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Biomedical subjects

Louis R Caplan

Publications and source records attributed to Louis R Caplan.

At least 55 records · Page 3Linked to original sources
PubMed2004

Cervicocranial arterial dissections.

Cervicocranial dissections are an increasingly recognized cause of stroke in the young. When the dissections narrow the vascular lumen, they often alter blood flow enough to cause transient ischemic attacks in the brain. Alterations in the endothelium activate the coagulation cascade, leading to the formation of intramural clot that may embolize distally to cause brain infarction. Pain and neuro-ophthalmic symptoms and signs are common manifestations.

Carotid Artery, Internal↗
PubMed2004

Cell therapy for stroke.

Increasing experimental evidence suggests that cell transplantation can enhance recovery from stroke in animal models of focal cerebral ischemia. Clinical trials have been investigating the effects of a human immortalized neuronal cell line and porcine fetal neurons in stroke victims with persistent and stable deficits. Preclinical studies are focusing on the effects of human stem cells from various sources including brain, bone marrow, umbilical cord, and adipose tissue. This review presents an overview of preclinical and clinical studies on cell therapy for stroke. We emphasize the current, limited knowledge about the biology of implant sources and discuss special conditions in stroke that will impact the potential success of neurotransplantation in clinical trials.

Cell Transplantation↗
PubMed2004

Thrombolysis 2004: the good, the bad, and the ugly.

Nearly 8 years have passed since the U.S. Food and Drug Administration (FDA) released recombinant tissue plasminogen activator (rt-PA) for treatment of patients with acute ischemic stroke. Yet thrombolysis remains an intensely controversial treatment strategy. Clearly thrombolysis is a step forward but there remain problems with its application. The author reviews early investigations that preceded the National Institute of Neurological Disorders and Stroke (NINDS) trial report, discusses NINDS and other randomized trials, and comments on results since the approval and release of tissue type plasminogen activator (tPA). Technology development and use have improved since the release of tPA, and the impact of this development is discussed. Finally, the author shares his advice to doctors about present thrombolytic management of patients with acute ischemic stroke.

Clinical Trials as Topic↗
PubMed2003

Determination of etiologic mechanisms of strokes secondary to coronary artery bypass graft surgery.

BACKGROUND AND PURPOSE: Current research focused on stroke in the setting of coronary artery bypass graft (CABG) surgery has missed important opportunities for additional understanding by failing to consider the range of different stroke mechanisms. We developed and implemented a classification system to identify the distribution and timing of stroke subtypes. METHODS: We conducted a regional study of 388 patients with the diagnosis of stroke after isolated CABG surgery in northern New England from 1992 to 2000. Data were collected on patient and disease characteristics, intraoperative and postoperative care, and outcomes. Stroke etiology was classified into 1 of the following: hemorrhage, thromboembolic (embolic, thrombotic, lacunar), hypoperfusion, other (subtype not listed above), multiple (>or=2 competing mechanisms), or unclassified (unknown mechanism). The reliability of the classification system was determined by percent agreement and kappa statistics. RESULTS: Embolic strokes accounted for 62.1% of strokes, followed by multiple etiologies (10.1%), hypoperfusion (8.8%), lacunar (3.1%), thrombotic (1.0%), and hemorrhage (1.0%). There were 54 strokes with unknown etiology (13.9%). There were no strokes classified as "other." Nearly 45% (105/235) of the embolic and 56% (18/32) of hypoperfusion strokes occurred within the first postoperative day. CONCLUSIONS: We used a locally developed classification system to determine the etiologic mechanism of 388 strokes secondary to CABG surgery. The principal etiologic mechanism was embolic, followed by stroke having multiple mechanisms and hypoperfusion. Regardless of mechanism, strokes predominantly occurred within the first postoperative day.

Cerebral Hemorrhage↗
PubMed2003

Patterns of perfusion-weighted imaging in patients with carotid artery occlusive disease.

BACKGROUND: The importance of hemodynamic factors in the pathophysiology of stroke and transient ischemic attacks in patients with internal carotid artery (ICA) stenosis or occlusion remains controversial. OBJECTIVE: To investigate whether perfusion-weighted imaging (PWI) could identify pathophysiologically meaningful categories in patients with symptomatic and asymptomatic ICA occlusive disease. METHODS: Thirty-eight consecutive patients with occlusion (22 patients) or severe stenosis (16 patients) of the ICA, determined by ultrasonography or magnetic resonance angiography, were identified from the Beth Israel Deaconess Medical Center Stroke Database, Boston, Mass. Thirty-five patients were symptomatic (29 who had strokes and 6 who had transient ischemic attacks) and 3 were asymptomatic. All symptomatic patients underwent PWI within the first 24 hours after symptom onset. The patterns of PWI were analyzed according to the degree of ICA stenosis and the clinical presentation. RESULTS: Three patterns of perfusion abnormalities were identified: extensive hypoperfusion involving the middle cerebral arterial and/or anterior cerebral arterial territories (25 patients), localized perfusion deficits involving predominantly the ipsilateral border zone areas (8 patients), and normal perfusion (5 patients). All 3 patterns were found whether or not the ICA was occluded. Patients who had acute stroke most frequently had extensive perfusion deficits involving 1 or 2 territories while patients who had transient ischemic attacks often had hypoperfusion affecting the border zone regions. All asymptomatic patients had normal perfusion. CONCLUSIONS: In our sample the pattern of PWI related to the clinical presentation but not to the degree of ICA disease (occlusive vs severe stenosis). Our study findings add further support to the hypothesis that hypoperfusion is a major contributing factor in the pathophysiology of carotid artery occlusive disease.

Adult↗
PubMed2003

Intra- and postoperative predictors of stroke after coronary artery bypass grafting.

BACKGROUND: Stroke is a devastating complication of coronary artery bypass graft surgery. An individual's risk of stroke is based in part on preoperative characteristics but also on intra- and postoperative factors. We developed a risk prediction model for stroke based on factors in intra- and postoperative care, after adjusting for a patient's preoperative risk. METHODS: We conducted a regional prospective study of 11,825 consecutive patients undergoing coronary artery bypass graft surgery surgery from 1996 to 2001. Data were collected on patient and disease characteristics, intra- and postoperative care and course, and outcomes. Stroke was defined as "a new focal neurologic deficit which appears and is still at least partially evident more than 24 hours after its onset." Logistic regression identified significant predictors of stroke. RESULTS: The incidence of stroke was 1.5%. The regression model significantly predicted the occurrence of stroke. As compared with cardiopulmonary bypass for less than 90 minutes, cardiopulmonary bypass for 90 to 113 minutes, odds ratio = 1.59, p = 0.022), cardiopulmonary bypass for 114 minutes or more (odds ratio = 2.36, p < 0.001), atrial fibrillation (odds ratio = 1.82, p < 0.001), and prolonged inotrope use (odds ratio = 2.59, p = 0.001) significantly improved our ability to predict stroke. Nearly 75% of all strokes occurred among the 90% of patients at low or medium preoperative risk. CONCLUSIONS: The inclusion of factors associated with intra- and postoperative care and course significantly improved the prediction model. Most strokes occurred among patients at low or medium preoperative risk, suggesting that many of these strokes may be preventable. Reduction in stroke risk may require modifications in intra- and postoperative care and course.

Age Distribution↗
PubMed2003

Cerebrovascular cases.

Five cases are presented illustrating some of the investigative and therapeutic dilemmas faced when treating patients with cerebrovascular disease in the outpatient clinic. The results of some recent major randomized controlled trials are applied to assist the decision-making process for individual patients. The investigation and management of patients with minor stroke or transient ischemic attack, and symptomatic or asymptomatic carotid stenosis are discussed. Issues raised include the role of angiography versus noninvasive imaging, carotid endarterectomy versus carotid stenting, and how to apply new evidence regarding antihypertensive and lipid-lowering therapy to patient management. The role of thrombolysis for acute stroke is discussed, and the work-up of a patient with attacks of dizziness and a patient with atypical headache are also presented.

Acute Disease↗