Mechanisms of ischemic stroke in HIV-infected patients.

OBJECTIVE: To evaluate the types and mechanisms of stroke in a large population of HIV-infected patients. METHODS: We reviewed records of consecutive HIV-infected patients with acute stroke admitted to a large metropolitan hospital between 1996 and 2004. Stroke mechanism was defined by consensus between two cerebrovascular neurologists using TOAST classification. RESULTS: A total of 82 patients were included, 77 with ischemic stroke and 5 with intracerebral hemorrhage. Mean age was 42 years and 89% were African American. Previous diagnosis of HIV infection was documented in 91% and AIDS diagnosis in 80%. Mean CD4 count was 113 cells/mm(3) and 85% had CD4 count <200 cells/mm(3). A total of 61% of patients had received combination antiretroviral treatment (CART). The mechanism of ischemic stroke was large artery atherosclerosis in 12%, cardiac embolism in 18%, small vessel occlusion in 18%, other determined etiology in 23%, and undetermined in 29% (including 19% with incomplete evaluation). Vasculitis was deemed responsible for the stroke in 10 patients (13%) and hypercoagulability in 7 (9%). Protein S deficiency was noted in 10/22 (45%) and anticardiolipin antibodies in 9/31 (29%) tested patients. When comparing patients with large or small vessel disease (atherothrombotic strokes) vs the rest of the population, there were no differences in exposure to CART or CD4 count, but patients with non-atherothrombotic strokes were younger (p = 0.04). Recent cocaine exposure was less common among patients with atherothrombotic strokes (p = 0.02). Strokes were fatal or severely disabling in 35% of cases. CONCLUSIONS: Stroke mechanisms are variable in HIV-infected patients, with a relatively high incidence of vasculitis and hypercoagulability. In our population of severely immunodepressed patients, exposure to combination antiretroviral treatment did not significantly influence the mechanism of stroke.

Surgical treatment of nonbacterial thrombotic endocarditis presenting with stroke.

BACKGROUND: Necropsy studies have shown that nonbacterial thrombotic endocarditis (NBTE) may be associated with cerebral infarctions and antemortem diagnosis is now possible. However, the best treatment for patients with NBTE presenting with stroke is not known. We describe three patients presenting with an acute embolic stroke secondary to large,mobile vegetations detected by transthoracic (one case) or transesophageal echocardiography (two cases). All patients underwent surgery for removal of the vegetations to prevent recurrent embolic events; valve replacement was necessary in two cases. The sterile nature of the vegetations was confirmed by pathological examination and negative stains and cultures of the surgical samples. A previously unrecognized hypercoagulable condition was diagnosed in all patients (antiphospholipid antibody syndrome in two cases and disseminated adenocarcinoma in one case). CONCLUSION: NBTE should be considered among the possible causes of embolic stroke even in the absence of history of cancer, hypercoagulability, or previous embolic manifestations. If NBTE is diagnosed, the possibility of underlying thrombophilia should be thoroughly investigated. Valvular surgery represents a valuable therapeutic alternative in patients with large mobile vegetations, valvular dysfunction or recurrent embolic events despite anticoagulation.

Anticoagulation and microembolus detection in a case of internal carotid artery dissection.

BACKGROUND: Microembolic signals (MES) have been demonstrated by transcranial Doppler (TCD) in cases of internal carotid artery dissection. The influence of treatment on MES in arterial dissection is uncertain. The authors here present a case of internal carotid artery dissection in which we detected a reduction of MES after the initiation of intravenous heparin. METHODS: A 37-year-old woman developed a right temporal headache 10 days prior to admission. This was followed by episodes of left arm numbness and weakness. Magnetic resonance imaging (MRI) showed a right frontal and deep subcortical ischemic infarct. Catheter angiography confirmed a right internal carotid artery dissection with intracranial extension. She was then monitored with TCD for MES before and after intravenous heparin was started. RESULTS: The first TCD, performed 12 days after symptom onset, showed 39 MES during 60 minutes of insonation of the right middle cerebral artery. Treatment with intravenous heparin resulted in a decline in MES by 50% after 96 hours. This decline continued and no further MES were detected after 11 days of anticoagulation. CONCLUSION: The authors were able to demonstrate a decline of MES with heparin anticoagulation in a case of internal carotid artery dissection.

[Detection of microembolus with transcranial doppler]. / Detección de microémbolos con Doppler transcraneal.

OBJECTIVES: To review techniques and the most important clinical applications of microembolus detection with transcranial Doppler. DEVELOPMENT: Technical aspects of microembolus detection are discussed initially; clinical circumstances in which embolus detection is currently used follow, such as carotid stenosis, cardiac pathology, monitoring during neuroangiography, coronary revascularization surgery and endarterectomy. Lastly, the potential clinical applications of this technique are reviewed: localization of an embolic source, risk of recurrent ischemia in patients with unstable atherosclerotic plaques, intraoperative monitoring and potential surgical technique modifications based on this information, contributions to the understanding of the pathophysiology of the fat embolism syndrome, and monitoring therapeutic efficacy of antithrombotics and thrombolytics. CONCLUSIONS: The ability to detect cerebral emboli with transcranial ultrasound has increased significantly our understanding about the pathogenesis of cerebral ischemia. Microembolus detection with transcranial Doppler is a powerful and novel diagnostic technique that allows to study the embolic process in vivo and in real time, instead of using indirect indicators of embolism (clinical and radiological features, possible embolic sources, etc.).

Transcranial doppler detection of fat emboli.

BACKGROUND AND PURPOSE: The fat embolism syndrome (FES) is characterized by the simultaneous occurrence of pulmonary and neurological symptoms as well as skin and mucosal petechiae in the setting of long-bone fractures or their surgical repair. Its pathophysiology is poorly understood, and effective treatments are lacking. We present 5 patients with long-bone fractures in whom in vivo microembolism was detected by transcranial Doppler. METHODS: Five patients with long-bone fractures were monitored with transcranial Doppler for microembolic signals (MESs) after trauma. Two patients also had intraoperative monitoring. A TC-2020 instrument equipped with MES detection software was used. Detected signals were saved for subsequent review. Selected signals satisfied criteria defined previously and were categorized as large or small. RESULTS: Cerebral microembolism was detected in all 5 patients and was transient, resolving within 4 days of injury. Intraoperative monitoring revealed an increase in MESs during intramedullary nail insertion. The characteristics of MESs after injury varied among patients, with large signals being more frequent in the only patient with a patent foramen ovale. CONCLUSIONS: Cerebral microembolism after long-bone fractures can be detected in vivo and monitored over time. These findings may have potential diagnostic and therapeutic implications.

Transcranial sonography in a patient with a persistent trigeminal artery.

Transcranial ultrasonography was performed in a patient with a persistent trigeminal artery, a remnant of fetal cerebral circulation that bridges the carotid and basilar territories. The study revealed low flow and reversal of flow in the vertebral and basilar arteries, respectively. The interpretation and significance of these findings are discussed.

[Non-invasive evaluation of extracranial and intracranial vascular disease]. / Diagnóstico no invasivo de la enfermedad vascular extra e intracraneal.

INTRODUCTION: Over the last 10 years the diagnosis of chronic and acute cerebrovascular disorders has been greatly improved. We have available now not only better anatomical imaging methods that allow a more precise localization and subtyping of the problem, but also physiological methods that look at the function and interaction between the brain's parenchyma and its perfusion. DEVELOPMENT: In this article the utility and clinical indications of ultrasonography (duplex and Transcranial Doppler) including the modern techniques of embolus detection are described. Also discussed are Magnetic resonance angiography, perfusion-diffusion magnetic resonance, computed tomographic angiography (angio-CT), single photon emission tomography (SPECT). Clinical examples of real cases exemplify the use of these techniques.

Internal carotid artery dissection causing a branch retinal artery occlusion in a young adult.

PURPOSE: To report a 34-year-old healthy man with an internal carotid artery dissection who presented with an ipsilateral branch retinal artery occlusion. METHOD: Case report. RESULTS: Ophthalmic examination of a young adult presenting with transient monocular visual loss and a superior nasal field defect disclosed a left inferior branch retinal artery occlusion. After fluorescein angiography, the patient had a vasovagal response, and his condition worsened to a left central retinal artery occlusion. Neurologic evaluation followed by carotid angiography disclosed a left internal carotid artery dissection with total occlusion of the internal carotid artery. CONCLUSION: The differential diagnosis of retinal arterial occlusion in a young healthy adult without any notable ocular or medical history, including trauma, should include spontaneous internal carotid artery dissection.

Cerebral microembolism and extracranial internal carotid artery dissection.

Although extracranial ICA dissection is recognized as a cause of cerebral infarction, 1-3 the pathogenesis of ischemic symptoms in an individual patient with the condition is not always understood, making treatment decisions difficult. We describe a patient with traumatic cervical ICA dissection diagnosed on the basis of noninvasive tests, in whom TCD ultrasonography was used to detect ipsilateral distal microembolization associated with clinical deterioration.

Effect of time and cerebrovascular symptoms of the prevalence of microembolic signals in patients with cervical carotid stenosis.

BACKGROUND AND PURPOSE: High-intensity transient signals (HITS) detect ed by transcranial Doppler ultrasonography correspond to microemboli in intracranial arteries. The aim of this study was to determine the time course of cerebral microembolism in patients with symptomatic internal carotid artery stenosis and to assess its relation to specific symptoms of cerebral ischemia. METHODS: On the basis of criteria established a priori, 69 middle cerebral arteries were selected from a series of consecutive studies obtained at our neurovascular laboratory. All patients had radiological evidence of cervical internal carotid artery disease and had corresponding symptoms. A TC-2000 instrument equipped with special software for microembolus detection was used. Accepted signals were unidirectional from baseline, had a chirping sound, were 9 dB higher than the surrounding blood, and lasted 25 milliseconds or more. RESULTS: HITS were identified in 20 of 69 (29%) arteries. The median interval between onset of symptoms and time of testing was 4 days for HITS-positive arteries and 12 days for those that were HITS negative (P=.0046). Fourteen of 32 (44%) arteries with transient ischemic attacks and 6 of 37 (16%) arteries with cerebral infarction were HITS positive (P=.012). CONCLUSIONS: In patients with symptomatic carotid stenosis, HITS are detected more frequently when patients are tested soon after symptoms of cerebral ischemia. HITS are also more prevalent in the territories of arteries with transient ischemic attacks rather than cerebral infarction. These findings may have diagnostic and therapeutic implications.