STROKE

Cerebrovascular Accident (CVA)

Strokes are, quite literally, brain attacks. The brain loses its supply of oxygenated blood, then quickly and dramatically perishes. Strokes are the most important neurological disease. They are common. They are deadly. 

What are the different kinds of strokes?

Ischemic stroke (80%) - not enough blood 

• Thrombotic - A plaque within the walls of a blood vessel can lead to occlusion, either by growing too large or by bursting and flooding the artery with pro-clotting junk. 

• Embolic - An emboli (clot) can travel to the brain. Commonly stems from problems in the heart (afib, old MI, aneurysm), valves (endocarditis) or venous blood (paradoxical clot slips through a hole in the heart). In afib the atria just sort of sit there and quiver. When blood sits still, it coagulates. Some people have an extra “pocket” in their left atrium called the left atrial appendage, and clots love to form there. Clots can also form on the inner walls of the heart over the sites of old heart attacks. These are known as mural thrombi (mural = painting on a wall). 

• Global hypoperfusion (Watershed stroke) - blood ain’t reaching the brain, but the highway (vessels) are clean. Happens during shock. 

Hemorrhagic stroke (20%) - too much blood. An artery can burst, flooding the brain tissue with blood, creating intense pressure while simultaneously depriving flow to downstream cells. 

• Intracerebral hemorrhage - a vessel within the brain parenchyma pops

• Subarachnoid hemorrhage - a vessel under the brain parenchyma pops (see subarachnoid page for more details)

Symptoms?

Ischemic strokes create focal lesions. The symptoms are mostly stable. 

Hemorrhagic strokes create progressive lesions. The symptoms tend to get worse and worse, as the mass effect kicks in. High intracranial pressure causes nausea, intractable vomiting, bad worsening headache, seizures, coma, posturing.

Diagnosis?

An MRI of the head is best, but a CT will often suffice. 

Treatment?

Ischemic - Give tPA if the symptoms started within 3 to 4 hours (tPA is a clot buster. This is a dangerous drug.) Don’t give tPA to someone already on blood thinners. Don’t give tPA to anyone with a hemorrhagic stroke. Don’t give tPA to someone who woke up with stroke symptoms (the symptoms might have begun hours ago during sleep). 

Hemorrhagic - not much, to be honest. Sometimes the neurosurgeon can drain the bleed, but many bleeds are too deep within the brain to access.