USMLE® Step 1 style questions USMLE
An 82-year-old woman is brought to the emergency department for evaluation of sudden onset left-sided weakness and lethargy. The patient lives at home with her son, who found the patient lethargic and unable to move the left side of her body. The son states over the past year, the patient has been forgetting names of common people as well as losing her abilities to perform activities of daily living. She recently became lost in the parking lot of a grocery store she has been shopping at for decades. She has no past medical history. Her temperature is 37°C (98.6°F), pulse is 101/min and regular, and blood pressure is 171/94 mmHg. The patient appears somnolent but is arousable to voice and pain. Physical examination reveals marked weakness of the left upper and left lower extremity with associated decreased sensation in the left arm and leg. The patient’s eyes are currently deviated towards the right. A noncontrast CT of the head is shown below:
Reproduced from: Radiopaedia
Which of the following best describes the most likely etiology of this patient’s clinical presentation?
Intracerebral hemorrhage exam links
Content Reviewers:Rishi Desai, MD, MPH, Yifan Xiao, MD
Contributors:Vincent Waldman, PhD, Evan Debevec-McKenney, Filip Vasiljević, MD
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.
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