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Biomedical subjects

D Freed

Publications and source records attributed to D Freed.

At least 19 recordsLinked to original sources
PubMed2001

Surgical management of isolated hemangioblastomas of the spinal cord.

OBJECTIVE: Intramedullary hemangioblastomas are rare tumors, accounting for just 3% of all intraspinal neoplasms. The purpose of this study is to define the occurrence of isolated intramedullary hemangioblastomas and to analyze the role of the radiological studies and surgery for these lesions. METHODS: The charts of 19 consecutive patients operated on for isolated spinal intramedullary hemangioblastoma were reviewed. Preoperatively, all patients underwent magnetic resonance imaging and nine underwent spinal angiography. For all patients, the surgical approach was via posterior laminectomy. RESULTS: Our study sample comprised 6 women and 13 men, with an average age of 31.5 years (range, 16-75 yr). The mean prodrome was 20.8 months. Pain was the most common complaint. In all cases, the neoplasms were associated with a syrinx or edema. Gross total resection was achieved in all patients. At last follow-up examination (mean, 50.1 mo), 13 patients (68%) had improved and 6 patients (32%) had stabilized as compared with their preoperative clinical status. CONCLUSION: Isolated intramedullary hemangioblastomas typically have an indolent clinical course. These tumors have characteristic imaging properties on magnetic resonance imaging and angiography. Surgical removal of these lesions results in excellent long-term functional outcome.

Adolescent↗
PubMed2001

Midterm survival of stented versus stentless valves: does concomitant coronary artery bypass grafting impact survival?

The purpose of this study was to examine the impact of concomitant coronary artery bypass grafting (CABG) and valve design on survival following aortic valve replacement (AVR) with stentless and stented bioprostheses. Survival data for 1798 patients undergoing AVR between 1991 and 1997 with either a stentless (Medtronic Freestyle = 700, Toronto SPV = 447; N = 1147) or stented (Hancock II = 224, Carpentier-Edwards SAV = 427; N = 651) valve were analyzed. Bivariable analyses using Kaplan-Meier survival curves and log-rank test were performed to compare survival probabilities by valve type. Multivariable stepwise Cox's proportional hazard models were used to control for potentially confounding variables. Concomitant CABG was performed in 41% of stentless and 46% of stented patients (P =.04). Survival probability at 5 years was 0.84 (95% CI = 0.81, 0.87) for stentless versus 0.79 (95% CI = 0.75, 0.83) for stented patients (P =.004). In the absence of concomitant CABG, survival was superior in stentless (0.84) over stented (0.80) patients, but these differences were not statistically significant (P =.053). In patients that underwent AVR with concomitant CABG, survival was significantly better in stentless patients (0.82) than in stented individuals (0.77, P =.049). The unadjusted hazard ratio for stented versus stentless was 1.44 (95% CI = 1.12, 1.86, P =.005). In the final Cox's proportional hazard model the variables that effected survival were valve type and age in decades. New York Heart Association class at the time of surgery had a marginal effect on survival. The data demonstrate improved midterm survival with stentless versus stented valves. Subgroup analysis suggests survival benefits of stentless valves may be greater in patients who undergo concomitant CABG surgery.

Aged↗
PubMed2000

Radical excision of intramedullary spinal cord tumors: surgical morbidity and long-term follow-up evaluation in 164 children and young adults.

OBJECT: The majority of intramedullary spinal cord tumors (IMSCT) in children and young adults are low-grade gliomas. Radical resection of similar tumors in the cerebral hemisphere or cerebellum is usually curative; however, the conventional management for IMSCTs remains partial resection followed by radiotherapy because of the concern for surgical morbidity. Nevertheless, radical resection of IMSCTs without routine adjuvant treatment has been the rule at our institution since 1980. In an attempt to resolve this controversy, the long-term morbidity and survival in a large series of children have been retrospectively reviewed. METHODS: The database records and current status of 164 patients 21 years of age and younger in whom an IMSCT was resected were reviewed. A gross-total resection (>95%) was achieved in 76.8% of the surgical procedures. Subtotal resections (80-95%) were performed in 20. 1%. The majority of patients (79.3%) had histologically low-grade lesions. There were no deaths due to surgery. When comparing the preoperative and 3-month postoperative functional grades, 60.4% stayed the same, 15.8% improved, and 23.8% deteriorated. Only 13 patients deteriorated by more than one functional grade. Patients with either no deficits or only mild deficits before surgery were rarely injured by the procedure, reinforcing the importance of early diagnosis and treatment. The major determinant of long-term patient survival was histological composition of the tumor. The 5-year progression-free survival rate was 78% for patients with low-grade gliomas and 30% for those with high-grade gliomas. Patients in whom an IMSCT was only partially resected (<80%) fared significantly worse. CONCLUSIONS: The long-term survival and quality of life for patients with low-grade gliomas treated by radical resection alone is comparable or superior to minimal resection and radiotherapy. The optimum therapy for patients with high-grade gliomas is yet to be determined.

Adolescent↗
PubMed1997

Intra-axial tumors of the cervicomedullary junction: surgical results and long-term outcome.

Until recently, intra-axial brainstem tumors were traditionally regarded as surgically inaccessible lesions with a uniformly poor prognosis. However, increasing data indicate that distinct subgroups of brainstem tumors exist that are amenable to surgical intervention. To address this question, we reviewed our experience in the operative management of 39 consecutive patients, in the magnetic resonance imaging (MRI) era, with intra-axial cervicomedullary tumors, in order to determine those factors associated with long-term outcome. Thirty-nine patients (26 male, 13 female) underwent surgery by a single surgeon (F.J.E.) between 1985 and 1994. Mean age of diagnosis was 14 years (range 3 months - 60 years); mean duration of preoperative symptoms was 24 weeks (range 1-168). Twenty patients presented with lower cranial nerve dysfunction and 19 presented with motor and/or sensory dysfunction. All patients were graded according to the McCormick Scale, pre- and postoperatively, and at the time of follow-up. All patients were evaluated with MRI scanning. Twenty-three patients had either previous biopsy or subtotal resection, 13 previous radiation therapy, and 6 previous chemotherapy. The mean time to follow-up was 48 months (range 7-138). Twelve patients underwent gross total resection, 7 near total resection (>90%), 15 subtotal resection (50-90%), and 5 partial resection (< 50%). Histologically, there were 15 low-grade fibrillary astrocytomas, 9 ependymomas, 7 gangliogliomas, 3 anaplastic astrocytomas, 3 juvenile pilocytic astrocytomas, and 2 mixed gliomas. Although the vast majority of tumors were low grade histologically, a higher proportion of the patients with high-grade lesions experienced tumor progression when compared to low-grade tumors (75 vs. 30%). Overall, the 5-year progression-free and total survivals were 60 and 89%, respectively. There was 1 death within the first postoperative month. Preoperative duration of symptoms greater than 15 weeks was associated with a longer progression-free survival. There was a trend for preoperative neurologic grade to predict functional neurologic outcome at follow-up. In summary, intra-axial tumors of the cervicomedullary junction are a distinct subset of brainstem tumors, predominantly of low-grade histology, with favorable long-term progression-free and total survivals following surgical resection. A long duration of preoperative symptoms may indicate an indolent clinical course and a more favorable prognosis. Our data also indicate that early surgical intervention is warranted prior to neurologic deterioration.

Adolescent↗
PubMed1997

Tricuspid endocarditis following a Papanicolaou smear: case report.

Infective endocarditis is an uncommon complication of obstetrical and gynecological practice and has not been reported in the literature to be associated with Papanicolaou smears. The authors report a nonintravenous drug user who developed group B streptococcal endocarditis of the tricuspid valve following a routine Papanicolaou smear. She required surgical excision of the valve and replacement after failed antibiotic therapy.

Adult↗
PubMed1996

Intramedullary spinal cord tumors in neurofibromatosis.

Neurofibromatosis (NF) describes the most commonly inherited disorders affecting the nervous system. These autosomal dominant, neurocutaneous syndromes are associated with multiple tumors of the nervous system, including neurofibromas, schwannomas, meningiomas, and intracranial gliomas. Spinal cord involvement in NF is typically from extramedullary growth of spinal nerve root tumors. Intramedullary spinal cord tumors in NF have been reported as scattered, single cases in literature. However, this association has not been clearly defined as have other nervous system neoplasms that are typically linked with NF. We present a series of nine patients with NF with intramedullary spinal cord tumors who were managed at our institution from 1984 to 1994. The patients' ages ranged from 4 to 31 years. There were seven male patients and two female patients. Three patients had NF-1 (von Recklinghausen's), five patients had NF-2, and one patient had NF, type uncertain. There were three cervicomedullary tumors, two cervical tumors, three cervicothoracic tumors, and one thoracic tumor. A histological examination revealed five ependymomas, three astrocytomas, and one intramedullary schwannoma. Two patients with malignant intramedullary spinal ocrd tumors have died with progressive disease. One other patient has required a subsequent operation for recurrent tumor. The other six patients are doing well, and their prognosis is expected to be related to their systemic disease. We conclude that there is a clinical entity of intramedullary spinal cord tumors associated with NF.

Adolescent↗
PubMed1996

Intramedullary spinal cord tumors in children under the age of 3 years.

Over a 13-year period extending from 1980 to 1993, 27 children less than 3 years of age underwent operation for removal of an intramedullary spinal cord tumor (IMSCT). The majority (18 of 27) of children had undergone surgery before being referred to New York University (NYU) Medical Center. The most common reasons for radiological investigation were pain (42%), motor regression (36%), gait abnormalities (27%), torticollis (27%), and progressive kyphoscoliosis (24%). Forty procedures were performed in 27 children. Nine children underwent two operations and two children underwent three procedures. A gross-total resection was achieved in 72% of the procedures. There was no surgical mortality. A comparison of the preoperative and 3-month postoperative functional grades for the first NYU procedure (NYU-1) yielded the following findings: 20 patients' conditions remained the same, five patients improved, and two patients deteriorated. The functional outcomes of a second operation (NYU-2) were similar. The majority of the children (24 of 27, 89%) had histologically determined low-grade lesions. There were 12 patients with low-grade astrocytomas (Grades I-III), eight with gangliogliomas, two with ganglioglioneurocytomas, one with a glioneurofibroma, and one child with a mixed astro/oligodendroglioma. Two children had anaplastic astrocytomas (Grades II-III) and one child had a glioblastoma multiforme. In a median follow-up review of 76 months, two patients died and two patients were lost to follow up. The 3- and 5-year progression-free survival (PFS) rates were 81.7% (standard error of the mean (SEM) 0.083) and 76.2% (SEM 0.094), respectively. Eight of 24 patients suffered a recurrence within a mean time of 45.4 +/- 28.9 months. All were treated with surgery (NYU-2). Lesions recurred in three of 12 children with low-grade astrocytomas, two of eight children with gangliogliomas, one child with an anaplastic astrocytoma, one child with a ganglioglioneurocytoma, and one child with a glioblastoma multiforme. At follow-up review, most of these children were doing well. Sixteen are in functional Grades I or II and 18 children attend a normal school system. The authors conclude that surgery for the removal of IMSCTs in children less than 3 years of age can be performed radically and safely. The postoperative functional performance is determined by the degree of the preoperative deficit. It is, therefore, of utmost importance to diagnose and treat these children as early as possible. Spinal cord tumors should be recognized as potentially excisable lesions on their initial presentation and when they recur. The optimum treatment for malignant lesions is still to be determined.

Child, Preschool↗
PubMed1995

Spinal cord ependymomas: MR imaging features.

PURPOSE: To assess the magnetic resonance (MR) imaging characteristics of spinal intramedullary ependymomas. MATERIALS AND METHODS: MR images obtained in 25 patients (aged 12-73 years) with proved intramedullary ependymomas were retrospectively reviewed. T1- and T2-weighted images were obtained in all patients. Gadopentetate dimeglumine was intravenously administered in 23 patients; enhanced sagittal and axial T1-weighted spin-echo images were reviewed. RESULTS: All tumors had hyperintense signal on T2-weighted images. In the 23 patients who received contrast material, all tumors became enhanced; enhancement was heterogeneous in 15 patients and homogeneous in eight patients. Twenty tumors had sharply defined, enhanced borders. Nineteen tumors were centrally located in the spinal cord. A hypointense rim on T2-weighted images was noted in five patients. CONCLUSION: Intramedullary ependymomas become enhanced after administration of gadopentetate dimeglumine; the enhanced borders are usually sharply marginated. They are characteristically located centrally in an expanded spinal cord. Hemosiderin is often present at the periphery of cervical ependymomas.

Adolescent↗
PubMed1994

Coordinate defects in human histocompatibility leukocyte antigen class II expression and antigen presentation in bare lymphocyte syndrome.

The human immunodeficiency, type II bare lymphocyte syndrome (BLS), has been attributed to a defect in the transcription of class II histocompatibility genes. Immunocompetence, as assessed by functional exogenous antigen presentation, was not restored in immortalized B cells, derived from a BLS patient, after transfection with HLA-DR class II structural genes. Incubation of protein antigens, as well as infectious virus, with DR-transfected BLS cells failed to induce activation of antigen-specific helper T lymphocytes. Peptide antigens were presented by class II molecules displayed on BLS cells, although the conformation of these class II proteins was altered as indicated by epitope mapping. This defect in antigen presentation was independent of the specific class II DR allele transfected into BLS cells. Genetic complementation analysis has been used with BLS cells to demonstrate that the defect in class II gene transcription is linked to the absence of a trans-acting factor. Similarly, functional class II dimers were restored after in vitro fusion of cells derived from two distinct BLS complementation groups, implying that specific transcriptional control elements are shared by a gene critical for antigen presentation and genes encoding HLA class II antigens. Thus, two important functionally linked pathways of class II molecules, structural gene expression and antigen presentation, share a common regulatory pathway defective in BLS.

Alleles↗
PubMed1994

Management of hydrocephalus in children with medulloblastoma: prognostic factors for shunting.

Patients with medulloblastoma frequently present with hydrocephalus. While not all patients with medulloblastoma will continue to suffer from hydrocephalus after tumor resection, there is a significant proportion who will require a permanent shunt. We have retrospectively reviewed a group of children with medulloblastoma not shunted preoperatively, and have identified several characteristics which are associated with a requirement for permanent shunt. We studied 42 patients and found that 17 patients (40%) required permanent shunts within 4 weeks of craniotomy. The shunted patients were younger (5.4 +/- 2.9 vs. 10.0 +/- 5.7 years; p < 0.01), had larger ventricles (p < 0.05), and had more extensive tumors (Chang's stage T3 and T4; p < 0.01). These variables were all independently significant. In addition, we found that the patients requiring postcraniotomy shunts had a much higher rate of morbidity including a postoperative pseudobulbar syndrome. Of interest, we found that none of our patients without the above characteristics required a shunt. In particular, we found that no patient older than 10 years required a shunt. Thus, we conclude that younger patients with moderate to severe preoperative hydrocephalus and extensive tumors may benefit from perioperative CSF diversion. Other patients not meeting the above criteria can probably be safely managed with perioperative corticosteroids alone.

Adolescent↗
PubMed1993

Adult intramedullary spinal cord ependymomas: the result of surgery in 38 patients.

Thirty-eight patients underwent surgery for an intramedullary spinal cord ependymoma. In 37 patients, postoperative magnetic resonance imaging confirmed that the tumor was totally removed. The morbidity of surgery was directly related to the preoperative neurological condition. Patients who were normal or nearly normal preoperatively were rarely worse after surgery, and those who had significant disability preoperatively were at greatest risk of being more impaired after surgery. There has been no tumor recurrence in any patient after a mean follow-up period of 24 months, and radiation therapy has not been employed as a surgical adjunct.

Adult↗
PubMed1992

Adult intramedullary astrocytomas of the spinal cord.

In this series, 25 adult patients with intramedullary astrocytomas were treated by radical excision alone. Six patients proved to have anaplastic astrocytoma; five of them died within approximately 2 years and the sixth has demonstrated disease progression. The other 19 patients were diagnosed as having low-grade astrocytoma (16 cases) or ganglioglioma (three cases); two of these had advanced preoperative neurological disability and died of medical complications. Fifteen of the remaining 17 patients have no clinical evidence of tumor recurrence after a mean follow-up period of 50.2 months; the other two have a small residual neoplasm that demonstrates no progression. Of these 17 patients, seven had previously received radiation therapy, but had clear evidence of tumor growth subsequently. This experience suggests that surgery is not beneficial for anaplastic spinal astrocytoma. However, in cases of low-grade tumor, radical excision is associated with minimal morbidity and an excellent long-term prognosis when carried out before significant disability occurs.

Adolescent↗
PubMed1991

Choice and conditioned reinforcement.

A potential weakness of one formulation of delay-reduction theory is its failure to include a term for rate of conditioned reinforcement, that is, the rate at which the terminal-link stimuli occur in concurrent-chains schedules. The present studies assessed whether or not rate of conditioned reinforcement has an independent effect upon choice. Pigeons responded on either modified concurrent-chains schedules or on comparable concurrent-tandem schedules. The initial link was shortened on only one of two concurrent-chains schedules and on only one of two corresponding concurrent-tandem schedules. This manipulation increased rate of conditioned reinforcement sharply in the chain but not in the tandem schedule. According to a formulation of delay-reduction theory, when the outcomes chosen (the terminal links) are equal, as in Experiment 1, choice should depend only on rate of primary reinforcement; thus, choice should be equivalent for the tandem and chain schedules despite a large difference in rate of conditioned reinforcement. When the outcomes chosen are unequal, however, as in Experiment 2, choice should depend upon both rate of primary reinforcement and relative signaled delay reduction; thus, larger preferences should occur in the chain than in the tandem schedules. These predictions were confirmed, suggesting that increasing the rate of conditioned reinforcement on concurrent-chains schedules may have no independent effect on choice.

Animals↗
PubMed1989

Frontal-lobe dysfunction and antisocial behavior: a review.

Despite the many functions attributed to the frontal-lobe in previous writings and studies, empirically derived and reliable frontal-lobe abilities are limited and specific. Research that examines frontal-lobe dysfunction (as evidenced by neuropsychological tests that measure these specific abilities) and its relationship to antisocial behavior is reviewed. Frontal-lobe dysfunction is discussed in the context of the "minimal brain dysfunction" hypothesis of criminal behavior. Three studies reviewed examine criminal behavior, three examine specifically violent criminal behavior, and three focus on psychopathy. The nature of the research reviewed leaves the relationship between frontal-lobe neuropsychological dysfunction and crime open to further study.

Antisocial Personality Disorder↗