SEARCH · PubMed Health

Results for “Radiosurgery”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 55 records · Page 3Linked to original sources

PubMed2005

Where to locate the isocenter? The treatment strategy for repeat trigeminal neuralgia radiosurgery.

PURPOSE: The purpose of this study is to investigate how the spatial relationship between the isocenters of the first and second radiosurgeries affects the overall outcome. METHODS AND MATERIALS: We performed a retrospective study on 40 patients who had repeat gamma knife radiosurgery for trigeminal neuralgia. Only one 4-mm isocenter was applied in both first and second radiosurgeries, with a maximum radiation dose of 75 Gy and 40 Gy, respectively. The MR scan of the first radiosurgery was registered to that of the second radiosurgery by a landmark-based registration algorithm. The spatial relationship between the isocenter of the first and the second radiosurgeries was thus determined. The investigating parameters were the distance between the isocenters of the two separate radiosurgeries and isocenter proximity to the brainstem. The outcome end points were pain relief and dysesthesias. The median follow-up for the repeat radiosurgery was 28 months (range, 6-51 months). RESULTS: Pain relief was complete in 11 patients, nearly complete (> or =90%) in 7 patients, partial (> or =50%) in 8 patients, and minimal (<50%) or none in another 14 patients. The mean distance between the two isocenters was 2.86 mm in the complete or nearly complete pain relief group vs. 1.93 mm in the others. Farther distance between isocenters was associated with a trend toward better pain relief (p = 0.057). The proximity of the second isocenter to the brainstem did not affect pain relief, and neither did placing the second isocenter proximal or distal to the brainstem compared with the first one. Three patients developed moderate dysesthesias (score of 4 on a 0-10 scale), and 2 other patients developed more significant dysesthesias (score of 7) after the second radiosurgery. Dysesthesias related neither to distance between isocenters nor to which isocenter was closer to the brainstem. CONCLUSIONS: Image registration between MR scans of the first and second radiosurgeries helps target delineation and radiosurgery treatment planning. Increasing the isocenter distance between the two radiosurgeries treated a longer segment of the trigeminal neuralgia nerve and was associated with a trend toward improved pain relief.

Adult↗

PubMed2004

Image-guided radiosurgery of head and neck cancers.

OBJECTIVES: Radiosurgery precisely delivers a single high dose or a few fractionated doses of radiation to a localized tumor via the stereotactic approach. Some head and neck sites are suitable for radiosurgery since there is minimal or no organ motion. The clinical studies were carried out to determine the accuracy of stereotactic radiosurgery and to demonstrate the effectiveness of radiosurgery in head and neck cancers. MATERIALS AND METHODS: Thirteen patients were treated with either single-dose or fractionated radiosurgery to the tumor. All patients except one with cancer of the lip had received prior treatments including surgery, radiotherapy, and chemotherapy for the primary cancers. The dose ranged 12 to 18 Gy for single-dose radiosurgery and 30 Gy in 5 or 6 fractions twice a week for fractionated radiosurgery. Tumor localization was achieved via the stereotactic approach. RESULTS: Accuracy of radiosurgery was within 1.5 mm. Despite the recurrent disease from previous heavy treatments, 9 patients (70%) showed a significant response (complete or >50% tumor reduction) to radiosurgery, and 3 patients had stable disease. Complete tumor response was achieved in 6 patients. All patients had excellent pain relief with functional and cosmetic preservation. There was no acute and subacute radiation toxicity detected clinically during the minimal follow-up of 6 months. CONCLUSION: Image-guided radiosurgery is effective in achieving the local tumor control and pain relief. Radiosurgery provided excellent functional and cosmetic preservation with minimal complication. The results indicate the potential of radiosurgery in the treatment of recurrent and selected primary head and neck cancers.

Carcinoma, Squamous Cell↗

PubMed2002

Stereotactic radiosurgery: the preferred management for patients with nonvestibular schwannomas?

PURPOSE: To review patient outcomes after radiosurgery of nonvestibular schwannomas. MATERIALS AND METHODS: From April 1992 to February 2000, 23 patients had radiosurgery at our center for nonvestibular schwannomas. Affected cranial nerves included the trochlear (n = 1), trigeminal (n = 10), jugular foramen region (n = 10), and hypoglossal (n = 2). Nine patients had undergone one or more prior tumor resections. One patient had a malignant schwannoma; 2 patients had neurofibromatosis. The median prescription isodose volume was 8.9 cc (range, 0.2 to 17.6 cc). The median tumor margin dose was 18 Gy (range, 12 to 20 Gy); the median maximum dose was 36 Gy (range, 24 to 40 Gy). The median follow-up after radiosurgery was 43 months (range, 12 to 111 months). RESULTS: Twenty-two of 23 tumors (96%) were either smaller (n = 12) or unchanged in size (n = 10) after radiosurgery. One patient with a malignant schwannoma had tumor progression outside the irradiated volume despite having both radiosurgery and fractionated radiation therapy (50.4 Gy); he died 4 years later. Morbidity related to radiosurgery occurred in 4 patients (17%). Three of 10 patients with trigeminal schwannomas suffered new or worsened trigeminal dysfunction after radiosurgery. One patient with a hypoglossal schwannoma had eustachian tube dysfunction after radiosurgery. No patient with a lower cranial nerve schwannoma developed any hearing loss, facial weakness, or swallowing difficulty after radiosurgery. CONCLUSIONS: Although the reported number of patients having radiosurgery for nonvestibular schwannomas is limited, the high tumor control rates demonstrated after vestibular schwannoma radiosurgery should apply to these rare tumors. Compared to historical controls treated with surgical resection, radiosurgery appears to have less treatment-associated morbidity for nonvestibular schwannomas, especially for schwannomas involving the lower cranial nerves.

Adolescent↗

PubMed1997

A cost-effectiveness and cost-utility analysis of radiosurgery vs. resection for single-brain metastases.

PURPOSE: The median survival of well-selected patients with single-brain metastases treated with whole-brain irradiation and resection or radiosurgery is comparable, although a randomized trial of these two modalities has not been performed. In this era of cost containment, it is imperative that health-care professionals make fiscally prudent decisions. The present environment necessitates a critical appraisal of apparently equi-efficacious therapeutic modalities, and it is within this context that we present a comparison of the actual costs of resection and radiosurgery for brain metastases. METHODS AND MATERIALS: Survival and quality of life outcome data for radiation alone or with surgery were obtained from two randomized trials, and radiosurgical results were obtained from a multiinstitutional analysis that specifically evaluated patients meeting surgical criteria. Only linear accelerator radiosurgery data were considered. Cost analysis was performed from a societal view point, and the following parameters were evaluated: actual cost, cost ratios, cost effectiveness, incremental cost effectiveness, cost utility, incremental cost utility, and national cost burden. The computerized billing records for all patients undergoing resection or radiosurgery for single-brain metastases from January 1989 to July 1994 were reviewed. A total of 46 resections and 135 radiosurgery procedures were performed. During the same time period, 454 patients underwent whole-brain radiation alone. An analysis of the entire bill was performed for each procedure, and each itemized cost was assigned a proportionate figure. The relative cost ratios of resection and radiosurgery were compared using the Wilcoxon rank sum test. Cost effectiveness of each modality, defined as the cost per year of median survival, was evaluated. Incremental cost effectiveness, defined as the additional cost per year of incremental gain in median survival, compared to the next least expensive modality, was also determined. To calculate the societal or national impact of these practices, the proportion of patients potentially eligible for aggressive management was estimated and the financial impact was determined using various utilization ratios for radiosurgery and surgery. RESULTS: Both resection and radiosurgery yielded superior survival and functional independence, compared to whole brain radiotherapy alone, with minor differences in outcome between the two modalities; resection resulted in a 1.8-fold increase in cost, compared to radiosurgery. The latter modality yielded superior cost outcomes on all measures, even when a sensitivity analysis of up to 50% was performed. A reversal estimate indicated that in order for surgery to yield equal cost effectiveness, its cost would have to decrease by 48% or median survival would have to improve by 108%. The average cost per week of survival was $310 for radiotherapy, $524 for resection plus radiation, and $270 for radiosurgery plus radiation. CONCLUSIONS: For selected patients, aggressive strategies such as resection or radiosurgery are warranted, as they result in improved median survival and functional independence. Radiosurgery appears to be the more cost-effective procedure.

Brain Neoplasms↗

PubMed1995

Reduction of hemorrhage risk after stereotactic radiosurgery for cavernous malformations.

The benefits of radiosurgery for cavernous malformations are difficult to assess because of the unclear natural history of this vascular lesion, the inability to image malformation vessels, and the lack of an imaging technique that defines "cure." The authors selected for radiosurgery 47 patients who harbored a hemorrhagic malformation in a critical intraparenchymal location remote from a pial or ependymal surface. Of these, 44 patients had experienced at least two hemorrhages before radiosurgery. The mean patient age was 39 years; six patients had previously undergone attempted surgical removal. The malformation was located in the pons/midbrain in 24 cases, the medulla in three, the thalamus in nine, the basal ganglia in three, deep in a parietal lobe in four, and deep in a temporal lobe in four. Patients had sustained initial hemorrhages from 0.5 to 12 years prior to radiosurgery (mean 4.12 years). In these patients, who were not typical of the majority of patients with cavernous malformations, there were 109 bleeds before radiosurgery in 193 prior observation-years, for 56.5% annual hemorrhage rate (including the first hemorrhage), or an annual rate of 32% subsequent to the first hemorrhage. The mean follow-up period after radiosurgery was 3.6 years (range 0.33-6.4 years). The proportion of patients with hemorrhage after radiosurgery was significantly reduced (p < 0.0001), as was the mean number of hemorrhages per patient (p = 0.00004). In the first 2 years after radiosurgery, there were seven bleeds in 80 observation-years (8.8% annual hemorrhage rate). In the 2- to 6-year interval after radiosurgery, the annual rate decreased to 1.1% (one bleed). After radiosurgery, 12 patients (26%) sustained neurological worsening that correlated with imaging changes. In eight patients these deficits were temporary; two underwent surgical resection and died. Two patients had new permanent deficits (4%). A significant reduction was observed in the hemorrhage rate after radiosurgery in patients who had deep hemorrhagic cavernous malformations, especially after a 2-year latency interval. This evidence provides further support to the belief that radiosurgery is an effective strategy for cavernous malformations, especially when located within the parenchyma of the brainstem or diencephalon.

Adult↗

PubMed1999

Long-term outcomes after meningioma radiosurgery: physician and patient perspectives.

OBJECT: Stereotactic radiosurgery is a primary or adjuvant management approach used to treat patients with intracranial meningiomas. The goal of radiosurgery is long-term prevention of tumor growth, maintenance of the patient's neurological function, and prevention of new neurological deficits. The object of this study is to report longer-term patient outcomes. METHODS: The authors evaluated 99 consecutive patients who underwent radiosurgery for meningioma between 1987 and 1992. Evaluation was performed using serial imaging tests, clinical evaluations, and a patient survey that was administered between 5 and 10 years after radiosurgery. Four patients underwent two radiosurgery procedures for separate meningiomas. The average tumor margin dose was 16 Gy and the median tumor volume was 4.7 ml (range 0.24-24 ml). Fifty-seven patients (57%) had undergone prior resection, of which 12 procedures were considered "total." Five patients received fractionated radiation therapy before radiosurgery. Eighty-nine patients (89%) had skull base tumors. The clinical tumor control rate (no resection required) was 93%. Sixty-one (63%) of 97 tumors became smaller, 31 (32%) remained unchanged in size, and five (5%) were enlarged. Resection was performed in seven patients (7%), six of whom had undergone prior resection. New neurological deficits developed in five patients (5%) 3 to 31 months after radiosurgery. Twenty-seven (42%) of 65 responding patients were employed at the time of radiosurgery and 20 (74%) of these remained so. Radiosurgery was believed to have been "successful" by 67 of 70 patients who completed an outcomes questionnaire 5 to 10 years later. At least one complication was described by nine patients (14%) and in four patients the complications resolved. CONCLUSIONS: Five to 10 years after radiosurgery, 96% of surveyed patients believed that radiosurgery provided a satisfactory outcome for their meningioma. Overall, 93% of patients required no other tumor surgery. Incidences of morbidity in this early experience were usually transitory and relatively mild. Radiosurgery provided long-term tumor control associated with high rates of neurological function preservation and patient satisfaction.

Adolescent↗

PubMed2000

Stereotactic radiosurgery for cavernous malformations.

OBJECT: The use of stereotactic radiosurgery to treat cerebral cavernous malformations (CMs) is controversial. To evaluate the efficacy and safety of CM radiosurgery, the authors reviewed the experience at the Mayo Clinic during the past 10 years. METHODS: Seventeen patients underwent radiosurgery for high-surgical-risk CMs in the following sites: thalamus/basal ganglia (four patients), brainstem (12 patients), and corpus callosum (one patient). All patients had experienced at least two documented hemorrhages before undergoing radiosurgery. Stereotactic magnetic resonance (MR) imaging was used for target localization in all cases. The median margin radiation dose was 18 Gy and the median maximum dose was 32 Gy. The median length of follow-up review following radiosurgery was 51 months. The annual hemorrhage rate during the 51 months preceding radiosurgery was 40.1%, compared with 8.8% in the first 2 years following radiosurgery and 2.9% thereafter. In 10 patients (59%) new neurological deficits developed that were associated with regions of increased signal on long-repetition time MR imaging performed a median of 8 months (range 5-16 months) after radiosurgery. Three patients recovered, giving the group a permanent radiation-related morbidity rate of 41%. Compared with 31 patients harboring arteriovenous malformations (AVMs) of sizes and in locations similar to those of the aforementioned CMs, who underwent radiosurgery during the same time period, the patients with CMs were more likely to experience radiation-related complications (any complication, 59% compared with 10%; p < 0.001; permanent complication, 41% compared with 10%; p = 0.02). CONCLUSIONS: It is impossible to conclude that radiosurgery protects patients with CMs against future hemorrhage risk based on the available data, although it appears that some reduction in the bleeding rate occurs after a latency interval of several years. The risk of radiation-related complications after radiosurgery to treat CMs is greater than that found after radiosurgery in AVMs, even when adjusting for lesion size and location and for radiation dose.

Adolescent↗

PubMed2000

Subnecrotic stereotactic radiosurgery controlling epilepsy produced by kainic acid injection in rats.

OBJECT: Any analysis of the potential role of stereotactic radiosurgery for epilepsy requires the experimental study of its potential antiepileptogenic, behavioral, and histological effects. The authors hypothesized that radiosurgery performed using subnecrotic tissue doses would reduce or abolish epilepsy without causing demonstrable behavioral side effects. The kainic acid model in rats was chosen to test this hypothesis. METHODS: Chronic epilepsy was successfully created by stereotactic injection of kainic acid (8 microg) into the rat hippocampus. Epileptic rats were divided into three groups: high-dose radiosurgery (60 Gy, 16 animals), low-dose (30 Gy, 15 animals), and controls. After chronic epilepsy was confirmed by observation of the seizure pattern and by using electroencephalography (EEG), radiosurgery was performed on Day 10 postinjection. Serial seizure and behavior observation was supplemented by weekly EEG sessions performed for the next 11 weeks. To detect behavioral deficits, the Morris water maze test was performed during Week 12 to study spatial learning and memory. Tasks involved a hidden platform, a visible platform, and a probe trial. After radiosurgery, the incidence of observed and EEG-defined seizures was markedly reduced in rats from either radiosurgically treated group. A significant reduction was noted after high-dose (60 Gy) radiosurgery in Weeks 5 to 9 (p < 0.003). After low-dose (30 Gy) radiosurgery, a significant reduction was found after 7 to 9 weeks (p < 0.04). During the task involving the hidden platform, kainic acid-injected rats displayed significantly prolonged latencies compared with those of control animals (p < 0.05). Hippocampal radiosurgery did not worsen this performance. The probe trial showed that kainic acid-injected rats that did not undergo radiosurgery spent significantly less time than control rats in the target quadrant (p = 0.03). Rats that had undergone radiosurgery displayed no difference compared with control rats and demonstrated better performance than rats that received kainic acid alone (p = 0.04). Radiosurgery caused no adverse histological effects. CONCLUSIONS: In a rat model, radiosurgery performed with subnecrotic tissue doses controlled epilepsy without causing subsequent behavioral impairment.

Animals↗

PubMed1993

[Stereotactic interstitial radiosurgery and percutaneous radiotherapy in treatment of cerebral metastases].

The efficacy of interstitial radiosurgery as an alternative or adjuvant to radiotherapy or surgery of cerebral metastases remains unclear. In a retrospective study (1982-1991) we compared 4 therapeutic regimes for cerebral metastases. The first group (n = 38) was treated with interstitial radiosurgery (Iodine-125) with a tumor dose of 60 Gy in combination with percutaneous radiotherapy with 40 Gy. The second group was treated by interstitial radiosurgery alone (n = 22) (tumor dose: 60 Gy). The third group was treated with percutaneous radiotherapy alone with a total dose of 40 Gy (n = 49). The fourth group (n = 21) consisted of recurrent cerebral metastases which were treated by interstitial radiosurgery alone (tumor dose: 60 Gy). Interstitial radiosurgery was performed in cases of circumscribed mostly solitary metastases < or = 5 cm in diameter. Medium survival was 17 months after interstitial radiosurgery in combination with radiotherapy, 12 months after radiosurgery alone and 7.7 months after percutaneous radiotherapy. The medium survival of recurrent metastases after interstitial radiosurgery was 6 months. Prognostically favourable for the outcome following radiosurgery were a Karnofsky Score > or = 70, a solitary metastasis, absence of disseminated disease and a longer time interval between diagnosis of the primary and diagnosis of the cerebral metastases. Interstitial radiosurgery + percutaneous radiotherapy was not superior to interstitial radiosurgery alone in the multivariate analysis. No patient died from a locally treated metastasis. Percutaneous radiotherapy was the treatment of choice for multiple or non-circumscribed cerebral metastases. Our results show that for solitary metastases stereotactic interstitial radiosurgery is a beneficial minimally invasive method.

Adult↗

PubMed2001

Stereotactic radiosurgery for motor cortex region arteriovenous malformations.

OBJECTIVE: The optimal management of arteriovenous malformations (AVMs) in critical brain locations remains controversial. To reduce the risk of an AVM hemorrhage and to enhance the possibility of preserving neurological function, stereotactic radiosurgery was performed in 33 patients with newly diagnosed or residual AVMs located within the motor cortex. The role of embolization also was examined. METHODS: During a 9-year study period, 33 patients with AVMs located primarily in the motor cortex region were treated with stereotactic radiosurgery. These patients were followed up radiographically for a minimum of 36 months, or less if obliteration was documented before 36 months had elapsed. Of the 33 patients, 9 underwent embolization and 1 underwent microsurgery before radiosurgery. Nine patients required a second radiosurgery. The mean AVM target volume was 4.35 cc, and the average radiation dose to the AVM margin was 20 Gy. The median follow-up was 36 months (range, 10-91 mo), and angiographic follow-up of eligible patients was performed 24 or 36 months after radiosurgery. RESULTS: Results were stratified by radiosurgical target volumes: less than 3 cc (Group 1), 3 to 10 cc (Group 2), and greater than 10 cc (Group 3). Overall (including second radiosurgery), 13 (87%) of 15 patients in Group 1 had complete obliteration confirmed by angiography. Nine (64%) of 14 patients in Group 2 exhibited nidus obliteration, and one (25%) of four patients in Group 3 demonstrated obliteration on a magnetic resonance imaging scan. Eight patients (24%) underwent second-stage radiosurgery after angiography revealed a persistent AVM nidus; three patients demonstrated complete obliteration on follow-up angiography. The obliteration rate was higher (87%) for AVMs with less than 3 cc target volume and lower (56%) for those with target volumes larger than 3 cc. One patient experienced worsening neurological function after radiosurgery, and one died from delayed AVM hemorrhage during the latency period. No patient bled after angiographically confirmed AVM obliteration. CONCLUSION: Stereotactic radiosurgery is a successful and safe management option for patients with motor cortex AVMs. The obliteration of AVMs and the attendant low morbidity rates indicate a primary role for radiosurgery in these patients. Staged radiosurgery may be necessary to increase obliteration rates for larger AVMs or for those that are not obliterated after the first procedure.

Adolescent↗

PubMed2001

High-dose trigeminal neuralgia radiosurgery associated with increased risk of trigeminal nerve dysfunction.

OBJECTIVE: Stereotactic radiosurgery is being used with more frequency in the management of patients with trigeminal neuralgia. To improve facial pain outcomes, many centers have increased the prescribed radiation dose to the trigeminal nerve. METHODS: Between April 1997 and December 1999, 68 patients underwent radiosurgery for trigeminal neuralgia with use of the Leksell gamma knife (Elekta Instruments, Norcross, GA) and a single 4-mm isocenter of radiation. Twenty-seven patients (40%) received 70 Gy (low dose) of irradiation and 41 patients (60%) received 90 Gy (high dose). The groups were similar with regard to age, sex, duration of pain, number of prior surgeries, and preexisting trigeminal deficits. The primary facial pain outcomes for analysis were excellent (pain-free, no medications) and good (pain-free, reduced medications). The mean length of follow-up after radiosurgery was 14.4 months (range, 2-36 mo). RESULTS: At last follow-up examination, 11 (41%) of the 27 patients with low-dose radiosurgery remained pain-free compared with 25 (61%) of the 41 patients with high-dose radiosurgery (P = 0.17). Additional surgery was performed in 12 low-dose patients (44%) and 8 high-dose patients (20%) (P = 0.05). High-dose radiosurgery was associated with an increased rate of permanent trigeminal nerve dysfunction (54% versus 15%, P = 0.003). Bothersome dysesthesias occurred in 13 high-dose patients (32%), whereas only 1 low-dose patient had this complication (P = 0.01). Three high-dose patients (8%) developed corneal numbness after radiosurgery. Pain recurred with more frequency in patients not developing trigeminal nerve dysfunction after radiosurgery (9 of 22 patients, 41 %) compared with those who sustained facial numbness, paresthesias, or dysesthesias (4 of 27 patients, 15%); however, the difference was not statistically significant (P = 0.08). CONCLUSION: Higher doses of radiation may correlate with better facial pain outcomes after radiosurgery for trigeminal neuralgia. However, the incidence of significant trigeminal nerve dysfunction is markedly increased after radiosurgery for patients receiving high-dose radiosurgery. Because of the nonselective nature of this ablative technique, dose prescription should be limited to less than 90 Gy.

Aged↗

PubMed1996

Radiosurgery and fractionated radiation therapy: comparison of different techniques in an in vivo rat glioma model.

To identify histological changes and effects on survival in rats harboring C6 gliomas, the authors compared radiosurgery to different fractionated radiation therapy regimens including doses of calculated biological equivalence. Rats were randomized to control (54 animals) or treatment groups after implantation of C6 glioma cells into the right frontal brain region. At 14 days, treated rats underwent stereotactic radiosurgery (35 Gy to tumor margin; 22 animals), whole-brain radiation therapy (WBRT) (20 Gy in five fractions; 18 animals), radiosurgery plus WBRT (13 animals), hemibrain radiation therapy (85 Gy in 10 fractions; 16 animals) or single-fraction hemibrain irradiation (35 Gy; 10 animals). When compared to the control group (median survival 22 days), prolonged survival was identified after radiosurgery (p < 0.0001), radiosurgery plus WBRT (p < 0.0001), WBRT alone (p = 0.0002), hemibrain radiation therapy to 85 Gy (p < 0.0001), and 35-Gy hemibrain single-fraction irradiation (p = 0.004). Compared to the control group (mean tumor diameter, 6.8 mm), the tumor size was reduced in all treatment groups except WBRT alone. Reduced tumor cell density was exhibited in rats that underwent radiosurgery (p = 0.006) and radiosurgery plus WBRT (p = 0.009) when compared with rats in the control group, a finding not observed after any fractionated regimen. Increased intratumoral edema was identified after radiosurgery (p = 0.03) and combined treatment (p = 0.05), but not after fractionated radiation therapy or 35-Gy single-fraction hemibrain irradiation. In this animal model, the addition of radiosurgery significantly increased tumor cytotoxicity, potentially at the expense of radiation effects to regional brain. We found no difference in survival benefit or tumor diameter in animals that underwent radiosurgery compared to the calculated biologically equivalent regimen of 10-fraction radiation therapy to 85 Gy. The histological responses after radiosurgery were generally greater than those achieved with biologically equivalent doses of fractionated radiation therapy.

Animals↗

PubMed1998

Vestibular schwannoma management. Part I. Failed microsurgery and the role of delayed stereotactic radiosurgery.

OBJECT: The purpose of this study was to analyze patient outcomes and to define the role of radiosurgery in patients who have undergone prior microsurgical resection of their vestibular schwannoma. METHODS: The authors evaluated the pre- and postoperative clinical and neuroimaging characteristics of 76 consecutive patients with 78 vestibular schwannomas who underwent radiosurgery after previous surgical resection. Twenty-nine patients (37% of tumors) had undergone more than one prior resection. Forty-three patients (55% of tumors) had significant impairment of facial nerve function (House-Brackmann Grades III-VI) after their microsurgical procedure; 50% had trigeminal sensory loss, and 96% had poor speech discrimination (< 50%). The median evaluation period following radiosurgery was 43 months (range 12-101 months). Tumor growth control after radiosurgery was achieved in 73 tumors (94%). Six patients underwent additional surgical resection despite radiosurgery (median of 32 months after radiosurgery), and one patient underwent repeated radiosurgery for tumor progression outside the irradiated volume. Eleven (23%) of 47 patients with Grades I to III facial function before radiosurgery developed increased facial weakness after radiosurgery. Eleven patients (14%) developed new trigeminal symptoms. CONCLUSIONS: Radiosurgery proved to be a safe and effective alternative to additional microsurgery in patients in whom the initial microsurgical removal failed. Stereotactic radiosurgery should be considered for all patients who have regrowth or progression of previously surgically treated vestibular schwannomas.

Adolescent↗

PubMed2000

Effects of stereotactic radiosurgery on an animal model of hippocampal epilepsy.

OBJECTIVE: Stereotactic radiosurgery has been shown in small clinical series to reduce or abolish seizures in patients with lesion-related or idiopathic epilepsy. The radiation dose necessary to eliminate epileptogenesis is unknown, and the histological and metabolic effects of radiosurgery remain undefined. We hypothesized that in a rat model of kainic acid-induced hippocampal epilepsy, radiosurgery could provide a significant reduction in seizure frequency while limiting biochemical and structural histological damage to the brain. METHODS: Kainic acid (8 g) was injected into the rat hippocampus using stereotactic targeting. Focal seizures so generated were identified with scalp and depth electroencephalography (EEG). Epileptic rats were randomized to a control group (n = 20) and to radiosurgery groups in which maximum doses of 20, 40, 60, or 100 Gy (8-9 animals per group) were administered. Over a 42-day period, seizure frequency was determined by direct observation for 8 hours per week. Scalp EEG was performed weekly in all animals. Magnetic resonance imaging (MRI) studies (T1- and T2-weighted water-proton and quantitative sodium images) were obtained on Days 7, 21, and 42. RESULTS: As compared with the control group, treated animals showed significant reductions in the number of seizures during each successive week after 20-Gy radiosurgery (P = 0.01-0.002). When we combined the number of seizures observed in the latter half of the study (Weeks 4-6), we found a significant reduction in seizures after 20-Gy (P = 0.007), 40-Gy (P = 0.03), 60-Gy (P = 0.03), and 100-Gy (P = 0.03) radiosurgery as compared with control animals. Increasing doses of radiosurgery correlated with higher percentages of rats that became seizure-free by EEG criteria. MRI-determined total sodium concentration in the injected hippocampus was 49.8+/-3 mmol/L, compared with 42.8 mmol/L on the contralateral side (within normal limits). This significant increase in sodium concentration was present in control rats (because of the kainic acid) and did not change with increasing radiosurgery dose. No parenchymal effects from radiosurgery were identified after 20, 40, and 60 Gy, and only two rats had necrosis at 100 Gy. All animals showed hippocampal injury from kainic acid by proton MRI and histological examination. CONCLUSION: In this rat hippocampal epilepsy model, stereotactic radiosurgery was followed by a significant dose-dependent reduction in the frequency of observed and EEG-defined seizures. These effects were not accompanied by increased radiation-induced structural or metabolic brain injury as assessed by proton and sodium MRI or histological examination. The role of radiosurgery as a new, nondestructive surgical therapy for idiopathic epilepsy warrants further investigation.

Animals↗

PubMed1996

Hemorrhage risk after stereotactic radiosurgery of cerebral arteriovenous malformations.

To analyze the effect of stereotactic radiosurgery on the hemorrhage rate of arteriovenous malformations (AVMs), we reviewed the clinical and angiographic characteristics of 315 patients with AVMs before and after radiosurgery. One hundred ninety-six patients sustained 263 bleeds in 10,939 patient-years before radiosurgery, for an annual nonfatal hemorrhage rate of 2.4%. Clinical follow-up after radiosurgery was available in 312 patients (mean, 47 +/- 20 mo); follow-up > or = 24 months was obtained in 295 patients (94%). Twenty-one patients had AVM bleeds at a median of 8 months (range, 1-60 mo) after radiosurgery. Two additional patients had three aneurysmal bleeds (at 5, 27, and 32 mo, respectively) for a 7.4% total risk of hemorrhage per patient. The actuarial hemorrhage rate until AVM obliteration was 4.8% per year (95% confidence interval, 2.4-7.0%) during the first 2 years after radiosurgery and 5.0% per year (95% confidence interval, 2.3-7.3%) for the third to fifth years after radiosurgery. Multivariate analysis of clinical and angiographic factors demonstrated that the presence of an unsecured proximal aneurysm was associated with an increased risk of postradiosurgical hemorrhage (relative risk, 4.56; 95% confidence interval, 1.77-11.70%; P < 0.001). No AVM hemorrhages were observed after radiosurgery in seven patients with intranidal aneurysms. No protective effect against hemorrhage was observed in patients who received an "optimal" radiation dose (> or = 25 Gy to the AVM margin) compared with patients who received < 25 Gy to the AVM margin (P = 0.36). No patient suffered a hemorrhage after angiography had confirmed complete obliteration (n = 140) or suffered from an early draining vein without residual nidus (n = 19). Stereotactic radiosurgery was not associated with a significant change in the hemorrhage rate of AVMs during the latency interval before obliteration. No protective benefit was conferred on patients who had incomplete nidus obliteration in early (< 60 mo) follow-up after radiosurgery. AVM patients with unsecured proximal aneurysms should have aneurysms obliterated either before radiosurgery or at the time of surgical resection of their AVMs.

Cerebral Angiography↗

PubMed1995

Radiosurgery of Benign Lesions.

The use of stereotactic radiosurgery is increasing at an accelerated rate throughout the United States and the rest of the world. The greatest success for radiosurgery has been in the treatment of benign intracranial mass lesions and arteriovenous malformations (AVM) in particular. The majority of large radiosurgery series report that AVM obliteration rates exceed 74% and serious complication rates (permanent brain injury) exceed less than 5%. Radiosurgery is being investigated as a treatment for high-risk angiographically occult vascular malformations (cavernous angiomas) with a history of hemorrhages, but is contraindicated in asymptomatic patients. Radiosurgery has been successfully established as an alternative to surgical resection of vestibular schwannomas (acoustic neuromas). Long-term tumor control rates with radiosurgery are above 85%. Radiosurgery offers tumor control comparable to surgery with better preservation of hearing and facial nerve function. Radiosurgery has also been found to be equally effective in controlling nonacoustic schwannomas and meningiomas. Radiosurgery offers the potential of faster and higher response rates in treating functional pituitary adenomas than fractionated radiotherapy with a greater chance of preserving normal pituitary function. Long-term studies with 10 to 15-year follow-up are still needed to fully compare the efficacy of radiosurgery with other modern techniques for treating pituitary adenomas and meningiomas (such as cranial base microsurgery and fractionated large-field radiotherapy). Overall, radiosurgery is a relatively safe and effective alternative to surgical resection of small AVMs and most benign intracranial tumors.

Journal Article↗

PubMed1995

Stereotactic radiosurgery of anterior skull base tumors.

Stereotactic radiosurgery is an increasingly safe and usually effective method of preventing growth of small to moderate-sized primary tumors of the anterior skull base. Tumor growth control is obtained in more than 90% of patients with skull base tumors having benign histology. Neurologic function is maintained in most patients. The risk of temporary or permanent injury to critical neural and vascular structures is significantly lower than the risk associated with microsurgery. The optic nerves, chiasm, and tracts are structures that appear most sensitive to the radiation doses used during radiosurgery of anterior skull base tumors. The incidence of injury to the optic apparatus is low when the dose to the nerve is less than 8 to 9 Gy (27). The incidence of injury to motor nerves, such as the oculomotor, trochlear, trigeminal, and abducens nerves, is extremely low at the doses used in clinical radiosurgery (27). To date no cases of delayed carotid injuries have been reported. Microsurgical complications (e.g., CSF leak, wound infection, and meningitis) do not occur after radiosurgery. Additional attractive features of radiosurgery are a relatively low, hospital-based cost and a rapid return of the patient of work. In the report of our experience with the first 207 patients treated with the Gamma Knife at the University of Pittsburgh, the average length of hospital stay was 2.24 days for a patient undergoing stereotactic radiosurgery for a skull base tumor and 11.44 days for a patient undergoing craniotomy for the same lesion. The total hospital charges were 30 to 70% lower for patients having radiosurgery (19). The average hospital stay and cost of radiosurgery are even lower now, because most radiosurgery patients are released from the hospital on the same day as their procedure. Patients are usually able to return to a full preoperative functional level and employment within 3 to 5 days. There are patients in certain clinical situations in which microsurgery clearly is required. These include patients experiencing rapidly progressive visual deterioration or who have endocrine-active pituitary tumors. A more rapid reduction in endocrine dysfunction is best achieved by microsurgical tumor excision. In patients in whom a tumor recurs despite "gross total removal," and in cases in which tumor is left behind to preserve critical nerve and vessel integrity, stereotactic radiosurgery is a very effective alternative to additional microsurgical operations. Stereotactic radiosurgery may also be the primary treatment of choice in patients who are unable or unwilling to accept the risk:benefit ratio of microsurgery.

Adult↗

PubMed1999

Stereotactic radiosurgery as a salvage treatment for locally persistent and recurrent nasopharyngeal carcinoma.

BACKGROUND: The purpose of this work was to study the efficacy of stereotactic radiosurgery as a salvage treatment in patients with locally persistent and recurrent nasopharyngeal carcinoma (NPC). METHODS: Between March 1996 and August 1997, 10 patients with locally persistent or recurrent NPC were treated by linac-based stereotactic radiosurgery. Four patients had radiosurgery for persistent disease after a first course of radiotherapy, 3 had radiosurgery as a boost after reirradiation for local recurrence, and 3 had radiosurgery for disease that recurred after reirradiation. The tumor volume ranged from 1.3 to 23.7 cc (median: 5.2). Treatment was prescribed at 80% isodose line and ranged from 12 to 18 Gy (median: 13.4), with a mean tumor surface dose ranged from 10-21 Gy (median: 14). The median clinical follow-up was 10.5 months (range 8-27), and the median imaging follow-up was 9.5 months (range 6-26). RESULTS: One patient had complete regression of tumor after radiosurgery, five had reduction in tumor size, three had no change, and one had progression of tumor. The overall response rate to radiosurgery was 60% (6/10), with 10% (1/10) developing in-field progression. Excluding patients receiving radiosurgery as a boost treatment after reirradiation, the response rate was 57% (4/7) and none developed in-field progression. Only one patient developed a new cranial neuropathy in the absence of disease progression. CONCLUSION: In selected patients with locally persistent or recurrent NPC, stereotactic radiosurgery can be considered as a salvage treatment with good short-term local control. The complications appear to be minimal except for treating recurrence in the cavernous sinus. Early results are encouraging although more experience and longer follow-up are still needed to better define the role of radiosurgery in the management of persistent and recurrent NPC.

Adenocarcinoma↗