Epidural hematomas (EDH) and subdural hematomas are two common wounds that you can get as a result of a head injury. In this article, you’ll learn about some of the commonalities between them and their major differences.
Before diving in, you’ll need to learn a few medical terms.
What Is a Hematoma?
A hematoma is a pool of blood somewhere in your body where it shouldn’t be (outside of your blood vessels). You’re already familiar with one of the most common types of hematomas: a bruise.
A bruise is usually the result of an injury that didn’t rupture your skin—but did damage your blood vessels underneath your skin.
Depending on a wide range of factors—like how bad the injury was, your age, and how healthy you are—a hematoma can resolve all on its own, or it can be life-threatening and require emergency surgery.
Epidural and subdural hematomas are pools of blood that have collected in different areas of your meninges—the 3 membranes that sit between your skull and your brain.
What Are the Meninges? Understanding the Membrane Between Your Brain and Your Skull
Your skull isn’t the only thing protecting your brain—three membranes surround and protect both your brain and your spinal cord. A membrane is just a thin sheet of tissue.
These membranes are known as meninges, and all three of them have unique structures, functions, and names.
Dura Mater—The Outer Layer
The outermost membrane is known as dura mater. This membrane is very thick and strong. It attaches to your skull and the middle membrane, and it protects your brain by anchoring it to your skull and absorbing the force of a blow to your head.
Arachnoid Mater—The Middle Layer
The middle membrane is known as arachnoid mater, and it also plays a protective role—it forms a small space (the subarachnoid space) around your brain that contains cerebrospinal fluid. That fluid also absorbs the force of blows to your head, though it has many other functions.
Pia Mater—The Innermost Layer
Finally, the inner layer is known as the pia mater, a very thin membrane that’s wrapped tightly around your brain, almost like plastic wrap. This final layer has a minor protective role—its main function is to get blood and oxygen into your brain.
Epidural and subdural hematomas are pools of blood that appear between these different layers.
What Is an Epidural Hematoma?
An epidural hematoma (EDH) is blood that’s collected between your skull and your dura mater, usually due to a rupture in an artery. When an EDH gets large enough, it starts to press on your brain.
This increases the general pressure inside your head (known as intracranial pressure), which can injure your brain. EDHs can grow very quickly because arteries bleed fast—they have much higher pressure than veins.
EDHs are usually caused by some sort of head trauma that has fractured your skull. The initial trauma damages your brain and causes the bleeding, and if the bleeding doesn’t stop, the epidural hematoma grows, putting more and more pressure on your brain.
This can be life-threatening and may require emergency surgery to reduce the pressure on your skull. They’re more common in young people (between 20 and 30 years old) because their dura mater is not attached as securely to their skull as someone older or younger.
Some common symptoms of an epidural hematoma include:
- Feeling dizzy, sleepy, and/or confused
- Headaches, nausea, and/or vomiting
- Having a single enlarged pupil (just one eye)
- Weakness in your body (on the opposite side of your enlarged pupil)
Another common symptom is losing consciousness, regaining it and seeming to be alert, and then starting to lose consciousness again. As the hematoma develops and presses down on your brain, it causes that second period of unconsciousness.
What Is a Subdural Hematoma?
A subdural hematoma (SDH) is pooling of blood between your dura mater and your arachnoid mater (this area is called the subdural space). Normally, this space doesn’t exist at all—the two layers are pressed against each other.
Because there are so many veins running between your dura mater and your arachnoid mater, damage to one of those veins from a head injury or TBI can cause those veins to bleed. The pooling blood then pushes the two layers apart from each other, forming the subdural space.
Subdural hematomas have many of the same symptoms as epidural hematomas, as listed in the previous section. However, there are some major differences.
Epidural vs. Subdural Hematomas: The Major Differences
For epidural vs. subdural hematomas, one of the first major differences is how quickly they develop.
Acute vs. Chronic
Epidural hematomas are almost always an immediate medical emergency—that’s because of how quickly your arteries bleed when they’re damaged. In medical terminology, we call this acute—something that happens suddenly and develops rapidly
A subdural hematoma, on the other hand, might take weeks to become severe. When an SDH is chronic—it happens slowly over time—it might take 3 weeks or more to result in symptoms. That said, it’s still possible for them to be acute.
Skull Fractures
A skull fracture is associated with around 90% of epidural hematomas. Subdural hematomas have no direct association—they can happen during any type of traumatic brain injury, whether your skull was fractured or not.
Location
Traumatic brain injuries are often described using the terms coup and countrecoup to indicate which part of the brain was damaged. Coup is an injury to your brain right underneath the point of impact.
Countrecoup is when your brain is injured on the opposite side of the impact—basically, the impact caused your brain to hit the opposite side of your skull, and that secondary impact caused the damage.
Epidural hematomas are usually on the coup side—right where you got hit.
On the other hand, subdural hematomas are usually on the contrecoup side—the opposite side of where you were hit.
Treatment and Imaging
As mentioned, epidural hematomas are almost always emergencies and require immediate surgery to reduce the pressure on your brain and control the bleeding. CT scans are the preferred method for diagnosing them—they’re much faster than an MRI and can quickly show the damage.
Subdural hematomas might require emergency surgery, but if they’re chronic, doctors may be more conservative. It’s even possible they’ll heal on their own.
MRI scans are usually used—the weeks an SDH takes to develop allow for an MRI, which is more sensitive and can see certain types of SDHs more accurately.
If You’ve had an Epidural or Subdural Hematoma, We’re Here to Help
If you’ve had a head injury of any sort—including epidural and subdural hematomas—we’re here to help.
Click here to contact us today and schedule a free consultation. We’ll talk about your injury, the symptoms you’re struggling with, and how we can help.
