A Non-Invasive Stereotactic Radiosurgery Instrument Stereotactic Radiosurgery Retreatment of Trigeminal Neuralgia: Prognostic Factors and Clinical Outcomes

Document Type

Conference Proceeding

Publication Date

11-1-2022

Publication Title

International Journal of Radiation Oncology Biology Physics

Abstract

Purpose/Objective(s)

Trigeminal neuralgia (TN) is a debilitating nerve disorder that affects approximately 4.5 per 100,000 people each year. While medical management is the first line of treatment for medically refractory patients, surgical intervention or a non-invasive stereotactic radiosurgery instrument may be used. The long-term outcomes of patients who have received GK SRS retreatment for refractory TN are not well elucidated. The objective of this study is to report the outcomes of patients with refractory TN following their first GK SRS treatment (T1).

Materials/Methods

381 patients have received ≥ T1 for TN from 2012-present at our institution. The outcomes of 59 patients with refractory TN who received ≥ 2 GK SRS treatments (T2) were analyzed. 53 cases (89.8%) received T2, 5 cases (8.5%) received 3 treatments, and 1 case (1.7%) received 4 treatments. For T1, 57 cases (96.6%) were treated to a dose of 40 Gy to the 50% isodose volume (IDV). For T2, 40 cases (71.4%) were treated to a dose of 35 Gy to the 50% IDV, and 16 cases (28.6%) were treated to a dose of 40 Gy to the 50% IDV. The Barrow Neurological Institute (BNI) pain intensity score was used to grade pain. Pain relief was defined as a post-GK SRS BNI score of I-III. Pain recurrence was defined as a post-GK SRS score of IV-V after initially achieving pain relief. Treatment failure was defined as a post-GK SRS score of IV-V without having achieved pain relief. Univariate analyses were performed to examine the effects of treatment planning, patient demographics, and TN symptom characteristics on outcomes.

Results

The median follow-up was 46 months after T1 (9-144 months). 52 cases (88.1%) had a BNI score of IV-V prior to T2. Overall, 52 cases (88.1%) and 49 cases (83.0%) achieved pain relief after T1 and T2, respectively. The median time to pain relief was 0.7 and 1.0 months after T1 and T2, respectively. The median freedom from pain recurrence was 7.7 and 13.7 months following T1 and T2, respectively. Only 6 cases (12.2%) developed pain recurrence following T2. High KPS scores, combined V1 + V2 pain distribution, and painless mastication prior to T1 were factors that reduced the risk of T1 treatment failure (21%, 58%, and 54%, respectively; p<0.05). Patients with lower BNI scores after T1 with subsequent pain recurrence had a 39% reduced risk of T2 failure (p<0.001). Neither isocenter location nor dose affected outcomes in this study. No T1 or T2 patients were entirely pain free without supplemental medical therapy. Only 1 patient (1.7%) developed CN VII weakness following T2. No patients developed CN V or CN VII weakness following T3 or T4.

Conclusion

GK SRS remains an effective treatment choice for patients with refractory TN. In fact, patients who fail or recur after T1 experience a longer pain-free interval following T2 with minimal toxicity. Low KPS score, painful mastication, and pain distributions other than V1 + V2 were all associated with increased risk of T1 failure. Patients who achieved lower BNI scores after T1 with pain recurrence were more likely to achieve pain relief after T2.

Volume

114

Issue

3 Suppl

First Page

e421

Comments

American Society for Radiation Oncology (ASTRO) Annual Meeting, October 23-26, 2022, San Antonio, TX.

DOI

10.1016/j.ijrobp.2022.07.1615

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