Search PubMed⌕ Search

Biomedical subjects

L D Lunsford

Publications and source records attributed to L D Lunsford.

At least 37 records · Page 2Linked to original sources
PubMed2000

Functional outcomes after gamma knife thalamotomy for essential tremor and MS-related tremor.

Twelve patients with a median age of 75 years underwent gamma knife thalamotomy for essential tremor (ET) (n = 9) or MS-related tremor (n = 3). All 11 evaluable patients noted improvement in action tremor. Six of eight ET patients had complete tremor arrest, and the violent action tremor in all three patients with MS was improved. One patient developed transient arm weakness. Stereotactic radiosurgery for ET and MS-related tremor is safe and effective for patients who may be poor candidates for other procedures.

Activities of Daily Living↗
PubMed2000

Development of a model to predict permanent symptomatic postradiosurgery injury for arteriovenous malformation patients. Arteriovenous Malformation Radiosurgery Study Group.

PURPOSE: To better predict permanent complications from arteriovenous malformation (AVM) radiosurgery. METHODS AND MATERIALS: Data from 85 AVM patients who developed symptomatic complications following gamma knife radiosurgery and 337 control patients with no complications were evaluated as part of a multi-institutional study. Of the 85 patients with complications, 38 patients were classified as having permanent symptomatic sequelae (necrosis). AVM marginal doses varied from 10-35 Gy and treatment volumes from 0.26-47.9 cc. Median follow-up for patients without complications was 45 months (range: 24-92). RESULTS: Multivariate analysis of the effects of AVM location and the volume of tissue receiving 12 Gy or more (12-Gy-Volume) allowed construction of a significant postradiosurgery injury expression (SPIE) score. AVM locations in order of increasing risk and SPIE score (from 0-10) were: frontal, temporal, intraventricular, parietal, cerebellar, corpus callosum, occipital, medulla, thalamus, basal ganglia, and pons/midbrain. The final statistical model predicts risks of permanent symptomatic sequelae from SPIE scores and 12-Gy-Volumes. Prior hemorrhage, marginal dose, and Marginal-12-Gy-Volume (target volume excluded) did not significantly improve the risk-prediction model for permanent sequelae (p >/= 0.39). CONCLUSION: The risks of developing permanent symptomatic sequelae from AVM radiosurgery vary dramatically with location and, to a lesser extent, volume. These risks can be predicted according to the SPIE location-risk score and the 12-Gy-Volume.

Case-Control Studies↗
PubMed2000

Effective treatment of experimental glioblastoma by HSV vector-mediated TNF alpha and HSV-tk gene transfer in combination with radiosurgery and ganciclovir administration.

Experiments were carried out in a nude mouse model of human glioblastoma to determine whether gamma-knife radiosurgery combined with herpes simplex virus thymidine kinase (tk) suicide gene therapy and tumor necrosis factor alpha (TNFalpha) gene transfer provided an improved multimodality treatment of this disease. Animals were inoculated intracerebrally with 2 x 10(5) U-87MG human glioblastoma cells to establish brain tumors. At 3 days postinoculation, the tumor region was injected with 2 x 10(6) infectious particles of highly defective herpes simplex viral vectors expressing the viral tk gene with the kinetics of a viral immediate early gene either alone (T.1) or together with TNF alpha (TH:TNF). Subgroups of animals were given daily intraperitoneal injections of ganciclovir (GCV) for 10 days and/or subjected to gamma-knife radiosurgery on the fifth day post tumor-cell implantation. Comparisons of animal survival showed that the TH:TNF vector in combination with radiosurgery and GCV administration provided the most effective therapy; eight of nine animals survived for 75 days compared to four of eight using the next best protocol. These findings suggest that gene therapy in combination with more conventional therapeutic methods may provide an improved strategy for extending the life expectancy of patients afflicted with this ultimately fatal disease.

Animals↗
PubMed2000

Stereotactic radiosurgery for hemangioblastomas of the brain.

OBJECTIVE: To assess the effectiveness of stereotactic radiosurgery in achieving tumor control and improving survival in patients with hemangioblastoma, we evaluated results from patients who were managed at the University of Pittsburgh and the Mayo Clinic. PATIENTS AND METHODS: Twenty-seven patients with 29 hemangioblastomas had stereotactic radiosurgery over a 10 year interval. The mean patient age was 32 years (range, 14-75 years). The tumor volumes varied from 0.36 to 27 ml (mean, 3.2 ml), and the mean tumor margin dose was 16 Gy (range, 11.7-20). Clinical and neuroimaging follow-up was obtained for all patients between 0.5 and 9 years (mean, 4 years) after radiosurgery. RESULTS: At this assessment, 21 patients (79%) were alive and six (21%) had died. The median survival after radiosurgery was 6.5 years (actuarial 5 year survival = 75.1 +/- 11.5%). The median survival from the initial diagnosis was 15 years. Twenty two of 29 evaluable tumors were controlled locally. The two-year actuarial control rate was 84.5 +/- 7.1% and at five years, 75.2 +/- 8.9%. Multivariate testing of factors affecting good outcome indicated that smaller tumor volume and higher radiosurgical dose (> 18 Gy) were significant. CONCLUSION: For small to moderate size hemangioblastomas, multiple or recurrent tumors, and for patients who are not surgical candidates, radiosurgery is a safe and effective option to control disease and improve survival.

Adolescent↗
PubMed2000

Stereotactic radiosurgery for brain metastases from breast cancer.

BACKGROUND: Stereotactic radiosurgery is an alternative to resection or to radiotherapy alone for patients with brain metastases. Outcomes after radiosurgery for patients with brain metastases specifically from breast cancer have not been defined. METHODS: We retrospectively studied survival and tumor control for all patients with brain metastases from breast cancer who underwent gamma knife stereotactic radiosurgery at the University of Pittsburgh. Univariate and multivariate analyses were used to determine which prognostic factors significantly affected survival. RESULTS: Thirty patients underwent radiosurgery between 1990 and 1997. A total of 58 metastases were treated. The median length of survival for all patients was 13 months from radiosurgery and 18 months from diagnosis of brain metastases. The tumor control rate on follow-up imaging was 93%. On multivariate analysis, the only factor that correlated with longer survival was the absence of multiple brain metastases. Age, presence of systemic disease, previous whole brain radiation, location, and total tumor volume did not significantly affect survival. Four patients had tumors with evidence of radiation-induced edema after radiosurgery but did not require resection. Two patients underwent delayed resection for tumor growth after radiosurgery. CONCLUSIONS: Stereotactic radiosurgery is an effective treatment for brain metastases from breast cancer and is associated with a low complication rate.

Adult↗
PubMed2000

The role of stereotactic cyst aspiration for glial and metastatic brain tumors.

OBJECTIVE: To evaluate the role of stereotactic cyst aspiration in the context of multimodality management of cystic glial and metastatic tumors, we retrospectively reviewed our experience with 38 patients during a 10-year interval. METHODS: All 38 patients had one or more computed tomography or magnetic resonance imaging guided stereotactic cyst aspirations. Twenty-seven patients had glial neoplasms and 11 had metastatic brain tumors. Twenty-two patients underwent cyst aspiration as the initial treatment modality while 15 patients had cyst aspiration following previous treatments. RESULTS: In the immediate postoperative period, 19 of the 27 (70%) patients with gliomas and nine of the 11 (82%) patients with metastatic tumors experienced symptomatic improvement. No procedure-related morbidity was encountered. Twelve patients (31.5%) eventually required a catheter-reservoir system. Thirty-seven percent of patients with cystic glial neoplasms and 18% of patients with metastatic tumors had delayed cytoreductive surgery by craniotomy subsequent to stereotactic cyst aspiration. Reduction in tumor volume following aspiration facilitated Gamma knife radiosurgery in seven patients. CONCLUSION: Single stereotactic aspiration is a low risk procedure that provides immediate relief of symptoms in patients with cystic brain tumors. It appears to be valuable together with the use of other therapeutic strategies.

Brain Neoplasms↗
PubMed2000

Radiosurgery: where we were, are, and may be in the third millennium.

Radiosurgery will celebrate its Golden Jubilee in the year 2001. More than 100,000 patients throughout the world have undergone radiosurgery since Lars Leksell first described the technique in 1951. Rapid developments in neuroimaging and even robotic technology in the past decade have contributed to improved outcomes and wider applications for radiosurgery. A variety of different radiosurgical techniques have been developed in the past two decades. Numerous studies have examined the benefits and risks of radiosurgery performed with various devices. The long-term results of radiosurgery are now available, and these results have established radiosurgery as an effective noninvasive treatment method for intracranial vascular malformations and many tumors. Additional applications of radiosurgery for the treatment of malignant tumors and functional disorders are being assessed. Radiosurgery is an impressive combination of minimally invasive technologies administered by a multidisciplinary team of surgeons, oncologists, medical physicists, and engineers.

Diagnostic Imaging↗
PubMed2000

Histological effects of trigeminal nerve radiosurgery in a primate model: implications for trigeminal neuralgia radiosurgery.

OBJECTIVE: Stereotactic radiosurgical treatment of the proximal trigeminal nerve is used to relieve the pain of trigeminal neuralgia. The mechanism of the radiosurgical effect is not understood. METHODS: Two adult baboons underwent stereotactic magnetic resonance imaging-guided radiosurgery, using a gamma knife. A single 4-mm isocenter was targeted to each proximal trigeminal nerve, just anterior to the pons, to deliver a maximal dose of 80 or 100 Gy (total of four nerves). A nonirradiated baboon brain and nerves served as control specimens. Six months after treatment, magnetic resonance imaging was again performed and the brains and nerves were studied using light and electron microscopy. RESULTS: Magnetic resonance imaging indicated a 4-mm-diameter area of contrast enhancement at the target site in each nerve. All irradiated nerves exhibited axonal degeneration and mild edema at the target, with remnants of some myelinated axons. Large and small myelinated and unmyelinated fibers were affected. No inflammation was observed. Nerve necrosis was identified after 100-Gy treatment. The trigeminal ganglion appeared normal. CONCLUSION: Radiosurgery at 80 Gy causes focal axonal degeneration of the trigeminal nerve. At higher doses, partial nerve necrosis is observed. We think that these effects influence the physiological features of trigeminal neuralgia.

Animals↗
PubMed2000

Successful management of sellar and suprasellar arachnoid cysts with stereotactic intracavitary irradiation: an expanded report of four cases.

OBJECTIVE: Sellar and suprasellar arachnoid cysts may be asymptomatic or may cause headache, optic nerve compression, endocrine dysfunction, or hydrocephalus. We propose a minimally invasive treatment strategy when intervention is indicated. METHODS: Four patients with sellar and suprasellar arachnoid cysts presented with headache, visual compromise, and endocrine dysfunction. Two of the four patients previously had undergone unsuccessful surgical intervention. The imaging studies of two patients were diagnostic of an arachnoid cyst. RESULTS: All four patients underwent stereotactic intracavitary radiation with cyst regression and symptomatic improvement. In each patient, the optic chiasm was decompressed successfully. There were no complications from the procedure. CONCLUSION: Stereotactic intracavitary irradiation of arachnoid cysts proved to be safe and effective. The procedure obviated the need for open cyst fenestration or shunting.

Arachnoid Cysts↗
PubMed2000

Radiosurgery for hemangiomas of the cavernous sinus and orbit: technical case report.

OBJECTIVE AND IMPORTANCE: Hemangiomas of neurosurgical interest are histologically benign vascular tumors that most often occur in the orbit or cavernous sinus. Hemangiomas can be diagnosed by their characteristic radiographic and angiographic appearance and their tendency to bleed excessively during attempted removal. Intracranial or intraorbital hemangiomas require treatment when they become symptomatic. CLINICAL PRESENTATION: We report four hemangioma patients who presented with ocular symptoms or signs, such as orbital pain, ophthalmoplegia, proptosis, or impaired visual acuity. Before our evaluation, two patients had each had incomplete resections aborted because of excessive blood loss, one patient had undergone a nondiagnostic transsphenoidal biopsy, and one patient had had an unsuccessful embolization. INTERVENTION: All four patients were treated with gamma knife radiosurgery. Tumors received a minimal tumor dose that ranged from 14 to 19 Gy. Follow-up evaluations were performed 6 to 24 months after radiosurgery and revealed a reduction in tumor volume in three patients and no tumor progression in the fourth. All patients had symptomatic improvement, but one had persistent diplopia. CONCLUSION: In this early experience, stereotactic radiosurgery proved to be an effective management strategy that avoided the potentially serious complications associated with surgery or embolization of cavernous sinus hemangiomas.

Adolescent↗
PubMed2000

Radiosurgery for childhood intracranial arteriovenous malformations.

OBJECTIVE: The optimal management of intracranial arteriovenous malformations (AVMs) in children remains controversial. Children with intracranial AVMs present a special challenge in therapeutic decision-making because of the early recognition of their future life-long risks of hemorrhage if they are treated conservatively. The goals of radiosurgery are to achieve complete AVM obliteration and to preserve neurological function. We present long-term outcomes for a series of children treated using radiosurgery. METHODS: The findings for 53 consecutive children who underwent at least 36 months of imaging follow-up monitoring after radiosurgery were reviewed. The median age at the time of treatment was 12 years (range, 2-17 yr). Thirty-one children (58%) presented after their first intracranial hemorrhaging episodes, two (4%) after their second hemorrhaging episodes, and one (2%) after five hemorrhaging episodes. Nineteen children (36%) presented with unruptured AVMs, and a total of 25 children (47%) exhibited neurological deficits. AVMs were graded as Spetzler-Martin Grade I (2%), Grade II (23%), Grade III (36%), Grade IV (9%), or Grade VI (30%). The median AVM volume was 1.7 ml (range, 0.11-10.2 ml). The median marginal dose was 20 Gy (range, 15-25 Gy). RESULTS: Results were stratified according to AVM volumes (Group 1, < or =3 ml; Group 2, >3 ml to < or =10 ml; Group 3, >10 ml). Twenty-eight patients (80%) in Group 1 and 11 (64.7%) in Group 2 achieved complete obliteration. The only patient in Group 3 did not achieve obliteration. Complications included brainstem edema (n = 1) and transient pulmonary edema (n = 1). Four patients experienced hemorrhaging episodes, 30, 40, 84, and 96 months after radiosurgery. Multivariate logistic regression analysis demonstrated that only volume was significantly correlated with obliteration rates (P = 0.0109). CONCLUSION: Radiosurgery is safe and efficacious for selected children with AVMs. The obliteration rates and the attendant low morbidity rates suggest a primary role for stereotactic radiosurgery for pediatric AVMs.

Adolescent↗
PubMed2000

Brain surgery with image guidance: current recommendations based on a 20-year assessment.

Image guidance promotes safe and effective surgical management of a wide array of intracranial diseases. To better define the historical importance of image guidance and to assess the relative contribution of each imaging modality to the safety and efficacy of selected procedures, we reviewed our 20-year experience at a single institution. A retrospective review of our departmental surgical records was performed to identify patients who underwent brain surgery with image guidance between January 1979 and January 1999. We identified the use of intraoperative fluoroscopy, endoscopy, computed tomography (CT), magnetic resonance imaging (MRI), ultrasound, and angiography in 7,388 patients. During this 20-year interval, advances in neuroimaging were translated into the operating room environment. Fluoroscopic guidance received the highest overall rating and was deemed critical for the performance of successful transsphenoidal surgery (n = 436) and effective percutaneous trigeminal neuralgia management (n = 1,121). Ultrasound and angiography both had limited roles; the latter was important to successful outcomes in 64 patients undergoing aneurysm management (n = 64) and arteriovenous malformation Gamma Knife radiosurgery (n = 786). Endoscopy also had a small role but had limited cost. Beginning in 1982, a dedicated operating room CT scanner was used during both morphologic and functional stereotactic surgery (n = 1,749). After 1986, MRI was used increasingly in the management of selected functional and tumor cases (n = 337); despite great versatility for patients undergoing Gamma Knife radiosurgery, the costs were relatively high. Frameless neuronavigation (n = 263) had excellent versatility and was relatively low in cost. During the last 20 years, image guidance techniques have facilitated minimally invasive brain surgery at our institution. The relative merits of all these imaging tools depended mostly on their versatility and relative costs. Major centers currently contemplating the incorporation of image guidance into routine brain surgery need not reproduce our own learning curve.

Brain Diseases↗
PubMed2000

Repeated radiosurgery for incompletely obliterated arteriovenous malformations.

OBJECT: The goal of this study was to define treatment results of repeated arteriovenous malformation (AVM) radiosurgery, namely AVM obliteration and complications. METHODS: The authors analyzed their experience with repeated AVM radiosurgery performed in 41 patients for whom follow-up review lasted at least 2 years. The median duration of follow up was 34 months (range 7-65 months) after repeated radiosurgery in this group. The residual nidus was located within the area of focus (in field) of the initial radiosurgery in 28 patients (68%). Initial doses to the margin varied from 12.5 to 20 Gy (median 18 Gy). During repeated treatment the dose to the margin varied from 12.5 to 20 Gy (median 17 Gy) and the retreated volumes ranged from 0.4 to 7 cm3 (median 2.1 cm3). Follow-up angiography performed at least 2 years postradiosurgery revealed complete AVM obliteration in 21 (70%) of 30 patients. The estimated overall 2-year obliteration rate, based on findings on magnetic resonance imaging (eight of 11 obliterated) and angiography (29 of 41 obliterated) was 71%. Obliteration rates correlated with margin doses (p = 0.0045) with a trend toward higher rates in cases with in-field nidus persistence (p = 0.0637). The dose-response curve for AVM nidus obliteration was not significantly different from that of the initial radiosurgery. In two patients (5%) intracranial AVM hemorrhage developed within 125.9 risk years after repeated radiosurgery (1.6% per patient year). Persistent symptomatic adverse radiation effects developed in two (5%) of 41 patients following repeated radiosurgery. Postradiosurgical imaging changes were identified in 11 (27%) of 41 patients, which correlated with a 12-Gy volume from repeated surgery (p = 0.019). CONCLUSIONS: When necessary, repeated AVM radiosurgery achieves obliteration with an acceptable risk. Despite the effects of previous irradiation, repeated radiosurgery required similar or slightly higher radiation doses to achieve the same in-field obliteration rates as those needed to obliterate an AVM that had not been treated by radiation previously.

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↗
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↗