GABA Agonism
The Early GABAergic Activation in Stroke Trial EGASIS looked at the use of diazepam administration within 12 hours after both ischemic and hemorrhagic stroke onset. The rationale for diazepam use includes both its inhibitory effect on harmful neuronal nitric oxide synthase activity and on neuronal hyperpolarization by increased GABA-A-mediated chloride conductance. Although the treatment seemed to worsen hemorrhagic stroke outcome due to an increase in pneumonia and death, in the subgroup of...
Trials of Heparin in Acute Ischemic Stroke
Placebo-Controlled Trials of UFH, LMWH, and Heparinoids The International Stroke Trial 1ST 8 was a randomized, placebo-controlled trial of UFH 5000 or 12,500 IU twice daily and aspirin 300 mg in 19,435 unselected patients with acute stroke within 48 hours of symptom onset. Because of limited availability of neuroimaging, 33 of participants were enrolled with suspected but not proven ischemic stroke, some of whom may have suffered primary intracerebral hemorrhage ICH . TABLE 7.1 Commonly used...
Mechanical Clot Disruption
There are several techniques available for mechanical thrombolysis. The most common is probing the thrombus with a microguidewire. This technique appears to be useful in facilitating chemical thrombolysis.12 Alternatively, a snare e.g., Amplatz Goose-Neck Microsnare, Microvena, White Bear Lake, MN can be used for multiple passes through the occlusion to disrupt the thrombus.54, 70 A snare can also be used for clot retrieval, mostly in situations in which the clot has a firm consistency or...
Stroke Subtype Predicts Outcome
Patients with large vessel atherothrombotic stroke have been reported to have worse short- and long-term survival as compared to other subtypes of stroke.5-11 In a population-based study from Rochester Minnesota, only 24 of patients classified as atherothrombotic were independent during the period of worst deficit and 50 were independent at 1 year.9 Large vessel atherothrombotic stroke patients also have the highest rate of recurrent stroke.6,10,11 Cardioembolic strokes may also have poor...
Decompressive Craniectomy
Malignant or life-threatening MCA territory infarction occurs in up to 10 of strokes and is associated with an 80 mortality rate. Stroke progression and FIGURE 5.4 Outcomes at 3 months in the CLOTBUST trial. Favorable outcomes were defined as a score of 0-1 on the modified Rankin Scale, indicating little or no disability. A total of 42 of patients in the target group who were eligible for follow-up and 29 of those in the control group met these criteria. Other outcomes included a modified...
Efficiency of Thrombolytic Administration
In the first 27 months of our own TeleStroke experience,30 26 consultations were requested 12 began within 3 hours of symptom onset. Eight of these 12 patients had acute ischemic stroke, of which 2 were not treated due to mild deficits. Three were diagnosed with TIA or migraine, and one with a subdural hematoma not detected at the local facility. For the 12 acute cases for whom rapid diagnosis and management was essential, we determined the mean times from symptom onset to start of TeleStroke...
References Mbz
1. Lo EH, Dalkara T, Moskowitz MA. Mechanisms, challenges and opportunities in stroke. 2. Syntichaki P, Tavernarakis N. The biochemistry of neuronal necrosis rogue biology Nat Rev Neurosci 2003 4 672-684. 3. Singhal AB, Lo EH, Dalkara T, Moskowitz MA. Advances in stroke neuroprotection hyperoxia and beyond. Neuroimaging Clin N Am 2005 15 697-720, xii-xiii. 4. Dirnagl U, Iadecola C, Moskowitz MA. Pathobiology of ischaemic stroke an integrated view. Trends Neurosci 1999 22 391-397. 5. Kidwell CS,...
The MERCI and MultiMERCI Trials
The MERCI trial was a prospective single-arm, multicenter trial designed to test the safety and efficacy of the MERCI clot retrieval device to restore the patency of intracranial arteries in the first 8 hours of an acute stroke. All patients were ineligible for IV rt-PA. The occlusion sites were the intracranial vertebral artery, basilar artery, ICA, ICA terminus, or proximal MCA branches M1 or M2 . Primary outcomes were of recanalization and safety, and secondary outcomes were neurological...
Thrombolytic Agents
Plasminogen Activators These drugs act by converting the inactive proenzyme, plasminogen, into the active enzyme, plasmin. Plasmin can digest fibrinogen, fibrin monomers, and cross-linked fibrin as found in a thrombus into fibrin degradation products. These agents vary in stability, half-life, and fibrin selectivity. The thrombolytics that have been reported for use in stroke IAT include urokinase UK , alte-plase, reteplase, pro-urokinase, and streptokinase SK .19,54 In general, the...
THE ARCHITECTURE OF A TELESTROKE SERVICE Equipment and Networking
The system in use at the Massachusetts General Hospital is shown diagrammati-cally in Figure 10.1. A videoconferencing link is established between a community hospital emergency physician and a tertiary care hospital stroke neurologist . All patients are examined on a stretcher in the community hospital's ED using a commercial videoconferencing system on a mobile cart Polycom, Inc., Austin, FIGURE 10.1 Schematic representation of the radiological imaging and videoconferencing VC links between...
Flow Augmentation
The NeuroFlo device CoAxia Inc., Maple Grove, MN is a dual balloon catheter uniquely designed for partial occlusion of the aorta above and below the origin of the renal arteries Fig. 4.6 . Through mechanisms that have yet to be elucidated, this device increases global cerebral perfusion within minutes of balloon inflation, with little or no increase in mean arterial blood pressure. The ongoing Safety and Efficacy of NeuroFlo Technology in Ischemic Stroke SENTIS trial is a prospective,...
Special Circumstances Cerebellar Infarction
Cerebellar infarction poses a particularly dangerous situation, as the posterior fossa acts as its own compartment, creating the possibility of brainstem compression, early herniation or obstructive hydrocephalus for ischemic strokes that swell, conditions that can develop suddenly and be fatal if not treated expeditiously. Certainly, patients with progressive brainstem signs from a compressive lesion should be considered at risk for fatal herniation and nearly always warrant a surgical...
Endovascular Thrombectomy
Mechanical thrombectomy is a promising novel technique in interventional stroke treatment. The devices differ with regard to where they apply force on the thrombus, taking either a proximal approach with aspiration devices see section on thromboaspiration below or a distal approach with basket- or snare-like devices. A study comparing the effectiveness of these two approaches Vasco35 vs. Catch device in a swine stroke model demonstrated that the proximal device allowed fast repeated...
Extracranialintracranial Arterial Bypass
EC-IC arterial bypass involves the use of general anesthesia, open craniotomy, and end-to-side anastomosis of the superficial temporal artery to a branch of the middle cerebral artery MCA Fig. 6.1 . Currently, this technique is being used primarily in the setting of intracranial aneurysm therapy, moyamoya disease, and FIGURE 6.1 CT angiography of an EC-IC bypass, showing the new intracranial course of the right superficial temporal artery, anastamosed to the middle cerebral artery M2 segment....
Management Of Cerebral Edema Associated With Ischemic Stroke
There are three types of ischemic strokes that are more commonly associated with an increased risk of morbidity and mortality moderate-to-large cerebellar strokes, large cerebral hemispheric strokes, and moderate-to-large strokes in the middle cranial fossa, where a theoretical compartment exists that may lead to early herniation if untreated. Kasner et al.45 evaluated 201 patients with large MCA strokes, and found several factors to be associated with the development of malignant or fatal...
Intracranial Embolectomy
Intracranial embolectomy involves the use of general anesthesia, open craniotomy, and arteriotomy for the retrieval of embolic material. In the past, it has been used most frequently to remove solid embolus from the proximal MCA, although reports of successful embolectomy of other intracranial vessels also exist.5'30'48-50 Its use has decreased in recent years, primarily due to the increased and more effective use of intravenous recombinant tissue plasminogen activator rt-PA , intra-arterial...
Identifying The Vascular Lesion
Ischemic stroke occurs because of impairments in microvascular perfusion of affected brain tissue. However, the vascular event that results in impaired perfusion often occurs in a macroscopically visible vessel. Imaging studies that can study these vessels provide several kinds of important information to the stroke neurologist. First, by definitively demonstrating a vascular lesion that could be responsible for ischemic symptoms, vascular imaging can help to cement the diagnosis of an acute...
Posterior Fossa Decompression
Decompression of the posterior fossa is the infratentorial equivalent of a decompres-sive hemicraniectomy. It is primarily intended for cerebellar infarction, usually in the distribution of the posterior inferior cerebellar artery PICA , and typically involves the removal of bone overlying the infarcted tissue Fig. 6.4 .41 Opening of the dura and evacuation of necrotic tissue is frequently done, but it depends on the timing of surgery and the clinical scenario. A frontal horn ventriculostomy is...
Thromboaspiration
Suction thrombectomy or thromboaspiration through either a microcatheter21,95 or a guiding catheter96 may be an option for fresh nonadhesive clot. As discussed above, aspiration devices have the advantage of causing less embolic events and vasos-pasm however, the more complex design of these devices makes them more difficult to navigate into the intracranial circulation. FIGURE 4.5 A 72-year-old man with medical history remarkable for hypertension and dyslipidemia presented with posterior...
Decompressive Hemicraniectomy
Decompressive hemicraniectomy is primarily intended to treat the high intracranial pressure associated with massive MCA infarction and subsequent swelling Fig. 6.3 . Focal areas of ischemia may result when intracranial pressure is greater than 20 mmHg, and global ischemia can occur when intracranial pressure exceeds 50mmHg.33 Therefore, removal of a large part of the calvarium, theoretically reducing intracranial hypertension, ongoing ischemia, and preventing swollen tissue from displacing...
Establishing The Diagnosis Of Ischemic Stroke
Recent years have seen the emergence of successful treatment strategies for ischemic stroke, but these are most effective only when initiated within several hours after stroke onset. Therefore, extremely rapid diagnosis and initiation of treatment are critical in avoiding death or severe disability. Unfortunately, there are a variety of other clinical conditions that may mimic the presentation of acute ischemic stroke. These include intracranial hemorrhage, seizure, sepsis, cardiogenic syncope,...