Learn about the different types of brain injuries


Types of Brain Injuries

We have compiled these resources and education materials on the different types of brain injuries to help you and your loved ones better understand life with a traumatic brain injury.

Our compassionate personal injury lawyers in Vancouver, BC have significant experience conducting brain injury litigation in Canada, and have found that educating survivors and their families on brain injuries helps create a stronger support network around the survivor and greatly assists with their recovery.

Should you have any specific questions that are not covered here, don’t hesitate to contact us at 604 713 8030 or 1 877 873 0699 (toll free).

General Brain and Head Injury Terminology:

Acquired Brain Injury (ABI)

Acquired brain injury (ABI) is brain damage caused by events after birth, rather than congenital or neurodegenerative disorders. ABI includes both traumatic brain injury (physical trauma due to accidents, assaults and neurosurgery, for example) and non-traumatic brain injury (caused by strokes, brain tumours, infection, poisoning, hypoxia, ischemia, encephalopathy or substance abuse).

Traumatic Brain Injury (TBI)

Traumatic brain injury (TBI) is any injury to the brain that results in structural damage to brain tissue and/or disrupted brain function. The injury may be caused by direct trauma (blunt force) or indirect trauma (whiplash or inhalation of toxic fumes) to the brain. TBI can vary in degree – mild, moderate and severe – and can cause temporary or permanent impairment. The damage may occur at the time of the injury or may develop later due to swelling and bleeding inside the head. All but “mild” TBI is usually accompanied by an immediate loss of consciousness (coma) and post-traumatic amnesia.

Mild Traumatic Brain Injury (MTBI)

Unlike moderate or severe traumatic injury, where the impairments caused by the injury are rarely doubted, mild brain injury often goes unrecognized and is sometimes never detected. The injured individual may not be aware of the extent of their injuries until they attempt to return to normal living and even then may not be able to determine why things don’t seem “normal.”

An injured survivor with mild traumatic brain injury suffers from a disruption of brain function, which may include a brief loss of consciousness, loss of memory of events immediately before or following the accident, an alteration of mental state at the time of the accident, or focal neurological deficits.

Determining and establishing the extent of the injury, whether it is permanent or temporary, and what difficulties will persist or worsen in the future, is very difficult. If not immediately diagnosed, the evidence for mild brain injury must be reconstructed. This is difficult but not usually impossible. Success is more likely to occur when the survivor has a strong, helpful family. Legal action in these cases often revolves around ‘causation’ or other possible causes of the brain injury. Read more about the symptoms of mild traumatic brain injury (MBTI).

Head Injury

Traumatic Brain Injury (TBI) is a subset of “head injury.” The terms “head injury” and “brain injury” are often used incorrectly and interchangeably. Head injuries are caused by trauma to the head, skull or scalp, but do not always result in injury to the brain itself.

Specific Brain and Head Injury Terminology:

Closed Head Injury

Some brain injuries are “closed head injuries,” where the skull has not been penetrated or fractured into brain tissue. Though survivors may not exhibit external signs of injury, a closed head injury can cause widespread damage and result in extensive, or “global,” neurological deficits. The injury can also be categorized as ‘mild,’ ‘moderate’ or ‘severe.’ These deficits can range from partial to complete paralysis; cognitive, behavioural and memory dysfunction; a persistent vegetative state; or death.

Skull Fracture

Skull fracture is a break in the bone that surrounds the brain. The fracture may heal on its own or, if there is tissue damage below the fracture, require remedial surgery. A skull fracture can be depressed, meaning part of the skull is pushed into the brain, but even a non-depressed skull fracture is very serious.

Anoxic Brain Injury

An anoxic brain injury is caused by a lack of oxygen to the brain. It usually results from lack of blood flow due to injury or bleeding and will cause the swelling of brain tissue. It may be secondary to trauma, accident, or sometimes medical malpractice.


Contusion or concussion is often mislabeled a “mild” injury to the brain resulting in bruising of brain tissue. This injury may cause headaches, vomiting, dizziness and problems with memory or concentration. It does not require surgery. While there is often little or no loss of consciousness, the long-term results may not be “mild.”


A coup injury is caused when the brain is thrust against one side of the skull. Because brain tissue is suspended in fluid, it often rebounds and collides with the opposite side of the skull. When it strikes both sides of the skull, the injury is sometimes called a coup-contrecoup injury.

Diffuse Axonal Injury (DAI)

Diffuse axonal injury (DAI) results when a rotational or shearing force is exerted on the nerve fibres. DAI may cause a loss of consciousness, or coma, which may last from a short time to an indefinite period.

The rotational force of this injury causes a shearing of the nerve connections and pathways. These pathways may tear and be lost, and once they are gone they cannot be rebuilt. The brain must then attempt to find alternate pathways to resume the functions of the severed paths.

DAI can be particularly devastating, because the brain stem is a critical relay station. It controls consciousness, alertness and basic bodily functions. Especially frustrating is that these injuries are microscopic and usually cannot be detected in radiographic studies, such as CT scans or routine MRI scans. Fortunately, improving technology is allowing DIA to be shown in higher resolution MRI scans.

Hematoma (epidural and subdural)

Epidural hematoma is a build-up of blood between the skull and the top lining of the brain (dura). This clot may cause pressure changes in the brain, and emergency surgery may be necessary. Surgery may be needed depending on the size of the clot. This bleeding may increase pressure on the brain, which forces it down the spinal column, compressing the brain stem and resulting in death. This is a neurosurgical emergency.

An intra-cerebral hemorrhage is a blood clot deep in the middle of the brain that is hard to remove. Pressure from this clot may cause tissue damage, and surgery may be needed to relieve the pressure.

A subdural hematoma refers to the formation of a blood clot between the brain tissue and the dura. If it occurs slowly over several weeks it is referred to as a subdural hematoma; if it occurs quickly it is referred to an acute subdural hematoma. The clot may cause pressure and need surgery to have it removed.


When the injured survivor cannot be awakened or aroused by any means, they are in a state of unconsciousness known as a coma. Clinically described, it is an inability to follow a one-step command consistently. This term, as well as the description ‘loss of consciousness,’ are used colloquially and incorrectly all the time. Court cases may involve arguments about the legal definitions of these terms.

Post Traumatic Amnesia (PTA)

Immediately after a TBI, the injured person is often disoriented and unable to remember events that occur after the injury. This state of confusion is called post-traumatic amnesia (PTA). The person may not remember their name, where they are, and what time it is. When continuous memory returns, PTA is considered to have resolved. If PTA lasts, new events cannot be stored in the memory. During PTA, the individual’s consciousness is “clouded.”

There are two types of amnesia: retrograde amnesia (loss of memories that were formed shortly before the injury) and anterograde amnesia (problems with creating new memories after the injury has taken place). Both retrograde and anterograde forms may be referred to as PTA, or the term may be used to refer only to anterograde amnesia.

The duration of PTA is sometimes used, on its own or in conjunction with the Glasgow Coma Scale and other methods, to measure the severity of traumatic brain injury. It is important to note that even a “very mild” injury may have long-term, serious consequences for a survivor.

PTA less than 5 minutes: Very mild

5 to 60 minutes: Mild

1 to 24 hours: Moderate

1 to 7 days: Severe

1 to 4 weeks: Very severe

More than 4 weeks: Extremely severe

Glasgow Coma Scale

The Glasgow Coma Scale (GCS) rates the brain injury survivor’s ability to open their eyes and respond to verbal commands and motor stimuli. Each level indicates a level of brain injury. The lowest possible cumulative score for the four sections is 3 (no response); the alert and oriented survivor is rated at 15.

A Glasgow Coma Scale (GCS) of:

3 to 8 indicates a severe brain injury

9 to 12 a moderate brain injury

13 to 15 a mild brain injury

Read about symptoms and treatment of traumatic brain injuries.

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