Secondary stroke prevention for stroke survivors

Dr. Nicholas Larochelle, M.D., Medical Director of Emergency Medicine, the Transfer Center, and the Stroke Program for the Concord Hospital health system discusses stroke symptoms, treatment, and prevention.

Stroke is the abrupt onset of neurological symptoms resulting from the interruption of blood flow to a part of the brain. Stroke is the leading cause of disability worldwide and a time-critical diagnosis. Early recognition and management helps to optimize patient outcomes. Though stroke can have various and often subtle symptoms, it is important to highlight BE FAST (Balance, Eyes, Face, Arm, Speech, and Terrible headache) as a way to remember and recognize the symptoms of stroke quickly. These symptoms include sudden loss of balance or coordination, visual loss or blurriness, weakness or paralysis in the face or arms, trouble with or slurred speech, and an extreme and abrupt headache.

The brain needs both oxygen and glucose to function. The delivery system is the auto-regulated blood flow to the brain through various arteries. In fact, the brain alone accounts for approximately 20 percent of the body’s total oxygen and glucose consumption. When blood flow to the brain is disrupted, either by a blockage in blood vessels or from bleeding, we see the development of free radicals and an inflammatory state that can damage brain tissue. Neuronal death can occur within minutes in the case of complete occlusion or blockage, destroying that brain tissue’s function. More commonly, blood flow is restricted and infarction, or tissue death, can occur within one hour to a few days, depending on the level and duration of the restriction.

Categorically, there are two major types of strokes: ischemic stroke and hemorrhagic stroke. Ischemic stroke, which accounts for 85 percent of all strokes, occurs when blood flow to the brain is obstructed, resulting in a blood-deprived area of the brain. This type of stroke can be either thrombotic or embolic. Thrombotic ischemic strokes occur as a result of the development of plaque over time from high blood pressure or the deposition of lipid due to high circulating cholesterol. An embolic ischemic stroke occurs when a clot from another area of the vascular system (ie heart) travels to the brain through the vascular system. The other major type of stroke is called a hemorrhagic stroke. In this type, a ruptured blood vessel leaks blood into the brain parenchyma disrupting neuronal function.

A transient ischemic attack (TIA), commonly referred to as a mini-stroke occurs when an individual experiences relatively brief neurological symptoms as the result of inadequate blood flow to an area of the brain for a short time. The tissue recovers and blood flow is restored on its own, but a TIA may signal a larger, more impactful stroke to come and should be taken very seriously.

The most common type of stroke we see in the ED is an ischemic stroke. When a patient arrives, there may be a small area that has already experienced neuronal death, but the real target of our therapy is the at-risk area that exists in the surrounding tissue. The penumbra, this zone of reversible ischemia (blood-deprivation) around a core of irreversible infarction (tissue death), may be salvageable in the first few hours. As we say, ‘time is brain,’ so we get to work immediately to determine eligibility for potential tissue-saving treatments. Advancements in neuroimaging and perfusion-based imaging allow us to individualize treatment better and understand the size of the salvageable tissue.

One of our acute treatments is tenecteplase (TNK), a clot-busting medication, which catalyzes the breakdown of clots to then enable reperfusion, or reestablishment of blood flow. Another treatment modality is mechanical thrombectomy, which is an endovascular surgical procedure to physically remove clot in a larger intracranial blood vessel. Less than 10 percent of stroke patients are candidates for either TNK or thrombectomy. For the other 90 percent of stroke patients, we investigate further to determine the etiology of the stroke and optimize measures to prevent future stroke. This can involve electrocardiograms (EKG), blood testing, CT/MRI scans, echocardiograms, carotid imaging, or a combination of these.

By some estimates, 80 to 90 percent of strokes are preventable through risk factor modification. Though a patient has certain risk factors that cannot be altered including age, prior stroke, and genetics, there are other modifiable risk factors. These include hypertension, tobacco use, blood glucose control, and cholesterol. The ABCD2 (Age, BP, Clinical features, Duration of symptoms, Diabetes) Score is used to predict individual patients’ risk of stroke recurrence and help determine which therapies are best by weighing the risks and benefits. Possible treatments may include anti-coagulation therapy (blood thinners) and anti-platelet agents, cholesterol-lowering medications, glycemic (blood sugar) control, or the Watchman procedure for atrial fibrillation. Patients are also urged to quit smoking, adopt a healthy diet, engage in moderate physical activity, and limit alcohol use.

Dr. Nicholas Larochelle of Concord Hospital Emergency Medical Associates spoke about secondary stroke prevention at the May Concord Hospital Trust “What’s Up Doc?” Donor Lecture Series. The monthly series, supported by the Walker Lecture Fund, features members of Concord Hospital’s medical staff speaking to Concord Hospital Trust donors about new and innovative medical treatments and services. You can watch Dr. Larochelle’s presentation on Concord Hospital’s YouTube channel at: youtube.com/concordhospital.