Why are vertebral arteries so fragile?
VERY curvy = more prone to backflow & plaque buildup (thrombus)
& extreme movements can easily tear artery walls and cause bleeds
Symptoms of aneurysm
usually none, or hard to tell that they are specifically related to an aneurysm and not just a simple headache, dizziness, etc.
Thunderclap headache
feels small/slight pain then BOOM its the worst pain of your life --> minutes to death
^ true for all hemorrhages, regardless of where they occur
What is an aneurysm?
ballooning of a blood vessel; weakened artery wall
- if it bursts --> hemorrhagic stroke
Drug used to treat stroke?
tPA: naturally breaks down blood clots --> works for ISCHEMIC STROKES ONLY
- critical 3 hour time period, if its too far past that time you could enhance/bring on a hemorrhagic stroke
- after a while vessel walls are also weak due to lack of oxygen, could cause potential aneurysms to burst --> hemorrhagic stroke
Venous thrombosis
blood clot that forms within a vein (as opposed to an artery)
- disrupts proper drainage from brain --> heart
- causes BACKUP/WASTE BUILD UP
- deficits in oxygen delivery
- FATAL!!
Berry aneurysm
aneurysm at anterior communicating/branching artery (artery between both anterior arteries) --> if it bursts is basically 100% fatal
- bloodflow here is DIRECTLY TIED TO BRAINSTEM --> affects heart rate & breathing & rapid onset of pain (thunderclap headache)
Subarachnoid hemorrhage
in subarachnoid space where CSF flows; not as severe --> cognitive changes & development of hydrocephalus until blood can be properly cleaned out
- could occur around base of brain = berry aneurysm --> fatal
What is a hemorrhage?
bleeding, loss of blood from a circulatory system
At home treatment for stroke
- early identification --> ACT F.A.S.T.
F: face; is one side of the face more droopy than the other
A: arms; is one arm weaker than the other (lack of control of motor movement)
S: speech; is their speech intact; ask them to repeat a simple sentence
T: time; call 911 as soon as possible
What causes venous thrombosis?
- can follow trauma
- can be due to blood disorder
Venous drainage system
- usually follow same pattern as arteries
*SPECIAL VENOUS DRAINAGE*: venous sinus carry DE-OXYGENATED BLOOD AWAY FROM BRAIN & back to the heart
- created by dura (splitting of periosteal dura & meningeal dura)
Intraventricular hemorrhage
vessels lining ventricular walls burst & BLEED INTO CSF --> not as severe; cognitive changes/slowing; can recover just takes a long time for body to go through proper reabsorption
- IF CLOTS OCCUR, it can lead to HYDROCEPHALUS bc its within ventricular system
- swelling
- brain tissue is intact bc it affected ventricles not cerebrum
What is a hemorrhagic stroke?
high pressure bleeding into the brain from the bursting of an aneurysm
- weakened, ballooned artery ruptures & shoots out high pressure blood into brain tissue (only have a matter of minutes before it is fatal)
- occur mainly at branching points bc the blood bounces & weakens walls
Short term treatment for stroke
intraventricular shunt: similar to shunt used for hydrocephalus; placed into lateral ventricle & drain blood into external collection bag
What are bridging veins?
small/delicate veins that bridge the subarachnoid space & CONNECT SAGGITAL SINUS TO CORTICAL TISSUE!!
- saggital sinus sits within the 2 layers of the dura mater; bridging veins go from cortical tissue/brain & bridge through dura mater to drain fluids into venous sinus (the reuptake region of the brain)
^ notice in picture how bridging veins go through dura
Developmental arteriovenous malformation (AVM)
tangle of abnormal blood vessels connecting ARTERIES & veins in the brain
- blocks/disrupts proper oxygenated blood from traveling to the brain (affects/tangles/improper branching to capillary beds --> affects oxygen exchange)
- increased risk of bleeding (due to immediate change from high pressure artery --> low pressure vein)
Intracerebral hemorrhage
bursting of smaller vessel deep in cerebrum; MAJOR DAMAGE --> high blood pressure causes major tissue damage
- below pia mater bc its within cerebrum
- shifts brain structure & nearby ventricles
- swelling
What are venous malformations?
unusual formations of the veins/veins & arteries that cause problems with blood flow to/away from brain; congenital vascular anomalies
- BRUISING/LOCALIZED BLEEDING
^ if this occurred in your leg it wouldn't be a big deal -->
IF THIS OCCURS IN YOUR BRAIN --> bleeding in brain is always problematic; especially if it involves arteries
Surgical treatment for ischemic stroke
insert catheter into artery & pulls out clots but also prevents emboli from breaking off & traveling throughout arteries
What happens to bridging veins when there is low CSF pressure?
the brain relies on a normal CSF pressure in the brain to properly float within the fluid
if CSF pressure is low: brain cannot comfortably float inside the CSF so it SAGS & PULLS ON BRIDGING VEINS --> headaches!!
Why are there less risks associated with venous blood flow than arterial blood flow?
venous bloodflow brings blood AWAY from brain; meaning the brain is not reliant on receiving blood from venous flow system; there will just be backup which can resolve over time & is less fatal
Arterial flow vs. Venous flow
- Arterial flow: like arteries, brings blood TO BRAIN & away from heart
- Venous flow: brings blood AWAY FROM BRAIN & to heart; drainage system of the brain (sinuses!!)
What happens at the capillary level between arteries & veins?
oxygen exchange, CO2 is taken out & O2 is put into the cell then transported through venuoles to the veins
Surgical treatment for hemorrhagic stroke
1) clip a ruptured aneurysm so the vessel wall will scar down & not bleed anymore
2) non-invasively insert a coil to PROMOTE CLOTTING so vessel wall doesn't burst & bleed out