Higher dose rate Gamma Knife radiosurgery may provide earlier and longer-lasting pain relief for patients with trigeminal neuralgia

OBJECT Gamma Knife radiosurgery (GKRS) utilizes cobalt-60 as its radiation source, and thus dose rate varies as the fixed source decays over its half-life of approximately 5.26 years. This natural decay results in increasing treatment times when delivering the same cumulative dose. It is also possible, however, that the biological effective dose may change based on this dose rate even if the total dose is kept constant. Because patients are generally treated in a uniform manner, radiosurgery for trigeminal neuralgia (TN) represents a clinical model whereby biological efficacy can be tested. The authors hypothesized that higher dose rates would result in earlier and more complete pain relief but only if measured with a sensitive pain assessment tool. METHODS One hundred thirty-three patients were treated with the Gamma Knife Model 4C unit at a single center by a single neurosurgeon during a single cobalt life cycle from January 2006 to May 2012. All patients were treated with 80 Gy with a single 4-mm isocenter without blocking. Using an output factor of 0.87, dose rates ranged from 1.28 to 2.95 Gy/min. The Brief Pain Inventory (BPI)-Facial was administered before the procedure and at the first follow-up office visit 1 month from the procedure (mean 1.3 months). Phone calls were made to evaluate patients after their procedures as part of a retrospective study. Univariate and multivariate linear regression was performed on several independent variables, including sex, age in deciles, diagnosis, follow-up duration, prior surgery, and dose rate. RESULTS In the short-term analysis (mean 1.3 months), patients’ self-reported pain intensity at its worst was significantly correlated with dose rate on multivariate analysis (p = 0.028). Similarly, patients’ self-reported interference with activities of daily living was closely correlated with dose rate on multivariate analysis (p = 0.067). A 1 Gy/min decrease in dose rate resulted in a 17% decrease in pain intensity at its worst and a 22% decrease in pain interference with activities of daily living. In longer-term follow-up (mean 1.9 years), GKRS with higher dose rates (> 2.0 Gy/min; p = 0.007) and older age in deciles (p = 0.012) were associated with a lower likelihood of recurrence of pain. DISCUSSION Prior studies investigating the role of dose rate in Gamma Knife radiosurgical ablation for TN have not used validated outcome tools to measure pain preoperatively. Consequently, differences in pain outcomes have been difficult to measure. By administering pain scales both preoperatively as well as postoperatively, the authors have identified statistically significant differences in pain intensity and pain interference with activities of daily living when comparing higher versus lower dose rates. Radiosurgery with a higher dose rate results in more pain relief at the early follow-up evaluation, and it may result in a lower recurrence rate at later follow-up.

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Temporal disconnection between pain relief and trigeminal nerve microstructural changes after Gamma Knife radiosurgery for trigeminal neuralgia

Journal of Neurosurgery ◽

10.3171/2019.4.jns19380 ◽

2020 ◽

Vol 133 (3) ◽

pp. 727-735

Author(s):

Peter Shih-Ping Hung ◽

Sarasa Tohyama ◽

Jia Y. Zhang ◽

Mojgan Hodaie

Keyword(s):

Pain Relief ◽

Trigeminal Neuralgia ◽

Pain Intensity ◽

Gamma Knife ◽

Trigeminal Nerve ◽

Diffusion Tensor ◽

Gamma Knife Radiosurgery ◽

Time Points ◽

Microstructural Effect

OBJECTIVEGamma Knife radiosurgery (GKRS) is a noninvasive surgical treatment option for patients with medically refractive classic trigeminal neuralgia (TN). The long-term microstructural consequences of radiosurgery and their association with pain relief remain unclear. To better understand this topic, the authors used diffusion tensor imaging (DTI) to characterize the effects of GKRS on trigeminal nerve microstructure over multiple posttreatment time points.METHODSNinety-two sets of 3-T anatomical and diffusion-weighted MR images from 55 patients with TN treated by GKRS were divided within 6-, 12-, and 24-month posttreatment time points into responder and nonresponder subgroups (≥ 75% and < 75% reduction in posttreatment pain intensity, respectively). Within each subgroup, posttreatment pain intensity was then assessed against pretreatment levels and followed by DTI metric analyses, contrasting treated and contralateral control nerves to identify specific biomarkers of successful pain relief.RESULTSGKRS resulted in successful pain relief that was accompanied by asynchronous reductions in fractional anisotropy (FA), which maximized 24 months after treatment. While GKRS responders demonstrated significantly reduced FA within the radiosurgery target 12 and 24 months posttreatment (p < 0.05 and p < 0.01, respectively), nonresponders had statistically indistinguishable DTI metrics between nerve types at each time point.CONCLUSIONSUltimately, this study serves as the first step toward an improved understanding of the long-term microstructural effect of radiosurgery on TN. Given that FA reductions remained specific to responders and were absent in nonresponders up to 24 months posttreatment, FA changes have the potential of serving as temporally consistent biomarkers of optimal pain relief following radiosurgical treatment for classic TN.

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Gamma Knife radiosurgery for trigeminal neuralgia: the impact of magnetic resonance imaging–detected vascular impingement of the affected nerve

Journal of Neurosurgery ◽

10.3171/2009.9.jns09196 ◽

2010 ◽

Vol 113 (1) ◽

pp. 53-58 ◽

Cited By ~ 22

Author(s):

Jason P. Sheehan ◽

Dibyendu Kumar Ray ◽

Stephen Monteith ◽

Chun Po Yen ◽

James Lesnick ◽

...

Keyword(s):

Pain Relief ◽

Mr Imaging ◽

Trigeminal Neuralgia ◽

Gamma Knife ◽

Trigeminal Nerve ◽

Gamma Knife Radiosurgery ◽

Vascular Compression ◽

Pain Intensity Score ◽

The Impact

Object Trigeminal neuralgia is believed to be related to vascular compression of the affected nerve. Radiosurgery has been shown to be reasonably effective for treatment of medically refractory trigeminal neuralgia. This study explores the rate of occurrence of MR imaging–demonstrated vascular impingement of the affected nerve and the extent to which vascular impingement affects pain relief in a population of trigeminal neuralgia patients undergoing Gamma Knife radiosurgery (GKRS). Methods The authors performed a retrospective analysis of 106 cases involving patients treated for typical trigeminal neuralgia using GKRS. Patients with or without single-vessel impingement on CISS MR imaging sequences and with no previous surgery were included in the study. Pain relief was assessed according to the Barrow Neurological Institute (BNI) pain intensity score at the last follow-up. Degree of impingement, nerve diameter preand post-impingement, isocenter placement, and dose to the point of maximum impingement were evaluated in relation to the improvement of BNI score. Results The overall median follow-up period was 31 months. Overall, a BNI pain score of 1 was achieved in 59.4% of patients at last follow-up. Vessel impingement was seen in 63 patients (59%). There was no significant difference in pain relief between those with and without vascular impingement following GKRS (p > 0.05). In those with vascular impingement on MR imaging, the median fraction of vessel impingement was 0.3 (range 0.04–0.59). The median dose to the site of maximum impingement was 42 Gy (range 2.9–79 Gy). Increased dose (p = 0.019) and closer proximity of the isocenter to the site of maximum vessel impingement (p = 0.012) correlated in a statistically significant fashion with improved BNI scores in those demonstrating vascular impingement on the GKRS planning MR imaging Conclusions Vascular impingement of the affected nerve was seen in the majority of patients with trigeminal neuralgia. Overall pain relief following GKRS was comparable in those with and without evidence of vascular compression on MR imaging. In subgroup analysis of those with MR imaging evidence of vessel impingement of the affected trigeminal nerve, pain relief correlated with a higher dose to the point of contact between the impinging vessel and the trigeminal nerve. Such a finding may point to vascular changes affording at least some degree of relief following GKRS for trigeminal neuralgia.

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Results of three or more Gamma Knife radiosurgery procedures for recurrent trigeminal neuralgia

Journal of Neurosurgery ◽

10.3171/2020.10.jns202323 ◽

2021 ◽

pp. 1-10

Author(s):

Mihir Gupta ◽

Varun Sagi ◽

Aditya Mittal ◽

Anudeep Yekula ◽

Devan Hawkins ◽

...

Keyword(s):

Pain Relief ◽

Adverse Effects ◽

Trigeminal Neuralgia ◽

Gamma Knife ◽

Gamma Knife Radiosurgery ◽

Recurrent Pain ◽

The Third ◽

Percutaneous Procedures ◽

Pain Outcomes

OBJECTIVE Gamma Knife radiosurgery (GKRS) is an established surgical option for the treatment of trigeminal neuralgia (TN), particularly for high-risk surgical candidates and those with recurrent pain. However, outcomes after three or more GKRS treatments have rarely been reported. Herein, the authors reviewed outcomes among patients who had undergone three or more GKRS procedures for recurrent TN. METHODS The authors conducted a multicenter retrospective analysis of patients who had undergone at least three GKRS treatments for TN between July 1997 and April 2019 at two different institutions. Clinical characteristics, radiosurgical dosimetry and technique, pain outcomes, and complications were reviewed. Pain outcomes were scored on the Barrow Neurological Institute (BNI) scale, including time to pain relief (BNI score ≤ III) and recurrence (BNI score > III). RESULTS A total of 30 patients were identified, including 16 women and 14 men. Median pain duration prior to the first GKRS treatment was 10 years. Three patients (10%) had multiple sclerosis. Time to pain relief was longer after the third treatment (p = 0.0003), whereas time to pain recurrence was similar across each of the successive treatments (p = 0.842). Complete or partial pain relief was achieved in 93.1% of patients after the third treatment. The maximum pain relief achieved after the third treatment was significantly better among patients with no prior percutaneous procedures (p = 0.0111) and patients with shorter durations of pain before initiation of GKRS therapy (p = 0.0449). New or progressive facial sensory dysfunction occurred in 29% of patients after the third GKRS treatment and was reported as bothersome in 14%. One patient developed facial twitching, while another experienced persistent lacrimation. No statistically significant predictors of adverse effects following the third treatment were found. Over a median of 39 months of follow-up, 77% of patients maintained complete or partial pain relief. Three patients underwent a fourth GKRS treatment, including one who ultimately received five treatments; all of them reported sustained pain relief at the extended follow-up. CONCLUSIONS The authors describe the largest series to date of patients undergoing three or more GKRS treatments for refractory TN. A third treatment may produce outcomes similar to those of the first two treatments in terms of long-term pain relief, recurrence, and adverse effects.

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The impact of cobalt-60 source age on biologically effective dose in high-dose functional Gamma Knife radiosurgery

Journal of Neurosurgery ◽

10.3171/2016.6.gks161497 ◽

2016 ◽

Vol 125 (Supplement_1) ◽

pp. 154-159 ◽

Cited By ~ 4

Author(s):

Benjamin H. Kann ◽

James B. Yu ◽

John M. Stahl ◽

James E. Bond ◽

Christopher Loiselle ◽

...

Keyword(s):

Effective Dose ◽

Dose Rate ◽

Gamma Knife ◽

Treatment Time ◽

Gamma Knife Radiosurgery ◽

High Dose ◽

Biologically Effective Dose ◽

Obsessive Compulsive ◽

Compulsive Disorder ◽

Dose Rates

OBJECTIVEFunctional Gamma Knife radiosurgery (GKRS) procedures have been increasingly used for treating patients with tremor, trigeminal neuralgia (TN), and refractory obsessive-compulsive disorder. Although its rates of toxicity are low, GKRS has been associated with some, if low, risks for serious sequelae, including hemiparesis and even death. Anecdotal reports have suggested that even with a standardized prescription dose, rates of functional GKRS toxicity increase after replacement of an old cobalt-60 source with a new source. Dose rate changes over the course of the useful lifespan of cobalt-60 are not routinely considered in the study of patients treated with functional GKRS, but these changes may be associated with significant variation in the biologically effective dose (BED) delivered to neural tissue.METHODSThe authors constructed a linear-quadratic model of BED in functional GKRS with a dose-protraction factor to correct for intrafraction DNA-damage repair and used standard single-fraction doses for trigeminal nerve ablation for TN (85 Gy), thalamotomy for tremor (130 Gy), and capsulotomy for obsessive-compulsive disorder (180 Gy). Dose rate and treatment time for functional GKRS involving 4-mm collimators were derived from calibrations in the authors' department and from the cobalt-60 decay rate. Biologically plausible values for the ratio for radiosensitivity to fraction size (α/β) and double-strand break (DSB) DNA repair halftimes (τ) were estimated from published experimental data. The biphasic characteristics of DSB repair in normal tissue were accounted for in deriving an effective τ1 halftime (fast repair) and τ2 halftime (slow repair). A sensitivity analysis was performed with a range of plausible parameter values.RESULTSAfter replacement of the cobalt-60 source, the functional GKRS dose rate rose from 1.48 to 2.99 Gy/min, treatment time fell, and estimated BED increased. Assuming the most biologically plausible parameters, source replacement resulted in an immediate relative BED increase of 11.7% for GKRS-based TN management with 85 Gy, 15.6% for thalamotomy with 130 Gy, and 18.6% for capsulotomy with 180 Gy. Over the course of the 63-month lifespan of the cobalt-60 source, BED decreased annually by 2.2% for TN management, 3.0% for thalamotomy, and 3.5% for capsulotomy.CONCLUSIONSUse of a new cobalt-60 source after replacement of an old source substantially increases the predicted BED for functional GKRS treatments for the same physical dose prescription. Source age, dose rate, and treatment time should be considered in the study of outcomes after high-dose functional GKRS treatments. Animal and clinical studies are needed to determine how this potential change in BED contributes to GKRS toxicity and whether technical adjustments should be made to reduce dose rates or prescription doses with newer cobalt-60 sources.

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Gamma knife radiosurgery for primary management for trigeminal neuralgia

Journal of Neurosurgery ◽

10.3171/jns.2000.93.supplement_3.0159 ◽

2000 ◽

Vol 93 (supplement_3) ◽

pp. 159-161 ◽

Cited By ~ 65

Author(s):

Ronald Brisman

Keyword(s):

Pain Relief ◽

Trigeminal Neuralgia ◽

Gamma Knife ◽

Gamma Knife Radiosurgery ◽

Content Type ◽

Group A ◽

Group B ◽

Primary Management ◽

Fine Print

Object. The purpose of this study was to assess the efficacy of gamma knife radiosurgery (GKS) as the primary rather than secondary management for trigeminal neuralgia. Methods. Eighty-two patients underwent GKS as their first neurosurgical intervention (Group A), and 90 patients underwent GKS following a different procedure (Group B). All GKS patients were treated with a maximum dose of 75 Gy. The single 4-mm isocenter was placed close to the junction of the trigeminal nerve and the brainstem. Six-month follow up was available for 126 patients and 12-month follow up for 84 patients. Excellent (no pain and no medicine) or good (at least 50% reduction in pain and less medicine) relief was more likely to occur in Group A than in Group B patients 6 and 12 months following GKS for trigeminal neuralgia (p = 0.058). Excellent or good results were also more likely in patients with trigeminal neuralgia without multiple sclerosis (MS) (p = 0.042). The number and type of procedures performed prior to GKS, the interval between the last procedure and GKS, and the interval from first symptom to GKS (within Groups A and B) did not affect 6-month outcome. The interval between first symptom and GKS was shorter in Group A patients without MS (87 months) than in Group B (148 months; p < 0.004). There were no significant differences between Group A and B patients with regard to sex, age, or laterality. Conclusions. Patients with trigeminal neuralgia who are treated with GKS as primary management have better pain relief than those treated with GKS as secondary management. Patients are more likely to have pain relief if they do not have MS.

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Long-term outcomes of Gamma Knife radiosurgery for classic trigeminal neuralgia: implications of treatment and critical review of the literature

Journal of Neurosurgery ◽

10.3171/2009.2.jns08977 ◽

2009 ◽

Vol 111 (2) ◽

pp. 351-358 ◽

Cited By ~ 102

Author(s):

Anil A. Dhople ◽

Jared R. Adams ◽

William W. Maggio ◽

Shahid A. Naqvi ◽

William F. Regine ◽

...

Keyword(s):

Pain Relief ◽

Trigeminal Neuralgia ◽

Gamma Knife ◽

Gamma Knife Radiosurgery ◽

Response Duration ◽

Invasive Treatment ◽

Median Response ◽

Late Failure

Object Few long-term studies of Gamma Knife surgery (GKS) for trigeminal neuralgia (TN) exist. The authors report their long-term experience with the use of GKS in a previously reported cohort of patients with TN that has now been followed since 1996. Methods One hundred twelve patients with TN were treated with GKS at the University of Maryland between June 1996 and July 2001. Of these, 67% had no invasive operations for TN prior to GKS, 13% had 1, 4% had 2, and 16% had ≥ 3. The right side was affected in 56% of cases, predominantly involving V2 (26%), V3 (24%), or a combination of both (18%) branches. The median age at diagnosis was 56 years, and median age at GKS was 64 years. The median prescription dose of 75 Gy (range 70–80 Gy) was delivered to the involved trigeminal nerve root entry zone. The authors assessed the degree of pain before and after GKS by using the Barrow Neurological Institute (BNI) pain scale. Results In total, 102 patients took the survey at least once, for a response rate of 91%. Although not found to alter the conclusions of this study, 7 cases of atypical TN were found and these patients were removed, for a total of 95 cases herein analyzed. The median follow-up was 5.6 years (range 13–115 months). Before GKS, 88% of patients categorized their pain as BNI IV or V (inadequate control or severe pain on medication), whereas the remainder described their pain as BNI III (some pain, but controlled on medication). After GKS, 64% reported a BNI score of I (no pain, no medications), 5% had BNI II (no pain, still on medication), 12% had BNI III, and 19% reported a BNI score of IV or V. The median time to response was 2 weeks (range 0–12 weeks) and the median response duration was 32 months (range 0–112 months). Eighty-one percent reported initial pain relief, and actuarial rates of freedom from treatment failure at 1, 3, 5, and 7 years were 60, 41, 34, and 22%, respectively. Response duration was significantly better for those who had no prior invasive treatment versus those in whom a previous surgical intervention had failed (32 vs 21 months, p < 0.02). New bothersome facial numbness was reported in 6% of cases. Conclusions This study represents one of the longest reported median follow-up periods and actuarial results for a cohort of patients with classic TN treated with GKS. Although GKS achieves excellent rates of initial pain relief, these results suggest a steady rate of late failure, particularly among patients who had undergone prior invasive surgical treatment. Despite a higher than expected recurrence rate, GKS remains a viable treatment option, particularly for patients who have had no prior invasive procedures. Patients with recurrences can still be offered salvage therapy with either repeat GKS, microvascular decompression, or rhizotomy.

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Gamma knife radiosurgery on the trigeminal ganglion for idiopathic trigeminal neuralgia: Results and review of the literature

Surgical Neurology International ◽

10.25259/sni-134-2019 ◽

2019 ◽

Vol 10 ◽

pp. 89

Author(s):

Salvador Somaza ◽

Eglee M. Montilla ◽

Maria C. Mora

Keyword(s):

Pain Relief ◽

Trigeminal Neuralgia ◽

Gamma Knife ◽

Trigeminal Ganglion ◽

Gamma Knife Radiosurgery ◽

Latency Period ◽

Satellite Glial Cells ◽

Idiopathic Trigeminal Neuralgia ◽

Collateral Effects

Background: In the present study, we evaluate the results of gamma knife surgery (GKS) for the treatment of trigeminal neuralgia (TN) using the trigeminal ganglion (TG’) and the adjacent fibers of trigeminal nerve as a target. Methods: From February 2013 to July 2017, we treated 30 cases of TN with GKS. In this group, all patients had an idiopathic typical TN. The radiosurgical target was conformed through two isocenters, 8 and 4 mm at the cavum de Meckel. The maximum dose was 86 Gy using the isodose line of 50%. The median age of the patients was 58.5 (range 28–94) years old, and the median time from diagnosis to GKS was 94 months (range 13–480 months). The median follow-up was 28.5 (range 12–49) months. Clinical outcomes were analyzed. Univariate and multivariate analyses were performed to evaluate factors that correlated with a favorable, pain-free outcome. Results: The mean time to relief of pain was 7 (range 1–40) days. The percentage of patients with significant pain relief was 93.3%. Relapse in pain was noted in four patients at 3, 16, 19, and 36 months. Nine patients were treated in acute status. Fourteen patients had intense pain between 1 and 7 days before the procedure. Among those with the recurrence of their symptoms, one patient had a microvascular decompression. Multivariate regression adjusted for age and sex suggests that, by 40 months, 70% of the patients treated with radiosurgery will remain pain free. At the last follow-up, GKS resulted in pain relief in 86.6% of patients. Our analysis suggests that, using this technique, we can expect that approximately 70% of patients with TN will have some degree of pain improvement at 3 years’ post radiosurgery. Conclusions: GKS on TG appears to be a reasonable treatment option with short latency period, minor collateral effects, and high percentage of pain control. The mechanism of action of radiosurgery could be related to the inactivation of the satellite glial cells in the TG.

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Long-term outcome of high-dose Gamma Knife surgery in treatment of trigeminal neuralgia

Journal of Neurosurgery ◽

10.3171/2013.1.jns12875 ◽

2013 ◽

Vol 119 (5) ◽

pp. 1166-1175 ◽

Cited By ~ 35

Author(s):

Byron Young ◽

Armin Shivazad ◽

Richard J. Kryscio ◽

William St. Clair ◽

Heather M. Bush

Keyword(s):

Quality Of Life ◽

Pain Relief ◽

Trigeminal Neuralgia ◽

Pain Intensity ◽

Gamma Knife ◽

Trigeminal Nerve ◽

Gamma Knife Surgery

Object Despite the widespread use of Gamma Knife surgery (GKS) for trigeminal neuralgia (TN), controversy remains regarding the optimal treatment dose and target site. Among the published studies, only a few have focused on long-term outcomes (beyond 2 years) using 90 Gy, which is in the higher range of treatment doses used (70–90 Gy). Methods The authors followed up on 315 consecutive patients treated with the Leksell Gamma Knife unit using a 4-mm isocenter without blocks. The isocenter was placed on the trigeminal nerve with the 20% isodose line tangential to the pontine surface (18 Gy). At follow-up, 33 patients were deceased; 282 were mailed an extensive questionnaire regarding their outcomes, but 32 could not be reached. The authors report their analysis of the remaining 250 cases. The patients' mean age at the time of survey response and the mean duration of follow-up were 70.8 ± 13.1 years and 68.9 ± 41.8 months, respectively. Results One hundred eighty-five patients (85.6%) had decreased pain intensity after GKS. Modified Marseille Scale (MMS) pain classifications after GKS at follow-up were: Class I (pain free without medication[s]) in 104 (43.7%), Class II (pain free with medication[s]) in 66 (27.7%), Class III (> 90% decrease in pain intensity) in 23 (9.7%), Class IV (50%–90% decrease in pain intensity) in 20 (8.4%), Class V (< 50% decrease in pain intensity) in 11 (4.6%), and Class VI (pain becoming worse) in 14 (5.9%). Therefore, 170 patients (71.4%) were pain free (Classes I and II) and 213 (89.5%) had at least 50% pain relief. All patients had pain that was refractory to medical management prior to GKS, but only 111 (44.4%) were being treated with medication at follow-up (p < 0.0001). Eighty patients (32.9%) developed numbness after GKS, and 74.5% of patients with numbness had complete pain relief. Quality of life and patient satisfaction on a 10-point scale were reported at mean values (± SD) of 7.8 ± 3.1 and 7.7 ± 3.4, respectively. Most of the patients (87.7%) would recommend GKS to another patient. Patients with prior surgical treatments had increased latency to pain relief and were more likely to continue medicines (p < 0.05). Moreover, presence of altered facial sensations prior to radiosurgery was associated with higher pain intensity, longer pain episodes, more frequent pain attacks, worse MMS pain classification, and more medication use after GKS (p < 0.05). Conversely, increase in numbness intensity after GKS was associated with a decrease in pain intensity and pain length (p < 0.05). Conclusions Gamma Knife surgery using a maximum dose of 90 Gy to the trigeminal nerve provides satisfactory long-term pain control, reduces the use of medication, and improves quality of life. Physicians must be aware that higher doses may be associated with an increase in bothersome sensory complications. The benefits and risks of higher dose selection must be carefully discussed with patients, since facial numbness, even if bothersome, may be an acceptable trade-off for patients with severe pain.

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Gamma Knife radiosurgery for bilateral trigeminal neuralgia

Journal of Neurosurgery ◽

10.3171/2018.6.jns172646 ◽

2019 ◽

Vol 131 (5) ◽

pp. 1591-1598

Author(s):

Corbin A. Helis ◽

Emory McTyre ◽

Michael T. Munley ◽

J. Daniel Bourland ◽

John T. Lucas ◽

...

Keyword(s):

Pain Relief ◽

Trigeminal Neuralgia ◽

Treatment Outcomes ◽

Gamma Knife ◽

Median Duration ◽

Gamma Knife Radiosurgery ◽

Persistent Symptoms ◽

Significant Difference ◽

Facial Numbness

OBJECTIVEA small subset of patients with trigeminal neuralgia (TN) will experience bilateral symptoms. Treatment in these patients is controversial because the population is heterogeneous and patients may have nonvascular etiologies of their pain. This study reports treatment outcomes in the largest cohort of patients with bilateral TN who have undergone Gamma Knife radiosurgery (GKRS) to date.METHODSA retrospective chart review identified 51 individual nerves in 34 patients with bilateral TN who were treated with GKRS at the authors’ institution between 2001 and 2015, with 12 nerves in 11 patients undergoing repeat GKRS for recurrent or persistent symptoms. Long-term follow-up was obtained by telephone interview. Pain outcomes were measured using the Barrow Neurological Institute (BNI) pain scale, with BNI IIIb or better considered a successful treatment.RESULTSThere was sufficient follow-up to determine treatment outcomes for 48 individual nerves in 33 patients. Of these nerves, 42 (88%) achieved at least BNI IIIb pain relief. The median duration of pain relief was 1.9 years, and 1-, 3-, and 5-year pain relief rates were 64%, 44%, and 44%, respectively. No patients experienced bothersome facial numbness, and 1 case of anesthesia dolorosa and 2 cases of corneal dryness were reported. Patients with a history of definite or possible multiple sclerosis were significantly more likely to experience BNI IV–V relapse. There was no statistically significant difference in treatment outcomes between patients in this series versus a large cohort of patients with unilateral TN treated at the authors’ institution. There was sufficient follow-up to determine treatment outcomes for 11 individual nerves in 10 patients treated with repeat GKRS. Ten nerves (91%) improved to at least BNI IIIb after treatment. The median duration of pain relief was 2.8 years, with 1-, 3-, and 5-year rates of pain relief of 79%, 53%, and 53%, respectively. There was no statistically significant difference in outcomes between initial and repeat GKRS. One case of bothersome facial numbness and 1 case of corneal dryness were reported, with no patients developing anesthesia dolorosa with retreatment.CONCLUSIONSGKRS is a safe, well-tolerated treatment for patients with medically refractory bilateral TN. Efficacy of treatment appears similar to that in patients with unilateral TN. GKRS can be safely repeated in this population if necessary.

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Biologically effective dose and prediction of obliteration of unruptured arteriovenous malformations treated by upfront Gamma Knife radiosurgery: a series of 149 consecutive cases

Journal of Neurosurgery ◽

10.3171/2020.4.jns201250 ◽

2020 ◽

pp. 1-11 ◽

Cited By ~ 1

Author(s):

Constantin Tuleasca ◽

Iulia Peciu-Florianu ◽

Henri-Arthur Leroy ◽

Maximilien Vermandel ◽

Mohamed Faouzi ◽

...

Keyword(s):

Radiation Dose ◽

Effective Dose ◽

Dose Rate ◽

Gamma Knife ◽

Arteriovenous Malformations ◽

Gamma Knife Radiosurgery ◽

Biologically Effective Dose ◽

Radiation Dose Rate ◽

The Mean

OBJECTIVEArteriovenous malformations (AVMs) present no pathologic tissue, and radiation dose is confined in a clear targeted volume. The authors retrospectively evaluated the role of the biologically effective dose (BED) after Gamma Knife radiosurgery (GKRS) for brain AVMs.METHODSA total of 149 consecutive cases of unruptured AVMs treated by upfront GKRS in Lille University Hospital, France, were included. The mean length of follow-up was 52.9 months (median 48, range 12–154 months). The primary outcome was obliteration, and the secondary outcome was complication appearance. The marginal dose was 24 Gy in a vast majority of cases (n = 115, 77.2%; range 18–25 Gy). The mean BED was 220.1 Gy2.47 (median 229.9, range 106.7–246.8 Gy2.47). The mean beam-on time was 32.3 minutes (median 30.8, range 9–138.7 minutes). In the present series, the mean radiation dose rate was 2.259 Gy/min (median 2.176, range 1.313–3.665 Gy/min). The Virginia score was 0 in 29 (19.5%), 1 in 61 (40.9%), 2 in 41 (27.5%), 3 in 18 (12.1%), and 4 in 0 (0%) patients, respectively. The mean Pollock-Flickinger score was 1.11 (median 1.52, range 0.4–2.9). Univariate (for obliteration and complication appearance) and multivariate (for obliteration only) analyses were performed.RESULTSA total of 104 AVMs (69.8%) were obliterated at the last follow-up. The strongest predictor for obliteration was BED (p = 0.03). A radiosurgical obliteration score is proposed, derived from a fitted multivariable model: (0.018 × BED) + (1.58 × V12) + (−0.013689 × beam-on time) + (0.021 × age) − 4.38. The area under the receiver operating characteristic curve was 0.7438; after internal validation using bootstrap methods, it was 0.7088. No statistically significant relationship between radiation dose rate and obliteration was found (p = 0.29). Twenty-eight (18.8%) patients developed complications after GKRS; 20 (13.4%) of these patients had transient adverse radiological effects (perilesional edema developed). Predictors for complication appearance were higher prescription isodose volume (p = 0.005) and 12-Gy isodose line volume (V12; p = 0.001), higher Pollock-Flickinger (p = 0.02) and Virginia scores (p = 0.003), and lower beam-on time (p = 0.03).CONCLUSIONSThe BED was the strongest predictor of obliteration of unruptured AVMs after upfront GKRS. A radiosurgical score comprising the BED is proposed. The V12 appears as a predictor for both efficacy and toxicity. Beam-on time was illustrated as statistically significant for both obliteration and complication appearance. The radiation dose rate did not influence obliteration in the current analysis. The exact BED threshold remains to be established by further studies.

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