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Biomedical subjects

L E Knepper

Publications and source records attributed to L E Knepper.

8 recordsLinked to original sources
PubMed1999

Measurement of hemostatic indexes in conjunction with transcranial doppler sonography in patients with ventricular assist devices.

BACKGROUND AND PURPOSE: Clinical thromboembolism (TE) remains an impediment to the chronic application of ventricular assist devices (VADs). Microembolic signals (MES) have been detected by transcranial Doppler ultrasound (TCD) in patients with VADs, although their origin and relation to TE remain undefined. We have investigated the hypothesis that hemostatic alterations are related to MES and that MES are associated with TE in a group of 27 VAD patients. METHODS: Indexes of coagulation, fibrinolysis, and cellular activation and aggregation were measured before and during the VAD implantation period in conjunction with TCD. Groups were defined on the basis of presence of MES, degree of MES showering, and incidence of TE. RESULTS: MES were observed in 67 (58%) of 115 of individual postoperative TCD measurements and in 21 (78%) of 27 patients. Of patients with TE, 10 (83%) of 12 had detectable MES compared with 11 (73%) of 15 patients without TE (P=0.66). MES were significantly associated with elevated thrombin generation during the implantation period, as reflected by plasma prothrombin fragment F1.2. Elevations in indexes of coagulation, platelet activation, and fibrinolysis relative to normal control subjects were found for patients with VADs with and without detected MES. CONCLUSIONS: Although no significant relation between MES and TE in VAD patients was found, the data support the hypothesis that MES are related to increased hemostatic activity in this patient group despite aggressive anticoagulant therapy.

Adolescent↗
PubMed1996

Natural history, prognosis, and lipid abnormalities of idiopathic ischemic childhood stroke.

A study was performed to assess the natural history, prognostic factors, and lipid and apolipoprotein abnormalities of idiopathic ischemic childhood stroke. A case series of 42 children, retrospectively identified with idiopathic ischemic strokes, were reassessed an average of 7.4 years (range, 1 to 19 years) after presentation. Patients were interviewed and examined, and fasting serum was obtained for lipid and apolipoprotein analysis. Poor outcome was defined as moderate to severe hemiparesis, special educational needs, epilepsy, recurrent stroke, or stroke-related death. Eighteen (43%) of the patients had a poor outcome. Among them were moderate to severe hemiparesis in 14 (78%), recurrent strokes in seven (39%), and one death. Poor outcome was evident early in their clinical course. Independent of outcome, lipid abnormalities including an elevated triglyceride and low-density lipoprotein cholesterol, and a depressed high-density lipoprotein cholesterol were seen in one third of all patients. A depressed ratio of apolipoprotein A-1 to apolipoprotein B (using adult normative values) was seen in half of the entire cohort. Clinical features of children with unexplained ischemic strokes at presentation and their subsequent course are described. Significant risk factors for a poor outcome include (1) persistence of hemiparesis 1 month after the stroke, (2) cortical as opposed to subcortical location, and (3) bilateral occlusive disease with telangiectasia on cerebral angiography. Previously described risk factors for an unfavorable prognosis, including occurrence during infancy and presentation with seizures, were not substantiated. Lipid abnormalities occur at an increased frequency in children after unexplained ischemic strokes. Prospective assessment of lipoprotein profiles are needed to further assess clinical significance. Assessing apolipoproteins may provide further insight than lipid values alone.

Adolescent↗
PubMed1995

Cerebrovascular disease in women.

Cerebrovascular disease is one of the leading causes of death in women in the United States. Pregnancy and hormonal therapy have been associated with an increased risk of stroke in young women. Other conditions, more common in women, such as migraine headaches, rheumatologic disorders and antiphospholipid antibodies predispose women to cerebral ischemia. Women may also respond differently to antiplatelet therapy. The identification and treatment of such conditions will improve outcome in women with stroke and may prevent recurrent cerebrovascular events.

Cerebrovascular Disorders↗
PubMed1990

Spontaneous improvement after acute ischemic stroke. A pilot study.

Recent clinical studies emphasize the importance of early (less than 12 hours after onset) treatment of patients with acute ischemic stroke. Therapies have been proposed as being effective because of early clinical improvement. The frequency and degree of spontaneous improvement in such patients, however, is unknown. We prospectively evaluated the course of 29 patients (19 men, 10 women) aged 33-82 years who were seen less than or equal to 12 hours after the onset of acute ischemic stroke. Seventeen patients were first evaluated less than or equal to 6 hours and the remaining patients at 6-12 hours after onset. All patients were examined using a modified National Institutes of Health Stroke Scale at baseline, 1, 2, 3, and 6 hours. No specific treatment for acute ischemic stroke was given during this time. Improvement (defined as a decrease of greater than or equal to 2 points from baseline score) was noted at 1 hour in seven patients (24%). By 6 hours 15 patients (52%) had improved, 12 (41%) were unchanged, and two (7%) were worse. Our results suggest that spontaneous, often dramatic improvement occurs in patients with acute ischemic stroke and should be taken into consideration in the design of any trial of acute treatment.

Adult↗
PubMed1989

Etiology of stroke in patients with Wernicke's aphasia.

We reviewed 49 patients with Wernicke's aphasia resulting from a stroke. Their aphasia was classified on the basis of comprehensive neuropsychological testing. Wernicke's aphasia was more common in older patients and in men. Cerebral infarction occurred in 38 patients (78%) and intracerebral hemorrhage in seven (14%); the remaining four patients (8%) developed aphasia after surgery for aneurysmal subarachnoid hemorrhage. Embolic events were the most common etiology of Wernicke's aphasia in the 38 patients with cerebral infarction, with cardiac emboli in 40% and large-vessel atheroemboli from a carotid source in 16%. In patients with Wernicke's aphasia secondary to infarction, an embolic source should be sought. Patients with Wernicke's aphasia should have computed tomography to exclude intracerebral hemorrhage before institution of anticoagulant therapy.

Adult↗
PubMed1988

Neurologic manifestations of atrial myxoma. A 12-year experience and review.

We present the results of a 12-year retrospective analysis of 11 patients, eight women and three men, aged 16-76 years, with pathologically documented atrial myxomas. Nine of the 11 patients were found to have a left atrial myxoma; right atrial myxomas were identified in two. Five of the 11 patients (45%) had abnormalities on neurologic examination, and five of five had computed tomographic evidence of nonhemorrhagic cerebral infarction. Neurologic symptoms were the initial presentation in four patients. Six patients reported a history of cardiac disease; eight of the 11 had abnormalities on cardiac auscultation. Echocardiography in 10 patients was diagnostic in all but one. Gated magnetic resonance imaging of the heart in two patients demonstrated myxoma position and movement. Follow-up examinations (varying from 1 month to 7 years after tumor resection) in nine of 11 patients demonstrated no recurrent neurologic symptoms. Cerebral infarction is a common complication of atrial myxomas and may be the presenting feature. Recurrent cerebral emboli before surgery is not uncommon. Cardiac auscultation may be normal, and electrocardiographic changes are often nonspecific. Delayed neurologic events following surgery are rare.

Adolescent↗
PubMedDate not supplied

Cerebral ventriculitis: MR findings.

Cerebral ventriculitis is an uncommon site and manifestation of infection of the central nervous system. We report the magnetic resonance findings in two patients with cytologic and CSF culture proof of ventriculitis. The findings included abnormal signal intensity of the ependyma and CSF on T2-weighted images. In addition, ependymal, meningeal, and dural enhancement was seen in one case, on T1-weighted images, after administration of Gd-diethylenetriamine pentaacetic acid.

Adult↗