Assessment of Pain Relief and Sensory Dysfunction Outcomes after CyberKnife Radiosurgery for Trigeminal Neuralgia...

The aim of this study was to evaluate clinical outcomes and identify patient- and treatment-related predictors of pain relief onset, long-term pain control, and sensory dysfunction in patients with medically refractory trigeminal neuralgia (TN) treated with CyberKnife radiosurgery (CKRS), incorporating radiobiological modeling of delivered doses.

A retrospective study was performed across 5 international institutions, analyzing 560 TN patients treated with CKRS between 2009 and 2024. Demographic, clinical, and dosimetric data were collected. Pain and sensory dysfunction outcomes were evaluated using the modified Barrow Neurological Institute Pain Intensity Scale (mBNI-PIS) and Facial Numbness Scale (BNI-FNS), respectively. Logistic regression and Cox proportional hazards models were used to identify predictors of pain relief, latency, long-term pain control, and facial numbness risk. Biological effective dose (BED) distributions were calculated accounting for sublethal DNA damage repair and treatment delivery timelines; retreatments were excluded.

In this study, pain relief (defined as BNI-PIS I-IIIa) was achieved in 92% of patients with a median latency of 12 weeks (range: 0-76 weeks). The median follow-up was 50 months (range: 6-175 months). Actuarial freedom-from-pain rates were 85%, 78%, 68%, and 58% at 12, 24, 60, and 120 months, respectively. Bothersome and severely bothersome facial numbness occurred in 5% and 1% of patients, respectively, while an additional 21% experienced non-bothersome numbness. Multivariate analysis identified older age, higher target maximum dose, and BED (>1,607 Gy_2.47) values and shorter beam-on and treatment times as predictors of early pain relief (<30 days), whereas neurovascular conflict (NVC) predicted delayed response. Older age and NVC were also associated with pain control maintenance. Multiple sclerosis predicted both reduced treatment response and increased pain recurrence risk. Maximum target dose of 77 Gy and integral BED of 59 mJ_2.47 (corresponding to a target volume of 47 mm3) were independently associated with a 10% hypoesthesia risk.

CKRS provides high pain relief onset (92%) and durable pain control (68% at 60 months) in TN patients, with low bothersome (5%) and severely bothersome (1%) facial numbness rates. The identified dosimetric thresholds offer practical guidance for optimizing treatment planning while balancing hypoesthesia risk.