Acute stroke

Introduction
Stroke occurs when blood flow to an area of brain is cut off. This lead to brain cells are deprived of oxygen and begin to die. When brain cells die during a stroke, abilities controlled by that area of the brain such as memory and muscle control are lost.

When blood flow to part of the brain stops for a short period of time, also called transient ischemic attack (TIA), it can mimic stroke-like symptoms. These symptoms appear and last less than 24 hours before disappearing. While TIAs generally do not cause permanent brain damage, they are a serious warning sign that a stroke may happen in the future and should not be ignored.

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. There are two types of hemorrhagic stroke called intracerebal and subarachnoid.

·         Intracerebral hemorrhage. In an intracerebral hemorrhage, a blood vessel in the brain bursts and spills into the surrounding brain tissue, damaging brain cells. Brain cells beyond the leak are deprived of blood and also damaged. High blood pressure, trauma, vascular malformations, use of blood-thinning medications and other conditions may cause an intracerebral hemorrhage.

·         Subarachnoid hemorrhage. In a subarachnoid hemorrhage, an artery on or near the surface of brain bursts and spills into the space between the surface of the brain and skull. This bleeding is often signaled by a sudden, severe headache.

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, disability or death. Ischemic strokes account for about 87% of all strokes. 

The most common ischemic strokes include:

·         Thrombotic stroke. A thrombotic stroke occurs when a blood clot (thrombus) forms in one of the arteries that supply blood to your brain. A clot may be caused by fatty deposits (plaque) that build up in arteries and cause reduced blood flow (atherosclerosis) or other artery conditions.

·         Embolic stroke. An embolic stroke occurs when a blood clot or other debris forms away from the brain, commonly in heart and is swept through the bloodstream to lodge in narrower brain arteries. This type of blood clot is called an embolus.

A stroke is a medical emergency. Prompt treatment is crucial. Early action can minimize brain damage and potential complications.Recognizing symptoms and getting medical attention quickly can save a life and minimize disability. (Strokeorg, 2014)

Presentation
Symptoms and signs of stroke

• Anterior circulation strokes
• Unilateral weakness
• Unilateral sensory loss or inattention
• Isolated dysarthria
• Dysphasia
• Vision:
• Homonymous hemianopia
• Monocular blindness
• Visual inattention
• Posterior circulation strokes
• Isolated homonymous hemianopia
• Diplopia and disconjugate movement of eyes
• Nausea and vomiting
• Incoordination and unsteadiness
• Unilateral or bilateral weakness and/or sensory loss
• Nonspecific signs
• Dysphagia
• Incontinence
• Loss of consciousness (Mayoclinicorg, 2015)

Risk factors

•Male
•Over age 55
•African American
•Diabetes
•Hypertension
•Hyperlipidemia (presence of excess lipids in the blood)
•Smoking
•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

Investigations   

·         Blood tests

·         Computerized tomography (CT) scan

·         Magnetic resonance imaging (MRI)

·         Carotid ultrasound

·         Cerebral angiogram

·         Echocardiogram

Management 

Treatments

·         Aspirin. Reduce the chances of  having another stroke. Aspirin prevents blood clots from forming.

·         Intravenous injection of tissue plasminogen activator (TPA). Also, called alteplase. An injection of TPA is usually given through a vein in the arm. This potent clot-busting drug needs to be given within 4.5 hours after stroke symptoms begin if it's given in the vein.

Emergency procedures

·         Medications delivered directly to the brain. Using a long, thin tube (catheter) through an artery in groin and thread it to the brain to deliver TPA directly into the area where the stroke is occurring. The time window for this treatment is somewhat longer than for intravenous TPA but is still limited.

·         Mechanical clot removal

·         .  Other procedures

·         Carotid endarterectomy. In a carotid endarterectomy, a surgeon removes plaques from arteries that run along each side of your neck to your brain (carotid arteries

·         Angioplasty and stents

       Surgical blood vessel repair. 

·         Surgical clipping. 

·         Coiling (endovascular embolization).

·         Surgical AVM removal. 

·         Intracranial bypass. 

·         Stereotactic radiosurgery. 

References 

Strokeorg. 2014. Strokeorg. [Online]. [17 April 2015]. Available from: http://www.stroke.org/understand-stroke/what-stroke

Nihgov. 2015. Acute stroke. no-date. PubMed Central (PMC). [Online]. [17 April 2015]. Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1071073/

Mayoclinicorg. 2015. Mayoclinicorg. [Online]. [15 April 2015]. Available from: http://www.mayoclinic.org/diseases-conditions/stroke/symptoms-causes/dxc-20117265