Treatment of trigeminal neuralgia: single-fraction LINAC-based radiosurgery option, mono-institutional experience...

To evaluate the efficacy and safety of single-fraction LINAC-based radiosurgery (RS) for patients with drug-resistant trigeminal neuralgia (TN).

We retrospectively reviewed 46 patients treated for TN between August 2008 and December 2024, 42 were evaluable. RS was delivered with a linear accelerator equipped with a micro-multileaf collimator. Diagnostic cisternography sequence MRI was co-registered with the CT plan to delineate the target volume and develop the treatment plan. The CTV was contoured on the retro-Gasserian ganglion. The dose was prescribed to the isocentre for all patients. The prognostic impact of parameters such as sex, side of TN, previous surgery, radiotherapy dose, clinical response probability, and response onset time was assessed. Statistical analysis was performed using the MedCalc software package and the Kaplan-Meier product limit method. Acute and late toxicities were graded according to the CTCAE v5.0 scale.

Patient characteristics For the 46 treated patients were as follows: 29 out of 46 females (63%) and 17 out of 46 males (37%), with a median age of 63 years (range, 32-88), and Karnofsky Performance Status (KPS) was 90 (range, 80-100). The median planning target volume (PTV) was < 0.1 cc. Dosimetric characteristics Median prescribed dose was 70 Gy (range, 40-75 Gy). Four patients were lost during follow-up, so overall 42 of the 46 patients were evaluable for RS response analysis. Clinical Outcomes After a very long median follow-up of 8.5 years (range, 0.6-13.5 years), the clinical response probability was 92% ± 4% at 1 year, 71% ± 7% at 2 years, and 53% ± 9% at 5 years. The median time to response onset was 3 months (range, 1-16 months), and the median clinical response probability was 62 months (range, 37-158 months). In the univariate analysis, there was a statistically significant difference in clinical response probability favouring the higher dose ≥ 70 Gy (p = 0.0036) with HR (CI 95%) of 3.5 (1.4-8.5). However, achieving an initial complete response did not significantly affect the duration of the response. Toxicity No acute toxicity was recorded. Chronic toxicity was rare, with two patients (4%) developing G2 hearing loss and one (2%) experiencing G1 tearing and paresthesia.

LINAC-based RS is a safe and effective non-invasive option for the treatment of medically refractory TN, particularly for patients without a neurovascular conflict but with significant comorbidities or contraindications to surgery. To obtain maximal and durable results, the prescribed dose must be at least 70 Gy and it is necessary to adhere to stringent dose constraints to maintain a low toxicity rate.