LECTURE 3

1.) Differentiate between the types of stroke(ischemic and hemorrhagic) and recognize transient iscemic attacks.

Ischemic Strokes
Ischemic strokes account for a majority of all strokes (75-85%).
There are two mechanisms:
1.) Vessels are occluded by buildup of arterial atherosclerotic plaques.
2.) Vessels are occluded by an embolus from another vessel.

Hemorrhagic Strokes
These occur when a blood vessel ruptures. These are associated with a high rate of morbidity and mortality.
There are two main types:
1.) Intracranial Hemorrhage (ICH)
2.) Subarachnoid Hemorrhage (SAH)
Common Causes:
1.) Hypertension-> ICH
2.) Aneurysmal Hemorrhage -> SAH (ciggarettes are a weak link)
3.) Subdural Hematoma
4.) AV Malformation
5.) Amyloid angiopathy

Transient Ischemic Attack
A brief episode of neurologic dysfunction from focal brainischemia or retinal ischemia with clinical symptoms lasting less than 1 hour without evidence of acute ifarct. After TIA there is a 10X risk of ischemic stroke. Peak risk is <= 3months with 50% chance within the first 48 hours. 2.) Given a clinical presentation recognize MCA, ACA, ICA strokes.
MCA: large portions of the frontal, parietal and temporal lobe
-Contralateral Hemiplegia
-hemianesthesia
-homonymous hemianopia
-When on dominant hemisphere you see aphasia when in non-dominant you see apraxia and/or sensory neglect

ICA: centrolateral portion of the cerebral hemisphere
Symptoms are identical to MCA except for occasional ipsilateral ocular symptoms (monocular blindness)

ACA: supplis medial portions of frontal and parietal lobes, corpus callosum, and ocasionaly caudate and internal capsule
-contralaterl hemiplegia (especially in the legs)
-grasp refelx
-urinary incontinence

Hints from class
if you see face and Arm you think MCA.
if you see leg you think ACA
if you see face arm and leg you think lacunar infarct

3.)Given a clinical presentation, recognize large vessel, lacunar, and embolic strokes.

Large Vessel Disease
This is the most common form of ischemic stroke. Subintimal plaques form @ or near bifurcations of arteries.
Mechanisms of ischemia:
1.) Flow Reduction
- High grade stenosis or occlusion
- usually distal to the bifurcation of the common carotid
- >70% stenosis is needed
2.) Artery to artery Embolism
- Non stenotic plaques <70%>Small Vessel Disease(lacunar)
These occur in penetrating arteries which originate from medium size vessels. Oclussion of the vessel causes a lacunar infarct (<1.5cm>Cardiogenic Embolism
Heartconditions which can lead to cardiogenic embolism
1.) non-rhematic AFIB (give warfarin to reduce stroke risk)
2.) acute MI
3.) prosthetic heart valves
4.) Other - rheumatic heart disease, Left ventricular throbi in previous MI, dilated cardiomyopathy, ventricular aneurysm, infective endocarditis and cardiac tumors.
Features for Clinical Diagnosis
1.) abrupt onset
2.) with cortical neurolgical deficit
3.) with potential source source of cardiac embolism

4.) Given a patient with a stroke, describte the diagnositc studies done for further evaluation.

1.) Blood Work
Everyone should get BGC, Serum Electrolytes, Renal Function Tests, CBC with plts, PT/INR and APTT. This is particularly important in assesing the possibility of using thrombolytics on the patient.
2.) Cardiac studies including EKG and echo
3.) CT/CTA
can be used to evaluate patients with symptoms of stroke and diagnose as hemorrhagic or ischemic. CTA can be used to find the particular area of the insult.
4.) MR/MRA
Can detect edema or swelling in advance of tissue destruction. However these studies tpically take a while, and often exaggerate the degree of stenosis. They can be used in a similar manner as CT/CTA.
5.) Angiography(CTA/MRA)
Can be used to determine etiology and/or outline treatment plans for patients. TPA can often be administered at the time of angiography. The TPA window is <<3 style="color: rgb(255, 0, 0);">5.) list the therapies for treatment of ischemic stroke.
Antiplatlet
This is the mainstay of stroke prevention. It is proven to reduce stroke in people with previous TIA and Stroke. Drugs include Aspirin and clopidrogel.
Warfarin
This is only recommended for the treatment of patients with AFIB.
Carotid Endarterectomy
In SYMPTOMATIC patients with recent TIA or stroke with ipsilateral carotid stenosis of >=70% can substantially benefit from carotid endarterectomy.
In ASYMPTOMATIC patients with >=60% stenosis and local surgical risk <3% should be considered for carotid endarterectomy.

ACUTE stroke
Don't overzealously treat mid to moderate hypertension, because this may help progression of nerve damage. Aspirin 60-300mg <=48 reduces risk of recrrence. tPA should be given if the patient can tolerate it and if <3hrs after stroke onset.