosurgery is a safe and effective treatment option for trigeminal neuralgia, with less risks than other surgical methods, which is especially important for older or frail patients. However, the radiation dose applied to the brainstem has important implications for efficacy as well as side effects. A larger brainstem dose may yield a higher degree of pain relief, but additionally may lead to an increased rate of numbness,” stated Dr. Smith.


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