Ischemic Stroke

Diagnosis and Treatment

Sheryl Martin-Schild, Hen Hallevi, Andrew Barreto

• Publisher: Rutgers University Press
• Year: 2018
• Print ISBN: 9780813592572
• eBook ISBN: 9780813592589
• Topic: Medicine
• Subtopic: Cardiology

Stroke is the fifth leading cause of death in the United States and is a leading cause of adult disability and discharge from hospitals to chronic care facilities. Despite the frequency and morbidity of stroke, there is a relative paucity of "stroke experts, " such as vascular neurologists and neurocritical care physicians, to care for these patients. Clinical research in the diagnosis and treatment of stroke has grown exponentially over the past two decades resulting in a great deal of new clinical information for attending physicians to absorb. Grounded in cutting-edge and evidence-based strategies, Ischemic Stroke closes the gap in stroke care by providing a cogent and intuitive guide for all physicians caring for stroke patients.Key topics explored cover all elements of stroke care, including examinations of: emergent evaluation of the suspected stroke patient, clinical signs and symptoms of stroke, mechanisms of ischemic stroke, neuroimaging, cardiac-based evaluation, thrombolytic therapy, endovascular therapy, critical care management, rehabilitation, cardiac arrhythmias, and structural heart disease.

1

Emergent Evaluation of the Suspected Stroke Patient

Lester Y. Leung and Andrew Barreto

TIME IS BRAIN

Acute stroke is a treatable medical emergency, and time is a critical determinant of permanent disability and death. For every minute the human brain is starved of oxygen and nutrients in acute ischemic stroke, 1.9 million neurons are lost.1 In acute intracerebral hemorrhage, patients can rapidly decompensate secondary to expansion of the hematoma, leading to obstructive hydrocephalus or brain herniation. Early recognition and treatment of both ischemic stroke and intracerebral hemorrhage can significantly reduce stroke severity and improve chances of achieving functional independence and, in an increasing number of cases, a return to baseline neurologic function.

While there are many efforts to bring patients with acute stroke to stroke centers during early, intervenable stages of their illnesses, there are few organized programs for medical providers to improve the detection and management of acute stroke in the inpatient and outpatient settings. Therefore, non-neurologists (including primary care physicians, hospitalists, intensivists, cardiologists, surgeons, anesthesiologists, and others) must remain vigilant in detecting symptoms of stroke early and develop clinical skills to optimize the management of acute stroke during the first few critical minutes and hours while calling for guidance from vascular neurology specialists.

THE STROKE CHAIN OF SURVIVAL

To organize care systems around rapid triage, evaluation, and treatment of acute stroke, the American Heart Association/American Stroke Association developed the stroke chain of survival.2

Detection

Most individuals with acute stroke develop their neurologic symptoms and deficits in the community setting. Because many strokes result in impaired awareness or communication, neurologic deficits must be recognized by family members, friends, co-workers, and bystanders. Unfortunately, public awareness of stroke symptoms is poor, with only modest improvements gained through several public health campaigns to improve awareness of stroke warning signs; risk factors; and time-limited, emergent treatments.3–11

However, clinicians are better equipped with background knowledge on stroke presentations and the emergent nature of the condition as well as with better familiarity with healthcare systems. Both inpatient and outpatient clinicians have opportunities to identify and triage patients with acute stroke symptoms in a healthcare setting with resources that can be mobilized to initiate the stroke evaluation or quickly transfer the patient to a stroke center. (Stroke symptoms and signs will be discussed in greater detail in Chapter 2.)

Dispatch

In the community, the initial contact between a patient or family member and the healthcare system ideally proceeds through a telephone call to emergency medical services (EMS): dialing 9-1-1. (Some individuals subscribe to remote activation of EMS through wearable devices.) The 9-1-1 operator attempts to obtain a few historical details to triage the urgency of the call; in some cases, a specialized EMS team that includes stroke experts available via video-conference telemedicine can be dispatched to evaluate the patient.12 Upon arriving on the scene, the EMS team quickly assesses the patient with the basic ABCs of resuscitation; proceeds with a brief, stroke-oriented clinical assessment; and then prepares the patient for transportation to the nearest hospital. Ideally, if the stroke is recognized by EMS personnel, the patient may actually bypass the nearest hospital and instead be taken to a certified primary or comprehensive stroke center.13 (The examination of the stroke patient is described in Chapter 2.)

For clinicians in outpatient and inpatient settings, the dispatch process is more heterogeneous. In clinic and outpatient procedure settings (even those connected to a hospital), the fastest method of patient transfer is usually through activation of EMS; however, the clinician can begin the initial clinical examination and obtain key historical details to convey to EMS. (Exceptions occur with procedural services such as cardiology that have inpatient services and beds where the patient can be quickly admitted and medically stabilized.) When a patient is admitted to a hospital without vascular neurology specialists, the inpatient clinician should call for emergent consultation with the hospitalist’s on-call neurologist or through telestroke services. When a patient is admitted to a hospital with a stroke service, a stroke activation or stroke code can be called to mobilize the neurology team for rapid assessment. (The key historical details that must be obtained by the clinician are described later in this chapter.)

Delivery

EMS is tasked with rapidly transporting patients to stroke centers that are capable of providing intravenous fibrinolytic therapy (IV tissue plasminogen activator, or IV tPA) for acute ischemic stroke. Outcomes are better for these patients.14 Additionally, some patients may benefit from intra-arterial therapies (mechanical thrombectomy), which are usually performed by appropriately trained vascular neurologists, interventional radiologists, or neurosurgeons. Other surgical treatments such as decompressive hemicraniectomies for large hemispheric strokes and hemicraniectomies and ventriculostomies for intracerebral hemorrhages are provided by neurosurgical specialists. Ideally, a city’s or region’s EMS services may be organized to routinely bring patients with possible acute stroke to these centers and provide prehospital notification. This expedites the mobilization of the stroke team and other ancillary services and permits faster treatment. For example, the stroke team meets the patient at the door and escorts her directly to the CT scanner, which has already been cleared and prepared for stroke neuroimaging.

During this phase, EMS providers and other clinicians use prehospital stroke scales to estimate stroke severity. Several scores have been developed, including the Los Angeles Prehospital Stroke Screen (LAPSS), a shortened version called the Los Angeles Motor Score (LAMS), and the Cincinnati Prehospital Stroke Scale (CPSS).15–17 Of these, LAMS and CPSS have been validated to help predict the presence of persistent large-vessel occlusions (LVOs) with high severity scores.18,19 Accordingly, these scores may help triage patients to centers that can deliver optimal, expedient care. In some regions, stroke centers that provide intra-arterial therapies (comprehensive stroke centers, CSCs) are within relatively close proximity to centers that only provide intravenous therapies (primary stroke centers, PSCs). Some PSCs lack additional capabilities, including emergent angiographic studies (CT angiography or MR angiography), MR imaging, or intensive care unit (ICU)–level care. In light of clinical trials demonstrating the efficacy of combined intravenous fibrinolysis and intra-arterial therapy for ischemic strokes due to LVO, early identification of patients with persistent LVO can help EMS providers direct patients to centers that can provide both therapies in a timely manner without delay in diagnosis, transport, or mobilization of specialized teams. In other situations, eligible patients may need to receive intravenous fibrinolysis at a PSC before rapid transport (e.g., via helicopter) to a CSC for subsequent intra-arterial therapy.

For the clinician evaluating a patient with acute stroke, arranging transportation to the next stage of care is vital. While EMS ground transport between a clinic and an adjacent hospital is straightforward, some patients may need to be transported by helicopter to the nearest stroke center. In some cases, transportation may occur after the non-neurologist clinician has assessed the patient, obtained requisite imaging and laboratory data, confirmed the absence of contraindications, and proceeded with treatment with IV tPA. If an in-hospital stroke activation is called, the clinician may need to arrange for hospital transport services to bring the patient to the CT scanner or assist the stroke team in transporting the patient.

Door

If the EMS services were able to provide prehospital notification of a patient’s arrival, the stroke team can be present when the patient enters the doors of the emergency department. The emergency medicine team is tasked with rapidly assessing the patient within 10 minutes of the patient’s arrival. During this phase, EMS communicates the initial historical details and findings from a prehospital stroke screening assessment.

The non-neurologist clinician evaluating a patient with possible acute stroke must provide essential details of the patient’s history and examination to expedite the evaluation and treatment of the patient. When EMS, an on-call neurologist, or the stroke team arrives, a brief assessment should be presented:

The patient is a 65-year-old woman with an acute onset of aphasia and right face and arm weakness in the setting of atrial fibrillation, not on anticoagulation. She was last seen normal 30 minutes ago by the physical therapists.

Some stroke centers have developed pathways through which patients with suspected stroke may be delivered from EMS directly to the CT scanner, dramatically reducing treatment times (i.e., “door-to-needle” time).20 Point-of-care laboratory testing is often implemented to quickly assess blood glucose, coagulation studies, and renal function. If a patient is eligible for fibrinolysis after head CT images are acquired, tPA can be drawn from a medication repository in the scanner room and administered while the patient is still in the CT scanner. Often, once renal function has been assessed, the patient then undergoes CT angiography to assess for critical stenosis and occlusions of the extracranial and intracranial blood vessels.

Data

In the emergency department, a few key data are quickly acquired in order to assist the decision-making process regarding intravenous fibrinolytic and intra-arterial therapies and to exclude common stroke mimics. While several laboratory tests, cardiac telemetry and electrocardiography, and vital signs are obtained, the most essential data required before the administration of IV tPA are as follows:

1. The National Institutes of Health Stroke Scales (NIHSS), a brief standardized examination quantifying the patient’s neurologic deficits.
2. Blood pressure, as the patient’s systolic blood pressure should be below 185 and diastolic blood pressure should be below 110 prior to administration of IV tPA.
3. Glucose measurement, generally obtained as a point-of-care fingerstick blood draw to exclude severe hypoglycemia and hyperglycemia (common stroke mimics).
4. A noncontrast head CT to exclude intracranial hemorrhage. (Imaging is discussed in greater detail in Chapter 4.)
5. Coagulation studies ...

Table of contents

• Cover
• Title Page
• Copyright
• Contents
• Contributors
• 1. Emergent Evaluation of the Suspected Stroke Patient
• 2. Clinical Signs and Symptoms of Stroke
• 3. Mechanisms of Ischemic Stroke
• 4. Neuroimaging of Acute Stroke
• 5. Cardiac-Based Evaluation of Ischemic Stroke
• 6. Thrombolytic Therapy for Acute Ischemic Stroke
• 7. Endovascular Management of Acute Ischemic Stroke
• 8. Critical Care Management of Ischemic Stroke
• 9. Stroke Rehabilitation
• 10. Cardiac Arrhythmias and Stroke
• 11. Evaluation and Prevention of Stroke due to Structural Heart Disease
• 12. Treatment of Symptomatic Carotid Stenosis
• 13. Intracranial Large-Vessel Disease
• 14. Small-Vessel Disease
• 15. Cryptogenic Stroke
• Index