Stroke: Summary, Prevention, and Treatment

Stroke is the leading cause of death and long-term disability worldwide, so it is vital to understand not only the condition but also how to prevent and treat stroke when it occurs. A stroke is defined as a disruption of blood supply to the brain, also known as a cerebrovascular accident (CVA). This is a medical emergency because the brain needs constant blood supply to perform routine functions. If the blood vessel becomes blocked, then the part of the brain that it supplies may have impaired function, which can lead to permanent disability or even death.

Strokes can fall under one of the three categories: ischemic, hemorrhagic, or transient ischemic attack (TIA). An ischemic stroke is when there is a blockage in the blood supply to the brain, depriving the brain of oxygen and causing cellular death. This is what most people think of when a stroke occurs, and in fact, ~87% of all strokes fall under this category. This blockage may be a blood clot or buildup of plaque in the vessels. Atherosclerosis, a narrowing of arteries due to plaque buildup, is a typical risk factor because it makes the blockage of vessels much more likely. The blockage or clot can also break off and travel through the bloodstream. At this point, it is referred to as an embolus and can lodge into a smaller artery in the brain.

A hemorrhagic stroke occurs when there is bleeding into the surrounding tissue or space due to a blood vessel in the brain rupturing. Hemorrhagic strokes are typically more dangerous and account for 13% of all strokes. High blood pressure (hypertension) and aneurysm are common causes of these strokes. An aneurysm occurs when the walls of the blood vessels weaken and bulge out. As blood flows into this “balloon,” the bulge grows larger and larger until it eventually ruptures into the surrounding space. This bleeding can occur in the subarachnoid space- a potential space below the arachnoid layer of the brain- called a subarachnoid hemorrhage. The stroke can also be due to intracerebral hemorrhage, which is when a small blood vessel deep inside the brain ruptures, spilling into the surrounding tissue and causing intense internal pressure. This often occurs due to heart disease or high blood pressure, which signals that the heart and vessels work overtime to provide sufficient oxygen to the brain. Over time, these blood vessels become brittle and prone to damage, increasing the risk of hemorrhagic stroke.

A transient ischemic attack (TIA) is considered a “mini-stroke” or a precursor to stroke because it resolves on its own. This is due to a temporary deficit of oxygen to a portion of the brain, possibly due to an embolus (traveling clot) or vasospasm (narrowing of vessels), and the symptoms typically resolve within 24 hours.

The most important part of stroke treatment is the rapid detection of symptoms. This led to a relatively well-known acronym being developed to recognize the symptoms of a stroke, referred to as F.A.S.T. In chronological order, F.A.S.T stands for facial weakness/drooping, arm weakness/drift, slurred speech/difficulty speaking, and time- call 9-1-1 immediately if the above symptoms are observed. Additionally, patients may experience sudden onset of severe headache, dizziness or loss of balance, blurred vision, or numbness or weakness on one side of the body.

A standard large-vessel stroke workup for the carotid and intracranial vessels would include some intracranial imaging, like an MRA or angiogram. Strokes present one-sided symptoms, and because of this, we can figure out whether the left or right hemisphere of the brain is affected. Aphasia, which refers to a language deficit, tells us that the stroke is due to impairment of the patient’s dominant hemisphere- usually the left. On the other hand, dysarthria, a weakness in the muscles that produce speech, can be a sign of right or left hemisphere deficit. Regarding sensation and movement, the affected side of the body and the affected hemisphere of the brain are contralateral (opposite) to each other. For example, if the right hemisphere is affected, the patient will present with left paresis or weakness. All strokes can cause varying degrees of memory problems.

As mentioned, stroke requires immediate medical attention. Clot-busting medications can be key to alleviating an ischemic stroke. Tissue plasminogen activator (tPA) is a powerful intravenous thrombolytic that breaks up vessel blockage by dissolving the clot and restoring blood flow. However, tPA must be administered within three hours of stroke onset. Therefore, knowing the last time patients exhibited normal function is essential. A mechanical embolectomy can be done within eight hours, which consists of physically removing the clot from the blood vessel. After 8 hours, an antiplatelet drug like aspirin can be given, which prevents platelets from sticking to each other so that the clot does not increase in size. Heparin and warfarin are anticoagulant medications used for a similar purpose of preventing clot formation. Immediate medical attention results in the most potent treatment, so it is crucial to understand the F.A.S.T. acronym. For hemorrhagic strokes, surgery may be required to stop the bleeding and relieve the pressure on the brain.

After acute treatment, stroke survivors will often need rehabilitation to regain the functions they lost. Rehabilitation can include physical therapy, speech therapy, occupational therapy, or counseling, with a customized treatment plan being developed based on the patient’s symptoms. For example, a patient with a stroke affecting the left hemisphere may have residual speech difficulties and require a speech therapist. Patients may also be placed on anticoagulants to prevent the recurrence of the stroke. A potential complication of anticoagulants is bleeding because the general clotting process is disrupted. Thus, anticoagulants are not an option for hemorrhagic strokes, and for this, treating hypertension would be the primary focus.

The chances of death from the first stroke are 15 to 35%, with an increase to 69% chance for subsequent strokes (Rerkasem et al., 2020). In high-risk patients, carotid surgery can be done to prevent stroke when medications are not sufficient. Often, patients with a stroke will have problems in their carotid artery, which supplies over 70% of the brain’s surface area. A carotid endarterectomy is a surgery that removes plaque or blockage in patients with a narrowing of their carotid artery. A carotid endarterectomy cuts off access to the brain by blocking the internal, common, and external carotid arteries. The internal carotid is opened, the clot or plaque is removed, and the artery and skin can be closed. Because complications can occur during and after this procedure, such as cervical hematoma (swelling) or cranial nerve injuries, it is crucial to use neuromonitoring modalities, such as Transcranial Doppler (TCD), Somatosensory Evoked Potential (SSEP), and Electroencephalogram (EEG). This intraoperative monitoring is paramount to avoid these complications, as patients under anesthesia will not be awake to be assessed otherwise. Carotid endarterectomy is considered beneficial for patients with 50% to 69% narrowing of their blood vessels and highly beneficial for those with 70 to 99% blockage (Rerkasem et al., 2020).

Other procedures can be done to alleviate blockage in the carotid artery. One such intervention is eversion. Here, the blocked artery is disconnected from the common carotid artery, the plaque is removed, and the artery is reattached. Meanwhile, carotid stenting consists of a metal stent placed inside the vessel, which fills up like a balloon, expanding the vessel's walls and relieving the blockage. Trans Carotid Artery Revascularization (TCAR) procedure is another relatively less invasive option, which reverses blood flow in the carotid so debris moves away from the brain. Again, a stent stabilizes the plaque against the artery's walls and reduces the blockage. 

Considering the danger of stroke, it is imperative to understand how to prevent it from occurring. In general, stroke is a disease that occurs with age, as the incidence of stroke doubles for each decade after age 55 (Boehme et al., 2017). Some risk factors are nonmodifiable, like age, race, having a family history of stroke or migraine, etc. At a young age, women are more likely to have a stroke, though at older ages, the risk becomes slightly higher for men (Boehme et al., 2017). However, other risk factors are modifiable, like hypertension, previous stroke, lifestyle issues (i.e., alcohol intake), obesity, high cholesterol, etc. Diabetes is an independent risk factor for stroke, and stroke accounts for ~20% of deaths in diabetics (Boehme et al., 2017). Healthy eating is key to managing these modifiable risk factors, as foods with high cholesterol and sugar should be avoided. Eating fruits and vegetables and foods with folic acid is also beneficial. Even moderate coffee consumption in women and green or black tea has positive effects. Healthy habits like exercise, cessation of smoking, lowering alcohol consumption, and minimizing stress are excellent protective measures against stroke. Those with chronic conditions like hypertension, diabetes, and atrial fibrillation should focus on management through medication (i.e., statins to lower cholesterol) or healthy lifestyle changes. These measures have been proven beneficial, as hypertension control has improved due to heightened awareness and treatment options, with approximately 50% controlled in 2008. Furthermore, the prevalence of hypertension in the US has remained at 29% (Boehme et al., 2017). 

For a condition that is both treatable and preventable, it is paramount to raise awareness of the ways that we can prevent stroke. Furthermore, understanding the significance of timely treatment and educating others about the signs of stroke can be the difference between the resolution of symptoms, permanent disability, or even death.

Bibliography

• Boehme, Amelia K., Charles Esenwa, and Mitchell S.V. Elkind. “Stroke Risk Factors, Genetics, and Prevention.” Circulation Research 120, no. 3 (2017): 472–95. https://doi.org/10.1161/circresaha.116.308398.

• Jahangiri, Faisal R. “Stroke I.” Richardson: University of Texas at Dallas, October 2023.

• Jahangiri, Faisal R. “Stroke II.” Richardson: University of Texas at Dallas, October 2023.

• Rerkasem, Amaraporn, Saritphat Orrapin, Dominic PJ Howard, and Kittipan Rerkasem. “Carotid Endarterectomy for Symptomatic Carotid Stenosis.” Cochrane Database of Systematic Reviews 2020, no. 9 (September 12, 2020). https://doi.org/10.1002/14651858.cd001081.pub4.