Biomedical subjects

D L Silbergeld

Publications and source records attributed to D L Silbergeld.

At least 19 recordsLinked to original sources

PubMed1996

Intrasellar abscess following transsphenoidal surgery.

BACKGROUND: Intrasellar abscess following transsphenoidal surgery has been described only twice in the English language medical literature. Overall mortality associated with intrasellar abscesses is 51%, while mortality in reported cases not treated surgically is 100%. METHODS: Two cases of intrasellar abscess following uncomplicated transsphenoidal surgery for pituitary pathology are reported. The incidence, radiographic features, clinical presentations, and treatment of intrasellar abscesses are discussed. RESULTS: Both patients described underwent uncomplicated transsphenoidal procedures for treatment of a primary pituitary lesion. Neither developed postoperative CSF rhinorrhea, and initial recovery was uneventful. The first patient presented with new symptoms several weeks after transsphenoidal surgery; the second patient almost two years postoperatively. The first displayed signs of an expanding sellar mass, requiring transsphenoidal drainage and postoperative antibiotics. The second presented with recurrent meningitis without discernible CSF leak, and was treated with transnasal endoscopic drainage in conjunction with antibiotic therapy. CONCLUSIONS: The high mortality associated with intrasellar abscess mandates its inclusion in the differential diagnosis of patients presenting with symptoms of meningitis or an expanding sellar mass after transsphenoidal intervention. Although antibiotic therapy is an important adjunct, surgical drainage is required for definitive treatment.

Brain Abscess↗

PubMed1996

Large-dose propofol alone in adult epileptic patients: electrocorticographic results.

The primary objective of this study was to evaluate the electrophysiologic effects of large-dose propofol, used as the sole anesthetic in patients with epilepsy. Nine patients with medically intractable complex partial epilepsy undergoing a three-stage approach to the surgical management of epilepsy were recruited. State I involved placement of the intracranial electrode array, while Stage II consisted of extraoperative localization of the seizure focus. The patients were studied during induction of anesthesia for Stage III (removal of electrodes and resection of seizure focus). Unpremedicated patients were induced with a propofol infusion (0.5 mg.kg-1.min-1) until one of the following occurred: 1) electrical seizure activity, 2) burst suppression, or 3) total dose of 10 mg/mg. Electrocorticography (ECoG) was recorded continuously during this period. Two patients were excluded from the study after experiencing delayed awakening after the Stage I procedure. Both had received propofol along with other anesthetics. No ECoG evidence of seizure activity was detected in the seven patients completing the study. Burst suppression was attained in six patients using a mean dose of 5.7 mg/kg +/- 2.6. We conclude that large dose propofol alone does not trigger electrical epileptiform activity on the ECoG of seizure patients.

Adolescent↗

PubMed1996

Early postoperative magnetic resonance imaging following nonneoplastic cortical resection.

Postcraniotomy residual tumor is often determined by magnetic resonance (MR) imaging. Magnetic resonance changes that occur in the postoperative setting must be defined to ensure both the optimum timing of postoperative image acquisition and the accurate assessment of images for residual tumor. Postoperative changes in nontumor parenchyma have previously been described for computerized tomography but not for MR imaging. In the present study, 11 patients without intracranial neoplastic disease (six females and five males with a median age of 36 years) submitted to MR imaging 17 to 28 hours after undergoing temporal lobectomies for epilepsy. Four of the operations were performed with the patients under general anesthesia and seven under local anesthesia. Postoperative MR images (T1-weighted, T1-weighted gadolinium enhanced, and T2-weighted) were reviewed. Extraaxial fluid, air, or blood was present in all cases. Enhancement of the resection bed parenchyma occurred in seven (64%) of 11 patients. In three of the remaining four patients, assessment of parenchymal enhancement was obscured by extraaxial fluid collections. Dural enhancement occurred adjacent to the resection site in all of the cases and remotely in 73%. Eight (73%) of 11 patients displayed enhancement of the pia-arachnoid of the ipsilateral cerebral convexity, two (18%) of the contralateral convexity, and four (36%) of the pia-arachnoid overlying the cerebellum. Contrary to previous reports, contrast enhancement of nonneoplastic human brain parenchyma can occur postoperatively within 17 hours. Benign parenchymal contrast enhancement is usually linear in appearance; nonneoplastic dural and leptomeningeal enhancement can occur both adjacent to and distant from the surgical site. Extraaxial fluid collections can hinder MR evaluation of the resection bed.

Adolescent↗

PubMed1995

The in vitro motility of human gliomas increases with increasing grade of malignancy.

BACKGROUND: Malignant gliomas are a highly invasive disease with a dismal prognosis despite aggressive therapeutic interventions. METHODS: The authors tested the hypothesis that increasing in vitro motility of human glial tumors correlates with increasing grade of malignancy. A radial dish assay was used to quantitatively assess the brain tumor cell motility of 14 low passage cell lines derived from human glial tumors of varied malignancy, and 3 cell lines derived from human glia. The egress of cells from a central region of high tumor cell density to a region of lower tumor cell density was determined at various time points. A motility coefficient (MC), the slope of distance traveled against time, was generated by simple linear regression analysis. RESULTS: The MC increased with the increased histologic grade of malignancy. Generation of a t-statistic was used to determine the significance of differences in motility among 5 histopathologic groups: 10 glioblastoma (World Health Organization Grade IV) cell lines (mean MC, 0.00396), 2 mixed anaplastic oligoastrocytoma (Grade III) cell lines (mean MC, 0.00382), 1 anaplastic astrocytoma (Grade III) cell line (mean MC, 0.00295), 1 Grade I glioma cell line (mean MC, 0.00206), and 3 human glial cell lines (mean MC, 0.00110). CONCLUSIONS: The radial dish assay provided a reproducible method for quantitatively assessing brain tumor cell motility. The higher MC observed with the malignant human glioma cell lines correlated with the tendency of these tumors to invade into adjacent brain tissue. The potential to inhibit glial tumor motility may provide an important therapeutic avenue in the future.

Brain Neoplasms↗

PubMed1995

Sjogren's cerebritis complicated by subarachnoid hemorrhage and bilateral superior cerebellar artery occlusion: case report.

We report a case of chronic Sjogren's cerebritis complicated by bilateral superior cerebellar artery occlusion and diffuse subarachnoid hemorrhage. Although primary Sjogren's syndrome with chronic leptomeningeal involvement has been well documented and a spectrum of central nervous system disease previously outlined, no case of intracranial subarachnoid hemorrhage with major intracranial vessel occlusion has been reported.

Cerebellum↗

PubMed1995

In vitro assessment of Taxol for human glioblastoma: chemosensitivity and cellular locomotion.

Although the antineoplastic efficacy of Taxol against a variety of tumors has been established, it has only recently been used for malignant brain tumors. We evaluated in vitro chemosensitivity of glioblastoma to Taxol and the affect of Taxol on glioblastoma cell locomotion. The clonogenic assay was used to evaluate the chemosensitivity of five human glioblastomas and the C6 rat glioma. Cells exposed to Taxol (0-250 nM) were suspended in agar in capillary tubes. Following incubation, colonies were counted to determine percent survival. All six cell lines demonstrated sensitivity to Taxol (LD50 1 nM to > 250 nM). However, even at concentrations exceeding those achievable clinically, all cell lines had surviving cells, indicating a saturation threshold for Taxol cytotoxicity. Cell locomotion was evaluated using the radial dish assay to determine the rate of egress of cells from a region of high cell density to the periphery. Increasing Taxol concentration caused increased locomotion in all six cell lines (p < 0.0001). Although Taxol has significant cytocidal impact, it increases in vitro locomotion of glioblastoma cells. These findings suggest that the clinical use of Taxol for glioblastoma may slow the growth of bulk disease, but may also lead to increased tumor invasion.

Cell Movement↗

PubMed1995

Assessment of brain tumor cell motility in vivo and in vitro.

Brain tumor dispersal far from bulk tumor contributes to and, in some instances, dominates disease progression. Three methods were used to characterize brain tumor cell motility in vivo and in vitro: 1) 2 weeks after implantation in rat cerebral cortex, single C6 cells labeled with a fluorescent tag had migrated to brain sites greater than 16 mm distant from bulk tumor; 2) time-lapse videomicroscopy of human brain tumor cells revealed motility of 12.5 microns/hr. Ruffling leading edges and pseudopod formation were most elaborate in more malignant cells; 3) an in vitro assay was devised to quantitatively evaluate motility from a region of high cell density to one of lower cell density. Human brain tumor cells were plated in the center of a petri dish, washed, and refed, establishing a 2-cm circular zone of cells in the dish center. Motility was determined by counting cells daily at predetermined distances from the central zone perimeter. Cells were found 1 cm from the perimeter by 24 hours and 3 cm from the perimeter by 4 days. Increasing serum concentration increased motility; however, neither fibronectin nor arrest of cells in the G0 phase by hydroxyurea altered motility. The addition of cytochalasin B to block cytoskeletal assembly prevented cell motility. Motility increased with increased malignancy. Subpopulations of cells were created by clonal amplification of cells that had migrated most rapidly to the dish periphery. Although morphologically indistinguishable when compared to the original cell line from which they were derived, these subpopulations demonstrated significantly increased motility.

Amidines↗

PubMed1995

Cortical stimulation mapping of phantom limb rolandic cortex. Case report.

Findings of intraoperative rolandic cortex mapping during awake craniotomy for a tumor in a patient with a contralateral upper-extremity amputation are presented. This patient sustained a traumatic amputation at the mid-humerus 24 years previously. Initially he had experienced rare painless phantom limb sensations but none in the past 10 years. Functional mapping during an awake craniotomy was performed to maximize safe tumor resection. Typical temporal and frontal speech areas were identified; motor representation of face and jaw extended more superiorly than sensory representation. Shoulder movements were evoked more laterally than usual at the superior aspect of the craniotomy. A small region of precentral gyrus, between the jaw and shoulder representations, elicited no detectable effect when stimulated. Somatosensory mapping showed a similar topographical distribution of face and mouth cortex; however, posterior and inferior to the shoulder motor cortex, right arm and hand (phantom) sensations were evoked. Evidence suggests that significant motor reorganization occurs following an amputation, with expansion of neighboring homuncular representations without loss of somatosensory representation, despite a long period of time without any sensation referable to the amputated limb. Contrary to models of sensory cortex plasticity, the plasticity of the adult cortex may be system specific, with reorganization present in motor, but not in sensory, cortical systems.

Amputation, Traumatic↗

PubMed1995

Invading C6 glioma cells maintaining tumorigenicity.

To characterize rat glioma cell invasion, 2 x 10(6) fluorophore-labeled or transfection-labeled C6 rat glioma cells were implanted in the rat frontal lobe. Eighty percent of the rats implanted formed bulk tumors (3-4 mm in diameter). Two weeks after implantation, fluorescence microscopy revealed single tumor cells in sites over 16 mm from the bulk brain tumor. Tumor cells distant from the bulk tumor remained single without mass formation and invaded primarily along white matter tracts. Two weeks after tumor implantation, three cell lines were created from each brain by disaggregation and initiation in culture of 1) bulk tumor, 2) contralateral hemisphere, and 3) cerebellum; all disaggregated specimens generated viable cultures. Cells cultured from the contralateral hemisphere were morphologically indistinguishable from cells from the bulk tumor and from the original C6 cell line. Cells cultured from the cerebellum were morphologically quite distinct from the C6 cell line. Cells from disaggregated specimens obtained from the tumor, contralateral hemisphere, and cerebellum were implanted in the frontal lobe of naive rats to test tumorgenicity. Bulk tumor formed in 58% of the rats implanted with specimens from tumor, in 75% of the rats implanted with specimens from contralateral hemisphere, and in only 12.5% of the rats implanted with specimens from the cerebellar hemispheres. Experiments using C6 cells labeled by transfection with the p3' ss DNA vector prior to implantation confirmed that the cells cultured from the contralateral hemisphere were derived from the implanted C6 cells. Experiments with C6 cells anchored in agar served to verify that movement to the contralateral hemisphere was secondary to parenchymal invasion rather than dispersion in the cerebrospinal fluid.

Amidines↗

PubMed1995

Modification of human glioma locomotion in vitro by cytokines EGF, bFGF, PDGFbb, NGF, and TNF alpha.

Cytokines exert receptor-mediated control over glia. Up-regulation of receptor expression of cytokine production corresponds with the acquisition of a neoplastic phenotype. A modified radial dish assay was used to determine whether in vitro locomotion of glioma cells is modified by the epidermal growth factor, the basic fibroblast growth factor, the bb dimer of platelet-derived growth factor, the nerve growth factor, or the tumor necrosis factor alpha. Human glioma cells were plated in the center of a petri dish with one of these cytokines in 0.5 ml agar (50 ng/ml if the cytokine was distributed evenly throughout the dish) at one edge, and 0.5 ml plain agar at the opposite edge. After 24 hours, a central zone of cells was established; the agar was gelatinized. Feeding medium was added to the dish, and slow elution from the agar established a cytokine gradient. Cell counts were performed daily over 6 to 10 days at predetermined distances on both sides of the central zone to assess directional cellular movement with respect to the cytokine gradient and the plain agar. The epidermal growth factor caused continuous chemoattraction, whereas the tumor necrosis factor alpha caused slight chemorepulsion for 24 to 48 hours, followed by strong chemoattraction. The bb dimer of platelet-derived growth factor, the basic fibroblast growth factor, and the nerve growth factor all maintained chemorepulsion over the entire 6 to 10 days. Therefore, the cytokines did affect glioma cell motility in vitro, and the modified radial dish assay used in this study provided a useful in vitro model for assessing the impact of the cytokines on glioma cell locomotion.(ABSTRACT TRUNCATED AT 250 WORDS)

Becaplermin↗

PubMed1994

The role of postoperative irradiation in the treatment of oligodendroglioma.

PURPOSE: Controversy regarding the role of adjuvant radiation therapy for the treatment of oligodendroglioma continues to exist. To better define the utility of postoperative irradiation for this tumor, the experience at the University of Washington was retrospectively examined. METHODS AND MATERIALS: The histologic samples of 63 patients given the diagnosis of oligodendroglioma were reviewed by a panel of neuropathologists and 41 were classified as pure oligodendroglioma. The two treatment groups included 14 patients treated with surgery only and 27 who received surgery and postoperative radiation and were analyzed using univariate and multivariate analysis with respect to prognostic factors, freedom from relapse, and survival. RESULTS: Univariate statistical analysis of 14 clinical variables showed that a poorer prognosis was associated in patients with high cell density (p = .008), necrosis (p = .017), hemiparesis (p = .026), and papilledema (p = .091), while patients presenting with seizures had a better prognosis (p = .0096). Multivariate analysis showed necrosis (p = .001) and hemiparesis (p = .02) to be associated with decreased survival. Multivariate and univariate analysis of the treatment groups found them to be homogenous with respect to prognostic factors. Survival times were significantly longer in the group treated with postoperative irradiation (median survival time 84 vs. 47 months, p = .032). The 5 and 10 year survival rates were 83% and 46%, respectively, for the irradiated patients compared with 51% and 36% for those treated with surgery alone. Freedom from tumor recurrence times were also longer in irradiated patients (median relapse free time 79 vs. 42 months, p = .01). CONCLUSION: Based on the results of this study, we recommend continuing the practice of treating oligodendroglioma with postresection irradiation until a prospective multicenter clinical trial is conducted to thoroughly evaluate the role of postoperative irradiation in the treatment of this tumor.

Adolescent↗

PubMed1994

Intraoperative transdural functional mapping. Technical note.

During craniotomy for supratentorial intraparenchymal space-occupying lesions, with the patient either under general anesthesia or awake, a smaller durotomy designed to expose only the region of resection may be desirable because of brain swelling. Similarly, during repeat craniotomy or craniotomy following cerebral injury or infection, pial-dural adhesions increase the risk of damage to essential cortex, making a limited dural opening desirable. Intraoperative transdural somatosensory evoked potentials and transdural cortical stimulation mapping permit localization of functional cortex prior to durotomy. These techniques can be combined with intraoperative transdural ultrasonography to identify topographical landmarks and borders of mass lesions.

Brain Mapping↗

PubMed1994

Resective surgery for medically intractable epilepsy associated with schizencephaly.

Four adults with unilateral (three cases) or bilateral (one case) closed schizencephaly, medically intractable epilepsy, and otherwise normal neurological examinations are presented. Three were examined preoperatively with magnetic resonance imaging and one with computerized tomography. Scalp electroencephalographic (EEG) studies in all four patients and electrocorticography via intracranial electrodes in two showed seizure origin in the cleft regions in two patients and in the ipsilateral temporal lobe in the other two. Temporal lobectomy was performed in the two patients with temporal lobe foci. Resection of superficial pachygyria around the cleft was performed in one patient. The authors conclude that the abnormal cortical mantle lining schizencephalic clefts may be epileptogenic. Alternatively, temporal allocortex may become the source of seizures. Therefore, these patients require careful EEG monitoring of the entire ipsilateral hemisphere as well as the cleft region.

Adult↗

PubMed1993

Pituitary oncocytomas: clinical features, characteristics in cell culture, and treatment recommendations.

To determine whether there are significant differences between oncocytomas and pituitary adenomas, we evaluated clinical features, treatment regimens and outcome in 23 males and 9 females (average age 64 years, range 43-81 years) with the histologic diagnosis of pure pituitary oncocytomas (> 95% oncocytes). Symptom duration was six to twelve months in 6 cases (19%) and more than one year in 19 cases (59%). Three patients presented with sudden onset of symptoms, and were found to have hemorrhage within their tumors. Visual loss (69%) and symptoms of hypopituitarism (44%) were the most common presenting complaints. Preoperative endocrine profiles revealed abnormalities in most cases, including pituitary insufficiency in 56% and hyperprolactinemia in 59%. The tumors were typically large at presentation; all but one had suprasellar extension. 28 patients underwent transsphenoidal tumor resections; 4 underwent subfrontal craniotomies. Gross dural invasion was found at surgery in 11 cases. At a mean followup of 31 months (range 2-68 months), recurrent tumor was identified in 4 patients (12.5%). Tumor size, dural invasion, preoperative endocrine profile, and postoperative radiotherapy did not correlate with recurrence. Among seven oncocytomas grown in culture, five demonstrated two distinct cell types consisting of oncocytes and typical adenoma cells, respectively. Oncocytomas often have a different clinical presentation than functional pituitary adenomas.

Adenoma, Oxyphilic↗

PubMed1993

Intraoperative electrocorticography during tumor resection: impact on seizure outcome in patients with gangliogliomas.

Gangliogliomas are indolent neoplasms that are often associated with long-standing intractable seizures. The seizure-free outcome following ganglioglioma resection alone (or "lesionectomy") has been generally favorable, ranging in most series from 50% to 65%. Thus, the value of resection of epileptogenic cortex in addition to tumor with regard to seizure outcome has been the subject of controversy. The authors describe a series of 12 patients with frontal or temporal lobe gangliogliomas associated with long-standing intractable seizures. In these patients, intraoperative electrocorticography was used to guide the resection of epileptogenic cortex along with tumor. Functional brain mapping, interictal and ictal monitoring of seizures, as well as thorough neuropsychological assessments were performed prior to resection in all cases. Outcome with regard to seizures, tumor recurrence, and neurological deficits was assessed with a mean follow-up period of 3.1 years. There was universal freedom from seizures postoperatively in 11 patients in whom complete or near-complete resection of epileptogenic cortex was achieved. In one patient in whom complete tumor resection and subtotal removal of epileptogenic cortex was achieved, a 95% reduction in seizure frequency was identified. No tumor recurrence or neurological deficits were observed. In a subset of four patients, neuropsychological and cognitive function were evaluated pre- and postoperatively. In these four, a clear trend toward improvement was noted in most functions. Thus, resection of epileptogenic cortex along with tumor may improve seizure outcome in selected patients with tumor-associated epilepsy without engendering identifiable neurological or cognitive deficits attributable to the incremental resection.

Adolescent↗

PubMed1993

A new device for cortical stimulation mapping of surgically unexposed cortex. Technical note.

Intraoperative functional mapping is an integral facet of many supratentorial procedures involving cortical resection. A new device is described that can be used in conjunction with a standard cortical stimulator and strip electrodes to stimulate intraoperative regions of unexposed cerebral cortex. This permits the use of a smaller craniotomy, while providing the ability for functional mapping of large areas of surface cortex.

Brain Mapping↗

PubMed1993

Approaches to epilepsy surgery.

The different approaches to epilepsy surgery are discussed. Despite considerable differences in rationale, patients, and operative technique, there are apparently similar outcomes. There are no controlled studies available comparing these different techniques.

Brain↗

PubMed1993

The tailored temporal lobectomy.

The indications, rationale, operative technique, risks, and outcome from the tailored temporal lobectomy are reviewed. The tailored lobectomy allows intraoperative identification of both electrically active cortex and functionally essential cortex, thus permitting maximal resection of epileptic regions without damage to Rolandic cortex or essential language cortex. This allows surgical strategy to be planned on the basis of preoperative interictal scalp electroencephalography recordings, thus lowering hospital costs and avoiding risk of implanting intracranial electrodes.

Brain Mapping↗