Topics and Speakers Mitchell S. V. Elkind, MD, MS
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Synopsis
Stroke is the third leading cause of death in the United States and the leading cause of serious long-term disability. In other parts of the world, particularly in Asia, stroke outranks heart disease as the leading cause of death. Given the massive health burden stroke places on individuals, it is critically important that physicians both recognize and treat stroke effectively. In this lecture, Dr Mitchell S. V. Elkind covers both the vascular physiology and pathophysiology of this complex disorder as well as clinical issues, including acute stroke management and prevention strategies.
Dr Elkind starts by presenting new definitions of stroke and transient ischemic strokes (TIAs). Stroke is defined as, "rapidly developing clinical signs of focal disturbance of brain function lasting more than 24 hours or leading to death with no apparent cause other than that of vascular origin." A TIA is a similar attack that lasts less than 24 hours.
In the past, TIAs were considered more benign than strokes, but they are now considered a very high risk condition. As Elkind points out, patients with TIAs have a very high-risk of developing another vascular event, such as stroke, within 48 hours of their initial TIA.
Dr Elkind offers a detailed examination of the two major type of strokes, hemorrhagic and ischemic. Approximately 20% of strokes are hemorraghic and 80% ischemic. Although symptoms can hint at the underlying type of stroke, only CAT scan can accurately distinguish what type of stroke a patient is having. He provides several examples of MRI scans showing examples of different subcategories of stroke, such as subarachnoid hemorrhage, cerebral artery infarction, and lacunar infarct.
The next area that Dr Elkind explains is blood vessel anatomy, which is key to understanding stroke. Four major blood vessels supply the brain: two carotid arteries in the front and two vertebral arteries in the back. It is important to remember that the carotid artery winds through the eye, making loss of vision an important warning sign of potential stroke. During a stroke, a core area of the brain suffers an infarct rather quickly from lack of blood flow. The surrounding area of tissue may be functionally impaired, giving the patient a clinical deficit, but not yet irreversibly damaged or dead. This area, called the penumbra or shadow, is an important target for intervention. Function may be restored with restoration of blood flow.
Management of acute ischemic stroke requires trying to interrupt the processes of stroke as well as restoring blood flow. Very low blood pressures may be worse for stroke patients than high blood pressure. Another critical issue is time, the sooner treatment commences the better, and different treatments are indicated depending on the window of time. Elkind focuses on a recent study that gave tissue-plasminogen activator (tPA) to thrombolise the clot. Despite the increased risk of hemorrhage associated with tPA, this risk is offset by the decreased risk of other comorbidities that can occur with stroke, including recurrent or enlarged stroke, edema, herniation, or seizures. He also reviews other options such as, ultrasound enhanced thrombolysis, cutting-edge clot-retraction device and free radical trapping agents.
The last topic covered is stroke prevention. Although the FDA approved the use of tPA several years, few patients actually receive this treatment for acute ischemic stroke. Therefore, the key to reducing the burden of disease is still prevention of stroke. Dr Elkind reviews the major strategies for prevention: risk factor control, carotid treatments, anticoagulation, and antiplatelet therapies. Finally, he describes current studies underway that examine alternative treatments for stroke.
