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W S Smith

Publications and source records attributed to W S Smith.

At least 19 recordsLinked to original sources
PubMed2003

Spinal manipulative therapy is an independent risk factor for vertebral artery dissection.

OBJECTIVE: To determine whether spinal manipulative therapy (SMT) is an independent risk factor for cervical artery dissection. METHODS: Using a nested case-control design, the authors reviewed all patients under age 60 with cervical arterial dissection (n = 151) and ischemic stroke or TIA from between 1995 and 2000 at two academic stroke centers. Controls (n = 306) were selected to match cases by sex and within age strata. Cases and controls were solicited by mail, and respondents were interviewed using a structured questionnaire. The medical records of interviewed patients were reviewed by two blinded neurologists to confirm that the patient had stroke or TIA and to determine whether there was evidence of arterial dissection. RESULTS: After interview and blinded chart review, 51 patients with dissection (mean age 41 +/- 10 years; 59% female) and 100 control patients (44 +/- 9 years; 58% female) were studied. In univariate analysis, patients with dissection were more likely to have had SMT within 30 days (14% vs 3%, p = 0.032), to have had neck or head pain preceding stroke or TIA (76% vs 40%, p < 0.001), and to be current consumers of alcohol (76% vs 57%, p = 0.021). In multivariate analysis, vertebral artery dissections were independently associated with SMT within 30 days (OR 6.62, 95% CI 1.4 to 30) and pain before stroke/TIA (OR 3.76, 95% CI 1.3 to 11). CONCLUSIONS: This case-controlled study of the influence of SMT and cervical arterial dissection shows that SMT is independently associated with vertebral arterial dissection, even after controlling for neck pain. Patients undergoing SMT should be consented for risk of stroke or vascular injury from the procedure. A significant increase in neck pain following spinal manipulative therapy warrants immediate medical evaluation.

Adult↗
PubMed2002

Deaths from stroke in US children, 1979 to 1998.

BACKGROUND: Studies have documented declining mortality from stroke in adults over the past two decades, with black adults at greater risk of death from stroke than whites in all years. As these findings have been attributed to control of stroke risk factors that are less important in children, trends and demographics of childhood stroke mortality are of interest, but have not been explored. METHODS: The authors analyzed death certificate data for ischemic and hemorrhagic stroke (subarachnoid hemorrhage [SAH] and intracerebral hemorrhage [ICH]) in children under 20 years of age in the United States for the years 1979 through 1998, covering approximately 1.5 billion person-years. RESULTS: Childhood mortality from stroke declined by 58% overall, with reductions in all major subtypes (ischemic stroke decreased by 19%; SAH, by 79%; ICH, by 54%). Black ethnicity was a risk factor for mortality from all stroke types (relative risk 1.74 for ischemic stroke; 1.76 for SAH; 2.06 for ICH; p < 0.0001 for all types). Male sex was a risk factor for mortality from SAH (relative risk 1.30, p < 0.0001) and ICH (relative risk 1.21, p < 0.0001), but not from ischemic stroke (relative risk 1.02, p = 0.76). CONCLUSIONS: Mortality from stroke in US children has decreased dramatically over the last 20 years. Black children are at greater risk of death from all stroke types than are white children. As control of known stroke risk factors is unlikely to account for declining stroke mortality and ethnic differences in children, unrecognized stroke risk factors may be important.

Adolescent↗
PubMed2001

Arterial dissection and stroke in children.

OBJECTIVE: To describe the clinical characteristics of dissections of cerebral arteries in children. METHODS: Searches of MEDLINE (1966-2000) and bibliographies were systematically performed for English-language publications that described patients <18 years old with anterior circulation arterial dissections (ACAD) or posterior circulation arterial dissections (PCAD). RESULTS: A total of 2,027 studies were reviewed; 118 patients were identified in 79 studies. Seventy-four percent of patients with ACAD (n = 73) and 87% with PCAD (n = 47) were male (p < 0.0001). When patients with preceding trauma were excluded, this male predominance persisted. All patients had evidence of cerebral ischemia at the time of diagnosis. Headache was reported in approximately half of patients. Sixty percent of ACAD were intracranial. ACAD with no preceding trauma were more commonly intracranial than those preceded by significant trauma (86 vs 25%, p = 0.002). The most common location for PCAD was the vertebral artery at the level of the C1-C2 vertebral bodies (53%). Recurrent ischemic events after the diagnosis of dissection were reported in 15% of PCAD and 5% of ACAD cases. None of the PCAD group and 10% of the ACAD group had recurrent dissections. CONCLUSIONS: There is a marked male predominance among children with cerebral arterial dissections that is not explained by trauma. Unlike adult ACAD, childhood ACAD are most commonly intracranial. Spontaneous ACAD, in particular, tend to be intracranial, while post-traumatic ACAD are more often extracranial. The vertebral artery segment most susceptible to dissection is similar between children and adults.

Aortic Dissection↗
PubMed2001

Advanced imaging of melorheostosis with emphasis on MRI.

OBJECTIVE: To describe the CT and MR imaging appearance of both osseous and extraosseous manifestations of melorheostosis. DESIGN AND PATIENTS: We retrospectively reviewed the CT (n=7) and/or MR imaging findings (n=12) of 17 patients with characteristic radiographic findings of melorheostosis (undulating cortical hyperostosis with marked uptake on radionuclide bone scintigraphy). RESULTS: CT and MR imaging revealed cortical hyperostosis as high attenuation and low signal intensity on all MR pulse sequences, respectively. Encroachment on the marrow space was seen in all cases resulting from endosteal involvement. Thirteen patients demonstrated 14 soft tissue masses with infiltrative margins in 80% of cases and seven showed extensive mineralization on CT or MR imaging (low intensity on all pulse sequences). Seven soft tissue masses were predominantly nonmineralized with intermediate signal intensity on T1-weighted and intermediate to high signal on T2-weighted MR images corresponding to vascularized fibrous tissue with variable collagen content pathologically. Enhancement after intravenous gadolinium was seen in all patients imaged with soft tissue masses (n=2). Two patients demonstrated muscle atrophy resulting from nerve involvement. CONCLUSIONS: The osseous abnormalities in melorheostosis are identical on advanced imaging and radiographs. Mineralized or nonmineralized soft tissue masses should be recognized as another manifestation of this disease as opposed to a more ominous finding, making biopsy unwarrranted.

Adolescent↗
PubMed2001

Pacing during ventricular fibrillation: factors influencing the ability to capture.

INTRODUCTION: Recent studies showed that pacing atrial and ventricular fibrillation (VF) is possible. The studies presented here determined which parameters influence the efficacy of a pacing train to capture fibrillating ventricular myocardium. Electrode type, current strength, order of pacing trains, polarity, and VF morphology preceding the pacing trains were investigated. METHODS AND RESULTS: A 504-electrode recording plaque sutured to the right ventricle of pig hearts was used to record the activations of VF and those resulting from the pacing stimulation. Capture of VF by pacing was determined by observing an animated display of the first temporal derivative of the electrograms. A series of electrodes in a line captured the heart more frequently during VF than did a point electrode. Increasing the current strength to 10 x diastolic pacing threshold increased the incidence of capture, but increasing this strength further did not. The second or third train of 40 stimuli had greater capture rates than did the first train during the same VF episode. Anodal and cathodal unipolar, and bipolar stimulation were equally efficacious in capturing VF. VF activation during the 1-second interval preceding pacing was more organized for pacing trains that captured than those that did not. The highest incidence of capture, 46% to 61% of pacing trains, occurred with a line of electrodes at 10 x diastolic pacing threshold delivered by the second or third train. CONCLUSION: The probability of a pacing train capturing fibrillating myocardium can be influenced by the pacing protocol parameters.

Animals↗
PubMed2001

Dural arteriovenous fistula associated with prothrombin gene mutation.

An association between dural arteriovenous fistula and cerebral sinus thrombosis is reported. It is clear in several cases that thrombosis precedes the development of the fistula while it is unclear that it occurs in every case. The authors report a case of a woman with sinus thrombosis and presence of prothrombin gene mutation who subsequently developed a large dural arteriovenous fistula. Various possible factors involved in the pathogenesis of a dural fistula are discussed, with emphasis on underlying thrombophilia and oral contraceptive use in this patient.

Adult↗
PubMed2001

Utilization of intravenous tissue-type plasminogen activator for ischemic stroke at academic medical centers: the influence of ethnicity.

BACKGROUND AND PURPOSE: We sought to measure the overall rate of usage of tissue-type plasminogen activator (tPA) for ischemic stroke at academic medical centers, and to determine whether ethnicity was associated with usage. METHODS: Between June and December 1999, 42 academic medical centers in the United States each identified 30 consecutive ischemic stroke cases. Medical records were reviewed and information on demographics, medical history, and treatment were abstracted. Rates of tPA use were compared for African Americans and whites in univariate analysis and after adjustment for age, gender, stroke severity, and type of medical insurance with multivariable logistic regression. RESULTS: Complete information was available for 1195 ischemic stroke patients; 788 were whites and 285 were African Americans: Overall, 49 patients (4.1%) received tPA. In the subgroup of 189 patients without a documented contraindication to therapy, 39 (20.6%) received tPA. Ten (20%) of those receiving tPA had documented contraindication. African Americans were one fifth as likely to receive tPA as whites (1.1% African Americans versus 5.3%; P=0.001), and the difference persisted after adjustment (OR 0.21, 95% CI 0.06 to 0.68; P=0.01). When comparison was restricted to those without a documented contraindication to tPA, the difference remained significant (OR 0.24, 95% CI 0.06 to 0.93; P=0.04). Medical insurance type was independently associated with tPA treatment. After adjustment for ethnicity and other demographic characteristics, those with Medicaid or no insurance were one ninth as likely to receive tPA as those with private medical insurance (OR 0.11, 95% CI 0.02 to 0.17; P=0.003). CONCLUSIONS: tPA is used infrequently for ischemic stroke at US academic medical centers, even among qualifying candidates. African Americans are significantly less likely to receive tPA for ischemic stroke. Contraindications to treatment do not appear to account for the difference.

Academic Medical Centers↗
PubMed2000

Modulation of CTP:phosphocholine cytidylyltransferase by membrane curvature elastic stress.

The activity of CTP:phosphocholine cytidylyltransferase, a rate-limiting enzyme in phosphatidylcholine biosynthesis, is modulated by its interaction with lipid bilayers [Kent, C. (1997) Biochim. Biophys. Acta 1348, 79-90]. Its regulation is of central importance in the maintenance of membrane lipid homeostasis. Here we show evidence that the stored curvature elastic stress in the lipid membrane's monolayer modulates the activity of CTP:phosphocholine cytidylyltransferase. Our results show how a purely physical feedback signal could play a key role in the control of membrane lipid synthesis.

Cell Membrane↗
PubMed2000

Stent angioplasty for cervical carotid artery stenosis in high-risk symptomatic NASCET-ineligible patients.

BACKGROUND AND PURPOSE: Although the North American Symptomatic Carotid Endarterectomy Trial (NASCET) has shown carotid endarterectomy (CEA) to be protective compared with medical therapy alone, its stringent eligibility criteria excluded patients with severe medical, angiographic, and neurological risk factors. We sought to determine the safety and efficacy of stent angioplasty in this high-risk subset for whom the perioperative morbidity and mortality of surgery are elevated. METHODS: Twenty-eight consecutive symptomatic NASCET-ineligible patients (10 female; median age, 72.2 years) underwent microcatheter-based carotid stent angioplasty. Half of the patients had sustained a previous stroke. Classification of surgical risk by Sundt criteria yielded no patients in grade 1, 3 patients in grade 2 (10.7%), 8 in grade 3 (28.6%), and 17 (60.7%) in grade 4. Stratification of stroke risk for medical therapy according to the European Carotid Surgery Trial (ECST) 5-point score showed 8 patients with a score of 3 (28.6%), 12 with 4 (42.8%), and 8 with 5 (28.6%). Follow-up was obtained in all patients at a median of 14 months. RESULTS: The procedure was technically successful in all cases (100%), with immediate stenosis reduction from a mean of 80.3% to 2.7%. There were no periprocedural deaths, 1 major stroke (3.6%), no minor strokes, and 3 transient ischemic attacks (10.7%). In-hospital complications included 2 nonfatal myocardial infarctions, 1 case of acute renal failure, and 1 groin hematoma requiring transfusion. There were 5 deaths during the follow-up period, all beyond 30 days after the procedure: 3 from cardiac causes, 1 from lung cancer, and 1 following unrelated surgery. The patient with major stroke died at 7.8 months during rehabilitation. No surviving patients had further strokes, and all except 1 (95.5%) remained asymptomatic. Anatomic follow-up in 20 patients showed occlusion in 2 (10%) (1 symptomatic, 1 asymptomatic) and intimal hyperplasia in 3 asymptomatic patients (15%). CONCLUSIONS: The clinical results and sustained freedom from symptoms and stroke during the short available follow-up period suggest that stent angioplasty may be useful in the treatment of symptomatic cervical carotid stenosis in high-risk patients despite a notable incidence of restenosis.

Aged↗
PubMed2000

The ichthyofauna of the marginal lagoons of the Sorocaba River, SP, Brazil: composition, abundance and effect of the anthropogenic actions.

The marginal lagoons of the Sorocaba River fulfil important functions in their lotic ecosystems and for its fish communities, providing shelter, food, and area for fish early stages of development. The lagoons are also an escape from the river pollution since the physical-chemical characteristics of their water are more stable than the river water. Nevertheless, these lagoons are under a series of impacts that contribute to reduce their diversity and stability such as water pollution, deforesting and river dumping. These impacts decrease habitat availability, and modify the fish community structure by reducing the number of species in the Sorocaba River, the floodplains and its marginal lagoons.

Animals↗
PubMed2000

Patient presentation, angiographic features, and treatment of strangulation-induced bilateral dissection of the cervical internal carotid artery. Report of three cases.

Domestic violence leading to strangulation by an abusive spouse can cause carotid artery dissection. This phenomenon is rare and has been described in only three previous instances. The authors present their management strategies in three additional cases. Three young women aged 24 to 43 years were victims of manual strangulation committed by their spouses 3 months to 1 year before presentation. Two of the patients suffered delayed cerebral infarctions before presentation and angiography demonstrated focal, mirror-image severe residual stenoses in the high-cervical internal carotid artery (ICA), which were characteristic of a healed chronic dissection; there was no evidence of fibromuscular dysplasia. One of these patients underwent unilateral percutaneous angioplasty with stent placement, and the other underwent bilateral percutaneous angioplasty. Both patients have recovered from their strokes and remain clinically stable at 8 and 20 months posttreatment, respectively. The third patient presented with bilateral ischemic frontal watershed infarctions resulting from an occluded left ICA and a severely narrowed right ICA. Given the extent of the established infarctions, this case was managed with a long-term regimen of anticoagulation medications, and the patient remains neurologically impaired. These cases illustrate the susceptibility of the manually compressed ICA to traumatic injury as a result of domestic violence. They identify bilateral symmetrical ICA dissection as a consistent finding and the real danger of delayed stroke as a consequence of strangulation. Endovascular therapy in which percutaneous angioplasty and/or stent placement are used can be useful in treating residual focal stenoses to improve cerebral perfusion and to lower the risk of embolic or ischemic stroke.

Adult↗
PubMed2000

Dynamic CT perfusion to assess the effect of carotid revascularization in chronic cerebral ischemia.

We present the case of a female patient who was studied with dynamic contrast-enhanced CT perfusion before and after carotid revascularization. Before treatment, there was decreased perfusion in the ipsilateral insula, which was shown to be resolved on the scan obtained 1 day after treatment, indicating the technical success of the revascularization. In the ipsilateral basal ganglia, there was delayed contrast agent clearance from the tissue, which was attributed to vasodilation; after revascularization, there remained a subtle stenotic effect. The observed changes in the dynamic CT perfusion study suggest that this technique may be a useful tool in the evaluation of patients with asymmetrical cerebral blood flow.

Aged↗
PubMed2000

Endovascular management of extracranial carotid artery dissection achieved using stent angioplasty.

BACKGROUND AND PURPOSE: Dissection of the carotid artery can, in certain cases, lead to significant stenosis, occlusion, or pseudoaneurysm formation, with subsequent hemodynamic and embolic infarcts, despite anticoagulant therapy. We sought to determine the therapeutic value of stent-supported angioplasty retrospectively in this subset of patients who are poor candidates for medical therapy. METHODS: Five men and five women (age range, 37-83 years; mean age, 51.2 years) with dissection of the internal (n=9) and common (n=1) carotid artery were successfully treated with percutaneous endovascular balloon angioplasty and stent placement. The etiology was spontaneous in five, iatrogenic in three, and traumatic in two. Seven of the treated lesions were left-sided and three were right-sided. RESULTS: The treatment significantly improved dissection-related stenosis from 74+/-5.5% to 5.5+/-2.8%. Two occlusive dissections were successfully recanalized using microcatheter techniques during the acute phase. Multiple overlapping stents were needed in four patients to eliminate the inflow zone and false lumen and establish an angiographically smooth outline within the true lumen. There was one case of retroperitoneal hemorrhage, but there were no procedural transient ischemic attacks (TIAs), minor or major strokes, or deaths (0%). Clinical outcome at latest follow-up (16.5+/-1.9 months) showed significant improvements compared with pretreatment modified Rankin score (0.7+/-0.3 vs 1.8+/-0.44) and Barthel index (99.5+/-0.5 vs 80.5+/-8.9). One delayed stroke occurred in a treated patient with contralateral carotid occlusion following a hypotensive uterine hemorrhage at 8 months; the remaining nine patients have remained free of TIA or stroke. CONCLUSION: In select cases of carotid dissection associated with critical hemodynamic insufficiency or thromboembolic events that occur despite medical therapy, endovascular stent placement appears to be a safe and effective method of restoring vessel lumen integrity, with good clinical outcome.

Adult↗
PubMed1999

Endovascular stenting of an acutely thrombosed basilar artery: technical case report and review of the literature.

OBJECTIVE AND IMPORTANCE: The goal of this report was to describe the successful percutaneous endovascular use of a Gianturco-Roubin-2 coronary stent in the treatment of an acute atherothrombotic occlusion of the basilar artery. To our knowledge, the percutaneous endovascular deployment of an intra-arterial stent for the treatment of an acute atherothrombotic occlusion of the basilar artery and the percutaneous endovascular placement of a Gianturco-Roubin-2 stent in the basilar artery have not been previously reported. CLINICAL PRESENTATION: An 83-year-old man presented with a recurrent, transient, locked-in syndrome resulting from a lower basilar artery occlusion caused by vertebrobasilar thrombosis superimposed on severe proximal basilar artery atheromatous stenosis. INTERVENTION: After successful superselective intra-arterial thrombolysis of the vertebrobasilar clot, balloon angioplasty of the underlying basilar artery stenosis was performed, without significant angiographic improvement. Percutaneous endovascular deployment of a Gianturco-Roubin-2 coronary stent of 4-mm diameter was subsequently performed, with excellent angiographic results. CONCLUSION: The patient made a very good neurological recovery but unfortunately died as a result of cardiogenic shock and sepsis. Detailed neuropathological follow-up results are presented; stent patency was revealed in the postmortem examination. The anatomic and pathophysiological considerations of basilar artery stent placement for the treatment of acute basilar artery occlusion related to atherosclerotic stenosis are discussed.

Acute Disease↗
PubMed1999

Endovascular recanalization with balloon angioplasty and stenting of an occluded occipital sinus for treatment of intracranial venous hypertension: technical case report.

OBJECTIVE AND IMPORTANCE: Dural sinus thrombosis can lead to intracranial venous hypertension and can be complicated by intracranial hemorrhage. We present a case report of a patient who underwent endovascular recanalization and stenting of a thrombosed occipital sinus. CLINICAL PRESENTATION: A 13-year-old patient with a history of chronic sinus thrombosis refractory to anticoagulant therapy presented with acute onset of aphasia and hemiparesis. Computed tomography and magnetic resonance imaging revealed hydrocephalus and cerebral edema. Angiography delineated multiple dural arteriovenous fistulae and persistent occlusion of the posterior sagittal, occipital, and bilateral transverse dural sinuses with retrograde cortical venous drainage. INTERVENTION: After embolization of the dural arteriovenous fistulae, a transvenous approach was used to recanalize and perform balloon angioplasty of the right internal jugular vein and the occipital and left transverse sinuses, resulting in subsequent clinical improvement. The patient's condition deteriorated 3 days later with reocclusion of both balloon-dilated sinuses. Repeat angioplasty and then deployment of an endovascular stent in the occipital sinus were performed, and reestablishment of venous outflow was achieved, resulting in a decrease of intracranial venous pressure from 41 to 14 mm Hg and neurological improvement. At the 3-month follow-up examination, the stented occipital sinus remained patent and served as the only conduit for extracranial venous outflow; the patient remained neurologically intact at the 12-month follow-up examination. CONCLUSION: This is the first report of mechanical recanalization, balloon angioplasty, and stent deployment in the occipital sinus to provide sustained venous outflow for the treatment of venous hypertension with retrograde cortical venous drainage in a patient with dural pansinus thrombosis refractory to anticoagulant therapy.

Adolescent↗
PubMed1999

Practice variability in management of transient ischemic attacks.

To define practice patterns in the management of transient ischemic attacks (TIAs), we surveyed practicing neurologists attending an educational conference in San Francisco, evaluating management decisions in 2 TIA case vignettes. In a vignette describing a hemispheric TIA 1 day prior with ipsilateral bruit, 53% chose admission, 47% elected an outpatient work-up, 28% treated with intravenous heparin and 70% chose aspirin, reflecting the disagreement about medical management of carotid stenosis in the literature. There was more agreement in the second case, a posterior circulation TIA 1 day prior with atrial fibrillation, in which 84% chose hospital admission, 74% chose intravenous heparin and 90% treated with some form of anticoagulation. There are areas of important practice variability in the management of TIAs. Further research is justified to guide patient care decisions in TIA patients.

Aged↗