What is stroke: Background & Definitions

 Only have a few seconds?.. Check take home points at the end of the article

We all can think of a loved one who suffered one or multiple strokes during their life time. It effects everyone  financially, physically, emotionally and mentally challenging. Understanding how and why it happens, will help you preventing stroke. 

Stoke is medically known as Cerebral Vascular Disease (CVA) occurs when an area of the brain is transiently or permanently affected by ischemia or bleeding. Stroke causes a sudden and convulsive onset of a focal neurologic deficit. Even though the signs and symptoms vary depending upon area of damage, stroke can cause changes in level of consciousness, motor control, sensory perception, and visual and speech function.

American Heart Association acronym is pretty easy to remember to get someone or yourself medical help as soon as possible. 

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Stroke is the 3rd leading cause of death in US (following cancer & heart disease), and sooner you get medical help, more likely that you will survive with least amount of deficits. There are about 1.5 million stroke survivors in the US today and 50% of survivors have residual neurological deficits. Incidence of mortality and morbidity from stroke has been on decline over last 20 years due to improved treatment of hypertension. However, yearly financial cost is still expensive-7 billion dollars. Today, mean survival time exceeds 7 years.  Greatest risk are those over 65 years old, but a considerable proportion of strokes occur in active young adults under the age of 45. It is not very likely but possible. 

mini-stroke-pictureOur body tries to warn us by giving us small or bigger clues. Transient Ischemic Attack(TIA) is considered a warning that a stroke might occur in the future. TIA lasts less than 24 hours and the neurological symptoms resolve fully.

If neurologic signs and symptoms that last longer than 24 hours but resolve within 3 weeks, that means you may have suffered a Reversible Ischemic Neurologic Deficit. That is another warning that you need to take very seriously.

Classification of Cerebrovascular Disease

Ischemic strokes are  more common than Hemorrhagic strokes. Ischemic Stroke is caused by lack of blood flow to the brain which immediately deprives brain tissue of necessary oxygen & nutrients. Hemorrhagic Stroke is a release of blood into the extravascular space of the brain causing localized or generalized pressure injuries to the brain tissue. Ischemia stroke is like a suffocation of the brain whereas hemorrhagic stroke is bleeding of the brain. In both cases, inability to deliver adequate oxygen & nutrients to the brain can result in damage in brain tissue, neurological dysfunction and disability.

Lets talk a little more in depth regarding these two types of stokes:

Ischemic strokes:

Ischemic strokes can be embolic or thrombotic vascular occlusion. While the impairments can be predicted from anatomic distribution of affected area, severe reduction or interruption of blood supply to the brain can cause generalized hypo-fusion, resulting in instant neurological signs. Damage maybe be reversible if ischemia lasts less than 1-3 hours. Hippocampus (responsible for memory and regulates emotions) and cerebellum (posture, balance, coordination) are most vulnerable areas.

Brain edema develops within minutes of arterial occlusion and reaches maximum level within 3 days. Intracranial pressure often leads to progressive neurologic deterioration and secondary structural damage. Predicting prognosis is challenging since excessive edema in the brain post stroke can hinder recovery  or recovery can accelerate as the edema resolves.  It is a wait and see period for all parties.

r7_ischemicstroke

Thrombosis development or existence of a blood clot within the vascular system. Acute formation of a thrombus may occlude the lumen of the artery and produce focal ischemia and infarction. Thrombosis formation is usually associated with atherosclerosis, diabetes mellitus and hypertension.

 

Stroke_Ischemic

Embolism a substance formed elsewhere in the vascular system travels in the bloodstream to lodge in a vessel and obstruct blood flow. Embolisms are most common at at sites of bifurcation or where the lumen is already narrowed. 75% of cardiac emboli lodge in the brain and there is an increased risk of stroke in patients with ischemic heart disease. Unfortunately, there is rarely a warning sign and it has such a rapid onset of deficits. Most associated with heart disease and can occur as a complication of neck and thoracic surgery, due to cardiac pump failure, heart attack and/or arrhythmia. 

Hemorrhagic Strokes:

Intracerebral Hemorrhage is a nontraumatic hemorrhage that is caused by rupture of small arterial or arteriolar aneurysms associated with hypertension. Actually Charot-Bouchard microaneurysms found in small cerebral vessels in 50% of hypertensive patients and may burst under influence of constant hypertension. Common vessels involved are Basal ganglia & thalamus – 70% Brainstem – 13% Cerebral white matter – 10% and Cerebellum – 9%. Damage is highly variable depending on location, speed and volume of bleeding. Prognosis for neurologic recovery may be better than following an ischemic infarct.

Subarachnoid Hemorrhage is a nontraumatic rupture of aneurysm of the major cerebral vessels of the brain. It is least common type 6-8% of all stroke cases. Aneurysm rupture are most common in PCA 30%, ACA 35-40%, MCA 20-25% and Basilar & PICA – 10%. 

Presentation may be sudden onset with minimal warning; consciousness regained quickly if lost, stiff neck, headache, drowsiness and confusion possibly persisting for weeks, and minimal focal neurologic signs.

Presentation may be sudden onset with or without loss of consciousness; focal neurologic signs associated with ischemia, may have delayed onset of focal signs owing to onset of vasospasm 4-12 days after rupture, and significant chance of rebleeding!

Presentation may be sudden onset of severe headache and loss of consciousness, followed by persistent coma and death.

Take home points:

  1. Regardless of the type, stroke can leave the survivor and the loved ones devastated. It can have no signs at all,  can be as mild as a slight headache and stiffness in the neck, can be more indicative as drowsiness, confusion and mild focal deficit, can present as more severe as semicoma, and vegetative disturbances or can be fetal.
  2. Stroke, Heart Disease and Cancer continue to remain as top three killers in the US.
  3. If you have co-morbities such as diabetes, hypertension, atherosclerosis, you may have increased your risk for having a stroke. Make sure you see your doctor regularly, maintain a healthy life style by making smart food choices, exercises regularly and stay away stress.
  4. Remember FAST is the easiest way to recognize signs of stroke.

Facial Asymmetry

Arm asymmetry 

Slurred speech

Telephone- call 911– Remember every second count!

Thanks for reading!

 

 

Sources:

  • Saladin LK, (1999)  Cerebrovascular Disease:  Stroke.  In Fredericks & Saladin “Pathophysiology of the Motor Systems: Principles and Clinical Presentations”.
  • FA Davis, Philadelphia. Pp. 487-510.

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