Overall, strokes can be divided into two main types. The first type, known as a hemorrhagic stroke, happens when an artery in the brain bleeds. This kind of stroke may be caused by an aneurysm (a bubble in the artery wall) that bursts or by a condition called arterial venous malformation, a tangle of abnormal blood vessels in the brain that may bleed due to the fragility of the vessel structure. The second and most common type of stroke, known as ischemic stroke, occurs when a blood clot blocks an artery that carries blood to the brain. Deprived of oxygen, brain cells die at a rate of two million cells per minute, increasing the risk of permanent brain damage leading to disability or death.
Recognizing symptoms and getting medical attention quickly can save a life and minimize disability. Stroke is a time-sensitive disease.
What is the incidence of stroke?
Approximately 795,000 new or recurrent strokes are diagnosed each year in the United States, making it the number one cause of adult disability and the fourth leading cause of death in America. This equates to one stroke every 40 seconds and one death from stroke every 3 to 4 minutes. Americans will pay nearly $34 billion in 2017 for stroke-related medical costs and disability.
What are the symptoms of a stroke?
•Sudden numbness or weakness of the face, arms or leg – especially on one side of the body
•Sudden confusion or trouble speaking or understanding speech
•Sudden trouble seeing in one or both eyes
•Sudden trouble walking, dizziness, or loss of balance or coordination
•Sudden severe headache with no known cause
What are the risk factors of stroke?
•Over age 55
•Hyperlipidemia (presence of excess lipids in the blood)
•Atrial fibrillation (abnormal and irregular heart rhythm that can alter the heart’s electrical system, resulting in poor blood flow to the body, shortness of breath and weakness)
•Family history of stroke
How are strokes diagnosed?
Advances in the treatment of stroke have led to the advent of primary stroke centers, or hospitals where a group of medical professionals who specialize in stroke, work together to diagnose, treat, and provide early rehabilitation to stroke patients. Comprehensive Stroke Center Certification recognizes hospitals that meet standards to treat the most complex stroke cases. Eligibility standards include all components of a Primary Stroke Center plus:
- Availability of advanced imaging techniques, including MRI/MRA, CTA, DSA and TCD
- Availability of personnel trained in vascular neurology, neurosurgery and endovascular procedures
- 24/7 availability of personnel, imaging, operating room and endovascular facilities
- ICU/neuroscience ICU facilities and capabilities
- Experience and expertise treating patients with large ischemic strokes, intracerebral hemorrhage and subarachnoid hemorrhage
Upon arrival at a hospital, the first order of business is to perform a Computed Axial Tomography (CAT) scan of the brain to determine if you are in fact suffering a stroke, and whether it is ischemic or hemorrhagic in nature. If the scan reveals an ischemic stroke (result of a clot), special CAT scans may be performed to enable physicians to view the arteries and determine the site of the blockage. These scans will also reveal the way blood flows to the brain, information that is used to assess the presence of brain damage or if there is at-risk brain tissue that could potentially be saved. At some institutions, a more sensitive Magnetic Resonance Imaging (MRI) scan may be performed instead of a CAT scan. While an MRI can more precisely detect abnormalities, these scans may take longer to perform. Thus, physicians may not opt for an MRI in order to ensure that the patient can be treated within the optimal three-hour window and have the best chance of recovery.
How are strokes treated?
In stroke treatment, the rule of thumb is “Time is brain”! The faster treatment can be initiated, the better the chance of a successful outcome. Current FDA-approved therapies include clot-busting medications (t-PA) that can be administered intravenously (through a needle in the arm) within three hours, and sometimes up to 4.5 hrs, of symptom onset, as well as certain devices that can break up or remove the clot when applied within six hours of symptom onset.
For larger clots, or emergent large vessel occlusions (ELVO), medications are less successful in restoring blood flow. Thrombectomy is a well-proven treatment for stroke with three simultaneous studies published in the New England Journal of Medicine. Thrombectomy is designed for the type of stroke with a large vessel occlusion, which leaves 75% of patients dead or permanently disabled. Combining these studies show that more than half of the patients treated with stroke thrombectomy become independent again. The sooner thrombectomy is performed, the higher the chance of success.
Currently, these devices include stent-retriever devices to mechanically engage the clot for removal or aspiration catheters that use suction to remove the clot. By placing these devices in specialized catheters (resembling long thin tubes) that are inserted into the body through an artery in the groin or wrist, and threaded up through the blood vessels to the site of the clot in the brain, physicians can maneuver the devices to break up the clot and remove it from the body.