Linear accelerator-based radiosurgery for trigeminal neuralgia: comparative outcomes of frame-based and mask-based techniques

OBJECTIVE Precise and accurate targeting is critical to optimize outcomes after stereotactic radiosurgery (SRS) for trigeminal neuralgia (TN). The aim of this study was to compare the outcomes after SRS for TN in which two different techniques were used: mask-based 4-mm cone versus frame-based 5-mm cone. METHODS The authors performed a retrospective review of patients who underwent SRS for TN at their institution between 1996 and 2019. The Barrow Neurological Institute (BNI) pain score and facial hypesthesia scale were used to evaluate pain relief and facial numbness. RESULTS A total of 234 patients were included in this study; the mean age was 67 years. In 97 patients (41.5%) radiation was collimated by a mask-based 4-mm cone, whereas a frame-based 5-mm cone was used in the remaining 137 patients (58.5%). The initial adequate pain control rate (BNI I-III) was 93.4% in the frame-based 5-mm group, compared to 87.6% in the mask-based 4-mm group. This difference between groups lasted, with an adequate pain control rate at >= 24 months of 89.9% and 77.8%, respectively. Pain relief was significantly different between groups from initial response until the last follow-up (>= 24 months, p = 0.02). A new, permanent facial hypesthesia occurred in 30.3% of patients (33.6% in the frame-based 5-mm group vs 25.8% in the mask-based 4-mm group). However, no significant association between the BNI facial hypesthesia score and groups was found. Pain recurrence occurred earlier (median time to recurrence 12 months vs 29 months, p = 0.016) and more frequently (38.1% vs 20.4%, p = 0.003) in the mask-based 4-mm than in the frame-based 5-mm group. CONCLUSIONS Frame-based 5-mm collimator SRS for TN resulted in a better long-term pain relief with similar toxicity profiles to that seen with mask-based 4-mm collimator SRS.