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Biomedical subjects

Robert D Brown

Publications and source records attributed to Robert D Brown.

15 recordsLinked to original sources
PubMed2004

Improved image quality of intracranial aneurysms: 3.0-T versus 1.5-T time-of-flight MR angiography.

BACKGROUND AND PURPOSE: We hypothesize that the nearly doubling of signal-to-noise ratio at 3.0 T compared with that at 1.5 T yields improved clinical MR angiograms and enables superior visualization of intracranial aneurysms. The goal of this study was to determine whether 3.0-T time-of-flight (TOF) MR angiography is superior to 1.5-T TOF MR angiography in the detection and characterization of intracranial aneurysms. METHODS: Fifty consecutive patients referred for MR angiography of a known or suspected intracranial aneurysm underwent 3-T TOF MR angiography. Seventeen of these 50 patients had also previously undergone 1.5-T TOF MR angiography and these images were used as a basis for comparison with images obtained at 3.0 T. Fourteen of 23 patients in whom aneurysms were identified also underwent prior conventional angiography, which was used as the reference standard. Readers blinded to patient history identified the presence and location of aneurysm(s) on angiograms and graded images for overall image quality by using a five-point scale. RESULTS: Twenty-eight aneurysms were identified in 23 of 50 patients. Seventeen aneurysms in 17 patients had been documented with 1.5-T MR angiography. The 3.0-T technique had a higher mean image quality score than that of the 1.5-T MR technique (P <.0001). Both 3.0-T and 1.5-T TOF MR angiography depicted all the aneurysms that had been documented by conventional angiography. CONCLUSION: 3D TOF MR angiography at 3 T offers superior depiction of intracranial aneurysms compared with that of 1.5-T TOF MR angiography.

Adult↗
PubMed2003

Cause-specific mortality after first cerebral infarction: a population-based study.

BACKGROUND AND PURPOSE: Mortality after cerebral infarction (CI) has remained unchanged during the past 20 years, despite advances in neurologic care. Key factors affecting survival may be underrecognized. The purpose of this study was to determine the rate and cause of mortality after first CI. METHODS: In this case-control, population-based study, all available medical records were reviewed for Rochester (Minnesota) residents with a first CI between 1985 and 1989 to identify morbidities and cause of death. Predictors for mortality were analyzed. RESULTS: First CI was recorded for 444 patients. Survival was 83% at 1 month, 71% at 1 year, and 46% at 5 years. The most frequent causes of death were cardiovascular events (22%), respiratory infection (21%), and initial stroke complications (14%). Recurrent stroke and cancer accounted for 9% and 7.5% of deaths, respectively. In the first month after CI, 51% of deaths were attributed to the initial CI, 22% to respiratory infections, and 12% to cardiovascular events. During the first year, 26% of deaths resulted from respiratory infections and 28% from cardiovascular disease. Mortality was higher among patients than controls for at least 2 years after CI. Age, cardiac comorbid conditions, CI severity, stroke recurrence, seizures, and respiratory and cardiovascular morbidities were independent predictors of death. CONCLUSIONS: In the first month after CI, mortality resulted predominantly from neurologic complications. Later mortality remained high because of respiratory and cardiovascular causes. To improve long-term survival after CI, aggressive management of pulmonary and cardiac disease is as important as secondary stroke prevention.

Aged↗
PubMed2003

The Ischemic Stroke Genetics Study (ISGS) Protocol.

BACKGROUND: The molecular basis for the genetic risk of ischemic stroke is likely to be multigenic and influenced by environmental factors. Several small case-control studies have suggested associations between ischemic stroke and polymorphisms of genes that code for coagulation cascade proteins and platelet receptors. Our aim is to investigate potential associations between hemostatic gene polymorphisms and ischemic stroke, with particular emphasis on detailed characterization of the phenotype. METHODS/DESIGN: The Ischemic Stroke Genetic Study is a prospective, multicenter genetic association study in adults with recent first-ever ischemic stroke confirmed with computed tomography or magnetic resonance imaging. Patients are evaluated at academic medical centers in the United States and compared with sex- and age-matched controls. Stroke subtypes are determined by central blinded adjudication using standardized, validated mechanistic and syndromic classification systems. The panel of genes to be tested for polymorphisms includes beta-fibrinogen and platelet glycoprotein Ia, Iba, and IIb/IIIa. Immortalized cell lines are created to allow for time- and cost-efficient testing of additional candidate genes in the future. DISCUSSION: The study is designed to minimize survival bias and to allow for exploring associations between specific polymorphisms and individual subtypes of ischemic stroke. The data set will also permit the study of genetic determinants of stroke outcome. Having cell lines will permit testing of future candidate risk factor genes.

Academic Medical Centers↗
PubMed2003

Familial clustering of stroke according to proband age at onset of presenting ischemic stroke.

BACKGROUND AND PURPOSE: The magnitude of inherited risk of stroke may lessen with age, and this would have implications for optimizing genomic approaches to identifying genetic risk factors for stroke. We investigated the relationship between age and inherited risk of stroke. METHODS: Family histories of stroke were obtained in systematic interviews with 310 adult men and women with recent CT- or MR-confirmed ischemic stroke. Probability of stroke in first-degree relatives was analyzed by logistic regression, adjusting for sibship size. RESULTS: The probability of having a sibling with stroke increased as proband age at stroke presentation increased. Per decade increase in proband age, the odds ratio was 1.65 (95% confidence interval [CI], 1.20 to 2.28; P=0.002) for a concordant sibling and 1.69 (95% CI, 1.15 to 2.49; P=0.008) for >or=2 first-degree relatives with a history of stroke. CONCLUSIONS: Clustering of stroke was not greater in families with probands manifesting symptoms of stroke in earlier than later adulthood. The relationship between proband age and positive family history of stroke does not suggest an upper age-limit cutoff for genomewide linkage studies.

Adult↗
PubMed2003

Cerebral ischemic events after diagnosis of mitral valve prolapse: a community-based study of incidence and predictive factors.

BACKGROUND AND PURPOSE: Association of mitral valve prolapse (MVP) with ischemic neurological events (INEs) is uncertain. METHODS: In the community of Olmsted County (Minn), we identified all MVP diagnosed (1989 to 1998) in patients in sinus rhythm with no prior history of INE. We measured INE rates and compared them with expected rates in our community to define the excess risk of INE. RESULTS: Among 777 eligible subjects (age, 49+/-20 years; 66% female; follow-up, 5.5+/-3.0 years), 30 patients had at least 1 INE during follow-up (at 10 years, 7+/-1%). Compared with expected INEs in the same community, subjects with MVP showed excess risk of lifetime INE (relative risk [RR], 2.2; 95% CI, 1.5 to 3.2; P<0.001) and during follow-up under purely medical management (RR, 1.8; 95% CI, 1.1 to 2.8; P=0.009). Independent determinants of INE were older age (RR, 1.08 per year; 95% CI, 1.04 to 1.11; P<0.001), mitral thickening (RR, 3.2; 95% CI, 1.4 to 7.4; P=0.008), atrial fibrillation (AFib) during follow-up (RR, 4.3; 95% CI, 1.9 to 10.0; P<0.001), and need for cardiac surgery (RR, 2.5; 95% CI, 1.1 to 5.8; P=0.03). INE 10-year rates were low in patients <50 years of age (0.4+/-0.4%, P=0.60 versus expected) but were excessive in patients >50 years of age (16+/-3%, P<0.001 versus expected) or with thickened leaflets (7+/-2%, P<0.001 versus expected). Predictors of follow-up AFib were age, mitral regurgitation, and left atrium diameter (all P<0.01). CONCLUSIONS: In the community, subjects with MVP display a lifetime excess rate of INE compared with expected. Clinical (older age) and echocardiographic (leaflets thickening) characteristics define patients with MVP at high risk for INE, and subsequent AFib or need for cardiac surgery, both related to the degree of mitral regurgitation, increase the risk of INE.

Age Factors↗
PubMed2003

Intracranial aneurysms in patients with coarctation of the aorta: a prospective magnetic resonance angiographic study of 100 patients.

OBJECTIVE: To determine the frequency of intracranial aneurysms (IAs) detected in patients with coarctation of the aorta (CoA) with use of magnetic resonance angiography. PATIENTS AND METHODS: From January 1, 1980, to September 30, 2002, 277 adult patients with CoA were seen at the Mayo Clinic in Rochester, Minn, and were invited to participate in a study to detect IAs. Of these 277 patients (mean +/- SD age, 41.6 +/- 16.5; 70 men), 100 underwent cranial magnetic resonance angiography. RESULTS: Ten patients had an IA (95% confidence interval, 5%-18%), with a mean diameter of 3.5 mm (range, 2.0-8.0 mm). The frequency of IA was significantly higher than that predicted in the general population (10% vs 2%; P < .001). One patient had surgical intervention. No clinical or geographical differences were found between patients with CoA and IA and patients with CoA and no IA. CONCLUSIONS: The frequency of IA among patients with CoA is approximately 5-fold that of the general population. Although no risk factors were identified in this cohort, additional prospective evaluation is warranted. These data suggest that noninvasive cerebral imaging to screen for IA should be considered in patients with CoA.

Adult↗
PubMed2003

Guglielmi detachable coil treatment of ruptured saccular cerebral aneurysms: retrospective review of a 10-year single-center experience.

BACKGROUND AND PURPOSE: We retrospectively analyzed our results with Guglielmi detachable coils (GDCs) for the endovascular occlusion of acutely ruptured saccular cerebral aneurysms over 10 years. METHODS: Between 1991-2000, 83 patients (mean age, 56.1 years) with aneurysmal subarachnoid hemorrhage were treated with endovascular GDCs. Patients with aneurysms due to trauma or dissection and those with mycotic or fusiform aneurysms were excluded. Mean follow-up in survivors was 19.1 months, and the mean Hunt-Hess grade at admission was 2.2. Angiographic follow-up was performed in 93% of surviving patients (mean interval, 11.6 months). The basilar caput (34 patients) and anterior communicating artery complex (19 patients) were most commonly treated. RESULTS: Sixty-four patients (77%) had a Glasgow Outcome Scale score (GOS) of 4 or 5, nine (11%) had a score of 2 or 3, and 10 (12%) died. At follow-up, 24 patients (35%) had complete aneurysm occlusion, 18 (26%) had a dog-ear remnant, 24 (35%) had a residual neck, and two (3%) had residual aneurysm filling. No treated aneurysm rebled. Three patients required surgical repair after incomplete endovascular treatment. Two or more GDC occlusion procedures were required in 28 patients (34%). Major procedural complications occurred in two patients (2%), resulting in serious neurologic disability or death. CONCLUSION: Endovascular treatment of ruptured cerebral aneurysms with GDCs has low morbidity, and it facilitates good overall outcomes in patients after subarachnoid hemorrhage. The short-term effectiveness of GDC occlusion in preventing aneurysmal rebleeding was excellent. Durability of the treatment in preventing long-term rebleeding as compared with direct surgical clipping warrants further study. Advances in device technology and technique may improve future outcomes.

Acute Disease↗
PubMed2002

The Siblings With Ischemic Stroke Study (SWISS) protocol.

BACKGROUND: Family history and twins studies suggest an inherited component to ischemic stroke risk. Candidate gene association studies have been performed but have limited capacity to identify novel risk factor genes. The Siblings With Ischemic Stroke Study (SWISS) aims to conduct a genome-wide scan in sibling pairs concordant or discordant for ischemic stroke to identify novel genetic risk factors through linkage analysis. METHODS: Screening at multiple clinical centers identifies patients (probands) with radiographically confirmed ischemic stroke and a family history of at least 1 living full sibling with stroke. After giving informed consent, without violating privacy among other family members, the proband invites siblings concordant and discordant for stroke to participate. Siblings then contact the study coordinating center. The diagnosis of ischemic stroke in potentially concordant siblings is confirmed by systematic centralized review of medical records. The stroke-free status of potentially discordant siblings is confirmed by validated structured telephone interview. Blood samples for DNA analysis are taken from concordant sibling pairs and, if applicable, from 1 discordant sibling. Epstein-Barr virus-transformed lymphoblastoid cell lines are created, and a scan of the human genome is planned. DISCUSSION: Conducting adequately powered genomics studies of stroke in humans is challenging because of the heterogeneity of the stroke phenotype and the difficulty of obtaining DNA samples from clinically well-characterized members of a cohort of stroke pedigrees. The multicentered design of this study is intended to efficiently assemble a cohort of ischemic stroke pedigrees without invoking community consent or using cold-calling of pedigree members.

Journal Article↗
PubMed2002

Intracranial saccular aneurysm enlargement determined using serial magnetic resonance angiography.

OBJECT: The goal of this study was to determine the frequency of enlargement of unruptured intracranial aneurysms by using serial magnetic resonance (MR) angiography and to investigate whether aneurysm characteristics and demographic factors predict changes in aneurysm size. METHODS: A retrospective review of MR angiograms obtained in 57 patients with 62 unruptured, untreated saccular aneurysms was performed. Fifty-five of the 57 patients had no history of subarachnoid hemorrhage. The means of three measurements of the maximum diameters of these lesions on MR source images defined the aneurysm size. The median follow-up period was 47 months (mean 50 months, range 17-90 months). No aneurysm ruptured during the follow-up period. Four patients (7%) harbored aneurysms that had increased in size. No aneurysms smaller than 9 mm in diameter grew larger, whereas four (44%) of the nine aneurysms with initial diameters of 9 mm or larger increased in size. Factors that predicted aneurysm growth included the size of the lesion (p < 0.001) and the presence of multiple lobes (p = 0.021). The location of the aneurysm did not predict an increased risk of enlargement. CONCLUSIONS: Patients with medium-sized or large aneurysms and patients harboring aneurysms with multiple lobes may be at increased risk for aneurysm growth and should be followed up with MR imaging if the aneurysm is left untreated.

Aged↗
PubMedDate not supplied

Spouses and unrelated friends of probands as controls for stroke genetics studies.

To plan a multisite, ischemic stroke genetic study, stroke patients were surveyed about the availability and characteristics of a convenience sample of spouse/friend controls. 65% of all stroke-affected probands reported a living spouse. A more detailed survey was conducted at the University of Virginia, Charlottesville, Va., USA: 51% of stroke patients reported a living, stroke-free spouse who would be willing to serve as a control, and 49% reported having a stroke-free friend who would be willing to serve as a control. Overall, 75% of stroke patients reported at least 1 individual willing to participate as a control. Cases without an identified control were more likely to be non-white (48%) than were cases with a control (13%; p = 0.00004). Cases were older than controls (67.3 vs. 59.2 years; p = 0.000002), and a greater proportion of cases than controls were male (57 vs. 33%; p = 0.0002). Without proper attention to matching, the use of a spouse/friend convenience sample would result in imbalances in basic demographic characteristics.

Adult↗