Treating Drug-Resistant Trigeminal Neuralgia

Stereotactic radiosurgery (SRS) with linear accelerators (LINACs) is a generally effective and safe therapeutic alternative for drug-resistant trigeminal neuralgia, according to findings published in Pain Physician.

Researchers from the Galician Health Authority in Santiago de Compostela, Spain reviewed 11 published articles and studies collected from various publishing databases in order to assess the effectiveness and safety of LINAC SRS used to treat patients with refractory trigeminal neuralgia. Studies were included in the analysis if they written in Spanish, French, English, and/ or Portuguese and included key words and terms such as “stereotactic,” “radiosurgery,” “linear accelerator,” “LINAC,” and “trigeminal neuralgia.”

Overall, the studies generally demonstrated effective results using SRS for the treatment of trigeminal neuralgia. The most recent study, which was from 2012, showed that 43.5 percent of the patient group treated with SRS experienced complete pain relief requiring no medication. Also in the study, 39.1 percent of patients had occasional pain but did not require medication, 4.3 percent of patients had mild pain that was sufficiently controlled with medication, and 27.3 percent had recurrences during the follow up period, compared to patients treated with equivalent doses of hypofractionated stereotactic radiotherapy (HFSRT).

The HFSRT patients showed equivalent improvements at rates of 36.4 percent, 36.4 percent, 18.2 percent, and 9.1 percent, respectively. The improvements were maintained across a mean follow up of 4.2 years. Other studies the investigators examined yielded similar results.

The authors also examined the safety of SRS, and found that all but 2 studies included recorded cases of facial numbness or hypoasthesia. Patients who suffered from facial numbness varied from 7.5 percent to 50 percent, though the frequency was about 26 percent. Sensory loss was also recorded in some studies, with about 8 percent of patients reported grade 4 numbness (categorized as > 50 percent sensory loss across multiple divisions) and about 5 percent with grade 5 numbness (defined as complete anesthesia).

Other side effects reported from the articles were infections/ ulcers (1-5 percent), ocular complications like dryness (2.4-8.3 percent), irritation (11 percent), and loss of corneal sensation (5 percent), as well as isolated cases of hearing loss and brainstem oedema. One patient who had undergone 5 prior surgical interventions had the appearance of neurotrophic keratoplasty.

Pain relief was present in 75-95.7 percent of patients with few severe complications, the researchers wrote; however, they cautioned that most of the articles reviewed were small sample sizes or case studies. Another reason the studies may not be completely comparable was that they all used heterogeneous equipment, treatment guidelines, and patient selection.

“The results suggest that SRS with LINACs could constitute an effective and safe therapeutic alternative for treating patients with drug-resistant trigeminal neuralgia,” the authors concluded. “This technique is successful in reducing pain in 90 to 98 percent of cases and more than 60 to 70 percent of patients remain pain free at 10 years. However, since it is a technique that requires a craniotomy, it tends to be restricted to young patients (< 65 years) not posing a high surgical risk.”