Image-Guided Robotic Radiosurgery for Trigeminal Neuralgia

Neurosurgery 83:1023–1030, 2018

Frameless, non-isocentric irradiation of an extended segment of the trigeminal nerve introduces new concepts in stereotactic radiosurgery for medically resistant trigeminal neuralgia (TN).

OBJECTIVE: To report the results of the largest single-center experience about imageguided robotic radiosurgery for TN.

METHODS: A cohort of 138 patients treated with CyberKnife®  (Accuray Incorporated, Sunnyvale, California) radiosurgery with a minimum follow-up of 36 mo were recruited. Pain relief, medications, sensory disturbances, rate and time of pain recurrence were prospectively analyzed.

RESULTS: Median follow-up was 52.4 mo; median dose 75 Gy; median target length 5.7- mm; median target volume 40 mm3; median prescription dose 60 Gy (80% isodose line). Actuarial pain control rate (Barrow Neurological Institute [BNI] class I-IIIa) at 6, 12, 24, and 36 mo were 93.5%, 85.8%, 79.7%, and 76%, respectively. Overall, 33 patients (24%) required a second treatment. Overall, 18.1% developed sensory disturbances after 16.4 ± 8.7 mo. One patient (0.7%) developed BNI grade IV dysfunction; 6 (4.3%) developed BNI grade III (somewhat bothersome) hypoesthesia after retreatment; BNI grade II (not bothersome) hypoesthesia was reported by 18 patients (11 after retreatment). Shorter nerve length (<6mmvs 6 mm), smaller nerve volume (<30mm3 vs>30mm3), and lower prescription dose (<58 vs>58 Gy) were associated with treatment failure (P=.01, P=.02, P=.03, respectively). Re-irradiation independently predicted sensory disturbance (P < .001).

CONCLUSION: Targeting a 6-mm segment of the trigeminal nerve with a prescribed dose of 60 Gy appears safe and effective. Persistent pain control was achieved in most patients with acceptable risk of sensory complications, which were typically found after re-irradiation.

KEYWORDS: Trigeminal neuralgia, Pain, Stereotactic radiosurgery, Robotic, Image-guided, CyberKnife