1135 - Gamma Knife Stereotactic Radiosurgery Dosing for Repeat Treatment of Trigeminal Neuralgia

04:00pm - 04:05pm ET

Room 107

Presenter(s)

Matthew Thoonkuzhy, MD - Tufts Medical Center, Boston, MA

M. Thoonkuzhy¹, M. Majid¹, D. Hettrick¹, G. Dong¹, N. Stambaugh², C. Stambaugh¹, J. E. Mignano¹, and J. K. Wu³; ¹Tufts Medical Center, Department of Radiation Oncology, Boston, MA, ²Diverging Mathematics, Boston, MA, ³Tufts Medical Center, Department of Neurosurgery, Boston, MA

Purpose/Objective(s):

Treatment of trigeminal neuralgia (TN) with Gamma Knife stereotactic radiosurgery (GKSRS) has demonstrated high rates of pain relief, with studies reporting efficacy between 70% and 95% with a low complication profile compared to surgery. However, pain recurrence remains a significant challenge, occurring in more than 20% of patients across multiple studies. Given its minimally invasive nature and safety profile, GKSRS is an ideal therapeutic option for retreatment for patients who experience recurrent or refractory pain.

Retreatment with GKSRS has shown promising results, with a median pain relief rate of 71.5% (range, 50–95%) reported. However, there is no clear consensus regarding the optimal dose for GKSRS retreatment. Concerns of increased toxicity, particularly the risk of facial numbness and other sensory disturbances, persist. In this study, we present our institutional experience with repeat GKSRS for TN, stratified into high- and low-dose cohorts (HD vs. LD).

Materials/Methods:

An IRB-approved retrospective review identified patients undergoing repeat GKSRS for recurrent TN from 2000–2020. Patients with insufficient follow-up data were excluded from the study. Patients were stratified by HD (70+ Gy) and LD (45 Gy) cohorts based on prescription dose at retreatment. The primary outcome was recurrence-free survival after second GKSRS treatment. Treatment-related adverse events were reviewed as a secondary outcome.

Results:

Between 2000 and 2020, 108 patients were retreated for TN with GKSRS. 87 patients had sufficient follow-up data (17 LD, 70 HD). Of the retreated cohort, 10 LD (58%) and 34 HD (49%) had recurrence of pain. The mean time to recurrence was 32.4 months (LD) vs. 29.4 months (HD) (p = 0.8). There was no statistical difference in median recurrence-free survival (?² = 0.3, p=0.6). 29% (N=5) of LD patients experienced =1 adverse event vs 53% (N=37) in HD (?² = 3.01, p = 0.08). The most common adverse event was facial paresthesia followed by eye discomfort. Only 3 patients indicated diminished bite strength or altered taste.

Conclusion:

There was no statistically significant difference in median recurrence-free survival between the LD and HD groups. Notably, a higher proportion of patients in the HD group experienced adverse events with a trend toward significance. These findings suggest that lower-dose retreatment may provide comparable durability of symptom control while potentially reducing treatment-related toxicities in TN.