Epidural hematoma

Definitions & Key takeaways

An epidural hematoma is a collection of blood above the dural mater, usually due to a head trauma. When blood accumulates in this space, it can result in raised intracranial pressure, damaging delicate nerve cells.

Epidural hematomas are most commonly caused by head injuries, such as those sustained in car accidents or falls. They can also be associated with childbirth (in newborns), cancer, or certain medical procedures. Symptoms vary depending on the size and location of the hematoma, but may include a headache, nausea and vomiting, loss of consciousness, seizures, or paralysis.

Chapters:

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Introduction0:00–0:21

Epidural hemorrhage can be broken down. "Epi" means above, "dural" refers to the outermost protective layer of the brain, which is called dura mater and and “hemorrhage” refers to bleeding.
So, an epidural hemorrhage is when there’s bleeding above the dura mater. OK - let’s start with some basic brain anatomy.

Physiology0:21–1:54

The brain is protected by the meninges, which are 3 thin layers of tissue which cover the brain and spinal cord. The inner layer of the meninges is the pia mater, the middle layer is the arachnoid mater, and the outer layer is the dura mater.
The pia and arachnoid maters, are also called leptomeninges. Between the leptomeninges, there’s the subarachnoid space, which houses cerebrospinal fluid, or CSF.
CSF is a clear, watery liquid which is pumped around the spinal cord and brain, cushioning them from impact and bathing them in nutrients.
The outer membrane, the dura mater consists of two layers. The internal layer of the dura mater lies above the arachnoid mater - the two are separated by the subdural space.
The external layer of the dura mater adheres to the inner surface of the skull. These two layers of the dura mater travel together, but at certain spots, the internal layer of the dura mater separates from the external one to form the meningeal folds.
The meningeal folds help divide the sections of the brain like the falx cerebri which separates the two hemispheres of the cerebrum, and the tentorium, which covers the cerebellum and separates it from the cerebrum.
Between the external layer of the dura mater and the inner surface of the skull, there are arteries that supply meninges.

Pathology1:54–2:56

The most common cause of epidural hemorrhage is a head trauma which might happen after tripping and falling in a bathtub.
The meningeal arteries are protected by the skull but can be damaged by a serious head trauma. The most common site is at the pterion which is the spot where the frontal, parietal, temporal and sphenoid bones join together.
This section of the skull is relatively thin and it’s located right above the middle meningeal artery. When a blood vessel is damaged and there’s active bleeding, it’s called a hemorrhage, and the collection of blood that results is called a hematoma.
In the case of an epidural hemorrhage, once a meningeal artery is torn, blood will pool between the skull and the external layer of the dura mater, separating it from the inner surface of the skull.
The blood builds up between the skull and the outer layer of the dura mater but cannot cross the suture lines where the dura mater adheres more tightly.

Symptoms2:56–4:29

If blood accumulates slowly, there may be a lucid interval which is when several hours pass before the onset of symptoms.
A large epidural hematoma on one side of the skull can cause a midline shift which is a displacement of the whole brain towards the opposite side of the skull.
A large epidural hematoma can also cause an increase in intracranial pressure, and that can cause the brain to shift or herniate.
There can be a supratentorial herniation where the cerebrum is pushed against the skull or the tentorium, and an infratentorial herniation where the cerebellum is pushed against the brainstem.
Both of these can be lethal. Supratentorial herniations can compress the arteries that nourish the brain leading to an ischemic stroke, and infratentorial herniations can compress part of the brainstem affecting consciousness, respiration, and heart rate.
The most common symptom of a epidural hemorrhage is loss of consciousness after the head trauma due to a concussion. In a slow epidural bleed, people might have a lucid interval which is when they improve temporarily right after the initial trauma, but then deteriorate as the epidural hematoma grows.
There can also be headaches and vomiting, as well as focal neurological symptoms like muscle weakness or sensory problems depending on the location of the hematoma.

Diagnosis4:29–5:33

Diagnosis of an epidural hemorrhage is typically done with an imaging study. On a CT scan, an epidural hematoma shows up as a hyperdense mass meaning that it looks “more white” than the surrounding healthy brain tissue.
Here’s a CT scan of an intracranial epidural bleeding. On the left of the skull, there’s a fracture, and underlying it is a hematoma, with the characteristic biconvex shape, meaning that it’s curved on both sides.
Epidural hemorrhages cause blood to build up between the outer layer of the dura mater and the skull. Since the outer layer of the dura mater adheres tightly to the skull at sutures, epidural hematomas don’t cross suture lines and they push on the brain forming a biconvex shape.
In contrast, the blood in a subdural hemorrhage is between the inner and outer layers of the dura mater. So on a CT scan, subdural hematomas follow the contour of the brain and form a crescent-shape and cross suture lines.

Treatment5:33–5:46

Most epidural hemorrhages are treated by craniotomy, which is when part of the skull bone is removed in order to remove accumulated blood below.
Alright, as a quick recap. An epidural hemorrhage is a bleeding above the dura mater caused by a head trauma most commonly in the temporal region called pterion, which lies above the middle meningeal artery.

Review5:46–6:21

A slow-forming epidural hemorrhage can cause a lucid interval where a person initially seems to improve before deteriorating again.
On a CT scan, epidural hematomas don’t cross suture lines and push on the brain forming a biconvex shape, unlike subdural hematomas cross suture lines and follow the contour of the brain forming a crescent-shape.