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Division Specific Biologically Effective Dose Predicts Gamma Knife Radiosurgery Outcomes in Multiple
Jose Valerio1,2,3, Arturo Ayala Arcipestre3, Guillermo de Jesús Aguirre Vera3
1Department of Neurosurgery, Neurosurgery Oncology Center of Excellence, Miami Neuroscience Center at Larkin, South Miami, Florida, USA.
Background And Objectives:
Outcomes after Gamma Knife surgery (GKS) for multiple sclerosis-related trigeminal neuralgia type 1 (MS-TN1) remain variable, and the role of biologically effective dose (BED) distribution across trigeminal nerve subregions is not well defined. This study evaluated whether BED-based volumetric parameters within the trigeminal root, the responsible division (RD), the root entry zone (REZ), and the adjacent brainstem predict pain relief, recurrence, and sensory toxicity after GKS.
Methods:
We retrospectively analyzed data from 248 patients with medically refractory MS-TN1 who were treated with GKS between 2012 and 2024. Three-dimensional BED-volume histograms were generated for the trigeminal root, RD, REZ, and brainstem. Dosimetric variables included maximum BED and percentage volume receiving ≥1000 Gy2.47. Outcomes included early pain relief, defined as Barrow Neurological Institute Class I-III at 1 month, pain recurrence, and facial hypoesthesia. Multivariable logistic regression and Cox proportional hazards models identified independent predictors.
Results:
Early pain relief occurred in 156 patients (62.8%). Among responders, 65 (41.7%) experienced recurrence. Facial hypoesthesia developed in 25 patients (9.9%). Higher trigeminal root V%BED1000 was independently associated with improved early pain relief and lower recurrence risk. Greater BED coverage of the RD correlated with more durable pain control, whereas elevated brainstem maximum BED combined with increased REZ V%BED1000 predicted facial hypoesthesia.
Conclusion:
Regional BED distribution influences outcomes after GKS for MS-TN1. Greater division-specific BED coverage was associated with more durable pain relief, whereas excessive exposure to the REZ and brainstem increases sensory toxicity. These findings suggest that anatomy-guided, BED-optimized planning may improve patient-specific radiosurgical targeting.
