Most of the time, blood will flow through the circle of Willis without interruption.
Anatomy of the Circle of Willis
The circle of Willis is made of up arteries.
Arteries are the blood vessels that transport oxygenated blood from the heart to tissues throughout the body.
Phil Boorman / Getty Images
The circle of Willis is a relatively small, symmetrical structure with a circumference of just a few centimeters.
Each blood vessel in the circle has a diameter of between 1.5 and 2.5 millimeters.
This is when blood flow is redirected whenever there is an obstruction of any sort.
This can limit the damage caused during serious events like stroke.
One of the more common variations is the absence of a posterior communicating artery.
A blockage of the ICA can cause problems on both sides of the brain.
Not every variation has serious consequences or any consequences at all.
These include variations where communicating arteries are duplicated or split into multiple branches.
These can still provide collateral circulation in the event of arterial ischemia or stenosis.
Brain Aneurysm
Abrain aneurysmis a defect in which an artery in the brain develops a bulging pouch.
The bulge can press on certain nerves, causing them to malfunction.
Pressure on the pituitary gland can cause the overproduction or underproduction of hormones that keep the body functioning normally.
A bigger concern is the spontaneous rupture of an aneurysm.
The loss of blood causes tissues to die, leading tosymptoms of a stroke.
Most cases are relatively mild, but some may require medical intervention.
For other defects, less invasive procedures likeangioplastyandstentingmay help reverse stenosis.
Thereafter, you may require extensive rehabilitation depending on which blood vessels are affected.
For example, if you have had a stroke of the ACA, you may need morecognitive rehabilitation.
If you had a stroke affecting the PCA, you may need moremotor rehabilitation.
If this occurs, blood can be rerouted so that damage to brain tissues is avoided or reduced.
Certain medical conditions can affect the circle of Willis and cause the system to break down.
These include stroke, brain aneurysms, traumatic brain injuries, and subclavian steal syndrome.
Certain treatments can limit the damage or avoid more serious complications.
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