Understanding stroke, the silent killer

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1999 --- Listening to Patient's Heartbeat with Stethoscope --- Image by © Michael Keller/CORBIS
1999 — Listening to Patient’s Heartbeat with Stethoscope — Image by © Michael Keller/CORBIS

A stroke is a condition in which the brain cells suddenly die because of a lack of oxygen. A stroke can be caused by an obstruction in the blood flow, or the rupture of an artery that feeds the brain. The patient may suddenly lose the ability to speak, there may be memory problems, or one side of the body can become paralyzed.1

This Medical News Today information article provides details on the two types of stroke, who are at risk, what its causes are, its symptoms, how a stroke is treated, and how strokes can beprevented.

The two main types of stroke

The two main types of stroke include ischemic stroke and hemorrhagic stroke.2

Ischemic stroke

Ischemic stroke accounts for about 87 percent of all strokes and occurs when a blood clot, or thrombus, forms that blocks blood flow to part of the brain.3

If a blood clot forms somewhere in the body and breaks off to become free-floating, it is called an embolus. This wandering clot may be carried through the bloodstream to the brain where it can cause ischemic stroke.

Hemorrhagic stroke

A hemorrhagic stroke occurs when a blood vessel on the brain’s surface ruptures and fills the space between the brain and skull with blood (subarachnoid hemorrhage) or when a defective artery in the brain bursts and fills the surrounding tissue with blood (cerebral hemorrhage).4

Both types of stroke result in a lack of blood flow to the brain and a buildup of blood that puts too much pressure on the brain.

The outcome after a stroke depends on where the stroke occurs and how much of the brain is affected. Smaller strokes may result in minor problems, such as weakness in an arm or leg. Major strokes may lead to paralysis or death. Many stroke patients are left with weakness on one side of the body, difficulty speaking,incontinence, and bladder problems.

Who gets stroke?

Anyone can suffer from stroke. Although many risk factors are out of our control, several can be kept in line through proper nutrition and medical care.

Risk factors for stroke include the following:

Heavy use of alcohol

Researchers from the University of Lille Nord de France, Lille, France, reported in the journal Neurology that heavy regular drinkers have a considerably higher risk of stroke early in life compared to others.7

Depression

Middle-aged women with clinical depression have a higher risk of stroke, researchers from the University of Queensland, Australia, reported in the journal Stroke.8

 

The authors gathered data on 10,547 Australian females aged from 47 to 52 years. They found that women with depression are more likely to have a stroke by a factor of 2.4, compared to women without depression.

Even after taking into account known stroke risk factors, depressed middle-aged women were still 1.9 times more likely to have a stroke.

Caroline Jackson, Ph.D., said “When treating women, doctors need to recognize the serious nature of poormental health and what effects it can have in the long term. Current guidelines for stroke prevention tend to overlook the potential role of depression.”

The researchers emphasized that although the risk was higher for women with depression, their total risk of stroke was still low.

What causes stroke?

Ischemic strokes are ultimately caused by a thrombus or embolus that blocks blood flow to the brain. Blood clots (thrombus clots) usually occur in areas of the arteries that have been damaged by atherosclerosis from a buildup of plaques.9

Embolus type blood clots are often caused by atrial fibrillation – an irregular pattern of heart beat that leads to blood clot formation and poor blood flow.

Hemorrhagic strokes can be caused by uncontrolled high blood pressure, a head injury, or aneurysms. High blood pressure is the most common cause of cerebral hemorrhage, as it causes small arteries inside the brain to burst.10 This deprives brain cells of blood and dangerously increases pressure on the brain.

Aneurysms – abnormal blood-filled pouches that balloon out from weak spots in the wall of an artery – are the most common cause of subarachnoid hemorrhage. If an aneurysm ruptures, blood spills into the space between the surfaces of the brain and skull, and blood vessels in the brain may spasm. Aneurysms are often caused or made worse by high blood pressure.

A study published in the American Journal of Human Genetics found a single gene defect can lead to stroke and deadly diseases of the aorta and coronary arteries.11

A less common form of hemorrhage stroke is when an arteriovenous malformation (AVM) ruptures. AVM is an abnormal tangle of thin-walled blood vessels that is present at birth.

An article published in the BMJ Online reported that migraines increase stroke risk during pregnancy.12

What are the symptoms of stroke?

Within a few minutes of having a stroke brain cells begin to die and symptoms emerge. It is important to recognize the symptoms, as prompt treatment is crucial to recovery.

Common symptoms include:

  • Trouble walking, loss of balance and coordination.13
  • Speech problems.13
  • Dizziness.13
  • Numbness, weakness, or paralysis.13
  • Blurred, blackened, or double vision.13
  • Sudden severe headache.13
  • Confusion.13

Smaller strokes (or silent strokes), however, may not cause any symptoms, but can still damage brain tissue.14

A transient ischemic attack (TIA) may be a sign of an impending stroke – TIA is a temporary interruption in blood flow to part of the brain. Symptoms of TIA are similar to stroke but last for a shorter period and do not leave noticeable permanent damage.15

How is stroke diagnosed?

Doctor assesses an MRI brain scan
Doctor assessing an MRI brain scan.

A stroke is a medical emergency, and anyone suspected of having one should be taken to hospital immediately so that tests can be run and the correct treatment can be provided as quickly as possible.

Physicians have several tools available to screen for stroke risk and diagnose an active stroke. These include:

  • Physical assessment – blood pressure tests and blood tests to see cholesterol levels, blood sugar levels, and amino acid levels.16
  • Ultrasound – a wand waved over the carotid arteries in the neck can provide a picture that shows whether there is any narrowing or clotting.17
  • Arteriography – a catheter is inserted into the arteries to inject a dye that can be picked up by X-rays.18
  • Computerized tomography (CT) scan – a scanning device that creates a 3-D image that can show aneurysms, bleeding, or abnormal vessels within the brain.19
  • Magnetic resonance imaging (MRI) – a magnetic field generates a 3-D view of the brain to look at tissue damaged by stroke.20
  • CT and MRI with angiography – scans that are aided by a dye that is injected into the blood vessels in order to provide clearer and more detailed images.21
  • Echocardiography – an ultrasound that makes images of the heart to check for embolus.22
  • Eye-movement analyzer may diagnose stroke – researchers from Johns Hopkins University School of Medicine in Baltimore created a device that can help diagnose stroke by expertly analyzing eye movements. They reported their findings in the journal Stroke. The electronic device is a small, portable, video-oculography machine. It detects eye movements that most doctors find hard to notice.23

How is stroke treated?

The primary goal in treating ischemic stroke is to restore blood flow to the brain. This will be attempted using a blood clot-busting drug called tissue plasminogen activator (tPA). A doctor will inject tPA into the patient’s arm. If for some reason the patient can’t receive the tPA then an anti-platelet medicine will be used instead.24

In addition, surgical procedures may be performed that can open up or widen arteries. These include carotid endarterectomy (removal of plaque and widening of the carotid artery) and angioplasty (a balloon that widens the carotid artery and is held open with a metallic mesh tube called a stent).24

Hemorrhagic stroke is treated differently than ischmic stroke. Surgical methods used to treat this stroke variant include aneurysm clipping, aneurysm embolisation, and arteriovenous malformation (AVM) removal.24

Aneurysm clipping consists of a small clamp placed at the base of the aneurysm that isolates it from the circulation of it’s attached artery and keeps the aneurysm from bursting or re-bleeding.24

Aneurysm embolisation (coiling) uses a catheter inserted into the aneurysm to deposit a tiny coil that fills the aneurysm, causing clotting and sealing off the aneurysm off from arteries. AVM removal is a surgical procedure to remove usually smaller AVMs or AMVs that are in more accessible portions of the brain in order to eliminate the risk of rupture.24

Most stroke victims will require rehabilitation after the event. A person’s condition is generally dependent on the area of the brain and the amount of tissue that was damaged. It is common for the rehabilitation process to include speech therapy, occupational therapy, physical therapy, and family education.

Investigators at Massachusetts General Hospital found that patients who had experienced strokes as long as six months earlier were able to regain brain function through the help of a novel robotic device that they squeezed with their hand.25

Recent developments on stroke treatment from MNT news

University of Oxford researchers discovered how the brain protects itself from damage caused by stroke. If researchers can identify the inbuilt biological mechanism that protects the brain researchers will be a step closer to developing effective treatments for stroke.26

Stem cell discovery: Astrocytes could repair stroke brain damage. A collaborative study published inNature Communications revealed that astrocytes may prove useful against stroke and other brain disorders.27

Most stroke patients have undiagnosed “attention” disorders

A study carried out by a team at Imperial College London found that many stroke patients have undiagnosed attention problems. Examples include difficulties filtering out distraction, reduction in alertness, and problems following instructions.28

The researchers tested 100 stroke patients and 62 controls (people who had not had a stroke). Five of the stroke patients had already been diagnosed with neglect – poor awareness and attention in one side of the body.

All the 162 participants were given an ANT (attention network test), a computer-based test which measures alertness, executive control and orientation. They also underwent an MRI brain scan.

The team found that more than half of the stroke patients had undiagnosed attention disorders.

Head investigator, Dr. Paul Bentley, said “We found that more than half of stroke patients have some form of attention problem, and these may be missed by routine bedside examinations.”

Dr. Bentley explained that MRI brain scans can help predict what type of attention problems stroke patients might have. Those with the front of the brain affected tended to have problems filtering out distraction, if the center of the brain was affected the patients were more likely to have poorer alertness, while lesions in the back of the brain were linked to difficulties following instructions.

How can stroke be prevented?

One way to prevent a stroke is to be aware of a transient ischemic attack (TIA) – or mini stroke – if one occurs, the symptoms are similar to stroke. Knowing the symptoms of stroke can lead to earlier treatment and better recovery.

Much of stroke prevention is based on living a healthy lifestyle, which include:

  • Identifying and controlling blood pressure.29
  • Not smoking. 29
  • Lowering cholesterol, sodium, and fat intake.29
  • Drinking alcohol only in moderation.29
  • Treating diabetes properly.29
  • Managing stress.29
  • Being physically active.29

Follow a healthy diet

If you eat plenty of tomatoes, your risk of developing stroke could be reduced significantly. Tomatoes are rich in lycopene, a powerful antioxidant. In a study published in Neurology, October 2012, researchers found that people with high blood concentrations of lycopene had a 59% lower risk of stroke compared to those with the lowest concentrations.30

Mediterranean diet helps prevent a genetic risk of stroke – a mutation in the Transcription Factor 7-like 2 (TCF7L2) gene, which is linked to the development of type 2 diabetes, is also associated with stroke risk, especially if the person is a homozygous carrier (carries two copies of the gene variant).31

Scientists from the CIBER Fisiopatología de la Obesidad y Nutriciόn, Spain, and Tufts University, USA, found that the Mediterranean diet may protect homozygous carriers of the gene variant.

The investigators explained in the journal Diabetes Care “Being on the Mediterranean diet reduced the number of strokes in people with two copies of the variant. The food they ate appeared to eliminate any increased stroke susceptibility, putting them on an even playing field with people with one or no copies of the variant.”

References

  1. “What Is Stroke?” National Stroke Association. Accessed 11 December 2013.
  2. “Types of Stroke” The American Heart Association. Accessed 11 December 2013.
  3. “Ischemic Strokes (Clots)” The American Heart Association. Accessed 11 December 2013.
  4. “Hemorrhagic Strokes (Bleeds)” The American Heart Association. Accessed 11 December 2013.
  5. “Stroke risk factors” National Stroke Foundation – Australia. Accessed 11 December 2013.
  6. “Gender differences in the association between parental divorce during childhood and stroke in adulthood: findings from a population-based survey” Esme Fuller-Thomson, Angela D. Dalton. International Journal of Stroke. DOI: 10.1111/j.1747-4949.2012.00935.x. 11 DEC 2012. Accessed 11 December 2013. Abstract. Accessed 11 December 2013.
  7. “Heavy alcohol intake and intracerebral hemorrhage – Characteristics and effect on outcome” Charlotte Cordonnier, MD, PhD, et al. Neurology. September 11, 2012 vol. 79 no. 11 1109-1115. doi: 10.1212/WNL.0b013e3182698d00.Abstract. Accessed 11 December 2013.
  8. “Depression and Risk of Stroke in Midaged Women” Caroline A. Jackson and Gita D. Mishra. Stroke. May 16, 2013. doi: 10.1161/​STROKEAHA.113.001147. Abstract. Accessed 11 December 2013.
  9. “Ischemic Stroke” The Internet Stroke Center. Accessed 11 December 2013.
  10. “Let’s Talk About Hemorrhagic Stroke” American Heart Association. Accessed 11 December 2013.
  11. “Mutations in smooth muscle alpha-actin (ACTA2) cause coronary artery disease, stroke, and Moyamoya disease, along with thoracic aortic disease.” Guo DC, Papke CL, Tran-Fadulu V, Regalado ES, Avidan N, Johnson RJ, Kim DH, Pannu H, Willing MC, Sparks E, Pyeritz RE, Singh MN, Dalman RL, Grotta JC, Marian AJ, Boerwinkle EA, Frazier LQ, LeMaire SA, Coselli JS, Estrera AL, Safi HJ, Veeraraghavan S, Muzny DM, Wheeler DA, Willerson JT, Yu RK, Shete SS, Scherer SE, Raman CS, Buja LM, Milewicz DM. Am J Hum Genet. 2009 May;84(5):617-27. doi: 10.1016/j.ajhg.2009.04.007. Abstract.Accessed 11 December 2013.
  12. “Migraines during pregnancy linked to stroke and vascular diseases: US population based case-control study” Cheryl D Bushnell, Margaret Jamison, Andra H James. BMJ published 10 March 2009. doi: http://dx.doi.org/10.1136/bmj.b664.Abstract. Accessed 11 December 2013.
  13. “Stroke” Better Health Channel, State Government of Victoria. Accessed 11 December 2013.
  14. “Silent Strokes”Cynthia K. Buccini. Bostonia, Boston University. Fall 2008. Accessed 11 December 2013.
  15. “TIA (Transient Ischemic Attack)” The American Heart Association. Accessed 11 December 2013.
  16. “Physical examination” Heart and Stroke Foundation. Accessed 11 December 2013.
  17. “Ultrasound” The Internet Stroke Center. Accessed 11 December 2013.
  18. “Cerebral or carotid angiography or arteriography” Heart and Stroke Foundation. Accessed 11 December 2013.
  19. “CT or CAT scan” Heart and Stroke Foundation. Accessed 11 December 2013.
  20. “MRI” The Internet Stroke Center. Accessed 11 December 2013.
  21. “CT/CT angiography and MRI findings predict recurrent stroke after transient ischemic attack and minor stroke: results of the prospective CATCH study.” Coutts SB, Modi J, Patel SK, Demchuk AM, Goyal M, Hill MD. Stroke. 2012 Apr;43(4):1013-7. doi: 10.1161/STROKEAHA.111.637421. Abstract. Accessed 11 December 2013.
  22. “Echocardiography” The Internet Stroke Center. Accessed 11 December 2013.
  23. “Quantitative Video-Oculography to Help Diagnose Stroke in Acute Vertigo and Dizziness: Toward an ECG for the Eyes”. David E. Newman-Toker, Ali S. Saber Tehrani, Georgios Mantokoudis, John H. Pula, Cynthia I. Guede, Kevin A. Kerber, Ari Blitz, Sarah H. Ying, Yu-Hsiang Hsieh, Richard E. Rothman, Daniel F. Hanley, David S. Zee, and Jorge C. Kattah. Stroke.published online before print 5 March 2013; DOI:10.1161/STROKEAHA.111.000033. Abstract. Accessed 11 December 2013.
  24. “How Is a Stroke Treated?” National Institutes of Health, Department of Health and Human Services. Accessed 11 December 2013.
  25. “Functional MRI of Rehabilitation in Chronic Stroke Using a Novel MR-Compatible, Hand-induced, Robotic Device.” A Aria Tzika, Dionyssios Mintzopoulos, Azadeh Khanicheh, Bruce Rosen, Loukas Astrakas, and Michael Moskowitz. Scientific paper SSQ15-07, presented at 94th scientific meeting of the Radiological Society of North America (RSNA) in Chicago, 4 December 2008. Abstract. Accessed 12 December 2013.
  26. ”TSC1 (hamartin) confers neuroprotection against ischemia by inducing autophagy” Michalis Papadakis et al. Nature Medicine (Feb 2013) doi:10.1038/nm.3097. Abstract. Accessed 12 December 2013.
  27. “hESC-derived Olig2+ progenitors generate a subtype of astroglia with protective effects against ischaemic brain injury” Peng Jiang, Chen Chen, Ruimin Wang, Olga V. Chechneva, Seung-Hyuk Chung, Mahendra S. Rao, David E. Pleasure, Ying Liu, Quanguang Zhang, and Wenbin Deng. Nature Communications. doi:10.1038/ncomms3196. Published 23 July 2013. Accessed 12 December 2013.
  28. “Triple dissociation of attention networks in stroke according to lesion location” Paul Rinne, Mursyida Hassan, Despina Goniotakis. Neurology. August 27, 2013, vol. 81 no. 9, pages 812-820. Abstract. Accessed 12 December 2013.
  29. “Lifestyle Changes To Prevent Stroke” American Heart Association. Accessed 12 December 2013.
  30. “Serum lycopene decreases the risk of stroke in men – A population-based follow-up study” Jouni Karppi, PhD et al.Neurology. October 9, 2012, vol. 79 no. 15 1540-1547. doi: 10.1212/WNL.0b013e31826e26a6. Abstract. Accessed 12 December 2013.
  31. “Mediterranean Diet Reduces the Adverse Effect of the TCF7L2-rs7903146 Polymorphism on Cardiovascular Risk Factors and Stroke Incidence”. Dolores Corella, DPHARM, PHD et al. Diabetes Care. doi: 10.2337/dc13-0955. August 13, 2013. Abstract.
  32. “Episodic migraine and obesity and the influence of age, race, and sex” B. Lee Peterlin, DO, Andrea L. Rosso, PhD, Michelle A. Williams, ScD, Jason R. Rosenberg, MD, Jennifer A. Haythornthwaite, PhD, Kathleen R. Merikangas, PhD, Rebecca F. Gottesman, MD, PhD, Dale S. Bond, PhD, Jian-Ping He, MD and Alan B. Zonderman, PhD. Neurology. doi: 10.1212/WNL.0b013e3182a824f7. August 27, 2013. Abstract. Accessed 12 December 2013.
  33. “Physical Activity and Risk of Cerebrovascular Disease in the European Prospective Investigation Into Cancer and Nutrition-Spain Study” José María Huerta, PhD; María-Dolores Chirlaque, MD; María-José Tormo, PhD; Diana Gavrila, MD; Larraitz Arriola, MSc; Conchi Moreno-Iribas, MD; Pilar Amiano, PhD; Eva Ardanaz, PhD; Aurelio Barricarte, PhD; Miren Dorronsoro, PhD; Nerea Egüés, MD; Nerea Larrañaga, MSc; Esther Molina-Montes, PhD; José Ramón Quirós, PhD; María-José Sánchez, PhD; Carlos A. González, PhD; Carmen Navarro, PhD. Stroke. doi: 10.1161/​STROKEAHA.112.670612. December 6, 2012. Abstract. Accessed 12 December 2013.
  34. “Statin therapy after first stroke reduces 10-year stroke recurrence and improves survival.” Milionis HJ, Giannopoulos S, Kosmidou M, Panoulas V, Manios E, Kyritsis AP, Elisaf MS, Vemmos K. Neurology. doi: 10.1212/WNL.0b013e3181a711cb. 2009 May 26. Abstract. Accessed 12 December 2013.

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Culled from: http://www.medicalnewstoday.com/articles/7624.php

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