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Biomedical subjects

L Dade Lunsford

Publications and source records attributed to L Dade Lunsford.

At least 37 records · Page 2Linked to original sources
PubMed2005

Radiosurgery of vestibular schwannomas: summary of experience in 829 cases.

OBJECT: Management options for vestibular schwannomas (VSs) have greatly expanded since the introduction of stereotactic radiosurgery. Optimal outcomes reflect long-term tumor control, preservation of cranial nerve function, and retention of quality of life. The authors review their 15-year experience. METHODS: Between 1987 and 2002, some 829 patients with VSs underwent gamma knife surgery (GKS). Dose selection, imaging, and dose planning techniques evolved between 1987 and 1992 but thereafter remained stable for 10 years. The average tumor volume was 2.5 cm3. The median margin dose to the tumor was 13 Gy (range 10-20 Gy). No patient sustained significant perioperative morbidity. The average duration of hospital stay was less than 1 day. Unchanged hearing preservation was possible in 50 to 77% of patients (up to 90% in those with intracanalicular tumors). Facial neuropathy risks were reduced to less than 1%. Trigeminal symptoms were detected in less than 3% of patients whose tumors reached the level of the trigeminal nerve. Tumor control rates at 10 years were 97% (no additional treatment needed). CONCLUSIONS: Superior imaging, multiple isocenter volumetric conformal dose planning, and optimal precision and dose delivery contributed to the long-term success of GKS, including in those patients in whom initial microsurgery had failed. Gamma knife surgery provides a low risk, minimally invasive treatment option for patients with newly diagnosed or residual VS. Cranial nerve preservation and quality of life maintenance are possible in long-term follow up.

Female↗
PubMed2004

Acoustic neuroma radiosurgery with marginal tumor doses of 12 to 13 Gy.

PURPOSE: To define tumor control and clinical outcomes of radiosurgery to marginal tumor doses of 12-13 Gy for unilateral acoustic neuroma patients. METHODS AND MATERIALS: Three hundred thirteen patients with previously untreated unilateral acoustic neuromas (vestibular schwannomas) underwent gamma knife radiosurgery between February 1991 and February 2001 with marginal tumor doses of 12-13 Gy (median, 13 Gy). Median follow-up was 24 months (maximum, 115 months; 36 patients with > or =60 months). Maximum doses were 20-26 Gy (median, 26 Gy), and treatment volumes were 0.04-21.4 mL (median, 1.1 mL). RESULTS: The actuarial 6-year clinical tumor control rate (no requirement for surgical intervention) for the entire series was 98.6 +/- 1.1%. Two patients required tumor resection; one had a complete resection for solid tumor growth and one required partial resection for an enlarging adjacent subarachnoid cyst. Six-year actuarial rates for preservation of facial nerve function, normal trigeminal nerve function, unchanged hearing level, and useful hearing were 100%, 95.6 +/- 1.8%, 70.3 +/- 5.8%, and 78.6 +/- 5.1%, respectively. The risk of developing trigeminal neuropathy correlated with increasing tumor volume (p = 0.038). CONCLUSIONS: Acoustic neuroma radiosurgery with doses of 12-13 Gy provides high rates of tumor control and cranial nerve preservation.

Adolescent↗
PubMed2004

The expanding role of neurosurgeons in the management of brain metastases.

BACKGROUND: Brain metastases are the most common type of intracranial tumor. Until recently, whole brain fractionated radiation therapy (WBRT) was the mainstay of treatment, thereby confining the role of neurosurgeons to resection of an occasional solitary, accessible, and symptomatic brain metastasis. Median survival after surgery and radiation typically ranged from 5 to 11 months. METHODS: We analyzed various demographic incidence reports and our series of brain metastasis patients treated with radiosurgery. During a 15-year interval (1987-2002), radiosurgery was performed on 5,032 patients of whom 1,088 (21.6%) had metastatic brain tumors. RESULTS: In the United States, 266,820 to 533,640 new cases of brain metastases will be diagnosed in the year 2003. Evidence to date demonstrates that radiosurgery provides effective local tumor control for brain metastases. Important prognostic factors affecting patient survival include the absence of active systemic disease, the patient's preoperative performance status, age, and the number of metastases. Survival and local tumor control rates attained with radiosurgery are superior to those of either conventional surgery or WBRT. The morbidity associated with radiosurgery of brain metastasis is very low, and the mortality rate approaches zero. CONCLUSIONS: Compelling evidence indicates that radiosurgery is an effective neurosurgical management strategy for intracranial brain metastases. Quite often, favorable tumor control and survival can be achieved without WBRT. With radiosurgery as a therapeutic option, neurosurgeons now have a vastly expanded armamentarium for treatment of patients with brain metastases. The large number of patients with brain metastases who require care by a neurosurgeon for optimal treatment has significant implications for both the patterns of neurosurgical training and practice in the United States.

Brain Neoplasms↗
PubMed2004

Gamma knife radiosurgery for trigeminal schwannomas.

BACKGROUND: Trigeminal schwannomas are uncommon tumors that may be microsurgically removed in selected cases, albeit with significant risk for new neurological morbidity. We evaluated the role of stereotactic radiosurgery as an alternative for patients with newly diagnosed or residual trigeminal schwannomas. METHODS: The records of 23 patients who underwent radiosurgery for trigeminal schwannoma were reviewed. The most frequent presenting symptoms were facial numbness (11 patients), diplopia (6 patients), and facial pain (3 patients). One patient presented with partial complex seizures as the first symptom. Twelve patients had undergone one or more prior resections. Eleven underwent radiosurgery on the basis of imaging diagnosis only. The mean tumor volume was 4.5 mL (range 0.46-11.2 cc). Radiosurgery was performed using a median marginal dose of 15 Gy (range, 13-20 Gy). RESULTS: At a median imaging follow-up of 40 months (range, 12-146), 20 of 22 evaluable patients (91%) had tumor growth control (regression in 15 and no further tumor growth in 5). One 80-year-old patient died of unrelated cause 4 months after radiosurgery. Two patients with enlarged tumors were treated effectively with repeat radiosurgery. Twelve of 23 patients (52%) reported improvement and 9 (39%) had no change in their symptoms. Two patients noted new neurological complaints (transient facial weakness in 1 patient and worsening of the preradiosurgery facial numbness in another patient). CONCLUSIONS: Radiosurgery is an effective minimally invasive management option for patients with residual or newly diagnosed trigeminal schwannomas.

Adolescent↗
PubMed2004

Survey of United States neurosurgical residency program directors.

OBJECTIVE: The field of neurosurgery in the United States faces many challenges. Neurosurgical program directors in the United States represent a logical source for inquiries about manpower issues, the training process, and Residency Review Committee (RRC) oversight. METHODS: Ninety-one active residency program directors were sent an anonymous 31-question survey. The respondents were given the option of adding additional comments. The questions were designed to address issues related to manpower, the training process, and RRC governance. Sixty-one responses were returned before an email reminder and 11 after the reminder (a total response rate of 79%). The data were entered into a database, and a descriptive analysis, with frequency distribution, was performed. RESULTS: The purpose of this review was to gain a preliminary understanding of the perceptions of program directors regarding the neurosurgical training process, the RRC, the oversight process, and projected manpower needs. A 79% response rate is high for a mail survey and likely reflects heightened concern and interest in such issues. The survey responses indicate general satisfaction with the role and governance of the RRC, significantly divergent perceptions of resident output and available positions, and serious concerns regarding the current training process. CONCLUSION: This survey suggests that a broader discussion of resident training issues would be valuable, perhaps using validated survey instruments.

Advisory Committees↗
PubMed2004

Management of cystic craniopharyngiomas with phosphorus-32 intracavitary irradiation.

OBJECTIVE: The efficacy of stereotactic intracavitary irradiation with phosphorus-32 ((32)P) for patients with cystic craniopharyngiomas was assessed on the basis of patient survival, tumor control, and visual and endocrinological function before and after treatment. Limited data are available regarding long-term outcomes. METHODS: Forty-nine patients were treated with stereotactic (32)P intracavitary irradiation. Of these, 25 had had no prior treatment as the primary treatment, and 24 were treated for residual or recurrent tumor cysts. At the time of (32)P intracavitary irradiation, 34 of the patients were adults, and 15 were children younger than 16 years of age. The mean cyst volume was 13 ml. The radiation dose varied from 189 to 250 Gy to the cyst wall during five half-lives of the isotope (mean, 224 Gy). The mean follow-up periods were 7 years after diagnosis and 4 years after (32)P treatment. RESULTS: The actuarial survival rates were 90% at 5 years after the diagnosis and 80% at 10 years. The actuarial tumor cyst control rates were 76% at 5 years and 70% at 10 years after the diagnosis. After treatment, 9 (23%) of 40 patients who underwent preoperative and postoperative visual testing were found to have delayed worsening in visual function, 6 as a result of tumor progression and 3 attributed to irradiation. Nineteen patients (48%) had improved visual function. Of 17 patients who had normal preoperative pituitary function or stalk effect, 12 (71%) had preserved and 5 (29%) had worsened visual function. No complications other than visual or endocrinological deterioration occurred in these patients. CONCLUSION: For patients with cystic craniopharyngiomas, (32)P intracavitary irradiation proved effective, with a low risk of complications, for the control of tumor cysts but not of solid tumor components.

Actuarial Analysis↗
PubMed2004

Experimental radiobiological investigations into radiosurgery: present understanding and future directions.

LARS LEKSELL BEGAN radiobiological investigations to study the effect of high-dose focused radiation on the central nervous system more than 5 decades ago. Although the effects of radiosurgery on the brain tumor microenvironment are still under investigation, radiosurgery has become a preferred management modality for many intracranial tumors and vascular malformations. The effects and the pathogenesis of biological effects after radiosurgery may be unique. The need for basic research concerning the radiobiological effects of high-dose, single-fraction, ionizing radiation on nervous system tissue is crucial. Information from those studies would be useful in devising strategies to avoid, prevent, or ameliorate damage to normal tissue without compromising treatment efficacy. The development of future applications of radiosurgery will depend on an increase in our understanding of the radiobiology of radiosurgery, which in turn will affect the efficacy of treatment. This article analyzes the current state of radiosurgery research with regard to the nature of central nervous system effects, the techniques developed to increase therapeutic efficacy, investigations into the use of radiosurgery for functional disorders, radiosurgery as a tool for investigations into basic central nervous system biology, and the additional areas that require further investigation.

Animals↗
PubMed2004

A call to define stereotactic radiosurgery.

Stereotactic radiosurgery is the single-session, precise delivery of a therapeutically effective radiation dose to an imaging-defined target. Conceived and developed during the past 5 decades, stereotactic radiosurgery has involved significant advances, which have improved patient outcomes and made it a critical component of modern neurosurgical practice and training. In this article, a short history of stereotactic surgery and radiosurgery are presented, and radiosurgery is contrasted to radiation therapy. Adherence to accepted, descriptive terms in defining stereotactic radiosurgery and radiation therapy permits a clear distinction among the results of the different radiation delivery techniques for patients, physicians, and other interested parties.

Radiosurgery↗
PubMed2004

Gene transfer to glial tumors using herpes simplex virus.

Glial tumors occur as intraaxial masses in the brain and are uniformly fatal due to lack of effective therapy. Resection combined with radiation and chemotherapy fails to eradicate malignant cells infiltrating into normal brain, and recurrence at the original site is ultimately fatal. Gene transfer offers the potential to enhance tumor cell killing while sparing surrounding normal brain. Several approaches have been developed to deliver genes to tumor cells in order to kill these cells. The first strategy involves the use of viral vectors that are replication-competent, but depend on attributes unique to the tumor cell to support viral growth. Both replication-competent adenovirus and herpes simplex virus (HSV) vectors have been employed in pre-clinical studies and most recently in human clinical trials. For this purpose, HSV vectors have been engineered that replicate in dividing cells, such as tumor cells, but not in normal neurons. The use of conditional replication competent viruses could allow for their spread in tumor tissue while minimizing damage to normal brain, thus increasing the specificity and effectiveness. Such mutants include those lacking the viral thymidine kinase (tk) gene (4-7), ribonucleotide reductase gene (8,9), a protein kinase gene, or a gene (gamma34.5) required for growth specifically in neurons (11-13).

Animals↗
PubMed2004

Stereotactic radiosurgery for brainstem arteriovenous malformations: factors affecting outcome.

OBJECT: Management options for arteriovenous malformations (AVMs) of the brainstem are limited. The long-term results of stereotactic radiosurgery for these disease entities are poorly understood. In this report the authors reviewed both neurological and radiological outcomes following stereotactic radiosurgery for brainstem AVMs over 15 years of experience. METHODS: Fifty patients with brainstem AVMs underwent gamma knife surgery between 1987 and 2002. There were 29 male and 21 female patients with an age range of 7 to 79 years (median 35 years). Anatomical locations of these AVMs included the midbrain (39 lesions), pons (20 lesions), and medulla oblongata (three lesions). The radiation dose applied to the margin of the AVM varied from 12 to 26 Gy (median 20 Gy). Forty-five patients were followed up from 5 to 176 months (mean 72 months). The angiographically confirmed actuarial obliteration rate was 66% at the final follow-up examination. Two patients experienced a hemorrhage before obliteration. The annual hemorrhage rate was 1.7% for the first 3 years after radiosurgery and 0% thereafter. Patients who had received irradiation at two or fewer isocenters had higher obliteration rates (80% compared with 44% for > two isocenters, p = 0.006), and this was related to a more spherical nidus shape. The rate of persistent neurological complications in patients treated using magnetic resonance imaging-based dose planning after 1993 was 7%, compared with 20% in patients treated before 1993. An older patient age, a lesion located in the tectum, and a higher radiosurgery-based score were significantly associated with greater neurological complications. CONCLUSIONS: Stereotactic radiosurgery provided complete obliteration of AVMs in two thirds of the patients with a low risk of latency-interval hemorrhage. Better three-dimensional imaging studies and conformal dose planning reduced the risk of adverse radiation effects. Younger patients harboring more spherical AVMs that did not involve the tectal plate had the best outcomes.

Adolescent↗
PubMed2004

Radiosurgery and radiotherapy: observations and clarifications.

OBJECT: Radiosurgery and radiation therapy represent important but unique treatment paradigms for patients with certain neoplasms, vascular lesions, or functional disorders. The authors discuss their differences. METHODS: Reviewing the authors' experiences shows how the roles of these approaches vary just as their techniques differ. The distinct differences include the method of target localization (intraoperative compared with pretreatment) and irradiation (focused compared with wide-field), their radiobiology (effects of a single high-dose compared with multiple fractions), the physicians and other health personnel involved in the conduct of these procedures (surgical team compared with radiation team), and the expectations that follow treatment. During the last decade, considerable confusion has grown regarding nomenclature, requisite physician training, and the roles of the physician and surgeon. Ten years ago, two task forces on radiosurgery were created by national organizations in neurosurgery and radiation oncology to address these issues of procedural conduct and quality-assurance requirements. At the present time these guidelines are widely ignored. Currently, many patients, payers, and regulatory agencies are bewildered. What are the differences among stereotactic radiosurgery, fractionated radiation therapy, and stereotactic radiation therapy? Radiosurgery is to radiation therapy as microsurgery is to "microtherapy." CONCLUSIONS: In this report the authors discuss terminology, training, and physician roles in this expanding field.

Brain Diseases↗
PubMed2003

Gamma knife radiosurgery of imaging-diagnosed intracranial meningioma.

PURPOSE: To evaluate tumor control and outcome from radiosurgery of meningiomas diagnosed by imaging without pathologic verification. METHODS AND MATERIALS: A total of 219 meningiomas diagnosed by imaging criteria underwent gamma knife radiosurgery to a median marginal tumor dose of 14 Gy (range 8.9-20), a median treatment volume of 5.0 cm(3) (range 0.47-56.5), and a median maximal dose of 28 Gy (range 22-50). The median follow-up was 29 months (range 2-164). RESULTS: Tumor progression developed in 7 cases, 2 of which turned out to be different tumors (metastatic nasopharyngeal adenoid cystic carcinoma and chondrosarcoma). One tumor was controlled, but the development of other brain metastases suggested a different diagnosis. The actuarial tumor control rate was 93.2% +/- 2.7% at 5 and 10 years. The actuarial rate of identifying a diagnosis other than meningioma was 2.3% +/- 1.4% at 5 and 10 years. The actuarial rate of developing any postradiosurgical injury reaction was 8.8% +/- 3.0% at 5 and 10 years. No pretreatment variables correlated with tumor control in univariate or multivariate analysis. The risk of postradiosurgery sequelae was lower (5.3% +/- 2.3%) in patients treated after 1991 (with stereotactic MRI and lower doses; p = 0.0104) and tended to increase with treatment volume (p = 0.0537). CONCLUSION: Radiosurgery of meningioma diagnosed by imaging without tissue confirmation is associated with a high rate of tumor control and acceptable morbidity but carries a small risk (2.3%) of an incorrect diagnosis.

Adolescent↗
PubMed2003

Radiosurgery for nonfunctioning pituitary adenoma.

OBJECT: Nonfunctioning pituitary adenomas comprise approximately 30% of all pituitary tumors. The purpose of this retrospective study was to evaluate the efficacy and role of gamma knife surgery (GKS) in the treatment of these lesions. METHODS: The authors conducted a review of cases in which GKS was performed at the University of Pittsburgh between 1987 and 2001. Forty-six patients with nonfunctioning pituitary adenomas and with at least 6 months of follow- up data were identified. In 41 of these patients some form of prior treatment such as transsphenoidal resection, craniotomy and resection, or conventional radiation therapy had been conducted. Five patients were deemed ineligible for microsurgery, and GKS served as the primary treatment modality. Endocrinological, ophthalmological, and radiological responses were evaluated. The mean radiation dose to the margin was 16 Gy. In all patients with microadenomas and 91% of those with macroadenomas tumor control was demonstrated after radiosurgery. Gamma knife surgery had essentially equal efficacy in terms of achieving tumor control in cases of adenomas with cavernous sinus invasion and suprasellar extension. No new endocrinopathies were noted following radiosurgery. In two patients, however, tumor growth and decline in visual function occurred. CONCLUSIONS: Gamma knife surgery is safe and effective in treating nonfunctioning pituitary adenomas. Radiosurgery may serve as a primary treatment modality in some or as a salvage treatment in others. Treatment must be tailored to meet the patient's symptoms, overall health, and tumor morphometry.

Adenoma↗
PubMed2003

The role of stereotactic radiosurgery for low-grade astrocytomas.

OBJECT: This study was conducted to examine the role of radiosurgery in the management of patients with recurrent or unresectable low-grade astrocytomas. METHODS: During a 13-year interval, 49 patients underwent stereotactic radiosurgery as part of multimodal treatment of their recurrent or unresectable low-grade astrocytomas. Thirty-seven of these patients (median age 14 years) harbored pilocytic astrocytomas and 12 patients harbored World Health Organization (WHO) Grade II fibrillary astrocytomas (median age 25 years). Tumors involved the brainstem in 22 cases, cerebellum in four, thalamus in six, temporal lobe in five, frontal lobe in four, and parietal lobe in three, as well as the hypothalamus, corpus callosum, insular cortex, optic tract, and third ventricle in one patient each. Each diagnosis was confirmed with the aid of stereotactic biopsy sampling in 17 patients, open biopsy sampling in five, partial resection in 13, and near-total resection in 14. Multimodal treatment included fractionated radiotherapy in 14 patients, stereotactic intracavitary irradiation in five, chemotherapy in two, cyst drainage in eight, ventriculoperitoneal shunt placement in five, and additional cytoreductive surgery in five. Tumor volumes ranged from 0.42 to 45.1 cm3. The median radiosurgical dose to the tumor margin was 15 Gy (range 9.6-22.5 Gy). After radiosurgery, serial neuroimaging demonstrated complete tumor resolution in 11 patients, reduced tumor volume in 12, stable tumor volume in 10, and delayed tumor progression in 16. No procedure-related death was encountered. Forty-five of 49 patients are alive at a median follow-up period of 32 months after radiosurgery and 63 months after diagnosis. Sixteen patients participated in follow-up review for more than 60 months. Three patients died of local tumor progression. CONCLUSIONS: Stereotactic radiosurgery is a potential alternative or adjunctive intervention in the management of selected patients with pilocytic or WHO Grade II fibrillary astrocytomas, usually performed for small-volume tumors in an attempt to avoid larger-field fractionated radiotherapy.

Adolescent↗
PubMed2003

Comparison of management options for patients with acoustic neuromas.

Management options for patients with vestibular schwannomas (acoustic neuromas) include observation, tumor resection, stereotactic radiosurgery, and fractionated radiotherapy. In this report the authors review their 15-year experience with radiosurgery and discuss indications and expectations in relation to the different approaches. They conducted a survey of neurosurgeons to determine management preferences in two different cases of intra- and extra-canalicular tumor presentations. Patient decisions must be based on quality information derived from peer-reviewed literature.

Disease Management↗
PubMed2003

The effect of radiosurgery during management of aggressive meningiomas.

BACKGROUND: Aggressive (atypical or malignant) meningiomas are difficult tumors to manage. We review the local control and survival rates of patients with aggressive meningiomas after multi-modality therapy that included stereotactic radiosurgery (SRS). METHODS: Thirty patients had SRS for treatment of malignant (n = 12) or atypical (n = 18) meningiomas. There were 17 (57%) males and 13 (43%) females with an average age of 58 years. The mean number of prior surgical resections was two. The median imaging follow-up was 2.3 (0.1-11.4) years; median clinical follow-up was 3.8 (0.25-11.5) years. RESULTS: After SRS, the overall median time until progression of neurologic signs was 48.0 (+/-6.51) months. Median time to neurologic progression was significantly worse for patients treated late after recurrence versus early after craniotomy. Atypical meningiomas had 5- and 10-year overall actuarial survival rates of 59% (+/-13), while malignant meningiomas had 5- and 10-year overall actuarial survival rates of 59% (+/-16) and 0%. These curves were not significantly different from one another. Atypical meningiomas had a 5-year progression-free survival (PFS) of 83% (+/-7%), while malignant meningiomas had a 5-year PFS of 72% (+/-10) (p = 0.018). On multivariate analysis, early SRS and smaller tumor volumes were associated with better PFS, while younger age was associated with better survival. One patient had an adverse radiation effect after SRS. CONCLUSIONS: Stereotactic radiosurgery is an important adjuvant management strategy for residual tumors identified early after craniotomy and partial resection. Aggressive use of early boost radiosurgery following craniotomy and radiation therapy is recommended for patients with malignant meningiomas.

Actuarial Analysis↗