STROKE

1. STROKE CNS Module Week 5

2. Introduction • Stroke: it represents a group of disease that cause a disturbance in brain function, often permanent, caused by : 1) blockage in vessels supplying blood to brain. 2) Rupture in vessels supplying blood to brain. • Unlike muscles, the brain cannot store nutrients, and thus it requires a constant supply of glucose and oxygen. • If the blood supply is interrupted for 30secs, unconsciousness results, permanent brain damage may follow in 4mins.

3. The brain • The brain can be divided into 3 areas: • Brain stem controls many of the body’s basic functions  breathing, chewing, swallowing and eye movements. • Cerebellum coordinates movements and balance. • Cerebrum Left hemisphere  receives input (sensations) from the right side of the body and control movement on the Right side. Conversely, the right brain controls the left side of the body.

4. The Cerebrum • Each side of the cerebrum divided into four lobes: • Frontal lobescontrol motor function, planning, and expression of language. • The temporal lobes involved with hearing, memory and behavior. • The parietal lobes  interpret sensation and control understanding of language. • The Occipital lobes  perceive and interpret vision. • Left brain is the dominant  performs most languages functions. • The right brain is the non-dominant  control the abilities to understand spatial relations, recognize faces, musical ability and focus attentions.

5. Stroke Risk Factors Characteristics and life-style: • Definite : - Cigarette smoking. - Excessive alcohol consumption. - Drug use (cocaine, amphetamines) - Age, sex, race. - familial and genetic factors. • Possible : - Oral contraceptive use. - Diet. - Personality type. - Obesity and physical inactivity. Disease or Disease Markers: • Hypertension. • Cardiac disease • TIA and elevated hematocrit. • Diabetes mellitus. • Sickle cell disease. • Elevated fibrinogen concentrations.

6. Stroke Other (5%) 1)Ischemia (70%) 2)Hemorrhage (25%) Embolism (15%) Lacunar (20%) Brain Hemorrhage (12.5%) Subarchnoid Hemorrhage (12.5%) Cerebral Atherothrombosis (10%) Infarction of unknown cause (25%), thought to be caused by embolism. Types of Stroke

7. Ischemic 1) Cerebral Atherothrombosis • Ischemic stroke is caused by a lack of blood flow to the brain. • One common type of ischemic stroke is cerebral atherothrombosis  caused by a clot (thrombus) block blood flow in an artery.  the narrowing leads to a low flow state (WATERSHED) ischemia. • If the resulting lack of oxygen  death of brain tissue and permanent damage (cerebral infarction). • Clots  form at or adjacent to an area of a vessel damaged by atherosclerosis (plaque of fatty substances, cholesterol, waste products of cells, Ca+2, and a blood-clotting material (fibrin) which builds up as thick, irregular deposits on the inner lining of an artery obstruct the opening of the blood vessels. • Atherothrombic stroke  preceded by TIAs and occur at low blood pressure.

8. 2) Cerebral Embolism • it is caused by a movable clot that forms in one part of the body and travels in the bloodstream until it lodges in an artery in the brain or in a vessel leading to the brain. • Emboli can be formed from Ca+2, cholesterol, air, blood proteins, platelets or by-products of an infection of the heart’s inner lining (endocarditis). • The most common cardiac condition associated with cerebral embolism are atrial fibrillation, valvular disease, prosthetic heart valve, endocarditits, congestive heart failure & myocardial infarction. • In atrial fibrillation  the two atrial chambers quiver rather than beat effectively  blood is not pumped out of the atria completely --> form clots. • Embolic strokes is the most common ischemic strokes • The use of anticoagulant drugs  reduce the risk of clot formation-before or after the stroke

9. Lacunar infarction (lacunar stroke) • It is the result of occlusions (complete blockage) of arterioles. The very small ends of the arteries that penetrate deep into the brain. • There are several syndromes that suggest that possibility of a lacunar infarction. • The most common is a pure motor stroke  the damage is confined to the main cabling system for motor signals from the brain to the spinal cord ( internal capsule).  the pt develops one-sided weakness without other symptoms • A lacunar stroke in the thalamus (the main sensory relay center to the brain)  cause a pure sensory stroke.

10. Hemorrhagic 1) Intracerebral hemorrhage • Blood leaks from small vessels at the base of the brain. • Long-term exposure to BP  weaken the walls of the small arteries  burst. • Other cause  brain tumor, trauma, arteriovenous malformation and stimulant drugs( amphetamines and cocaine). • Onset of symptoms  acute with severe headache and consciousness. • Hemorrhage inside the cerebellar ( for the coordination of movement and balance)  disequilibrium or dizziness, incoordination ( especially trouble in walking), headache, nausea and vomiting.

11. 2) Subarchnoid hemorrhage • It is caused by an aneurysm or a vascular malformation  blood go out from the blood vessels and worsened by that mass of blood pushing up against adjacent areas of the brain and blood vessels. • Clinical features  sudden onset of an excruciating headache with a stiff neck, change in consciousness, nausea, vomiting, diffuse intellectual impairment and seizures.

12. Arteriovenous malformation( AVM) • It is a tangle of arteries and veins without the small vesseles (capillaries) that normally connect the two. • The walls of the vessels are often thin and have high rates of blood flow, conditions that predispose to bleeding, putting pressure on structures within the brain, or shunting blood away from normal areas of the brain. • Small (AVM)  no need to be treated. • Large  surgically ( by radiation)

13. Diagnosis and assessing stroke 1) History and examination: in examination test neurological function (orientation, memory, emotional control, motor skills, tactile sensation, hearing, vision, and ability to read, write, and speak). • General examination blood pressure, coronary heart disease. 2)Laboratory tests: - samples of blood, urine, cerebrospinal fluid  infection or low levels of blood sugar. • Screening may be done for diabetes, elevated blood cholesterol, bleeding disorders, and abnormalities in blood proteins  risk factors for cardiac disease and recurrent stroke. 3) Imaging studies: • CT and MRI  for exclusion of tumors, abscesses, and bleeding from trauma. Also to differentiate between ischemic and hemorrhagic stroke. • To determine the size and the location of the stroke.

14. 4) Cardiac evaluation: • ECG  cardiac evaluation. • Echocardiograms  pinpoint a source of an embolus. 5) Angiography: • To detect many abnormalities that cause stroke, including narrowing or occlusion of blood vessel, embolus, atherosclerosis, dissections, arteriovenous malformation and aneurysms. 6) Ultrasound: • To visualize structures an blood flow within the body. Two types : • Carotid ultrasound  measure blood flow in the carotid arteries. • Transcranial Doppler  to measure flow in the intracranial arteries. 7) Blood flow studies: • PET (positron emission tomography), SPECT (single-photon-emission computed tomography and Xenon inhalation  provide information on blood flow in the brain. • These test  show changes immediately after the onset of stroke symptoms, while CT or MRI  remain negative for several hours or days after stroke.

15. Treatment (Treatment of acute stroke) • It concentrates on maintaining fluids and electrolytes, avoiding the secondary complication of stroke and paralysis. • Anticoagulant medications: • Heparin sometimes used to treat acute ischemic stroke. It does not dissolve existing clot, it can prevent the formation of new ones  help to prevent subsequent stroke. • Bcz it increase the tendency to bleed  restrict in pt with recurrent stroke( pt with more than one TIA, or a cardiac source of embolism (MI, atrial fibrillation, valvular disease ). • Surgery: • not used to treat acute stroke but maybe indicated in hemorrhagic stroke (subarchanioid and brain hemorrhages) or a recent blockage of a carotid artery.

16. Long-term treatment of stroke Therapy may include modification of risk factors, drugs or surgery or a combination. 1- Modification of risk factors: • Treatment of high blood pressure, and diabetes along with smoking cessation. • Also by controlling weight, lowering cholesterol and moderating alcohol intake. 2- Drugs : • Antiplatelet medications: • Aspirin inhibit platelet function lessen the tendency of blood to clot  lowers the risk of stroke and stroke related death. • Anticoagulants: • It interfere with clotting mechanism by affecting the action of enzymes necessary for clotting. • Warfarin (Coumadin)  is the commonly used anticoagulant bcz it is a more powerful drug than aspirin. • It is recommended only when aspirin therapy has failed or when it is clear that the source of the clot is the heart • pt should be tested with prothrombin test  measure the speed of clotting.

17. 3- Surgery - The goal in surgery  to provide a pathway for blood to get to the brain. - By carotid endartectomy  a stenosis ( narrowing) or ulceration of an atherosclerotic plaque in the carotid artery is removed.