Types of Traumatic Brain Injury

There are many types of traumatic brain injury (TBI), or a sudden injury that causes damage to the brain, and they fall into two categories: either closed or penetrating.

Closed injuries occur when the head experiences a bump or blow and nothing enters the skull. Penetrating, or open, head injuries occur when something enters the skull, like a bullet or knife.

Symptoms of a traumatic brain injury can vary and are classified as mild, moderate, or severe.

This article explains types of traumatic brain injuries. It will also discuss potential causes and symptoms.

Closed Traumatic Brain Injuries

Closed head injuries may result from a blow to the head, shaking, or a forceful back-and-forth movement. With this type of injury, the brain moves around within the skull, which can lead to bruising, internal bleeding, and brain tissue tears.

Concussions

Concussions are the most common type of traumatic brain injury and are typically caused by a bump or blow to the head. This can cause the brain to move around in the skull, which leads to damage.

Symptoms of a concussion tend to show up shortly after the injury. However, it is possible for symptoms to show up days later. Most individuals recover within a few weeks, but it can take longer.

Concussions are generally considered mild, or not life-threatening. However, experiencing multiple concussions has been linked to an increased chance of brain conditions later in life.

Coup Contrecoup

A coup contrecoup injury describes a brain injury where the site of the trauma and opposite side of the brain experience damage. Coup refers to the injury at the site of trauma and contrecoup refers the injury on the opposite side of the brain. The contrecoup injury is often worse than the coup injury and may involve a hemorrhagic contusion, which is when there is bleeding inside of the brain.

This type of TBI occurs when a blow is strong enough to cause the brain to hit the opposite side of the skull. Because this type of injury impacts two areas of the brain, it can lead to more severe injuries and symptoms.

Skull Fracture

Skull fractures describe a break in the skull bone.

There are several types:

• Linear skull fracture: This describes a break in the skull bone without the bone moving or being displaced. This is the most common skull fracture.
• Depressed skull fracture: This describes when part of the skull becomes sunken due to injury.
• Basilar skull fracture: This describes a break in the bone at the skull's base. This is the most severe type of skull fracture.

Contusions

A contusion describes a bruise in the brain that occurs due to direct trauma to the head. This can cause bleeding and swelling.

Contusions may occur along with other injuries like a skull fracture or a hematoma, which is a pooling of blood outside of the blood vessel.

Diffuse Axonal Injury (DAI)

DAI describes the tearing of the brain's axons, which carry nerve signals away from one nerve cell to another. This can occur if the brain moves around or shakes in the skull due to a head injury.

DAI can lead to damage to several areas of the brain, or a coma, which is unconsciousness for a prolonged period of time.

Epidural Hematomas

Epidural hematomas occur when blood accumulates between the dura, the outermost layer of tissue covering the brain, and the skull. These hematomas rapidly put pressure on the brain.

These blood clots are typically caused by skull fractures.

Subdural Hematomas

With subdural hematomas, blood seeps below the hard covering of the brain, and pressure builds up. These blood clots are associated with skull fractures, as well as deadly head injuries. "Subdural" means the bleeding is between the dura and the brain.

Because the bleeding can occur quickly, this injury can lead to death. Blood thinning medications, alcohol use, and multiple head injuries increase the risk for this condition.

Penetrating Brain Injury

Penetrating brain injuries can occur as a result of gunshot wounds and impaled objects. With this type of injury, something enters the skull and directly damages the brain tissue.

Open head injuries may include penetrating skull fractures, like a depressed skull fracture in some cases, that occur when the injury involves a cut or wound on the head.

Primary vs. Secondary Brain Injury

A primary brain injury is the damage that occurs during the moment of the injury. For example, in a car accident, this is the brain injury that occurs upon impact.

A secondary brain injury develops as a result of the primary injury. A secondary injury can occur within hours, days, or weeks of the primary injury.

Examples of secondary brain injury include:

• Poor blood flow to the brain tissue
• Brain swelling
• Low or high blood pressure
• Increased skull pressure

What Are Causes of Traumatic Brain Injury?

A TBI may be caused by:

• Falls
• Car crashes
• Gun-related injury
• Intimate partner violence, child abuse, and other assaults
• Sports injuries

Symptoms of Mild, Moderate, and Severe TBI

Symptoms will vary depending on the specific injury and its severity.

Symptoms of a mild TBI may include:

• Headache
• Confusion
• Feeling dizzy and lightheaded
• Blurry vision
• Fatigue or exhaustion
• Loss of consciousness
• Change in mood, behavior, or sleep
• Difficulty focusing and remembering information

Moderate to severe symptoms of TBI may include mild symptoms, as well as vomiting, seizures, movement and speech difficulties, eye changes, coma, and in some cases death.

Summary

Traumatic brain injuries can be either closed or open. Closed injuries are non-penetrating and occur when the head experiences a blow, bump, or forceful back-and-forth movement. Open injuries occur when something penetrates the skull, like a bullet or knife.

Causes can vary and may include assault, falls, sports injuries, and car accidents. Symptoms will vary depending on the severity of the injury.