Types of Traumatic Brain Injury

There Are Many Different Ways to Injure the Brain

Unequal Pupils
Unequal pupils can be a sign of traumatic brain injury or an injury to one eye. It can be from a harmless condition called aniscoria, or it can be from an eye doctor appointment, like this is. (c) Deborah Austin

There are several types of traumatic brain injury, but they all fall into just two categories: closed or penetrating. Closed head injuries refer to being hit on the head hard enough to injure the brain without touching it directly. This kind of traumatic brain injury doesn't have to come from a direct hit, either. It can come from shockwaves, like an explosion, or from being shaken violently, like shaken baby syndrome.

Penetrating brain injuries are from such things as gunshot wounds and impaled objects. Penetrating brain injuries are less common than closed head injuries and much more straightforward: Something enters the skull and directly damages the brain tissue.

Closed Traumatic Brain Injuries

Closed head injuries are more complicated and have several different presentations (patterns of signs and symptoms). These are the different types of closed traumatic brain injury:

  • Concussions: These are the most common type of traumatic brain injury. Not too much is known about how concussions work. While concussions are generally considered minor, suffering multiple concussions has been linked to an increased chance of brain conditions later in life.
  • Epidural hematomas: These are the most deadly type of traumatic brain injury. Epidural hematomas occur when blood accumulates between the hard covering of the brain and the skull, rapidly putting pressure on the brain. At first, because of the way victims of epidural hematomas respond, it might be difficult to tell the difference between an epidural hematoma and a concussion.
  • Subdural hematomas: Subdural hematomas are similar to epidural hematomas, but they often don't cause noticeable neurological problems as quickly or dramatically. In this case, blood seeps more slowly below the hard covering of the brain, taking more time to build up pressure. Subdural hematomas are more common in those taking blood thinners and those with alcoholism.
  • Cerebral aneurysm: A cerebral aneurysm is a weak blood vessel in the brain that can burst unexpectedly. Aneurysms may rupture during times of stress or with trauma to the head, but often there is no way to determine why an aneurysm ruptures. When an aneurysm ruptures spontaneously, it's commonly called a hemorrhagic stroke.

The differences in signs and symptoms between each type of traumatic brain injury are subtle. Diagnosing is almost impossible without specialized equipment. First aid is pretty much the same for all types of traumatic brain injury.

Sources:

Ala-Seppälä H, et al. Injury Profiles, Demography and Representativeness of Patients With TBI Attending a Regional Emergency Department. Brain Inj. 2016 Jun 13:1-6. [Epub ahead of print]

Huisman TA, Poretti A. Trauma. Handb Clin Neurol. 2016;136:1199-220. doi: 10.1016/B978-0-444-53486-6.00062-4.

Esnault P, et al. Blunt Cerebrovascular Injuries in Severe Traumatic Brain Injury: Incidence, Risk Factors, and Evolution. J Neurosurg. 2016 Jul 29:1-7. [Epub ahead of print]

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