LINAC stereotactic radiosurgery for trigeminal neuralgia \u2013retrospective two-institutional examination of treatment outcomes

Ali Rashid,Jan P Boström,Gunnar Surber,Thomas M Kinfe,Bogdan Pintea,Klaus Hamm

doi:10.1186/s13014-018-1102-2

Abstract

BackgroundIn this pooled 2-center series LINAC radiosurgery (SRS) has been applied as a treatment option for a subset of refractory trigeminal neuralgia (TN) patients. This study approached to retrospectively assess the efficacy and safety of LINAC SRS and to provide a brief overview addressed to the technical development from frame-based towards frameless robotic SRS.MethodsFrom 2001 to 2017 n = 55 patients (pts) were treated, n = 28 were female (51%), mean age: 66 years (range 36–93 years); TN etiology: 37 classic TN, 15 multiple sclerosis (MS)-related TN, 2 symptomatic TN, and 1 atypical TN. Previous treatment was present in n = 35 (63.6%) pts. (some multiple or combined) with n = 23 microsurgical vascular decompression and n = 17 percutaneous retrogasserian rhizotomy. A 6 MV LINAC (4–5 mm collimators) was applied in all pts. (n = 26 framebased - n = 29 frameless robotic). The dorsal root entry zone (DREZ) was targeted in n = 35 cases and the retrogasserian target in n = 20 pts. with a homogeneous dose for the entire study cohort (90 Gy). SRS outcome was measured using the Barrow Neurological Institute (BNI) score for pain and hypaesthesia and statistically evaluated by univariate and multivariate analyzes.ResultsMean follow-up (FU) was 30 months (2 lost FU); the total rate of post SRS BNI pain I-IIIa (=painfree w or w/o medication) was 69% (88% for the classic TN pts), 29% (38.8% classic TN) were classified as BNI pain I-II (=painfree w/o medication). A BNI hypaesthesia II-III was present in 9.4% (n = 5) and BNI hypaesthesia IV in n = 2. Between groups analysis demonstrated no correlation of SRS responsiveness with age, gender, MS- or not MS-associated TN, previous surgery, framebased/frameless robotic SRS. DREZ targeting significantly better suppressed TN compared to RG targeting (p = 0.01). Additionally, a statistical trend for a better BNI pain outcome (p = 0.07) along with a significant increase in BNI hypaesthesia (p = 0.01) was found when using a larger partial trigeminal 70 Gy volume.ConclusionOur retrospective analysis support LINAC SRS as an effective and safe treatment option in TN. Frameless robotic SRS of TN is safe when using a dedicated LINAC system. A target definition closer to the brainstem and tendencially a larger target volume were associated with a better outcome for pain.

Highlights

In this pooled 2-center series linear accelerator (LINAC) radiosurgery (SRS) has been applied as a treatment option for a subset of refractory trigeminal neuralgia (TN) patients
We found a significant difference of the Barrow Neurological Institute (BNI) pain score at 1st FU depending to the target point (Figs. 3 and 4), the dorsal root entry zone (DREZ) target proofed to be better than the RG target (2.1 vs. 3.1, p = 0.01), but there were no significant differences for the BNI I-IIIa and BNI I-II
There was no significant difference in the multivariate analysis between framebased and frameless robotic stereotactic radiosurgery (SRS), here we found only a weak statistical tendency for a slightly better outcome (BNI pain and BNI hypaesthesia) for the framebased SRS in the univariate analysis

Summary

Introduction

In this pooled 2-center series LINAC radiosurgery (SRS) has been applied as a treatment option for a subset of refractory trigeminal neuralgia (TN) patients. The first, the classic form of TN (with no apparent cause other than neurovascular compression) is characterized by sudden shocks of severe facial pain lasting from a fraction of a second to 120 s in the distribution of the facial divisions of the trigeminal nerve often precipitated by innocuous stimuli to the affected side of the face. First-line treatment in the pain management of TN remains pharmacotherapy (carbamazepine, gabapentin, and oxcarbazepine) [1]. In case such medications are found to be inappropriate effective and/or associated with adverse side effects, invasive approaches, namely microsurgical vascular decompression (MVD) or ablative procedures like rhizotomy may be utilized [3,4,5]. Previous studies indicate that MVD provides long-lasting pain relief with a responder rate of around 80% [6,7,8]

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Discussion

Conclusion