Biologically Effective Dose and Dose Rate in Gamma Knife Radiosurgery for Trigeminal Neuralgia: A Systematic Review...

Gamma Knife radiosurgery (GKRS) is used in the treatment of trigeminal neuralgia (TN) to deliver precise, focused ionizing radiation to the trigeminal nerve, thereby reducing its ability to transmit pain signals. Understanding the impact of unique radiobiological parameters, such as the biologically effective dose (BED) and dose rate, in GKRS is essential to optimize treatment protocols and ensure predictable therapeutic outcomes. We conducted a systematic review and meta-analysis to evaluate how BED and dose rate impact GKRS effectiveness and toxicity.

We searched medical and health care databases from inception to May 19, 2024, for publications reporting on the impact of GKRS BED and/or dose rate on TN outcomes. Following 2 rounds of screening conducted in duplicate, we used random-effects meta-analysis and meta-regression to examine the association between dose rate and pain relief.

Of 6950 citations identified, 8 publications reported data on BED and dose rate association with GKRS patient outcomes in TN. Eight cohorts reported on 2596 patients in 6 countries. The "beam-on" time ranged from 27 to 171 minutes, and the prescription dose ranged from 62.5 to 95 Gy. The median BED_2.47 was 2105 Gy (range, 1968-2675), the median dose rate was 2.2 Gy/min (range, 2.06-2.81), and the median maximum brainstem dose was 20.7 Gy (range, 14.8-34.7). The meta-analysis suggested that higher dose rates may be associated with higher rates of pain relief (relative risk, 1.36 [95% CI, 1.10-1.67]; P = .005). Meta-regression demonstrated a nonsignificant relationship between dose rate and pain relief, with an estimated 26% increase in the likelihood of pain control for each 1 Gy/min increase in the median dose rate (β, 0.26 [95% CI, -1.09, 1.60]; P = .71).

Higher dose rates in GKRS may be associated with better pain relief in TN. Dose rate should be considered in the treatment of TN when using GKRS.