The relationship of dose to nerve volume in predicting pain recurrence after stereotactic radiosurgery in trigeminal neuralgia.

OBJECTIVE Approximately 75%-92% of patients with trigeminal neuralgia (TN) achieve pain relief after Gamma Knife surgery (GKS), although a proportion of these patients will experience recurrence of their pain. To evaluate the reasons for durability or recurrence, this study determined the impact of trigeminal nerve length and volume, the nerve dose-volume relationship, and the presence of neurovascular compression (NVC) on pain outcomes after GKS for TN. METHODS Fifty-eight patients with 60 symptomatic nerves underwent GKS for TN between 2013 and 2015, including 15 symptomatic nerves secondary to multiple sclerosis (MS). High-resolution MRI was acquired the day of GKS. The median maximum dose was 80 Gy for initial GKS and 65 Gy for repeat GKS. NVC, length and volume of the trigeminal nerve within the subarachnoid space of the posterior fossa, and the ratio of dose to nerve volume were assessed as predictors of recurrence. RESULTS Follow-up was available on 55 patients. Forty-nine patients (89.1%) reported pain relief (Barrow Neurological Institute [BNI] Grades I-IIIb) after GKS at a median duration of 1.9 months. The probability of maintaining pain relief (BNI Grades I-IIIb) without requiring resumption or an increase in medication was 93% at 1 year and 84% at 2 years for patients without MS, and 68% at 1 year and 51% at 2 years for all patients. The nerve length, nerve volume, target distance from the brainstem, and presence of NVC were not predictive of pain recurrence. Patients with a smaller volume of nerve (< 35% of the total nerve volume) that received a high dose (≥ 80% isodose) were less likely to experience recurrence of their TN pain after 1 year (mean time to recurrence: < 35%, 32.2 ± 4.0 months; > 35%, 17.9 ± 2.8 months, log-rank test, χ2 = 4.3, p = 0.039). CONCLUSIONS The ratio of dose to nerve volume may predict recurrence of TN pain after GKS. Prospective studies are needed to determine the optimal dose to nerve volume ratio and whether this will result in longer pain-free outcomes.

[1]  J. Gaudart,et al.  Long-term safety and efficacy of Gamma Knife surgery in classical trigeminal neuralgia: a 497-patient historical cohort study. , 2016, Journal of neurosurgery.

[2]  J. Flickinger,et al.  Early radiosurgery provides superior pain relief for trigeminal neuralgia patients , 2015, Neurology.

[3]  Yi-Chieh Hung,et al.  Radiosurgery target location and individual anatomical variation in trigeminal nerves. , 2014, Journal of neurosurgery.

[4]  G. Cruccu,et al.  Magnetic resonance imaging contribution for diagnosing symptomatic neurovascular contact in classical trigeminal neuralgia: A blinded case-control study and meta-analysis , 2014, PAIN®.

[5]  M. Sindou,et al.  Atrophic changes in the trigeminal nerves of patients with trigeminal neuralgia due to neurovascular compression and their association with the severity of compression and clinical outcomes. , 2014, Journal of neurosurgery.

[6]  A. Laxton,et al.  Predictive nomogram for the durability of pain relief from gamma knife radiation surgery in the treatment of trigeminal neuralgia. , 2014, International journal of radiation oncology, biology, physics.

[7]  A. Baschnagel,et al.  Trigeminal neuralgia pain relief after gamma knife stereotactic radiosurgery , 2014, Clinical Neurology and Neurosurgery.

[8]  E. Shaw,et al.  Predictive variables for the successful treatment of trigeminal neuralgia with gamma knife radiosurgery. , 2012, Neurosurgery.

[9]  J. Sheehan,et al.  Gamma Knife radiosurgery for trigeminal neuralgia : the impact of magnetic resonance imaging – detected vascular impingement of the affected nerve Clinical article , 2010 .

[10]  L Dade Lunsford,et al.  Gamma Knife stereotactic radiosurgery for idiopathic trigeminal neuralgia. , 2010, Journal of neurosurgery.

[11]  Seong-Hyun Park,et al.  The retrogasserian zone versus dorsal root entry zone: comparison of two targeting techniques of gamma knife radiosurgery for trigeminal neuralgia , 2010, Acta Neurochirurgica.

[12]  J. Ono,et al.  Comparison of the results of 2 targeting methods in Gamma Knife surgery for trigeminal neuralgia. , 2008, Journal of neurosurgery.

[13]  J. Brotchi,et al.  Neurovascular compression anatomy and pain outcome in patients with classic trigeminal neuralgia treated by radiosurgery. , 2008, Neurosurgery.

[14]  R. Foroni,et al.  GAMMA KNIFE RADIOSURGERY FOR TRIGEMINAL NEURALGIA: RESULTS AND POTENTIALLY PREDICTIVE PARAMETERS—PART I IDIOPATHIC TRIGEMINAL NEURALGIA , 2007, Neurosurgery.

[15]  J. Régis,et al.  INFLUENCE OF NERVE RADIATION DOSE IN THE INCIDENCE OF TRIGEMINAL DYSFUNCTION AFTER TRIGEMINAL NEURALGIA RADIOSURGERY , 2007, Neurosurgery.

[16]  K. Burchiel,et al.  High-resolution Three-dimensional Magnetic Resonance Angiography and Three-dimensional Spoiled Gradient-recalled Imaging in the Evaluation of Neurovascular Compression in Patients with Trigeminal Neuralgia: A Double-blind Pilot Study , 2006, Neurosurgery.

[17]  R. Bhadelia,et al.  Association between neurovascular contact on MRI and response to gamma knife radiosurgery in trigeminal neuralgia , 2005, Neuroradiology.

[18]  J. Petit,et al.  Gamma knife surgery for trigeminal neuralgia: outcome, imaging, and brainstem correlates. , 2004, International journal of radiation oncology, biology, physics.

[19]  S. Renowden,et al.  How accurate is magnetic resonance angiography in predicting neurovascular compression in patients with trigeminal neuralgia? A prospective, single-blinded comparative study , 2003, British journal of neurosurgery.

[20]  A. Khandji,et al.  Trigeminal Nerve-Blood Vessel Relationship as Revealed by High-resolution Magnetic Resonance Imaging and Its Effect on Pain Relief after Gamma Knife Radiosurgery for Trigeminal Neuralgia , 2002, Neurosurgery.

[21]  A. Shetter,et al.  Gamma knife radiosurgery for trigeminal neuralgia: the initial experience of The Barrow Neurological Institute. , 2000, International journal of radiation oncology, biology, physics.