Summary of Intracerebral hemorrhage
Transcript for Intracerebral hemorrhage
Content Reviewers:Rishi Desai, MD, MPH, Yifan Xiao, MD, Vincent Waldman, PhD, Kyle Slinn, RN, BScN, MEd, Evan Debevec-McKenney
There are two main types of stroke: a hemorrhagic stroke, which occurs when an artery ruptures and bleeds within the brain, and an ischemic stroke, which occurs when an artery gets blocked.
Hemorrhagic strokes can be further split into two types, an intracerebral hemorrhage which is when bleeding occurs within the cerebrum, and a subarachnoid hemorrhage which is when bleeding occurs between the pia mater and arachnoid mater of the meninges - the inner and middle layers that wrap around the brain.
We’ll be focusing on intracerebral hemorrhages which are more common.
An intracerebral hemorrhage that involves just the brain tissue is called an intraparenchymal hemorrhage, whereas if the blood extends into the ventricles of the brain which store cerebrospinal fluid, it’s called an intraventricular hemorrhage.
OK - let’s start with some basic brain anatomy. The brain has a few regions - the most obvious is the cerebrum, which is divided into two cerebral hemispheres, each of which has a cortex - an outer region - divided into four lobes including the frontal lobe, parietal lobe, temporal lobe, and the occipital lobe.
There are also a number of additional structures - including the cerebellum, which is down below, as well as the brainstem which connects to the spinal cord.
The right cerebrum controls muscles on the left side of your body and vice versa.
The frontal lobe controls movement, and executive function, which is our ability to make decisions.
The parietal lobe processes sensory information, which lets us locate exactly where we are physically and guides movements in a three-dimensional space.
The temporal lobe plays a role in hearing, smell, and memory, as well as visual recognition of faces and languages.
Finally, there’s the occipital lobe which is primarily responsible for vision.
Within the cortex are deeper structures like the internal capsule, which is like a highway that allows information to flow through neurons that are going to and from the cerebral cortex.
There’s also the basal ganglia, which helps controls smooth movement and cognitive function, along with the cerebellum.
The cerebellum also helps with muscle coordination and balance.
And finally, there’s the brainstem, which plays a vital role in functions like heart rate, blood pressure, breathing, intestinal motility, and consciousness.
The brain receives blood from the left and right internal carotid arteries, as well as the left and right vertebral arteries, which come together to form the basilar artery.
The internal carotid arteries turn into the left and right middle cerebral arteries which serve the lateral portions of the frontal, parietal, and temporal lobes of the brain.
Each of the internal carotid arteries also give off branches called the anterior cerebral arteries which serve the medial portion of the frontal and parietal lobes and connect with one another with a short little connecting blood vessel called the anterior communicating artery.
Meanwhile, the vertebral arteries and basilar artery give off branches to supply the cerebellum and the brainstem.
In addition, the basilar artery divides to become the right and left posterior cerebral artery which mainly serve the occipital lobe and some of the temporal lobe as well as the thalamus.
Finally, the internal carotid arteries each give off a branch called the posterior communicating artery which attaches to the posterior arteries on each side.
So together, the main arteries and the communicating arteries complete what’s called the Circle of Willis - a ring where blood can circulate from one side to the other in case of a blockage.
There are a few ways that an intracerebral hemorrhage might happen. The most common one is through hypertension or high blood pressure.
Hypertension can lead to various vessel wall abnormalities.
Hypertension can lead to hyaline arteriolosclerosis, which results from hydrostatic pressure pushing proteins out of the blood vessel lumen and into the interstitial space within the blood vessel walls. Over time as more of these proteins deposit in the walls, the blood vessels become more stiff and brittle, and therefore more vulnerable to rupture.