Neuroscience 210

• Number one cause of disability
• number 3 cause of death (1st is heart disease, then cancer)
• 3 billion dollar a year cost

• apoplexy--struck down with violence
• 1599--stroke first used to describe apoplective seizures
• Hippocrates originally described this affliction

AKA CVA--cerebrovascular accident.

WHO definition--a neurological deficit of cerebrovascular cause that persists beyond 24 hours or is interrupted by death within 24 hours.

1. Ischemic--blockage of artery resulting in loss of blod flowby a thrombus (clot) -clot can form and a part can break off and move on to cause another blockage = 80% of strokes

• 2. Spontaneous intracranial hemorrhage (10-15%)
• Aneurysmal subarachnoid hemorrhage (5-10%)

strokes visualized with CT scans --hemmorrhage look like bright spots on the scan

• vision
• headache
• weakness
• trouble speaking
• diziness

• sudden onset of:
• unilateral weakness or numbness
• difficulty speaking/understanding
• loss or change in vision
• severe and unusual headache (can indicate subarachnoid hemorrhage)
• loss of balance or dizziness

• stroke symptoms are dependent on the area of brain affected by ischemia or hemorrhage
• on the motor strip, legs are usually the first to be distrupted, they are in the fold between the two hemispheres.

Broca's= non fluent--slow halting, effortful speech, frustrated, relatively good comprehension

Wernike's=fluent= empty speech, word salad, poor comprehension

Dysarthria--slurring of speech

• usually from right parietal lobe damage
• inattention to the left side of speace and even their own body
• very disabling as patients lack insight into deficits

• contains the internal capsule--info from cortex to spinal cord, damage causes contralateral weakness
• white matter is the brain's wiring

vertebral artery==two arteries come together to form one--posterior

internal carotid artery-- supplies anterior 2/3 of cerebral hemisphere

• anterior circulation of the brain done by the anterior cerebral artery and the middle cerebral artery--branches of the internal carotid artery
• posterior circulation of the brain by posterior cerebral artery, basilar artery, vertebral artery

circle of Willis-- structure at base of brain that is formed by the joining of carotid and basilar arteries, has redundancies so if one part is blocked blood can still flow

supplies lateral surface of hemisphere and deep structures like the basal ganglia and subcortical white matter

• blockages affect contralateral face and arm areas, causes weakeness
• causes dysphasia (left hemisphere) and neglect (right hemisphere)

• supplies medial surface of hemisphere
• causes contralateral leg weakeness/numbness

• contralateral weakness
• neglect (if in right )
• aphasia, dysphagia
• contralateral visual loss

affects the internal capsule--contralateral weakness--affects face, arm and legs, even small strokes can be debilitating

vertebral and basilar arteries supply posterior and medial regions of hemispheres, brainstem, diencephalon and cerebellum

posterior cerebral artery and cerebellar arteries--3 branches

• lacunar syndrome--weak and ataxic on the contralateral side
• brainstem contains wiring downstream for the internal capsule

contralateral hemianopsia (blind on one side of visual space)

pons--entire brainstem stroke at the pons, afferents are spared, can feel but completely paralysed.

only stroke with bilateral symptoms

symptoms of stroke that resolve within 24 hours of onset

• WARNING sign for major stroke
• ~50% of all TIA are associated with permanent damage, particularly if symptoms last > 1 hour

• age
• hyptertension (high blood pressure)
• smoking--chemicals entering bloodstream
• diabetes
• irregular heartbeat (atrial fibrillation)--blood will pool because it is not being moved, clots form and might get out of the heart and move until it gets to artery it cant fit through and cause a blockage.

• the heart
• arteries in the neck
• arteries in the brain

plaques can form (often at intersections of arteries) and pieces can break off and go on to cause a stroke or cause platelets to stick to it and cause a blockage

• Insufficiency of blood supply and oxygen and glucose to meet the metabolic demands of the brain
• critical thing is that ATP stops being made . ATP keeps potassium out, and water out. if there is no ATP water can move in the cell (imaging measures water, shows the core region of damage)

• 65 mL/100g/min is regular CBF
• once it drops to between 20-10 the tissue is electrically silent--penumbral tissue that is functionally inactive but structurally fine

at 10 there is K release and cell death

Thrombolysis--tPA--busts the clot and restores blood flow to the brain, helps to save the penumbra regions

• 2nd most common stroke type
• higher rates in Asians and Africans--higher blood pressure rates

subarachnoid hemorrhage is 3rd most common

• size of the stroke matters--initial levels of consciousness and hematoma volume prodiects death
• if they are alert and have a hematoma <30 ml, 17% mortality rate
• if they are drowsy/in a coma with a hematoma there is a 91% mortality rate

amyloid proteins deposited in the vessles makes them more brittle and prone to rupture

• hemostatic drugs--to speed clotting
• acute blood pressure reduction--reducing the pressure

weakness in vessel wall, if it is in a focal area, and aneurysm is caused, and rupture causes a subarachnoid hemorage

risk factors are hypertension, smoking, and genetics

rupture of aneurysm, treated by surgical clip or endovascular coil which causes it to clot

• treatment varies with type of stroke, can't tell difference without imaging , requires brain scan
• time is brain!

• ischemia--tPA
• hemorrhage--no proven therapy
• aneurysm--clip/coil

can be prevented with high BP treatment(lower blood pressure=lower stroke), stopping smoking, taking low doses of asprin (stops platelets from becoming active and spiny and sticking to each other) Warfarin (rat posion) for patients with atrial fibrilation--blood thinner, prevents clotting in heart