Gamma Knife Radiosurgery (gamma + knife_radiosurgery)

Distribution by Scientific Domains


Selected Abstracts


Long-Term Hearing Results in Gamma Knife Radiosurgery for Acoustic Neuromas,

THE LARYNGOSCOPE, Issue 6 2008
Matthew L. Bush MD
Abstract Objectives: There are many studies that have examined functional outcomes following Gamma Knife treatment; however, few have reported long-term audiometric data. This study analyzed the long-term hearing results of Gamma Knife radiosurgery in the treatment of acoustic neuromas. Study Design: Retrospective cohort study. Methods: Seventeen patients were selected from our acoustic neuroma Gamma Knife registry of 113 patients treated from 1991 to 2005. Pretreatment audiograms were analyzed for pure-tone average and word recognition scores and assigned a Gardner-Robertson classification score (GRC). Either a current audiogram was obtained or the most recent audiogram (if the patient was lost to follow-up) was reviewed from clinic charts and these were compared with the preoperative results. Audiometric data of the pre- and posttreatment normal ear were obtained and used as the patient's own control. Results: The tumor size ranged from 0.5 to 2.8 cm (mean, 1.33 cm) and patients received a range of 12.5,16 Gy (mean, 13.82 Gy) to 50% isodose line. Patient follow-up ranged from 3 to 82 months with a mean of 33.6 months. Pretreatment pure-tone average for the involved side group was 30.6 dB HL with a word recognition score of 74%. Pretreatment mean GRC was 1.76. posttreatment pure-tone average for the group was 59.7 dB HL with a word recognition score of 37%. posttreatment mean GRC was 3.29. Comparing pre- versus post-Gamma Knife radiosurgery results on the treatment ear, means were statistically significantly different for both pure-tone average and word recognition scores, based on a paired-samples t test (P < .001 for both). The group "normal" ear pure-tone average was 14 dB HL and 17.75 dB HL pre- and posttreat-ment, respectively. Normal ear pre- and posttreatment word recognition score and GRC were 93% and 98%, and 1.13 and 1.31, respectively. Conclusion: Gamma Knife radiosurgery remains a noninvasive treatment option for patients with acoustic neuromas; however, they may experience a delayed hearing loss. Of those patients with useful audition pretreatment, 42% maintained useful hearing posttreatment. [source]


Proliferation Potential in Recurrent Acoustic Schwannoma Following Gamma Knife Radiosurgery versus Microsurgery,

THE LARYNGOSCOPE, Issue 6 2002
Frank Lee MD
Abstract Objective To evaluate the proliferation potential of recurrent acoustic schwannoma following gamma knife radiosurgery (GKR) versus microsurgery. Study Design Retrospective study. Methods A review of surgical records of the House Ear Clinic revealed 8 patients who had undergone GKR and 15 patients who had undergone microsurgery who had unilateral acoustic schwannoma recurrences. Immunohistochemical studies were performed to evaluate the expression of proliferating cell nuclear antigen (PCNA) on archival paraffin-embedded blocks. Results All 8 GKR and 15 microsurgical tumors had positive staining for PCNA. The recurrent GKR tumors had significantly lower proliferation levels than in the microsurgical group (P = .03). Two GKR tumors had high proliferation levels. Conclusions Our study indicates that recurrent vestibular schwannomas treated with GKR have lower proliferation potential as assessed by PCNA compared with recurrences following microsurgery. Radiation-induced apoptosis is thought to contribute to the lower tumor cell proliferation in GKR tumor. The two GKR tumors with high proliferation potential could be a result of radiation-induced sporadic mutation, resulting in high tumor cell proliferation. [source]


Long-Term Hearing Results in Gamma Knife Radiosurgery for Acoustic Neuromas,

THE LARYNGOSCOPE, Issue 6 2008
Matthew L. Bush MD
Abstract Objectives: There are many studies that have examined functional outcomes following Gamma Knife treatment; however, few have reported long-term audiometric data. This study analyzed the long-term hearing results of Gamma Knife radiosurgery in the treatment of acoustic neuromas. Study Design: Retrospective cohort study. Methods: Seventeen patients were selected from our acoustic neuroma Gamma Knife registry of 113 patients treated from 1991 to 2005. Pretreatment audiograms were analyzed for pure-tone average and word recognition scores and assigned a Gardner-Robertson classification score (GRC). Either a current audiogram was obtained or the most recent audiogram (if the patient was lost to follow-up) was reviewed from clinic charts and these were compared with the preoperative results. Audiometric data of the pre- and posttreatment normal ear were obtained and used as the patient's own control. Results: The tumor size ranged from 0.5 to 2.8 cm (mean, 1.33 cm) and patients received a range of 12.5,16 Gy (mean, 13.82 Gy) to 50% isodose line. Patient follow-up ranged from 3 to 82 months with a mean of 33.6 months. Pretreatment pure-tone average for the involved side group was 30.6 dB HL with a word recognition score of 74%. Pretreatment mean GRC was 1.76. posttreatment pure-tone average for the group was 59.7 dB HL with a word recognition score of 37%. posttreatment mean GRC was 3.29. Comparing pre- versus post-Gamma Knife radiosurgery results on the treatment ear, means were statistically significantly different for both pure-tone average and word recognition scores, based on a paired-samples t test (P < .001 for both). The group "normal" ear pure-tone average was 14 dB HL and 17.75 dB HL pre- and posttreat-ment, respectively. Normal ear pre- and posttreatment word recognition score and GRC were 93% and 98%, and 1.13 and 1.31, respectively. Conclusion: Gamma Knife radiosurgery remains a noninvasive treatment option for patients with acoustic neuromas; however, they may experience a delayed hearing loss. Of those patients with useful audition pretreatment, 42% maintained useful hearing posttreatment. [source]


Radiosurgical treatment of vestibular schwannomas in patients with neurofibromatosis type 2

CANCER, Issue 2 2009
Tumor control, hearing preservation
Abstract BACKGROUND: The radiosurgical treatment of vestibular schwannomas in patients with neurofibromatosis type 2 (NF2) is controversial. The authors investigated the radiologically proven tumor control rate after gamma knife radiosurgery. The factors that affect tumor control and serviceable hearing preservation were analyzed. METHODS: Thirty-six lesions in 30 patients were included. The median lengths of the clinical and radiologic follow-ups were 48.5 months and 36.5 months, respectively. The median tumor volume was 3.2 cm3. The mean marginal dose was 12.1 grays (Gy) (range, 8,14 Gy) at an isodose line of 50%0.6%. The Kaplan-Meier method and Cox proportional hazards model were used for the statistical analyses. RESULTS: The actuarial tumor control rate was 81%, 74%, and 66%, respectively, in the first, second, and fifth years. Five tumors required a salvage surgery because of tumor control failure. A low marginal dose and a young age at radiosurgery were associated with poor tumor control. Of the 16 tumors with which ipsilateral hearing was serviceable, the actuarial serviceable hearing preservation rates were 50%, 45%, and 33%, respectively, in the first, second, and fifth years. Better ipsilateral hearing (Gardner-Robertson grade 1, compared with grade 2) at the time of radiosurgery was associated with significantly greater serviceable hearing preservation. CONCLUSIONS: Gamma knife radiosurgery for vestibular schwannomas in NF2 patients provided 5-year tumor control in approximately two-thirds of patients and preserved serviceable hearing in approximately one-third. The rates of other cranial nerve deficits were low, and no secondary malignancy was observed. Radiosurgery should be included in treatment options for NF2 patients. Cancer 2009. 2009 American Cancer Society. [source]


Repeat Trigeminal Nerve Radiosurgery for Refractory Cluster Headache Fails to Provide Long-Term Pain Relief

HEADACHE, Issue 2 2007
Shearwood McClelland III MD
Objective/Background.,Medically refractory cluster headache (MRCH) is a debilitating condition that has proven resistant to many modalities. Previous reports have indicated that radiosurgery for MRCH provides little long-term pain relief, with moderate/significant morbidity. However, there have been no reports of repeated radiosurgery in this patient population. We present our findings from the first reports of repeat radiosurgery for MRCH. Methods.,Two patients with MRCH underwent repeat gamma knife radiosurgery at our institution. Each fulfilled clinical criteria for treatment, including complete resistance to pharmacotherapy, pain primarily localized to the ophthalmic division of the trigeminal nerve, and psychological stability. Both patients previously received gamma knife radiosurgery (75 Gy) for MRCH with no morbidity, but no long-term improvement of pain relief (Patient 1 = 5 months, Patient 2 = 10 months) after treatment. For repeat radiosurgery, each patient received 75 Gy to the 100% isodose line delivered to the root entry zone of the trigeminal nerve, and was evaluated postretreatment. Pain relief was defined as: excellent (free of MRCH with minimal/no medications), good (50% reduction of MRCH severity/frequency with medications), fair (25% reduction), or poor (less than 25% reduction). Results.,Following repeat radiosurgery, long-term pain relief was poor in both patients. Neither patient sustained any immediate morbidity following radiosurgery. Patient 2 experienced right facial numbness 4 months postretreatment, while Patient 1 experienced no morbidity. Conclusion.,Repeat radiosurgery of the trigeminal nerve fails to provide long-term pain relief for MRCH. Given the reported failures of initial and repeat radiosurgery for MRCH, trigeminal nerve radiosurgery should not be offered for MRCH. [source]


MR angiography fusion technique for treatment planning of intracranial arteriovenous malformations

JOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 3 2006
Kiaran P. McGee PhD
Abstract Purpose To develop an image fusion technique using elliptical centric contrast-enhanced (CE) MR angiography (MRA) and three-dimensional (3D) time-of-flight (TOF) acquisitions for radiosurgery treatment planning of arteriovenous malformations (AVMs). Materials and Methods CE and 3D-TOF MR angiograms with disparate in-plane fields of view (FOVs) were acquired, followed by k-space reformatting to provide equal voxel dimensions. Spatial domain addition was performed to provide a third, fused data volume. Spatial distortion was evaluated on an MRA phantom and provided slice-dependent and global distortion along the three physical dimensions of the MR scanner. In vivo validation was performed on 10 patients with intracranial AVMs prior to their conventional angiogram on the day of gamma knife radiosurgery. Results Spatial distortion in the phantom within a volume of 14 14 3.2 cm3 was less than 1 mm (1 standard deviation (SD)) for CE and 3D-TOF data sets. Fused data volumes were successfully generated for all 10 patients. Conclusion Image fusion can be used to obtain high-resolution CE-MRA images of intracranial AVMs while keeping the fiducial markers needed for gamma knife radiosurgery planning. The spatial fidelity of these data is within the tolerance acceptable for daily quality control (QC) purposes and gamma knife treatment planning. J. Magn. Reson. Imaging 2006. 2006 Wiley-Liss, Inc. [source]


Proliferation Potential in Recurrent Acoustic Schwannoma Following Gamma Knife Radiosurgery versus Microsurgery,

THE LARYNGOSCOPE, Issue 6 2002
Frank Lee MD
Abstract Objective To evaluate the proliferation potential of recurrent acoustic schwannoma following gamma knife radiosurgery (GKR) versus microsurgery. Study Design Retrospective study. Methods A review of surgical records of the House Ear Clinic revealed 8 patients who had undergone GKR and 15 patients who had undergone microsurgery who had unilateral acoustic schwannoma recurrences. Immunohistochemical studies were performed to evaluate the expression of proliferating cell nuclear antigen (PCNA) on archival paraffin-embedded blocks. Results All 8 GKR and 15 microsurgical tumors had positive staining for PCNA. The recurrent GKR tumors had significantly lower proliferation levels than in the microsurgical group (P = .03). Two GKR tumors had high proliferation levels. Conclusions Our study indicates that recurrent vestibular schwannomas treated with GKR have lower proliferation potential as assessed by PCNA compared with recurrences following microsurgery. Radiation-induced apoptosis is thought to contribute to the lower tumor cell proliferation in GKR tumor. The two GKR tumors with high proliferation potential could be a result of radiation-induced sporadic mutation, resulting in high tumor cell proliferation. [source]


A multicenter, prospective pilot study of gamma knife radiosurgery for mesial temporal lobe epilepsy: Seizure response, adverse events, and verbal memory,

ANNALS OF NEUROLOGY, Issue 2 2009
Nicholas M. Barbaro MD
Objective The safety, efficacy, and morbidity of radiosurgery (RS) must be established before it can be offered as an alternative to open surgery for unilateral mesial temporal lobe epilepsy. We report the 3-year outcomes of a multicenter, prospective pilot study of RS. Methods RS was randomized to 20 or 24Gy targeting the amygdala, hippocampus, and parahippocampal gyrus. Seizure diaries evaluated the final seizure remission between months 24 and 36. Verbal memory was evaluated at baseline and 24m with the Wechsler Memory Scale,Revised (WMS-R) and California Verbal Learning Test (CVLT). Patients were classified as having "significant improvement," "no change," and "significant impairment" based on relative change indices. Results Thirteen high-dose and 17 low-dose patients were treated. Both groups showed significant reductions in seizures by 1 year after treatment. At the 36-month follow-up evaluation, 67% of patients were free of seizures for the prior 12 months (high dose: 10/13, 76.9%; low dose: 10/17, 58.8%). Use of steroids, headaches, and visual field defects did not differ by dose or seizure remission. The prevalence of verbal memory impairment was 15% (4/26 patients); none declined on more than one measure. The prevalence of significant verbal memory improvements was 12% (3/26). Interpretation RS for unilateral mesial temporal lobe epilepsy offers seizure remission rates comparable with those reported previously for open surgery. There were no major safety concerns with high-dose RS compared with low-dose RS. Additional research is required to determine whether RS may be a treatment option for some patients with mesial temporal lobe epilepsy. Ann Neurol 2009 [source]


Radiosurgical treatment of vestibular schwannomas in patients with neurofibromatosis type 2

CANCER, Issue 2 2009
Tumor control, hearing preservation
Abstract BACKGROUND: The radiosurgical treatment of vestibular schwannomas in patients with neurofibromatosis type 2 (NF2) is controversial. The authors investigated the radiologically proven tumor control rate after gamma knife radiosurgery. The factors that affect tumor control and serviceable hearing preservation were analyzed. METHODS: Thirty-six lesions in 30 patients were included. The median lengths of the clinical and radiologic follow-ups were 48.5 months and 36.5 months, respectively. The median tumor volume was 3.2 cm3. The mean marginal dose was 12.1 grays (Gy) (range, 8,14 Gy) at an isodose line of 50%0.6%. The Kaplan-Meier method and Cox proportional hazards model were used for the statistical analyses. RESULTS: The actuarial tumor control rate was 81%, 74%, and 66%, respectively, in the first, second, and fifth years. Five tumors required a salvage surgery because of tumor control failure. A low marginal dose and a young age at radiosurgery were associated with poor tumor control. Of the 16 tumors with which ipsilateral hearing was serviceable, the actuarial serviceable hearing preservation rates were 50%, 45%, and 33%, respectively, in the first, second, and fifth years. Better ipsilateral hearing (Gardner-Robertson grade 1, compared with grade 2) at the time of radiosurgery was associated with significantly greater serviceable hearing preservation. CONCLUSIONS: Gamma knife radiosurgery for vestibular schwannomas in NF2 patients provided 5-year tumor control in approximately two-thirds of patients and preserved serviceable hearing in approximately one-third. The rates of other cranial nerve deficits were low, and no secondary malignancy was observed. Radiosurgery should be included in treatment options for NF2 patients. Cancer 2009. 2009 American Cancer Society. [source]