Impact of target location on the response of trigeminal neuralgia to stereotactic radiosurgery

Object The authors evaluate the impact of target location on the rate of pain relief (PR) in patients with intractable trigeminal neuralgia (TN) undergoing stereotactic radiosurgery (SRS). Methods The authors conducted a retrospective review of 99 patients with idiopathic TN who were identified from a prospectively maintained database and were treated with SRS targeting the dorsal root entry zone with a maximum dose of 80 Gy. Targeting of the more proximal portion of a trigeminal nerve with the 50% isodose line overlapping the brainstem was performed in 36 patients (proximal group). In a matched group, 63 patients received SRS targeting the 20% isodose line tangential to the emergence of the brainstem (distal group). The median follow-up time was 33 months (range 6–124 months). Results The actuarial rate of maintenance of Barrow Neurological Institute (BNI) Pain Score I–IIIa was attained in 89% of patients at 1 year, 81% at 2 years, and 69% at 4 years, respectively, after SRS. Kaplan-Meier analysis revealed that durability of PR was only associated with the proximal location of the radiosurgical target (log-rank test, p = 0.018). Radiosurgery-induced facial numbness (BNI Score II or III) developed in 35 patients, which was significantly more frequent in the proximal group (19 patients [53%] compared with 16 [25%] in the distal group [p = 0.015]). Conclusions The radiosurgical target appears to affect the duration of pain relief in patients with idiopathic trigeminal neuralgia with the target closer to the brainstem affording extended pain relief. However, the proximal SRS target was also associated with an increased risk of mild to moderate facial numbness.

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Gamma Knife Radiosurgery for Trigeminal Neuralgia: A Comparison of Dose Protocols

Brain Sciences ◽

10.3390/brainsci9060134 ◽

2019 ◽

Vol 9 (6) ◽

pp. 134 ◽

Cited By ~ 2

Author(s):

Warren Boling ◽

Minwoo Song ◽

Wendy Shih ◽

Bengt Karlsson

Keyword(s):

Patient Satisfaction ◽

Pain Relief ◽

Trigeminal Neuralgia ◽

Gamma Knife Radiosurgery ◽

Sensory Disturbance ◽

Kaplan Meier ◽

Facial Numbness ◽

Satisfaction With Treatment ◽

Treatment Plans ◽

Prescription Dose

Purpose: A variety of treatment plans including an array of prescription doses have been used in radiosurgery treatment of trigeminal neuralgia (TN). However, despite a considerable experience in the radiosurgical treatment of TN, an ideal prescription dose that balances facial dysesthesia risk with pain relief durability has not been determined. Methods and Materials: This retrospective study of patients treated with radiosurgery for typical TN evaluates two treatment doses in relation to outcomes of pain freedom, bothersome facial numbness, and patient satisfaction with treatment. All patients were treated with radiosurgery for intractable and disabling TN. A treatment dose protocol change from 80 to 85 Gy provided an opportunity to compare two prescription doses. The variables evaluated were pain relief, treatment side-effect profile, and patient satisfaction. Results: Typical TN was treated with 80 Gy in 26 patients, and 85 Gy in 37 patients. A new face sensory disturbance was reported after 80 Gy in 16% and after 85 Gy in 27% (p = 0.4). Thirteen failed an 80 Gy dose whereas seven failed an 85 Gy dose. Kaplan–Meier analysis found that at 29 months 50% failed an 80 Gy treatment compared with 79% who had durable pain relief after 85 Gy treatment (p = 0.04). Conclusion: The 85 Gy dose for TN provided a more durable pain relief compared to the 80 Gy one without a significantly elevated occurrence of facial sensory disturbance.

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CYBERKNIFE RADIOSURGERY AS A FIRST TREATMENT FOR IDIOPATHIC TRIGEMINAL NEURALGIA

Neurosurgery ◽

10.1227/01.neu.0000341714.55023.8f ◽

2009 ◽

Vol 64 (suppl_2) ◽

pp. A96-A101 ◽

Cited By ~ 42

Author(s):

Laura Fariselli ◽

Carlo Marras ◽

Michela De Santis ◽

Marcello Marchetti ◽

Ida Milanesi ◽

...

Keyword(s):

Pain Relief ◽

Trigeminal Neuralgia ◽

Pain Control ◽

Root Entry Zone ◽

Successful Treatment Outcome ◽

Robotic Radiosurgery ◽

Idiopathic Trigeminal Neuralgia ◽

Facial Numbness ◽

Cyberknife Radiosurgery

Abstract OBJECTIVE To report the level of effectiveness and safety, in our experience, of CyberKnife (Accuray, Inc., Sunnyvale, CA) robotic radiosurgery as a first-line treatment against pharmacologically refractory trigeminal neuralgia. METHODS We treated 33 patients with the frameless CyberKnife system as a monotherapy. The retrogasserian portion of the trigeminal nerve (a length of 4 mm, 2–3 mm anterior to the root entry zone) was targeted. Doses of 55 to 75 Gy were prescribed to the 100% isodose line, according to a dose escalation protocol. The patients were evaluated for the level of pain control, time to pain relief, hypesthesia, and time to pain recurrence. RESULTS The median age was 74 years. All but 2 patients (94%) achieved a successful treatment outcome. The follow-up period was 9 to 37 months (mean, 23 months). The Barrow Neurological Institute Pain Intensity Scale (BPS) score before radiosurgery was III in 2 patients (6%), IV in 8 patients (24%), and V in 23 patients (70%). The time to pain relief was 1 to 180 days (median, 30 days). No facial numbness was observed. Only 1 patient developed a transitory dysesthesia of the tongue. After treatment, the BPS score was I, II, or III in 31 patients (97%). Pain recurred in 33% (11 patients) at a mean of 9 months (range, 1–43 months). Three patients with recurrences had low pain control by medication (BPS score, IV), and 1 patient (BPS score, V) needed a radiofrequency lesioning (BPS score, I at 12 months). CONCLUSION CyberKnife radiosurgery for trigeminal neuralgia allows pain relief at safe doses and is suggested for pharmacologically refractory trigeminal neuralgia. Higher prescribed doses were not associated with improvement in pain relief or recurrence rate.

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Immediate versus delayed adjuvant chemoradiation for resected pancreatic cancer: An analysis of local control and survival.

Journal of Clinical Oncology ◽

10.1200/jco.2012.30.4_suppl.301 ◽

2012 ◽

Vol 30 (4_suppl) ◽

pp. 301-301 ◽

Cited By ~ 1

Author(s):

Stephanie Krejcarek Childs ◽

Harvey J. Mamon ◽

Jennifer Yon-Li Wo ◽

Lawrence Scott Blaszkowsky ◽

Carlos Fernandez-del Castillo ◽

...

Keyword(s):

Pancreatic Cancer ◽

Massachusetts General Hospital ◽

Significant Risk ◽

Rank Test ◽

Kaplan Meier ◽

Pathologic Features ◽

Increased Risk ◽

Additional Chemotherapy ◽

Ecog Ps ◽

The Impact

301 Background: Patients with resected pancreatic cancer have a significant risk of both local and distant failures. Because of the importance of chemotherapy (CT) highlighted by recent trials, the ongoing RTOG 0848 delays chemoradiation (CRT) randomization to after 5 cycles of chemotherapy (CT). However, the impact of delaying CRT on LR is unknown. We evaluated the patterns of failure and outcomes for patients treated with immediate vs. delayed CRT. Methods: 174 consecutive patients with resectable pancreas cancer who received post-operative CRT at the Massachusetts General Hospital and Brigham & Women’s Hospital/Dana-Farber Cancer Institute between 1998-2010 were retrospectively reviewed on an IRB approved protocol. CRT was delivered to 50.4 Gy with concurrent 5FU or capecitabine. Patient baseline characteristics, pathologic features, and CA19-9 were obtained. Patients were divided into immediate CRT vs. delayed CRT, defined as receiving any CT prior to CRT. LR was independently re-reviewed and confirmed. LR, PFS, and OS were calculated using the Kaplan-Meier method and groups compared using the log-rank test. Results: Median age was 62 (range, 34-83), 75 were male, and ECOG PS was 0-1 in 95% of patients. Median tumor size was 3 cm, 67% had positive nodes, and 33% had positive margins. Mean pre-operative and post-operative CA 19-9 was 813 U/mL and 19 U/mL, respectively. 123/174 (72%) patients received immediate CRT, of whom 101 received additional chemotherapy (5FU or gemcitabine (GEM)). 51/174 (28%) received delayed CRT, and received a median of 4 cycles of GEM prior to CRT. Median follow-up was 33 months (range, 3.6-67). 6/51 (12%) delayed CRT had LR prior to initiation of CRT. 25/51 in the delayed CRT group had a LR (49%) vs. 35/124 patients (28%) in the immediate CRT group. The 1-year LR rates in the immediate and delayed CRT groups were 18% and 40%, respectively (p=0.0093). There was no difference between immediate or delayed CRT, respectively, in mPFS (12.8 mo vs. 12.2 mo, p=0.6544) or mOS (24.8 mo vs. 26.7 mo, p=0.7163). Conclusions: Delayed radiation is associated with an increased risk of LR, though this did not appear to impact PFS or OS.

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Characteristics and management of the offending veins in microvascular decompression surgery for trigeminal neuralgia

Neurosurgical Review ◽

10.1007/s10143-020-01411-2 ◽

2020 ◽

Author(s):

Hidetoshi Kasuya ◽

Shigeru Tani ◽

Yuichi Kubota ◽

Suguru Yokosako ◽

Hidenori Ohbuchi ◽

...

Keyword(s):

Pain Relief ◽

Trigeminal Neuralgia ◽

Microvascular Decompression ◽

Decompression Surgery ◽

Venous Infarction ◽

Middle Cerebellar Peduncle ◽

Root Entry Zone ◽

Complete Pain Relief ◽

Facial Numbness ◽

Cerebellar Peduncle

Abstract The optimal technique of microvascular decompression (MVD) for trigeminal neuralgia (TN) caused by venous conflict remains unclear. The objectives of this study are to characterize the offending veins identified during MVD for TN and to evaluate intraoperative technique applied for their management. From 2007 till 2019, 308 MVD surgeries were performed in 288 consecutive patients with TN, and in 58 of them, pure venous conflict was identified. In 44 patients, the offending vein was interrupted, as was done for small veins arising from the cisternal trigeminal nerve (CN V) or its root entry zone (REZ) causing their stretching (19 cases), small veins on the surface of REZ (9 cases), transverse pontine vein (TPV) compressing REZ or distal CN V (12 cases), and superior petrosal vein (SPV) using flow conversion technique (4 cases). In 14 other cases, the offending vein was relocated, as was done for the SPV or the vein of cerebellopontine fissure (8 cases), TPV (3 cases), and the vein of middle cerebellar peduncle (3 cases). Complete pain relief after surgery was noted in 49 patients (84%). No one patient experienced major neurological deterioration. Postoperative facial numbness developed in 14 patients (24%), and in 8 of them, it was permanent. In 14 patients, MRI demonstrated venous infarction of the middle cerebellar peduncle, which was associated with the presence of any (P = 0.0180) and permanent (P = 0.0002) facial numbness. Ten patients experienced pain recurrence. Thus, 39 patients (67%) sustained complete pain relief at the last follow-up (median, 48 months), which was significantly associated with the presence of any (P = 0.0228) and permanent (P = 0.0427) postoperative facial numbness. In conclusion, in cases of TN, small offending veins arising from REZ and/or distal CN V and causing their stretching may be coagulated and cut. In many cases, TPV can be also interrupted safely or considered as collateral way for blood outflow. The main complication of such procedures is facial numbness, which is associated with the venous infarction of middle cerebellar peduncle and long-term complete pain relief.

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Impact of AKAP6 polymorphisms on Glioma susceptibility and prognosis

BMC Neurology ◽

10.1186/s12883-019-1504-2 ◽

2019 ◽

Vol 19 (1) ◽

Cited By ~ 2

Author(s):

Ming Zhang ◽

Yonglin Zhao ◽

Junjie Zhao ◽

Tingqin Huang ◽

Yuan Wu

Keyword(s):

Regression Model ◽

Cox Regression ◽

High Grade Glioma ◽

Rank Test ◽

Nucleotide Polymorphisms ◽

Chinese Han ◽

Kaplan Meier ◽

Increased Risk ◽

Surgical Methods ◽

The Impact

Abstract Purpose Glioma is the most common primary malignant brain tumor with high mortality and poor prognosis. Our aim was to clarify the correlation between Kinase-anchored protein 6 (AKAP6) gene polymorphisms and glioma susceptibility and prognosis in Chinese Han population. Methods Five single-nucleotide polymorphisms (SNPs) of AKAP6 were genotyped by Agena MassARRAY in 575 glioma patients and 500 healthy controls. Logistic regression model was utilized to calculate odds ratios (OR) and 95% confidence intervals (CI). The associations between polymorphisms and survival were assessed using the log-rank test, Kaplan-Meier analysis and Cox regression model. Results We found that rs2239647 polymorphism was strongly associated with an increased risk of glioma (OR = 1.90, p = 0.007) and a worse prognosis for glioma, especially in high-grade glioma (HR = 1.67, p = 0.034). Stratified analysis showed that rs2239647 increased the risk of glioma in female (OR = 1.62, p = 0.016). Whereas, rs4261436 (HR = 0.70, p = 0.045) and rs17522122 (HR = 0.75, p = 0.016) were associated with better prognosis of astrocytoma. In addition, we also found that surgical methods and chemotherapy are critical factors for the prognosis of glioma patients. Conclusions This study firstly provided evidence for the impact of AKAP6 polymorphisms on susceptibility and prognosis of glioma, suggesting AKAP6 variants might have potential roles in the etiology of glioma.

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Stereotactic radiosurgery for trigeminal neuralgia: a multiinstitutional study using the gamma unit

Journal of Neurosurgery ◽

10.3171/jns.1996.84.6.0940 ◽

1996 ◽

Vol 84 (6) ◽

pp. 940-945 ◽

Cited By ~ 264

Author(s):

Douglas Kondziolka ◽

L. Dade Lunsford ◽

John C. Flickinger ◽

Ronald F. Young ◽

Sandra Vermeulen ◽

...

Keyword(s):

Pain Relief ◽

Trigeminal Neuralgia ◽

Stereotactic Radiosurgery ◽

Good Control ◽

Dose Selection ◽

Entry Zone ◽

Content Type ◽

Root Entry Zone ◽

Fine Print

✓ A multiinstitutional study was conducted to evaluate the technique, dose-selection parameters, and results of gamma knife stereotactic radiosurgery in the management of trigeminal neuralgia. Fifty patients at five centers underwent radiosurgery performed with a single 4-mm isocenter targeted at the nerve root entry zone. Thirty-two patients had undergone prior surgery, and the mean number of procedures that had been performed was 2.8 (range 1–7). The target dose of the radiosurgery used in the current study varied from 60 to 90 Gy. The median follow-up period after radiosurgery was 18 months (range 11–36 months). Twenty-nine patients (58%) responded with excellent control (pain free), 18 (36%) obtained good control (50%–90% relief), and three (6%) experienced treatment failure. The median time to pain relief was 1 month (range 1 day–6.7 months). Responses remained consistent for up to 3 years postradiosurgery in all cases except three (6%) in which the patients had pain recurrence at 5, 7, and 10 months. At 2 years, 54% of patients were pain free and 88% had 50% to 100% relief. A maximum radiosurgical dose of 70 Gy or greater was associated with a significantly greater chance of complete pain relief (72% vs. 9%, p = 0.0003). Three patients (6%) developed increased facial paresthesia after radiosurgery, which resolved totally in one case and improved in another. No patient developed other deficits or deafferentation pain. The proximal trigeminal nerve and root entry zone, which is well defined on magnetic resonance imaging, is an appropriate anatomical target for radiosurgery. Radiosurgery using the gamma unit is an additional effective surgical approach for the management of medically or surgically refractory trigeminal neuralgia. A longer-term follow-up review is warranted.

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Radiosurgery target location and individual anatomical variation in trigeminal nerves

Journal of Neurosurgery ◽

10.3171/2014.7.gks141432 ◽

2014 ◽

Vol 121 (Suppl_2) ◽

pp. 203-209 ◽

Cited By ~ 8

Author(s):

Yi-Chieh Hung ◽

Cheng-Chia Lee ◽

Kang-Du Liu ◽

Wen-Yuh Chung ◽

David Hung-Chi Pan ◽

...

Keyword(s):

Pain Relief ◽

Trigeminal Neuralgia ◽

Target Location ◽

Anatomical Variation ◽

Anatomical Variations ◽

High Dose ◽

Root Entry Zone ◽

Radiation Induced ◽

Clinical Conditions ◽

Trigeminal Nerves

ObjectThe authors evaluated individual anatomical variations in the trigeminal nerves of patients with medically intractable trigeminal neuralgia and clarified the relationships among the variations, radiosurgical target locations, and the clinical outcomes after high-dose Gamma Knife surgery (GKS).MethodsFrom 2006 through 2011, the authors conducted a retrospective review of 106 cases of primary or secondary trigeminal neuralgia consecutively treated with GKS targeting the dorsal root entry zone (DREZ) for which a maximal dose of 90 Gy and a 20% isodose line to the brainstem were used. A questionnaire was used to evaluate patients' pre- and post-GKS clinical conditions. To evaluate individual anatomical variations among trigeminal nerves, the authors used 3 parameters: the length of the trigeminal nerve in the cistern (nerve length), the length of the target between the radiation shot and the brainstem (targeting length), and the ratio between nerve length and targeting length (targeting ratio).ResultsThe median length of the trigeminal nerves in the 106 patients was 9.6 mm (range 6.04−20.74 mm), the median targeting length was 3.8 mm (range 1.81−10.84 mm), and the median targeting ratio was 38% (range 13%− 80%). No statistically significant differences in pain relief and pain recurrence were detected among patients with these various nerve characteristics. However, radiation-induced facial hypesthesia correlated with nerve length and targeting ratio (p < 0.05) but not with absolute distance from the brainstem (targeting length).ConclusionsIn trigeminal neuralgia patients who received DREZ-targeted GKS, the rate of pain relief did not differ according to anatomical nerve variations. However, the frequency of facial hypesthesia was higher among patients in whom the nerve was longer (> 11 mm) or the targeting ratio was lower (< 36%). Adjusting the target according to the targeting ratio, especially for patients with longer nerves, can reduce facial hypesthesia and enable maintenance of effective pain control.

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Impact of AKAP6 Polymorphisms on Glioma Susceptibility and Prognosis

10.21203/rs.2.10771/v2 ◽

2019 ◽

Author(s):

Ming Zhang ◽

Yonglin Zhao ◽

Junjie Zhao ◽

Tingqin Huang ◽

Yuan Wu

Keyword(s):

Regression Model ◽

Cox Regression ◽

High Grade Glioma ◽

Rank Test ◽

Nucleotide Polymorphisms ◽

Chinese Han ◽

Kaplan Meier ◽

Increased Risk ◽

Surgical Methods ◽

The Impact

Abstract Purpose Glioma is the most common primary malignant brain tumor with high mortality and poor prognosis. Our aim was to clarify the correlation between AKAP6 gene polymorphisms and glioma susceptibility and prognosis in Chinese Han population. Methods Five single-nucleotide polymorphisms (SNPs) of AKAP6 were genotyped by Agena MassARRAY in 575 glioma patients and 500 healthy controls. Logistic regression model was utilized to calculate odds ratios (OR) and 95% confidence intervals (CI). The associations between polymorphisms and survival were assessed using the log-rank test, Kaplan-Meier analysis and Cox regression model. Results We found that rs2239647 polymorphism was strongly associated with an increased risk of glioma (OR = 1.90, p = 0.007) and a worse prognosis for glioma, especially in high-grade glioma (HR = 1.67, p = 0.034). Stratified analysis showed that rs2239647 increased the risk of glioma in female (OR = 1.62, p = 0.016). Whereas, rs4261436 (HR = 0.70, p = 0.045) and rs17522122 (HR = 0.75, p = 0.016) were associated with better prognosis of astrocytoma. In addition, we also found that surgical methods and chemotherapy are critical factors for the prognosis of glioma patients. Conclusions This study firstly provided evidence for the impact of AKAP6 polymorphisms on susceptibility and prognosis of glioma, suggesting AKAP6 variants might have potential roles in the etiology of glioma.

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

Journal of Neurosurgery ◽

10.3171/2016.12.jns161862 ◽

2018 ◽

Vol 128 (3) ◽

pp. 891-896 ◽

Cited By ~ 6

Author(s):

Amparo Wolf ◽

Amy Tyburczy ◽

Jason Chao Ye ◽

Girish Fatterpekar ◽

Joshua S. Silverman ◽

...

Keyword(s):

Pain Relief ◽

Trigeminal Neuralgia ◽

Trigeminal Nerve ◽

Volume Ratio ◽

Optimal Dose ◽

Rank Test ◽

High Dose ◽

Neurovascular Compression ◽

Pain Outcomes ◽

The Impact

OBJECTIVEApproximately 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.METHODSFifty-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.RESULTSFollow-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).CONCLUSIONSThe 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.

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Linear Accelerator Radiosurgery Using 90 Gray for Essential Trigeminal Neuralgia: Results and Dose Volume Histogram Analysis

Neurosurgery ◽

10.1227/01.neu.0000083550.03928.d8 ◽

2003 ◽

Vol 53 (4) ◽

pp. 823-830 ◽

Cited By ~ 58

Author(s):

Bryan W. Goss ◽

Leonardo Frighetto ◽

Antonio A.F. DeSalles ◽

Zachary Smith ◽

Timothy Solberg ◽

...

Keyword(s):

Pain Relief ◽

Trigeminal Neuralgia ◽

Nerve Root ◽

Linear Accelerator ◽

Treatment Plan ◽

Case Series ◽

Entry Zone ◽

Root Entry Zone ◽

Dose Volume ◽

Facial Numbness

Abstract OBJECTIVE To evaluate treatment of essential trigeminal neuralgia with 90 Gy delivered by a linear accelerator dedicated to radiosurgery. METHODS This is a retrospective case series of 25 patients with essential trigeminal neuralgia treated from March 1999 to March 2001. All were treated with 90 Gy by means of a 5-mm collimator directed to the nerve root entry zone. Patient follow-up (range, 8–52 mo; median, 18 mo) was completed by an uninvolved party. Dose volume histograms of the brainstem were developed for the 20, 30, and 50% isodose lines by means of radiosurgery planning software. RESULTS All patients obtained good to excellent pain relief with treatment. Nineteen (76%) of 25 patients achieved excellent pain relief (pain-free without medication). Six patients (24%) achieved good pain relief (50–90% reduction of pain with or without medication). Median time to pain relief was 2 months. Eight patients (32%) experienced relapse 4 to 13 months after treatment. Eight patients (32%) developed facial numbness, but none developed painful numbness. Mean brainstem volume within the 50% isodose line and occurrence of numbness was statistically significant (P = 0.03). There was no correlation between brainstem volume treated and outcome. CONCLUSION Dedicated linear accelerator-based stereotactic radiosurgery that uses a 5-mm collimator to deliver 90 Gy to the nerve root entry zone is a safe and effective method for the treatment of essential trigeminal neuralgia. Care should be taken to limit brainstem volume included in the 50% isodose line in the treatment plan to avoid facial numbness.

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