Introduction: To assess efficacy of initial and long-term outcomes associated with distal isocenter (ISO) placement in patients treated for trigeminal neuralgia (TN) with LINAC radiosurgery (SRS).
Methods: Between 2007-2012, 32 cases of TN were treated with LINAC SRS. All patients had post SRS follow-up pain relief assessments of at least 6 months. Treatment was delivered with a 4 mm cone using conformal arc therapy. Median prescription dose was 85 Gy (range (r): (75-85), mean isodose line was 100% (r: 80-100), and median number of arcs was 12. (r: 12-12). Pain before and after SRS was scored as level I-V per the BNI pain intensity scoring criteria. Pain relief was graded as an improvement to BNI levels I, II, III from pre-SRS BNI levels IV or V. Relevant toxicities including post SRS facial numbness were also measured.
Results: Mean distance of ISO to root entry zone (REZ) was 8.99 mm (2.9-16.24). Mean distance of ISO to tangent intersecting brain stem (BS) was 4.9 mm (2.9-7.9). Mean maximum BS dose was 15.2 Gy (6.8-29.75). Mean BS V10 was 0.08 cc (0-0.208). With median follow-up of 20 months (r: 6-60), 81% reported initial pain relief, with mean time to initial pain relief of 0.74 months (r: 0.03-2). 57% reported long term pain relief with mean duration of long term pain relief of 16.1 months (r: 6-38). 57% of those reporting long term pain relief reported complete pain relief. Only one patient developed bothersome post SRS facial numbness.
Conclusions: LINAC Radiosurgery with distal ISO placement leads to comparable long term pain control outcomes to most large published series using proximal REZ isocenter placement. The small mean BS V10 value and the lack of significant toxicities observed argue for consideration of this technique in treatment planning.
Patient Care: Improve Trigeminal Neuralgia Radiosurgery Treatment Planning
Learning Objectives: To assess efficacy of initial and long-term outcomes associated with distal isocenter (ISO) placement in patients treated for trigeminal neuralgia (TN) with LINAC radiosurgery (SRS).