Stroke

CT scan of the brain showing a prior right-sided ischemic stroke from blockage of an artery. Changes on a CT may not be visible early on.
There are two main categories of strokes. Ischemic (top), typically caused by a blood clot in an artery (1a) resulting in brain death to the affected area (2a). Hemorrhagic (bottom), caused by blood leaking into or around the brain from a ruptured blood vessel (1b) allowing blood to pool in the affected area (2b) thus increasing the pressure on the brain.
A slice of brain from the autopsy of a person who had an acute middle cerebral artery (MCA) stroke
CT scan of an intraparenchymal bleed (bottom arrow) with surrounding edema (top arrow)
Illustration of an embolic stroke, showing a blockage lodged in a blood vessel.
Histopathology at high magnification of a normal neuron, and an ischemic stroke at approximately 24 hours on H&E stain: The neurons become hypereosinophilic and there is an infiltrate of neutrophils. There is slight edema and loss of normal architecture in the surrounding neuropil.
A CT showing early signs of a middle cerebral artery stroke with loss of definition of the gyri and grey white boundary
Dens media sign in a patient with middle cerebral artery infarction shown on the left. Right image after 7 hours.
12-lead ECG of a patient with a stroke, showing large deeply inverted T-waves. Various ECG changes may occur in people with strokes and other brain disorders.
Walking with an orthosis after a stroke
Stroke deaths per million persons in 2012
Hippocrates first described the sudden paralysis that is often associated with stroke.

Medical condition in which poor blood flow to the brain causes cell death.

- Stroke
CT scan of the brain showing a prior right-sided ischemic stroke from blockage of an artery. Changes on a CT may not be visible early on.

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Automated arm blood pressure meter showing arterial hypertension (shown by a systolic blood pressure 158 mmHg, diastolic blood pressure 99 mmHg and heart rate of 80 beats per minute)

Hypertension

Long-term medical condition in which the blood pressure in the arteries is persistently elevated.

Long-term medical condition in which the blood pressure in the arteries is persistently elevated.

Automated arm blood pressure meter showing arterial hypertension (shown by a systolic blood pressure 158 mmHg, diastolic blood pressure 99 mmHg and heart rate of 80 beats per minute)
Determinants of mean arterial pressure
Illustration depicting the effects of high blood pressure
Rates of hypertension in adult men in 2014.
Diagram illustrating the main complications of persistent high blood pressure
Image of veins from Harvey's Exercitatio Anatomica de Motu Cordis et Sanguinis in Animalibus
Graph showing, prevalence of awareness, treatment and control of hypertension compared between the four studies of NHANES

Long-term high blood pressure, however, is a major risk factor for stroke, coronary artery disease, heart failure, atrial fibrillation, peripheral arterial disease, vision loss, chronic kidney disease, and dementia.

CT scan of a spontaneous intracerebral bleed, leaking into the lateral ventricles

Intracerebral hemorrhage

Sudden bleeding into the tissues of the brain, into its ventricles, or into both.

Sudden bleeding into the tissues of the brain, into its ventricles, or into both.

CT scan of a spontaneous intracerebral bleed, leaking into the lateral ventricles
Axial CT scan showing hemorrhage in the posterior fossa
Spontaneous ICH with hydrocephalus on CT scan

It is one kind of bleeding within the skull and one kind of stroke.

A bleeding wound in the finger

Bleeding

Blood escaping from the circulatory system from damaged blood vessels.

Blood escaping from the circulatory system from damaged blood vessels.

A bleeding wound in the finger
A subconjunctival hemorrhage is a common and relatively minor post-LASIK complication.
Micrograph showing abundant hemosiderin-laden alveolar macrophages (dark brown), as seen in a pulmonary hemorrhage. H&E stain.

Intracerebral hemorrhage – bleeding in the brain caused by the rupture of a blood vessel within the head. See also hemorrhagic stroke.

Universal blue circle symbol for diabetes

Diabetes

Group of metabolic disorders characterized by a high blood sugar level over a prolonged period of time.

Group of metabolic disorders characterized by a high blood sugar level over a prolonged period of time.

Universal blue circle symbol for diabetes
Overview of the most significant symptoms of diabetes
Retinopathy, nephropathy, and neuropathy are potential complications of diabetes
Autoimmune attack in type 1 diabetes.
Reduced insulin secretion and absorption leads to high glucose content in the blood.
The fluctuation of blood sugar (red) and the sugar-lowering hormone insulin (blue) in humans during the course of a day with three meals. One of the effects of a sugar-rich vs a starch-rich meal is highlighted.
Mechanism of insulin release in normal pancreatic beta cells. Insulin production is more or less constant within the beta cells. Its release is triggered by food, chiefly food containing absorbable glucose.
Rates of diabetes worldwide in 2014. The worldwide prevalence was 9.2%.
Mortality rate of diabetes worldwide in 2012 per million inhabitants

Serious long-term complications include cardiovascular disease, stroke, chronic kidney disease, foot ulcers, damage to the nerves, damage to the eyes and cognitive impairment.

CT scan of the brain showing subarachnoid hemorrhage as a white area in the center and stretching into the sulci to either side (marked by the arrow)

Subarachnoid hemorrhage

Bleeding into the subarachnoid space—the area between the arachnoid membrane and the pia mater surrounding the brain.

Bleeding into the subarachnoid space—the area between the arachnoid membrane and the pia mater surrounding the brain.

CT scan of the brain showing subarachnoid hemorrhage as a white area in the center and stretching into the sulci to either side (marked by the arrow)
Circle of Willis with the most common locations of ruptured aneurysms marked
A lumbar puncture in progress. A large area on the back has been washed with an iodine-based disinfectant leaving brown coloration
Xanthochromia versus normal CSF.
ECG changes resembling those of an STEMI in a woman who had an acute CNS injury from a subarachnoid hemorrhage.
Arteriogram showing a partially coiled aneurysm (indicated by yellow arrows) of the posterior cerebral artery with a residual aneurysmal sac. The person was a 34-year-old woman initially treated for a subarachnoid hemorrhage.
Autopsy of a case with subarachnoid hemorrhage. The arachnoid mater is left in place on the exterior surface, containing extensive hemorrhage that also fills the sulci, as detailed in magnified image.
Average number of people with SAH per 100,000 person-years, broken down by age.

It is a form of stroke and comprises about 5 percent of all strokes.

Leads aVL and aVF of an electrocardiogram showing atrial fibrillation. There are irregular intervals between heart beats. No P waves are seen and there is an erratic baseline between QRS complexes. The heart rate is about 125 beats per minute.

Atrial fibrillation

Abnormal heart rhythm (arrhythmia) characterized by rapid and irregular beating of the atrial chambers of the heart.

Abnormal heart rhythm (arrhythmia) characterized by rapid and irregular beating of the atrial chambers of the heart.

Leads aVL and aVF of an electrocardiogram showing atrial fibrillation. There are irregular intervals between heart beats. No P waves are seen and there is an erratic baseline between QRS complexes. The heart rate is about 125 beats per minute.
Normal rhythm tracing (top) Atrial fibrillation (bottom)
How a stroke can occur during atrial fibrillation
Non-modifiable risk factors (top left box) and modifiable risk factors (bottom left box) for atrial fibrillation. The main outcomes of atrial fibrillation are in the right box. BMI=Body Mass Index.
A 12-lead ECG showing atrial fibrillation at approximately 132 beats per minute
Diagram of normal sinus rhythm as seen on ECG. In atrial fibrillation the P waves, which represent depolarization of the top of the heart, are absent.
ECG of atrial fibrillation (top) and normal sinus rhythm (bottom). The purple arrow indicates a P wave, which is lost in atrial fibrillation.
3D Medical Animation still shot of Left Atrial Appendage Occlusion

Atrial fibrillation is associated with an increased risk of heart failure, dementia, and stroke.

Chest X-ray of a pneumonia caused by influenza and Haemophilus influenzae, with patchy consolidations, mainly in the right upper lobe (arrow)

Pneumonia

Inflammatory condition of the lung primarily affecting the small air sacs known as alveoli.

Inflammatory condition of the lung primarily affecting the small air sacs known as alveoli.

Chest X-ray of a pneumonia caused by influenza and Haemophilus influenzae, with patchy consolidations, mainly in the right upper lobe (arrow)
Main symptoms of infectious pneumonia
The bacterium Streptococcus pneumoniae, a common cause of pneumonia, imaged by an electron microscope
Cavitating pneumonia due to MRSA as seen on a CT scan
A chest x-ray of a patient with severe viral pneumonia due to SARS
Pneumonia fills the lung's alveoli with fluid, hindering oxygenation. The alveolus on the left is normal, whereas the one on the right is full of fluid from pneumonia.
A chest X-ray showing a very prominent wedge-shaped area of airspace consolidation in the right lung characteristic of acute bacterial lobar pneumonia
CT of the chest demonstrating right-sided pneumonia (left side of the image)
A pleural effusion: as seen on chest X-ray. The A arrow indicates fluid layering in the right chest. The B arrow indicates the width of the right lung. The volume of the lung is reduced because of the collection of fluid around the lung.
Deaths from lower respiratory infections per million persons in 2012
WPA poster, 1936/1937
Pneumonia seen by ultrasound
Right middle lobe pneumonia in a child as seen on plain X-ray

Risk factors for pneumonia include cystic fibrosis, chronic obstructive pulmonary disease (COPD), sickle cell disease, asthma, diabetes, heart failure, a history of smoking, a poor ability to cough (such as following a stroke), and a weak immune system.

Areas of the brain are supplied by different arteries. The major systems are divided into an anterior circulation (the anterior cerebral artery and middle cerebral artery) and a posterior circulation

Cerebral circulation

Movement of blood through a network of cerebral arteries and veins supplying the brain.

Movement of blood through a network of cerebral arteries and veins supplying the brain.

Areas of the brain are supplied by different arteries. The major systems are divided into an anterior circulation (the anterior cerebral artery and middle cerebral artery) and a posterior circulation
Cerebrovascular System
The ophthalmic artery and its branches.
The anterior and posterior circulations meet at the Circle of Willis, pictured here, which rests at the top of the brainstem. Inferior view.
Dural venous sinuses bordered by hard meninges (shown in blue) direct blood outflow from cerebral veins to the internal jugular vein at the base of skull

The failure of these safeguards may result in a stroke.

Warfarin

Medication that is used as an anticoagulant .

Medication that is used as an anticoagulant .

Vitamin K1-warfarin interaction effect. When warfarin levels are high, people have more risk of bleeding. Conversely, lower levels of warfarin lead to increased risk of blood clots. There is a narrow range where the benefits of warfarin are greater than the risks, its therapeutic window. Certain drugs, herbal medicines, and foods can interact with warfarin, increasing or decreasing a previously stable warfarin level.
Acyclic tautomer (left) and cyclic hemiketal tautomer (right)
3 mg (blue), 5 mg (pink) and 1 mg (brown) warfarin tablets (UK colours)
Warning label on a tube of rat poison laid on a dike of the Scheldt river in Steendorp, Belgium. The tube contains bromadiolone, a second-generation ("super-warfarin") anticoagulant.

It is commonly used to prevent blood clots such as deep vein thrombosis and pulmonary embolism, and to prevent stroke in people who have atrial fibrillation, valvular heart disease or artificial heart valves.

Aspirin

Medication used to reduce pain, fever, or inflammation.

Medication used to reduce pain, fever, or inflammation.

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Aspirin is also used long-term to help prevent further heart attacks, ischaemic strokes, and blood clots in people at high risk.