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Trigeminal Neuralgia Treated With Stereotactic Radiosurgery: An Analysis of Dose and Dose-Rate on Pain Control and Treatment Outcomes
E466
International Journal of Radiation Oncology Biology Physics
risk of heterotopic ossification (HO) for superior optimization of prophylactic radiation therapy (RT) delivery. Materials/Methods: This is a single-institution retrospective analysis of patients referred for postoperative RT for HO prevention. From January 1998 through January 2010, 619 patients with DAF were treated surgically followed by RT. One hundred twenty-four patients (20%) underwent CT-based simulation and treatment planning, and 80% underwent a “clinical setup.” All patients received a single fraction of 700 cGy to the midplane using 6 - 18 MV photons (AP/PA portals). Fields were designed to include the soft tissues around the hip joint. No bone shielding or sparing of a skin strip was attempted. In all patients, RT was delivered within 72 hours post-surgery. Heterotopic ossification occurrence was evaluated by standard x-rays by 3 independent reviewers (radiologist, orthopedic surgeon, and radiation oncologist). We classified the sites of HO formation into 5 anatomical compartments; Compartment A, B, C, D, and E corresponding to the anterior, posterior, superior, medial, and lateral to the femur, respectively. Results: The median patient age was 34, range (13 - 85). The median BMI was 28.5, range (17 - 65). The causes of the DAF were: fall 45 (7%) and motor vehicle accident 574 (93%). The median time intervals from fracture to surgery and surgery to RT were 1 and 1 day, respectively. Four hundred nine (66%) were male, while 210 (34%) were female. Ethnically, 321 (52%) were African-American, 283 (46%) Caucasian, and 15 (2%) others. Two hundred seventy-two (44%) injured their left hip, and 347 (56%) had a right hip fracture. Two hundred ninety-one (47%) patients received RT alone, 261 (42%) were given RT + indomethacin, and 67 (11%) received RT + other (analgesics). At a median follow-up of 10 months (range 3120), the incidence of HO, despite prophylactic measures, was 17% (108/ 619). Specifically, the incidence of Brooker grade 1, 2, 3, and 4 were 12, 41, 36, and 11%, respectively. The pattern of failures within the RT field in compartment A, B, C, D, and E were 30, 50, 96, 55, and 40%, respectively. Of note, the extent of HO in compartments A, B, and E correlated with Brooker Grades 3 and 4, while those in compartments C and D correlated to Brooker Grades 1 and 2. Conclusion: Our data suggest that there is higher incidence and risk of HO formation within the RT field in the superior and medial soft tissue compartments around femur after DAF despite prophylactic measures. As the severity of HO progresses, the likelihood of involvement of all the soft tissues around the hip joint seems inevitable. Computed tomography-based planning and dos- painting to optimize dose delivery to the superior and medial soft tissues surrounding the femur may be a reasonable approach to maximize local control and functional outcomes. Author Disclosure: W.F. Mourad: None. S. Packianathan: None. G.V. Russell: None. J.K. Ma: None. R.A. Shourbaji: None. M. Ryniak: None. B.M. Rabatic: None. D. Zaenger: None. R. He: None. P.N. Mobit: None. C. Yang: None. D. Shasha: None. S. Vijayakumar: None.
visit, each patient’s pain was defined as excellent if the patient was painfree and off medications; good if they had rare pain or pain free on doses of medications not producing side effects; fair if they had persistent pain but less severe than prior to treatment; or poor if they had no significant response to therapy. Cox proportional hazards modeling was performed to determine time to pain failure (fair or poor pain control). Results: Median age at first pain onset was 63 years, median age at time of SRS was 71 years, and median follow-up was 36.5 months from the time of SRS. A majority of patients (828, 95%) were clinically diagnosed with typical trigeminal neuralgia. Pain was localized to the V1 (236, 27%), V2 (634, 73%), and V3 (499, 57%) nerve distribution. Fifty-five patients (6%) never responded to treatment were excluded. The 5 and 10-year rates of excellent to good pain relief were 84% (95%CI: 80-87%) and 69% (95% CI 62-75%). The 4-year rate of sustained pain response was 79%, 82%, and 89% in patients treated to 82 Gy, 83-86 Gy, and 90 Gy, respectively. When analyzed by tercile, patients treated to 82 Gy had an increased risk of pain failure following SRS compared to patients treated to 90 Gy (HR 2.0, PZ.0007). The median dose rate (dose/treatment time) across all patients was 1.7 Gy/minute. Patients treated with dose rates <1.7 Gy/ minute had an increased risk of pain failure compared to patients treated with higher dose rates (HR 1.5, PZ.04); moreover, when dose rate was evaluated as a continuous variable, a higher dose-rate was also associated with decreased risk for pain recurrence (PZ.03). Nine patients (1%) were diagnosed with anesthesia dolorosa. Conclusion: Patients with typical TN have high-initial response rates to SRS and patients treated to higher doses (>82Gy) are more likely to have a sustained response to treatment as are patients treated at dose rates exceeding <1.7 Gy/minute. The effect of these variables on treatmentrelated side effects, such as numbness, will provide valuable comparable information for determining the most appropriate treatment parameters. The effects of these radiation variables should be verified in a larger consortium-based analysis. Author Disclosure: R. Kotecha: None. S. Modugula: None. E.S. Murphy: None. M.W. Jones: None. R.P. Kotecha: Partner; East Central Michigan Radiation Oncology Associates. D. Ouillette: None. C.A. Reddy: None. N.M. Woody: None. J.H. Suh: Consultant; Varian Medical Systems. G. Barnett: None. A. Machado: Consultant; Functional Neuromodulation, Spinal Modulation. Distribution rights from intellectual property; Autonomic Technologies, CardioNomic, Enspire DBS. S. Nagel: None. G. Neyman: Consultant; Elekta. S.T. Chao: Speaker’s Bureau; Varian Medical Systems.
3164 Trigeminal Neuralgia Treated With Stereotactic Radiosurgery: An Analysis of Dose and Dose-Rate on Pain Control and Treatment Outcomes R. Kotecha,1 S. Modugula,1 E.S. Murphy,1 M.W. Jones,2 R.P. Kotecha,3 D. Ouillette,2 C.A. Reddy,1 N.M. Woody,1 J.H. Suh,1 G. Barnett,1 A. Machado,1 S. Nagel,1 G. Neyman,1 and S.T. Chao1; 1Cleveland Clinic, Cleveland, OH, 2MidMichigan Health, Midland, MI, 3ECMRO, Midland, MI Purpose/Objective(s): To analyze the effect of dose and dose-rate on treatment outcome in patients undergoing stereotactic radiosurgery (SRS) for trigeminal neuralgia. Materials/Methods: A retrospective review was performed of patient records for 871 patients who underwent SRS for a diagnosis of trigeminal neuralgia (TN) from two institutions. All patients were treated using a single 4mm isocenter placed on the root of the trigeminal (V) nerve. Patients were divided into terciles based on treatment doses 82 Gy (353 patients), 83-86 Gy (85 patients), and 90 Gy (433 patients) prescribed to the 100% isodose line. For dose calculation the “effective” 4mm output was 0.87 before Perfexion device and 0.814 afterwards. At each follow-up
3165 First In-Human Stereotactic Arrhythmia Radioablation (STAR) of Ventricular Tachycardia: Dynamic Tracking Delivery Analysis and Implications B.P. Fahimian,1 B.W. Loo, Jr,1 S.G. Soltys,1 P. Zei,1 A.T. Lo,1 P.J. Maguire,2 E. Gardner,2 and L. Wang1; 1Stanford University, Stanford, CA, 2CyberHeart Inc., Mountain View, CA Purpose/Objective(s): Ablative radiosurgery of functional cardiac disorders such as arrhythmias may provide an alternative to patients that have either failed or have medical contra-indications to conventional techniques; however, a primary challenge to the implementation of stereotactic arrhythmia radio-ablation (STAR) is the adequate compensation of the target motion. In this work, we presented the dynamic tracking data of the first inhuman radio-ablation of ventricular tachycardia (VT). Through analysis of during-treatment images and tracking surrogate data taken throughout the patient treatment, we determined the tracking accuracy and attaining the first in-patient estimate of the motion margin necessary for such treatments. Materials/Methods: To enable radiographic tracking of the heart, a temporary fiducial in the form of a pacing wire was placed on the ventricular apex under fluoroscopic guidance. The ablation volume for the circumferential VT substrate was contoured by the electrophysiologist using commercial software, from which an expansion to include the interior volume plus a 5mm margin yielded the PTV. A dose of 25 Gy to the 75% isodose line was optimized on the radiosurgery platform and configured for
International Journal of Radiation Oncology Biology Physics
risk of heterotopic ossification (HO) for superior optimization of prophylactic radiation therapy (RT) delivery. Materials/Methods: This is a single-institution retrospective analysis of patients referred for postoperative RT for HO prevention. From January 1998 through January 2010, 619 patients with DAF were treated surgically followed by RT. One hundred twenty-four patients (20%) underwent CT-based simulation and treatment planning, and 80% underwent a “clinical setup.” All patients received a single fraction of 700 cGy to the midplane using 6 - 18 MV photons (AP/PA portals). Fields were designed to include the soft tissues around the hip joint. No bone shielding or sparing of a skin strip was attempted. In all patients, RT was delivered within 72 hours post-surgery. Heterotopic ossification occurrence was evaluated by standard x-rays by 3 independent reviewers (radiologist, orthopedic surgeon, and radiation oncologist). We classified the sites of HO formation into 5 anatomical compartments; Compartment A, B, C, D, and E corresponding to the anterior, posterior, superior, medial, and lateral to the femur, respectively. Results: The median patient age was 34, range (13 - 85). The median BMI was 28.5, range (17 - 65). The causes of the DAF were: fall 45 (7%) and motor vehicle accident 574 (93%). The median time intervals from fracture to surgery and surgery to RT were 1 and 1 day, respectively. Four hundred nine (66%) were male, while 210 (34%) were female. Ethnically, 321 (52%) were African-American, 283 (46%) Caucasian, and 15 (2%) others. Two hundred seventy-two (44%) injured their left hip, and 347 (56%) had a right hip fracture. Two hundred ninety-one (47%) patients received RT alone, 261 (42%) were given RT + indomethacin, and 67 (11%) received RT + other (analgesics). At a median follow-up of 10 months (range 3120), the incidence of HO, despite prophylactic measures, was 17% (108/ 619). Specifically, the incidence of Brooker grade 1, 2, 3, and 4 were 12, 41, 36, and 11%, respectively. The pattern of failures within the RT field in compartment A, B, C, D, and E were 30, 50, 96, 55, and 40%, respectively. Of note, the extent of HO in compartments A, B, and E correlated with Brooker Grades 3 and 4, while those in compartments C and D correlated to Brooker Grades 1 and 2. Conclusion: Our data suggest that there is higher incidence and risk of HO formation within the RT field in the superior and medial soft tissue compartments around femur after DAF despite prophylactic measures. As the severity of HO progresses, the likelihood of involvement of all the soft tissues around the hip joint seems inevitable. Computed tomography-based planning and dos- painting to optimize dose delivery to the superior and medial soft tissues surrounding the femur may be a reasonable approach to maximize local control and functional outcomes. Author Disclosure: W.F. Mourad: None. S. Packianathan: None. G.V. Russell: None. J.K. Ma: None. R.A. Shourbaji: None. M. Ryniak: None. B.M. Rabatic: None. D. Zaenger: None. R. He: None. P.N. Mobit: None. C. Yang: None. D. Shasha: None. S. Vijayakumar: None.
visit, each patient’s pain was defined as excellent if the patient was painfree and off medications; good if they had rare pain or pain free on doses of medications not producing side effects; fair if they had persistent pain but less severe than prior to treatment; or poor if they had no significant response to therapy. Cox proportional hazards modeling was performed to determine time to pain failure (fair or poor pain control). Results: Median age at first pain onset was 63 years, median age at time of SRS was 71 years, and median follow-up was 36.5 months from the time of SRS. A majority of patients (828, 95%) were clinically diagnosed with typical trigeminal neuralgia. Pain was localized to the V1 (236, 27%), V2 (634, 73%), and V3 (499, 57%) nerve distribution. Fifty-five patients (6%) never responded to treatment were excluded. The 5 and 10-year rates of excellent to good pain relief were 84% (95%CI: 80-87%) and 69% (95% CI 62-75%). The 4-year rate of sustained pain response was 79%, 82%, and 89% in patients treated to 82 Gy, 83-86 Gy, and 90 Gy, respectively. When analyzed by tercile, patients treated to 82 Gy had an increased risk of pain failure following SRS compared to patients treated to 90 Gy (HR 2.0, PZ.0007). The median dose rate (dose/treatment time) across all patients was 1.7 Gy/minute. Patients treated with dose rates <1.7 Gy/ minute had an increased risk of pain failure compared to patients treated with higher dose rates (HR 1.5, PZ.04); moreover, when dose rate was evaluated as a continuous variable, a higher dose-rate was also associated with decreased risk for pain recurrence (PZ.03). Nine patients (1%) were diagnosed with anesthesia dolorosa. Conclusion: Patients with typical TN have high-initial response rates to SRS and patients treated to higher doses (>82Gy) are more likely to have a sustained response to treatment as are patients treated at dose rates exceeding <1.7 Gy/minute. The effect of these variables on treatmentrelated side effects, such as numbness, will provide valuable comparable information for determining the most appropriate treatment parameters. The effects of these radiation variables should be verified in a larger consortium-based analysis. Author Disclosure: R. Kotecha: None. S. Modugula: None. E.S. Murphy: None. M.W. Jones: None. R.P. Kotecha: Partner; East Central Michigan Radiation Oncology Associates. D. Ouillette: None. C.A. Reddy: None. N.M. Woody: None. J.H. Suh: Consultant; Varian Medical Systems. G. Barnett: None. A. Machado: Consultant; Functional Neuromodulation, Spinal Modulation. Distribution rights from intellectual property; Autonomic Technologies, CardioNomic, Enspire DBS. S. Nagel: None. G. Neyman: Consultant; Elekta. S.T. Chao: Speaker’s Bureau; Varian Medical Systems.
3164 Trigeminal Neuralgia Treated With Stereotactic Radiosurgery: An Analysis of Dose and Dose-Rate on Pain Control and Treatment Outcomes R. Kotecha,1 S. Modugula,1 E.S. Murphy,1 M.W. Jones,2 R.P. Kotecha,3 D. Ouillette,2 C.A. Reddy,1 N.M. Woody,1 J.H. Suh,1 G. Barnett,1 A. Machado,1 S. Nagel,1 G. Neyman,1 and S.T. Chao1; 1Cleveland Clinic, Cleveland, OH, 2MidMichigan Health, Midland, MI, 3ECMRO, Midland, MI Purpose/Objective(s): To analyze the effect of dose and dose-rate on treatment outcome in patients undergoing stereotactic radiosurgery (SRS) for trigeminal neuralgia. Materials/Methods: A retrospective review was performed of patient records for 871 patients who underwent SRS for a diagnosis of trigeminal neuralgia (TN) from two institutions. All patients were treated using a single 4mm isocenter placed on the root of the trigeminal (V) nerve. Patients were divided into terciles based on treatment doses 82 Gy (353 patients), 83-86 Gy (85 patients), and 90 Gy (433 patients) prescribed to the 100% isodose line. For dose calculation the “effective” 4mm output was 0.87 before Perfexion device and 0.814 afterwards. At each follow-up
3165 First In-Human Stereotactic Arrhythmia Radioablation (STAR) of Ventricular Tachycardia: Dynamic Tracking Delivery Analysis and Implications B.P. Fahimian,1 B.W. Loo, Jr,1 S.G. Soltys,1 P. Zei,1 A.T. Lo,1 P.J. Maguire,2 E. Gardner,2 and L. Wang1; 1Stanford University, Stanford, CA, 2CyberHeart Inc., Mountain View, CA Purpose/Objective(s): Ablative radiosurgery of functional cardiac disorders such as arrhythmias may provide an alternative to patients that have either failed or have medical contra-indications to conventional techniques; however, a primary challenge to the implementation of stereotactic arrhythmia radio-ablation (STAR) is the adequate compensation of the target motion. In this work, we presented the dynamic tracking data of the first inhuman radio-ablation of ventricular tachycardia (VT). Through analysis of during-treatment images and tracking surrogate data taken throughout the patient treatment, we determined the tracking accuracy and attaining the first in-patient estimate of the motion margin necessary for such treatments. Materials/Methods: To enable radiographic tracking of the heart, a temporary fiducial in the form of a pacing wire was placed on the ventricular apex under fluoroscopic guidance. The ablation volume for the circumferential VT substrate was contoured by the electrophysiologist using commercial software, from which an expansion to include the interior volume plus a 5mm margin yielded the PTV. A dose of 25 Gy to the 75% isodose line was optimized on the radiosurgery platform and configured for