Research Paper: Stroke

2016 Research Paper: Stroke STEP NUS SUNBURST BRAIN CAMP NG XIN NI, XIE JIAYING, YEE TING HUI, ZHANG QING YANG RIVER VALLEY HIGH SCHOOL

Contents 1. INTRODUCTION... 2 1.1. IMPORTANCE OF UNDERSTANDING STROKE... 2 2. TYPES OF STROKES AND THEIR CAUSES... 2 2.1. ISCHEMIC STROKE... 2 2.1.1. THROMBOTIC STROKE... 3 2.1.2. EMBOLIC STROKE... 3 2.2. HAEMORRHAGIC STROKE... 3 2.2.1. INTRACEREBRAL HAEMORRHAGE (ICH)... 3 2.2.2. SUBARACHNOID HAEMORRHAGE... 3 2.3. TRANSIENT ISCHEMIC ATTACK (TIA)... 3 3. SIGNS AND SYMPTOMS... 4 4. TREATMENT... 4 4.1. TREATING ISCHEMIC STROKE... 4 4.1.1. TISSUE PLASMINOGEN ACTIVATOR (tpa)... 4 4.1.2. ENDOVASCULAR PROCEDURES... 4 4.1.3. LONG TERM TREATMENT... 5 4.2. TREATING HAEMORRHAGIC STROKE... 5 4.2.1. MEDICAL TREATMENT... 5 4.2.2. ENDOVASCULAR PROCEDURES... 5 4.2.3. SURGICAL TREATMENT... 5 4.2.4. DECOMPRESSIVE CRANIOTOMY... 6 5. PREVENTION... 6 6. ONE INTERESTING THING ABOUT STROKE... 6 6.1. WHY WE FIND IT INTERESTING... 7 7. CONCLUSION... 7 8. REFERENCES... 8 1

1. INTRODUCTION Stroke, also known as Cerebral Vascular Accident (CVA), occurs when blood supply to a region of brain cells is interrupted. As a result, the brain cells die due to insufficient supply of oxygen and nutrients, often leading to long term disabilities, or even death. Stroke needs to be fully understood to minimise the risk of suffering from one, in both adults and young children. Stroke can be classified into ischemic stroke, haemorrhagic stroke and transient ischemic attack. 1.1. IMPORTANCE OF UNDERSTANDING STROKE Figure 1 - The leading causes of deaths around the world in 2012 (WHO, 2014) Stroke is one of the leading causes of death around the world across all age groups (Figure 1). Each year, approximately 15 million people suffer a stroke, in which six million die and another five million are left permanently disabled (World Heart Federation, 2016). Survivors have to cope with temporary or permanent physical disabilities, including paralysis and speech impairment. Stroke patients commonly face socio-economic challenges, such as mental trauma, depression and unemployment (Mapulanga, Nzala, & Mweemba, 2014). Coupled with the heavy medical fees for treating stroke, stroke patients and their families face immense financial stress. In addition, only 10% of stroke patients are able to fully recover after rehabilitation. As a severe medical condition that has widespread impacts on the lives of patients and their families, steps need to be taken to minimise the occurrence and fatalities of stroke. A better understanding of stroke allows us to take measures to prevent stroke and to treat stroke more effectively. 2. TYPES OF STROKES AND THEIR CAUSES 2.1. ISCHEMIC STROKE Ischemic stroke is the most common type of stroke and is responsible for about 87% of all stroke cases around the world. Ischemic stroke occurs when a clot blocks an artery in the brain. Clots are caused by atherosclerosis, which involves the build-up of fats and cholesterol and the formation of plaque in the arteries, narrowing the arteries and restricting blood flow (WebMD, 2016). 2

Drugs, trauma to blood vessels in the neck and blood clotting disorder are other possible causes for ischemic stroke (The Internet Stroke Center, 2016). Ischemic stroke can be further classified into thrombotic stroke and embolic stroke. 2.1.1. THROMBOTIC STROKE Thrombotic stroke results from formation of a blood clot, known as a thrombus, inside one of the brain's arteries. The thrombus that triggers the thrombotic stroke is usually a result of atherosclerosis, as fat deposits narrow the blood vessels. Thrombotic stroke can be triggered in both large and small blood vessels (Drugs.com, 2016). In some cases, migraines or headaches can also result from thrombotic stroke. In severe cases, a migraine headache can cause a brain artery to go into prolonged spasms, allowing a blood clot to form. 2.1.2. EMBOLIC STROKE The embolic stroke is triggered by an embolus. An embolus is a blood clot that is formed elsewhere in the body apart from the brain, usually from blood vessels in the heart, upper neck and chest. A blood clot breaks free from the initial blood vessel and travels along with the bloodstream to the brain. As it travels along, it enters a small blood vessel in which it is unable to pass through therefore preventing blood flow. An embolus can form from air bubbles in the bloodstream, fat globules or plaque from an artery. It can also result from irregular heartbeat, known as atrial fibrillation, in which the heart is unable to pump blood effectively, causing blood to pool and clot (Pietrangelo, 2014). 2.2. HAEMORRHAGIC STROKE A haemorrhagic stroke is often the result of either a burst in brain aneurysm or a leak in weakened blood vessels. The pressure and swelling, resulting from blood spilling into or around the brain, damages cells and tissues in the brain. It is less common than ischemic stroke but it has a high mortality rate. Only 15% of all strokes are haemorrhagic, yet they are responsible for 40% of death cases (National Stroke Association, 2016). Haemorrhagic stroke can be further classified into intracerebral haemorrhage and subarachnoid haemorrhage. 2.2.1. INTRACEREBRAL HAEMORRHAGE (ICH) ICH results from blood leaks inside the brain. The most common cause of ICH is hypertension. Chronic hypertension can result in pathophysiological alteration in the vessel wall which causes rupture of small penetrating arteries and arterioles (The Internet Stroke Center, 2016). In some cases, ICH can result from arteriovenous malformation (AVM) in brain or genetic conditions that cause abnormal connection between arteries. 2.2.2. SUBARACHNOID HAEMORRHAGE Subarachnoid haemorrhage results from bleeding in the space between the brain and the subarachnoid space. It can be caused by AVM, head injury and bleeding disorder. Studies also showed that anticoagulants such as warfarin have resulted in larger haemorrhages in patients (Edelson, 2016). 2.3. TRANSIENT ISCHEMIC ATTACK (TIA) Also known as a mini stroke, TIA occurs when there is a temporary obstruction of blood flow to the brain, depriving the brain of oxygen and nutrients. The patient suffers symptoms similar to that of ischemic stroke, but the symptoms last for a few minutes and usually disappear within a day, hence 3

creating no permanent damage to the brain (Stroke Foundation, 2016). However, TIA is often a warning that a stroke is likely to occur soon and studies have shown that 10-15% of TIA patients suffer a stroke within three months and 40% of them experience a stroke within the next day (Nordqvist, 2014). Thus, TIA patients require immediate medical attention in order to reduce the risk of experiencing stroke. 3. SIGNS AND SYMPTOMS Symptoms of stroke are not definite as they depend on the area of brain affected, as different areas of the brain have different functions. Symptoms are usually related to a decrease in cognitive functions and consciousness such as: headaches, difficulty moving and difficulty coordinating hands and legs. Clear warning signs include drooping of the face, arm weakness and speech difficulty (American Heart Association, 2016). Using ischemic stroke as an example, the severity depends on the artery that is clogged. A larger artery clogged results in more blockage of blood flow to greater portions of the brain, tending to cause the most severe disabilities and even paralysis. On the other hand, an ischemic stroke which occurs in a small artery tends to have minimal symptoms as blood flow is restricted to only a small part of the brain (Drugs.com, 2016). The onset duration of stroke also differs between different types of stroke experienced. Embolic stroke occurs suddenly, often without warning. While majority of patients with ICH reported a progressive onset over minutes to hours in contrast to a rapid onset in patients with ischemic stroke, clinical features of ICH depends on the location as well as severity of the bleed. 4. TREATMENT 4.1. TREATING ISCHEMIC STROKE 4.1.1. TISSUE PLASMINOGEN ACTIVATOR (tpa) tpa is the most effective treatment, and can be transfused directly into a vein in the patient s arm (Figure 2). tpa aids in dissolving the blood clot, thus restoring blood flow to the portions of the brain being deprived of blood flow. When administered within 3 to 4.5 hours, depending on the patient s health conditions, patients usually have higher chances of recovery from the stroke and suffer less long-term disabilities (American Heart Association, 2016). Figure 2 - Diagram depicting administration of tpa through an intravenous line (Drugs.com, 2016) 4.1.2. ENDOVASCULAR PROCEDURES Stent-retriever thrombectomy is conducted to remove the blood clot, where a stent retriever (Figure 3), is directed to the position of the blood clot in the brain. To extract the blood clot, doctors insert a stent retriever with the help of a microcatheter through an artery in the groin up to the blocked artery in the brain. The stent retriever attaches to the clot, hence doctors are able to remove the blood clot by 4

pulling out the stent retriever. As such, blood flow can be restored. Special suction tubes may also be used. This procedure must be conducted within six hours of acute stroke symptoms, and only after a patient receives tpa (American Heart Association, 2016). Figure 3 Diagram depicting stent retriever and blood clot (Hughes, 2015) 4.1.3. LONG TERM TREATMENT Depending on the nature of the stroke, long term treatment can differ. For a thrombotic stroke, an antiplatelet agent can be used to interfere with platelet activation process in primary haemostasis, decreasing platelet aggregation and hence inhibiting thrombus formation. Examples of antiplatelet are aspirin, clopidogrel (Plavix) and aspirin combined with dipyridamole (Aggrenox). For embolic strokes, oral anticoagulant drug is prescribed to prevent the coagulation of blood, hence preventing formation of blood clots (Drugs.com, 2016). 4.2. TREATING HAEMORRHAGIC STROKE 4.2.1. MEDICAL TREATMENT The initial care of a person with haemorrhagic stroke comprises of: determining the cause of the bleeding. controlling the body blood pressure. stopping any medication that could increase bleeding (e.g. warfarin, aspirin) measuring and controlling the pressure within the brain (Caplan, 2016). Further haemorrhagic stroke treatment to prevent recurrences depends on the cause of the stroke (e.g. high blood pressure, use of anticoagulant medications, head trauma, blood vessel malformation). 4.2.2. ENDOVASCULAR PROCEDURES These procedures are similar to that mentioned in section 4.1.2, and are not as invasive as surgical treatments. A catheter is inserted via a major artery in the leg or arm, then guided to the site of excessive localized swelling of the wall of the artery. Then, the catheter deposits a mechanical agent, such as a coil, so that the artery does not burst (American Heart Association, 2016). 4.2.3. SURGICAL TREATMENT Surgical treatment can be carried out to cease the bleeding caused by haemorrhagic stroke. When a ruptured aneurysm (swelling of the vessel that breaks) causes a stroke, a metal clamp can be placed at the base of the aneurysm via surgical means to secure it (American Heart Association, 2016). The location of the aneurysm must be known and a piece of the skull must be removed to access the aneurysm. The piece of the skull will be replaced. This can be done to prevent and treat a stroke to prevent further bleeding. Coil embolization is an interventional procedure that is less invasive than clipping and similar to stent-retriever thrombectomy. A catheter is guided along blood vessels in the body from the groin to 5

location of the aneurysm in the brain, and the area at the aneurysm is filled with the tiny coil. A blood clot forms within the coil, blocking blood flow into the aneurysm and preventing it from rupturing again. Other materials may also be injected to obliterate an aneurysm or AVM (Caplan, 2016). 4.2.4. DECOMPRESSIVE CRANIOTOMY In a life-threatening situation, this procedure can be done to open the skull and/or remove the blood. Factors that determine if decompressive craniotomy should be carried out are: the location and size of haemorrhage, the patient s age and medical condition, and the prospects of the patient recovering from the stroke. 5. PREVENTION Each year, high blood pressure contributes to more than 12.7 million stroke cases worldwide, which is about 84% of all stroke cases around the world (WHO, 2002). Some risk factors of high blood pressure include old age, inheritance, kidney disease and other disorders, but diet and lifestyle changes can reduce the risk of having high blood pressure and suffering a stroke (WebMD, 2016). Promoting a healthier lifestyle in people will be able to save lives. Healthy Diet A healthy diet consisting of less red meat, less salt and more vegetables lower cholesterol levels, which reduces the build-up of plaque in blood vessels and decreases the risk of getting hypertension and stroke. Exercise Consistent exercise and maintaining a healthy body weight lowers blood pressure and blood cholesterol levels as well (Havard University, 2015). No Smoking Smoking increases risk of suffering by two to four times as compared with lifelong non-smokers or those who have quit smoking for at least ten years. Toxins present in cigarette smoke thicken blood, leading to hypertension and increases plaque deposition in blood vessels (Shah & Cole, 2010). 6. ONE INTERESTING THING ABOUT STROKE Figure 4 - Statistics on the 10 Leading Causes of Death in United States in 2014, highlighting the ranking of stroke in each age group (Centers for Disease Control and Prevention, 2016) 6

While adult stroke is common and widely known, it is interesting to note that stroke is prevalent among children as well. In fact, stroke is one of the top ten causes of death among young children (Figure 4), occurring in about 1 in 4000 live births (National Stroke Association, 2016). Paediatric stroke most likely occurs in infants during childbirth and in infants below 1 year of age. However, causes that are common in adults, such as hypertension, are rare in children. Instead, risk factors are related to hereditary disorders such as congenital heart defects and sickle-cell disease, or complications that occurred during pregnancy and childbirth (National Stroke Association, 2016). Paediatric stroke has high morbidity and mortality rate. Approximately 10-25% of will die, about 25% of children will experience a recurrence and 66% of children will have long term neurological impairments or develop disorders such as seizures and learning or developmental problems. As the effects of one stroke attack during childhood can be long-lasting and severe, there are profound effects on the quality of life of the child and family and magnifies the economic and emotional burden carried by the family and society (Tsze & Valente, 2011). However, early detection of paediatric stroke can allow for more effective treatments and improved outcomes. Since it is widely known that the occurrence of stroke in children is rare, paediatric stroke is commonly undiagnosed or misdiagnosed. Doctors often do not suspect stroke in children who also present symptoms similar to that of other diseases. Hence, diagnosis and treatment for paediatric stroke patients are often delayed, thus the damage for many children is often severe. In one report, 19 out of 45 children with a stroke did not receive a correct diagnosis until 15 hours to 3 months after the first occurrence of the stroke (Braun, Kappelle, Kirkham, & Deveber, 2006). There are encouraging statistics that show that diagnosis of paediatric stroke has doubled from that of a decade ago, as there are more children who are able to survive with risk factors for stroke such as congenital heart disease and sickle cell disease. In addition, there is increased awareness for paediatric stroke and more doctors will be able to provide children with immediate treatment if a stroke ever occurs (Roach, deveber, Riela, & Wiznitzer, 2011). With the rise of new technology such as genetic screening, prospective parents can be informed about the stroke risk of their child and be ready to provide necessary treatment if a stroke ever occurs. 6.1. WHY WE FIND IT INTERESTING Unbeknownst to many, stroke is actually a common cause of death in children and has severe and long-lasting effects on children. Paediatric stroke is often unknown to the layman, and sometimes overlooked by the medical world, resulting in delayed treatment for the affected children. Since immediate diagnosis and treatment can improve the circumstances of the child and reduce the effects of the stroke, more research needs to be conducted to help these children. 7. CONCLUSION Stroke is a medical emergency, where blood supply to regions of the brain is interrupted leading to brain damage. Hence, immediate treatment is required or the effects can be potentially fatal. Given that there is a low chance that one can fully recover from a stroke, a healthy diet and lifestyle are key to reducing the chances of suffering a stroke. Stroke is most commonly found in the elderly population, but stroke occurs in young children as well. Paediatric stroke needs more public awareness such that young children can receive the necessary and immediate treatment required to minimise the effects of the stroke. 7

8. REFERENCES American Heart Association. (2016). Stroke Treatments. Retrieved from American Heart Association: http://www.strokeassociation.org/strokeorg/aboutstroke/treatment/stroke- Treatments_UCM_310892_Article.jsp#.VxTw8zB97IU American Heart Association. (2016). Stroke Warning Signs and Symptoms. Retrieved from American Heart Association: http://www.strokeassociation.org/strokeorg/warningsigns/stroke- Warning-Signs-and-Symptoms_UCM_308528_SubHomePage.jsp Braun, Kappelle, Kirkham, & Deveber. (2006). Diagnostic pitfalls in paediatric ischaemic stroke. Developmental medicine and child neurology. Caplan, L. R. (2016). Patient information: Hemorrhagic stroke treatment (Beyond the Basics). Retrieved from UpToDate: http://www.uptodate.com/contents/hemorrhagic-stroke-treatmentbeyond-the-basics Centers for Disease Control and Prevention. (25 February, 2016). Ten Leading Causes of Death and Injury - Images. Retrieved from Centers for Disease Control and Prevention: http://www.cdc.gov/injury/wisqars/leadingcauses_images.html Drugs.com. (2016). Thrombotic Stroke. Retrieved from Drugs.com: http://www.drugs.com/healthguide/thrombotic-stroke.html Edelson, E. (30 September, 2016). Blood Thinner Linked to Increased Brain Bleeding. Retrieved from abc NEWS: http://abcnews.go.com/health/healthday/story?id=5915653&page=1 Havard University. (9 October, 2015). 7 things you can do to prevent a stroke. Retrieved from Harvard Health Publications: http://www.health.harvard.edu/womens-health/8-things-youcan-do-to-prevent-a-stroke Hughes, S. (11 February, 2015). SWIFT PRIME: 'Dramatic' Benefit of Stent Retriever in Stroke. Retrieved from Medscape: http://www.medscape.com/viewarticle/839623 Mapulanga, M., Nzala, S., & Mweemba, C. (2014). The Socio-economic Impact of Stroke on Households in Livingstone District, Zambia: A Cross-sectional Study. Annals of Medical and Health Sciences Research, 104-111. Retrieved from http://www.ncbi.nlm.nih.gov/pmc/articles/pmc4145508/ National Stroke Association. (2016). Hemorrhagic stroke. Retrieved from National Stroke Association: http://www.stroke.org/understand-stroke/what-stroke/hemorrhagic-stroke National Stroke Association. (2016). Pediatric Stroke. Retrieved from National Stroke Association: http://www.stroke.org/understand-stroke/impact-stroke/pediatric-stroke Nordqvist, C. (8 September, 2014). What is a mini-stroke? What is a transient ischemic attack (TIA)? Retrieved from Medical News Today: http://www.medicalnewstoday.com/articles/164038.php Pietrangelo, A. (10 February, 2014). Embolic Stroke: Symptoms, Treatments, and Long-Term Outlook. Retrieved from Healthline: http://www.healthline.com/health-slideshow/embolicstroke-symptoms Roach, E. S., deveber, G., Riela, A., & Wiznitzer, M. (17 May, 2011). Recognition and Treatment of Stroke in Children. Retrieved from National Institute of Neurological Disorders and Stroke: http://www.ninds.nih.gov/news_and_events/proceedings/stroke_proceedings/childneurology. htm Shah, R. S., & Cole, J. W. (2010). Smoking and stroke: the more you smoke the more you stroke. Expert Review of Cardiovascular Therapy. Stroke Foundation. (2016). Transient Ischaemic Attack TIA. Retrieved from Stroke Foundation: https://strokefoundation.com.au/about-stroke/types-of-stroke/transient-ischaemic-attack-tia The Internet Stroke Center. (2016). Intracerebral Hemorrhage. Retrieved from The Internet Stroke Center: http://www.strokecenter.org/patients/about-stroke/intracerebral-hemorrhage/ 8

The Internet Stroke Center. (2016). Ischemic Stroke. Retrieved from The Internet Stroke Center: http://www.strokecenter.org/patients/about-stroke/ischemic-stroke/ Tsze, D. S., & Valente, J. H. (2011). Pediatric Stroke: A Review. Emergency Medicine International. WebMD. (2016). Causes of High Blood Pressure. Retrieved from WebMD: http://www.webmd.com/hypertension-high-blood-pressure/guide/blood-pressure-causes WebMD. (2016). How Atherosclerosis Causes Half of All Strokes. Retrieved from WebMD: http://www.webmd.com/stroke/how-artherosclerosis-causes-50-percent-of-strokes WHO. (2002). The World Health Report 2002. Retrieved from World Health Organisation: http://www.who.int/whr/2002/en/whr02_en.pdf WHO. (May, 2014). The top 10 causes of death. Retrieved from World Health Organization: http://www.who.int/mediacentre/factsheets/fs310/en/ World Heart Federation. (2016). Stroke. Retrieved from World Heart Federation: http://www.worldheart-federation.org/cardiovascular-health/stroke/ 9