Gamma knife radiosurgery for trigeminal neuralgia: is anterior selective targeting a reasonable alternative?

To compare clinical outcomes and complication profiles of the anterior selective targeting (AST), which selectively targets the V2-V3 preganglionic region to minimize V1 exposure, versus dorsal root entry zone targeting (DREZ) in trigeminal neuralgia (TN).

We retrospectively analyzed 34 medically refractory TN patients treated with Gamma Knife radiosurgery (GKRS) at the Gamma Knife Radiosurgery Centre of Gazi University (January 2022-April 2023). Target selection was non-randomized and based on dermatomal symptoms and MRI anatomy: AST was used in patients without V1 involvement when trigeminal divisions could be confidently separated within Meckel's cave on 1.5-T MRI; otherwise, DREZ targeting was performed. GKRS was delivered using a single 4-mm collimator shot with 43 Gy prescribed to the 50% isodose line. At 12 months, outcomes included changes in Visual Analog Scale (VAS) and Barrow Neurological Institute (BNI) pain scores, BNI facial numbness score, corneal reflex status, medication changes, pain-free interval, subjective pain assessment, patient satisfaction, and beam-on time.

Symptom duration was longer in AST group (p = 0.031). Both groups showed significant reductions in VAS and BNI after GKRS (p < 0.05). ΔVAS and ΔBNI were slightly greater in the DREZ group (p = 0.039 and p = 0.045). No significant between-group differences were observed in medication use, pain-free interval, subjective pain assessment, satisfaction, facial numbness and corneal reflex status. Two DREZ patients had decreased corneal reflex. Beam-on time was shorter with AST (median 64.8 vs. 86.1 minutes; p < 0.001).

In selected TN patients without V1 involvement, AST provides effective pain control with comparable 12-month outcomes to DREZ and shorter beam-on time. Given its relative distance from the brainstem and reduced V1 inclusion, AST may be considered for initial or repeat GKRS in selected cases.