Showing papers by "Michael E. Sughrue published in 2009"

Facial nerve preservation after vestibular schwannoma Gamma Knife radiosurgery

Abstract: Objective Facial nerve preservation is a critical measure of clinical outcome after vestibular schwannoma treatment. Gamma Knife radiosurgery has evolved into a practical treatment modality for vestibular schwannoma patients, with several reported series from a variety of centers. In this study, we report the results of an objective analysis of reported facial nerve outcomes after the treatment of vestibular schwannomas with Gamma Knife radiosurgery. Materials and methods A Boolean Pub Med search of the English language literature revealed a total of 23 published studies reporting assessable and quantifiable outcome data regarding facial nerve function in 2,204 patients who were treated with Gamma Knife radiosurgery for vestibular schwannoma. Inclusion criteria for articles were: (1) Facial nerve preservation rates were reported specifically for vestibular schwannoma, (2) Facial nerve functional outcome was reported using the House–Brackmann classification (HBC) for facial nerve function, (3) Tumor size was documented, and (4) Gamma Knife radiosurgery was the only radiosurgical modality used in the report. The data were then aggregated and analyzed based on radiation doses delivered, tumor volume, and patient age. Results An overall facial nerve preservation rate of 96.2% was found after Gamma Knife radiosurgery for vestibular schwannoma in our analysis. Patients receiving less than or equal to 13 Gy of radiation at the marginal dose had a better facial nerve preservation rate than those who received higher doses (≤13 Gy = 98.5% vs. >13 Gy = 94.7%, P 1.5 cm3 95.5%, P < 0.0001). Superior facial nerve preservation was also noted in patients younger than or equal to 60 years of age (96.8 vs. 89.4%, P < 0.0001). The average reported follow up duration in this systematic review was 54.1 ± 31.3 months. Conclusion Our analysis of case series data aggregated from multiple centers suggests that a facial nerve preservation rate of 96.2% can be expected after Gamma knife radiosurgery for vestibular schwannoma. Younger patients with smaller tumors less than 1.5 cm3 and treated with lower doses of radiation less than 13 Gy will likely have better facial nerve preservation rates after Gamma Knife radiosurgery for vestibular schwannoma.

Non-audiofacial morbidity after Gamma Knife surgery for vestibular schwannoma

Abstract: Object While many studies have been published outlining morbidity following radiosurgical treatment of vestibular schwannomas, significant interpractitioner and institutional variability still exists. For this reason, the authors conducted a systematic review of the literature for non-audiofacial-related morbidity after the treatment of vestibular schwannoma with radiosurgery. Methods The authors performed a comprehensive search of the English-language literature to identify studies that published outcome data of patients undergoing radiosurgery treatment for vestibular schwannomas. In total, 254 articles were found that described more than 50,000 patients and were analyzed for satisfying the authors' inclusion criteria. Patients from these studies were then separated into 2 cohorts based on the marginal dose of radiation: ≤ 13 Gy and > 13 Gy. All tumors included in this study were < 25 mm in their largest diameter. Results A total of 63 articles met the criteria of the established search protocol, which ...

Radiobiology of vestibular schwannomas: mechanisms of radioresistance and potential targets for therapeutic sensitization

Abstract: Vestibular schwannomas (VS) are benign tumors arising from the Schwann cells of cranial nerve VIII. Historically the prevailing therapy for patients with VS has been microsurgical resection. More recently, stereotactic radiosurgery (SRS) and fractionated stereotactic radiotherapy have gained acceptance as effective alternatives. Although the side effect profile and rates of tumor control appear to be favorable for SRS, there is a subset of radioresistant tumors that continue to progress despite properly administered radiation treatment. In this review, the authors summarize what is known about the mechanism of radioresistance in VS at the clinical and molecular level. An improved understanding of the radiobiological behavior of VS may help guide appropriate patient selection for SRS and potentially aid in the design of novel therapies to treat radioresistant tumors.

Bioethical considerations in translational research: primate stroke.

Abstract: Controversy and activism have long been linked to the subject of primate research. Even in the midst of raging ethical debates surrounding fertility treatments, genetically modified foods and stem-cell research, there has been no reduction in the campaigns of activists worldwide. Plying their trade of intimidation aimed at ending biomedical experimentation in all animals, they have succeeded in creating an environment where research institutions, often painted as guilty until proven innocent, have avoided addressing the issue for fear of becoming targets. One area of intense debate is the use of primates in stroke research. Despite the fact that stroke kills more people each year than AIDS and malaria, and less than 5% of patients are candidates for current therapies, there is significant opposition to primate stroke research. A balanced examination of the ethics of primate stroke research is thus of broad interest to all areas of biomedical research.

Pre-operative dopamine agonist therapy improves post-operative tumor control following prolactinoma resection

Abstract: Objective Normalization of serum prolactin concentrations in patients with prolactinomas is an accepted endpoint of therapy. Clinical signs and symptoms of hyperprolactinemia are usually resolved when prolactin levels are lowered to within the normal range. While most patients are treated with dopamine agonist drugs, some patients require surgical resection of their tumors. We sought to determine whether preoperative treatment with dopamine agonists alters the outcome of surgical intervention. Methods and results We present an analysis of 253 patients with prolactinomas treated surgically during the period of time when dopamine agonist therapy was first introduced and prior to its widespread use as first-line therapy. We compared both short- and long-term outcomes of patients treated with dopamine agonists prior to surgery with those undergoing surgery as their initial treatment modality. Our data showed that that patients treated with dopamine agonists prior to surgery experienced greater reductions in prolactin levels, had lower prolactin levels, were more likely to have normal prolactin levels at long term follow-up, and were less likely to require additional therapy to control their prolactin levels. Conclusion Our study provides strong evidence suggesting that, regardless of initial prolactin level, preoperative dopamine agonist therapy is not detrimental. In fact, pretreatment with dopamine agonist drugs, possibly by inducing tumor regression, seemed to improve the surgeon’s ability to resect a greater percentage of the tumor and led to better control of the prolactin level.

Immunological considerations of modern animal models of malignant primary brain tumors

Abstract: Recent advances in animal models of glioma have facilitated a better understanding of biological mechanisms underlying gliomagenesis and glioma progression. The limitations of existing therapy, including surgery, chemotherapy, and radiotherapy, have prompted numerous investigators to search for new therapeutic approaches to improve quantity and quality of survival from these aggressive lesions. One of these approaches involves triggering a tumor specific immune response. However, a difficulty in this approach is the the scarcity of animal models of primary CNS neoplasms which faithfully recapitulate these tumors and their interaction with the host's immune system. In this article, we review the existing methods utilized to date for modeling gliomas in rodents, with a focus on the known as well as potential immunological aspects of these models. As this review demonstrates, many of these models have inherent immune system limitations, and the impact of these limitations on studies on the influence of pre-clinical therapeutics testing warrants further attention.

The complement cascade: new avenues in stroke therapy.

Abstract: Recent evidence has shown that after the initial occlusion, a large portion of stroke patients achieve some degree of reperfusion either through collateral circulation or clot dissolution. However, it appears that this reperfusion may lead to increased inflammation-induced damage. Even though the exact mechanism of this secondary injury is unclear, several experimental studies have indicated an intimate connection between complement and this secondary form of damage. We review the available literature and attempt to identify promising clinical therapeutic targets.

Vision salvage after resection of a giant meningioma in a patient with a loss in light perception.

Abstract: Clinical approaches to the surgical management of optic chiasm compression stress quick action, as several case series have demonstrated minimal vision restoration following aggressive decompression in patients presenting more than 3 days after the onset of blindness. The authors here report the case of a 48-year-old woman who presented with near-complete binocular vision loss but regained visual function following surgical removal of a giant planum-tuberculum meningioma, which was performed 8 days after a documented loss in light perception. The interval between the patient's vision loss and successful vision-restoring decompressive surgery is the longest recorded to date in the literature. This case shows the importance of aggressive decompression of mass lesions despite extended intervals of optic nerve dysfunction.

Sarcoidosis of the pineal gland: an unusual presentation of neurosarcoidosis

Abstract: Introduction Sarcoidosis is an inflammatory disease characterized by noncaseating granulomas that is rarely found as primary CNS pathology. We report an unusual case of sarcoidosis involving the pineal gland with radiographic, histopathology, and clinical data. Case report A 45-year-old man without evidence of systemic sarcoidosis presented with a history of gradual onset of blurry vision and diplopia that progressed over 3 months. MR imaging demonstrated an enhancing mass in the pineal region. A suboccipital craniotomy was performed with resection of the mass through a supra-cerebellar infratentorial approach. Histopathologic analysis did not reveal a pineoblastoma but instead revealed noncaseating granulomas within the pineal gland. Extensive hematologic laboratory examinations, cerebral spinal fluid studies, and cultures for infection were all negative. This mass lesion was diagnosed as solitary neurosarcoidosis of the pineal gland, without dissemination. The patient was treated with steroids and at 4-year follow-up is asymptomatic with an unremarkable MRI scan. Conclusion This is an unusual case of pineal sarcoidosis mimicking a tumor with associated MRI, CT and histopathologic findings reported together. Although rare, sarcoidosis of the pineal gland should not be excluded from a comprehensive differential diagnosis of an enhancing pineal region mass.