CyberKnife® Treatment Delivery System (Accuray, Sunnvale, California) stereotactic radiosurgery (CK SRS) provides safe, effective pain relief for patients with both forms of trigeminal neuralgia (TN), according to a retrospective multi-institutional study led by Raj Singh of Marshall University, Huntington, West Virginia.
Singh and colleagues assessed the effectiveness of CK SRS and examined potential prognostic factors and treatment-related toxicities in 162 patients with TN, a debilitating pain condition of the trigeminal nerve. The patients had initial visual analog scale (VAS) scores ≥ 3 and were from 16 community radiation therapy centers. Patient selection was based on a 2007-2015 screening of the RSSearch Patient Registry, an international SRS/SBRT (stereotactic body radiation therapy) database featuring details on screening, treatments and outcomes for more than 15,000 patients.
“We tried to identify patients most likely to benefit from treatment in the TN population—based on our findings, those with type 1 TN and VAS pain scores > 7/10. Patients meeting such criteria were found to benefit the most from SRS,” says Singh, an MS3 and research associate in Marshall’s Department of Radiation Oncology, Joan C. Edwards School of Medicine (JCESOM). “Also, we were interested in examining whether dose escalation (ie, maximum doses of > 75 Gy) resulted in superior pain relief, which was not found to be the case.”
Singh also found that < 20% of patients reported related toxicities, all of which were CTCAE (Common Terminology Criteria for Adverse Events) grade 1 or 2. In addition, results showed that patients with type 1 TN (characterized by short bursts of pain) are more likely to benefit from SRS in the long-run, compared to type 2 TN patients, he says. Specifically, 82% of type 1 TN patients had lasting pain relief at 1-year follow-up, compared to 88% immediately following treatment.
“Patients with type 2 TN may also have similar pain relief immediately following SRS as compared to those with type 1 TN, which is a new finding in the literature,” he told Applied Radiation Oncology.
While pain relief for type 2 TN appeared less durable than that for type 1 TN at 1-year post-treatment, data on this were limited. “As such, practitioners should refer patients with type 1 TN and severe pain for consideration of SRS,” says Singh. “Other treatment modalities may be more appropriate to examine for type 2 TN patients following failure of pharmacologic management.”
Singh and colleagues launched their research due to limited studies regarding outcomes following use of SRS for TN with the CyberKnife platform. Likewise, few series have examined outcomes in multi-institutional community settings, nor have they compared such outcomes to academic center series, he says.
While it is difficult to assess utilization of SRS for treating patients with trigeminal neuralgia, some physician gatekeepers may not know of its potential.
“Some primary care practitioners are not aware of SRS being a treatment modality for TN,” says Singh, “and as such, SRS may be considered and/or discussed less often as a treatment option than is indicated or warranted.”
To expand knowledge, prospective studies are needed to establish prognostic factors for long-term pain relief after CK SRS, and determine ways to optimize RT planning and dosing.
In the meantime, treatment decisions for patients with TN can be guided by Singh’s primary findings: “Type 1 TN patients with severe pain are most likely to benefit from treatment,” and “higher maximum doses (> 75 Gy) do not produce superior results as compared to patients treated with Dmax < 75 Gy.”
For the full study, Stereotactic radiosurgery for trigeminal neuralgia: A retrospective multi-institutional examination of treatment outcomes, click here: http://www.cureus.com/articles/4272-stereotactic-radiosurgery-for-trigeminal-neuralgia-a-retrospective-multi-institutional-examination-of-treatment-outcomesBack To Top