Biomedical subjects

Ronald E Warnick

Publications and source records attributed to Ronald E Warnick.

7 recordsLinked to original sources

PubMed2005

Adaptation of a standard low-field (0.3-T) system to the operating room: focus on pituitary adenomas.

iMRI is a reliable and safe tool to monitor the extent of resection and to avoid complications in the transsphenoidal surgical approach for pituitary tumors. The best indication for its application in transsphenoidal surgery is for patients with pituitary macroadenomas with suprasellar extension. The low-field 0.3-T magnet has a diagnostic imaging quality that provides surgeons with good intraoperative detail of the anatomic relations in the sellar region. In our experience, iMRI provided a distinct benefit in planned STR for invasive macroadenomas that compress the optic chiasm and in planned GTR for noninvasive tumors. The iMRI design adopted at our center includes important features, such as the use of ferromagnetic surgical instruments, elimination of patient transportation, and capability as a shared resource, that allow multipurpose diagnostic use and increased cost-effectiveness.

Adenoma↗

PubMed2004

Results of contemporary surgical management of radiation necrosis using frameless stereotaxis and intraoperative magnetic resonance imaging.

OBJECTIVE: Radiation necrosis is a well-known complication of radiotherapy for malignant brain tumors. Although surgery was once considered the mainstay of treatment, no recent reports have evaluated the use of intraoperative magnetic resonance imaging (IOMRI) and frameless stereotaxis during surgical resection of radiation necrosis. In this retrospective review, we evaluate the effectiveness of surgical resection using frameless stereotaxis and IOMRI for the treatment of radiation necrosis. METHODS: From October 1999 through February 2002, 11 patients who had malignant brain tumors underwent surgery for radiation necrosis. The diagnosis of radiation necrosis was based primarily on MRI and clinical suspicion. Frameless stereotaxis was used in all patients and IOMRI was used in nine. All patients underwent at least one radiation treatment before surgery and nine patients had multiple treatments. Patient outcome was based on changes in steroid dose, Karnofsky Performance Score (KPS), and neurologic deficit. RESULTS: Optimal resection as confirmed by IOMRI was achieved in all patients by the use of frameless stereotaxis alone; no additional resection was performed in any patient. For nine patients taking steroids (mean preoperative dose 24 mg/day) before treatment of necrosis, all had a substantial reduction in steroid dosage (mean postoperative dose 8 mg/day) after surgical treatment. Postoperatively, KPS improved in four patients, remained stable in four, and worsened in three. Three complications that resulted from surgery included wound infection, asymptomatic carotid dissection, and pulmonary embolism; thus, overall morbidity including both surgical complications and neurologic deterioration was 54%. CONCLUSIONS: In this review, frameless stereotaxis was helpful in guiding the surgeon; however, IOMRI did not provide any additional benefit for the surgical treatment of radiation necrosis. Surgical treatment of radiation necrosis was associated with high risks of complication or neurologic deficit. Given the success of medical therapies, including hyperbaric oxygen, we believe that surgical treatment of radiation necrosis should be reserved for symptomatic patients in whom medical therapy has failed.

Adult↗

PubMed2003

Neuro-oncology research opportunities in North America: results of a survey by the AANS/CNS section on tumors.

OBJECTIVE: A primary goal of the AANS/CNS Section on Tumors is to foster neuro-oncology research. The Research Committee was charged with the responsibility of assessing the neuro-oncology research opportunities currently available within neurosurgery residency programs and proposing strategies to enhance these activities. METHODS: Two separate surveys were mailed to all neurosurgery program directors (112) and neurosurgery residents (872) in North America. The initial mailing was in December 1997 and a follow-up mailing was sent in June 1998 to those who did not respond. RESULTS: Seventy-seven (69%) program directors and 279 (32%) neurosurgery residents responded to the survey. Neuro-oncology research rotations of varying duration (usually <12 months) were available at most residency programs (87%). Research mentors included equal numbers of neurosurgeons and outside faculty. Funding sources were well distributed among departmental (27%), federal (24%), institutional (22%), and private (19%) sources. Common basic science research areas included molecular biology, gene therapy, and pathology, whereas image-guided surgery was the most frequent area of clinical research. Approximately one-third of the responding residents had completed a neuro-oncology research rotation, mainly in an area of basic science, which resulted in an average of two publications and three presentations at national meetings. The most significant challenges for residents pursuing neuro-oncology research were concurrent clinical responsibilities, lack of faculty mentors, and insufficient research funding. CONCLUSIONS: Neuro-oncology research opportunities are available within most neurosurgery residency programs and appear to attract a reasonable number of productive trainees. The results of this survey have identified several important ways in which the AANS/CNS Section on Tumors can enhance neuro-oncology research opportunities and a comprehensive strategy for accomplishing these goals is presented.

Data Collection↗

PubMed2003

Postoperative management of patients after stereotactic biopsy: results of a survey of the AANS/CNS section on tumors and a single institution study.

As little consensus exists on the postoperative care of patients undergoing stereotactic biopsy, we sought to establish a new algorithm for their postoperative management. First, we surveyed active members of the AANS/CNS Section on Tumors to determine national practice patterns for patients after stereotactic biopsy. Second, we retrospectively reviewed 84 consecutive stereotactic biopsy procedures at our institution to assess the potential benefit of routine computed tomography (CT) scanning and intensive care unit (ICU) monitoring. Finally, we prospectively applied this new algorithm in 54 patients to assess its validity. Of 629 surgeons, 263 (42%) responded; they were experienced neurosurgeons (mean 15 years in practice) who performed more than 10 stereotactic biopsies per year. Most surgeons (59%) routinely ordered postoperative CT scans, and the remainder ordered scans based on specific indications. Patients were transferred from the recovery room to a special care unit (47%), regular room (47%), or home (6%). In our retrospective review, 81 patients underwent 84 stereotactic biopsy procedures; 79 underwent postoperative CT scanning and all 81 were monitored overnight in the ICU. Among five (6%) patients who experienced intraoperative hemorrhage, two (2%) underwent craniotomy to control arterial bleeding. Three (4%) patients developed new neurological deficits, which occurred within 2 h of surgery. In both groups, CT scans were helpful in excluding hemorrhage that would require re-operation. In the remaining patients (90%), findings on routine postoperative CT did not alter patient management and ICU monitoring appeared unnecessary because neurological complications occurred within 2 h postoperatively. We confirmed these results in the prospective study of 54 patients undergoing stereotactic biopsy without routine postoperative CT scanning or ICU monitoring. In contrast with national practice patterns reported, we recommend that CT scanning and ICU monitoring be reserved for patients who have intraoperative hemorrhage or new deficits after surgery. All other patients can be monitored for 2 h in the recovery room and transferred to a regular hospital room without a postoperative CT scan.

Adult↗

PubMed2002

Management strategy for adult patients with dorsal midbrain gliomas.

OBJECTIVE: Dorsal midbrain gliomas (DMGs) involving the tectum occur more commonly in children than in adults. These lesions are often indolent in nature, and patients require treatment only for obstructive hydrocephalus. Because limited information is available concerning adults with this type of lesion, we describe our experience and management strategy in adults with DMGs. METHODS: We retrospectively reviewed the charts and magnetic resonance imaging scans of five adult patients (four men, one woman; mean age, 51.6 yr; range, 23-69 yr) who were treated from March 1992 to August 2001 for DMGs involving the tectum. The mean follow-up time for these patients was 71.4 months (range, 25-113 mo). We analyzed the data to determine the optimal treatment strategy and outcomes of patients with DMGs. Tumor volume was analyzed objectively with Scion Image software (Scion Corp., Frederick, MD) to document changes in volume and determine whether treatment strategy differed significantly with tumor size. RESULTS: Tumors in two of these patients were found incidentally, and three others presented with obstructive hydrocephalus. Magnetic resonance imaging scans demonstrated an isolated tectal glioma in one patient, tectal and tegmental (periaqueductal) gliomas in three patients, and a tectal glioma with right thalamic extension in one patient. Treatment consisted of routine follow-up for the two asymptomatic patients and cerebrospinal fluid diversion surgery for the three patients with hydrocephalus. Volumetric analysis demonstrated that all asymptomatic patients had tumors smaller than 9.3 cm(3), and symptomatic patients had tumors larger than 28.5 cm(3). All follow-up magnetic resonance imaging scans revealed stable dorsal midbrain lesions, and no patient required tumor-specific therapy. CONCLUSION: Although tumors of the dorsal midbrain occur primarily in the pediatric population, similar tumors may occur in adults. As has been learned from experience with children, these lesions are often clinically and radiographically stable and require only appropriate therapy for obstructive hydrocephalus. We advocate a similar conservative strategy of routine imaging follow-up and treatment for hydrocephalus in adult patients. Surgery and other therapy should be reserved for patients with progressive lesions.

Adult↗

PubMedDate not supplied

Safety, tolerability, and tumor response of IL4-Pseudomonas exotoxin (NBI-3001) in patients with recurrent malignant glioma.

PURPOSE: This was an open-label, dose-escalation trial of intratumoral administration of IL-4 Pseudomonas exotoxin (NBI-3001) in patients with recurrent malignant glioma. PATIENTS AND METHODS: A total of 31 patients with histologically verified supratentorial grades 3 and 4 astrocytoma were studied. Of these, 25 patients were diagnosed with glioblastoma multiforme (GBM) while six were diagnosed with anaplastic astrocytoma. Patients were over 18 years of age and had Karnofsky performance scores > or = 60. Patients were assigned to one of four dose groups in a dose-escalation fashion: 6 microg/ml x 40 ml, 9 microg/ml x 40 ml, 15 microg/ml x 40 ml, or 9 microg/ml x 100 ml of NBI-3001 administered via convection-enhanced delivery intratumorally using stereotactically placed catheters. Patients were followed with serial MRI scans and clinical assessments every four weeks for the first 16 weeks and then every eight weeks until week 26. RESULTS: No drug-related systemic toxicity, as evident by lack of hematological or serum chemical changes, was apparent in any patients; treatment-related adverse effects were limited to the central nervous system. No deaths were attributable to treatment. Drug-related grade 3 or 4 toxicity was seen in 39% of patients in all dose groups and 22% of patients at the maximum tolerated dose of 6 microg/ml x 40 ml. The overall median survival was 8.2 months with a median survival of 5.8 months for the GBM patients. Six-month survival was 52% and 48%, respectively. Gadolinium-enhanced magnetic resonance imaging of the brain showed areas of decreased signal intensity within the tumor consistent with tumor necrosis following treatment in many patients. CONCLUSIONS: NBI-3001 appears to have an acceptable safety and toxicity profile when administered intratumorally in patients with recurrent malignant glioma.

Adult↗

PubMedDate not supplied

Stereotactic radiosurgery for patients with solid brain metastases: current status.

The goal of this article is to provide a contemporary update on the use of stereotactic radiosurgery (SRS) for the treatment of intracranial metastatic disease. We discuss the rationale for employing SRS in brain metastases and describe the critical factors that predict outcome. We highlight the main clinical indications for SRS including treatment of recurrent brain metastases after previous whole brain radiation therapy (WBRT), as a boost after WBRT, and as sole therapy for newly diagnosed tumors. For each clinical scenario, we offer a treatment algorithm based on our clinical experience. The article also addresses the most common complications associated with SRS and their treatment.

Brain Neoplasms↗