Types of Brain Injuries

Mild TBI (concussion)

• Temporary disruption of brain function
• May or may not involve loss of consciousness
• Common symptoms: headache, dizziness, confusion, memory or concentration problems
• Most people recover within weeks, though some develop persistent symptoms

Moderate TBI

• Loss of consciousness lasting minutes to hours
• Confusion lasting days or weeks
• Brain imaging often shows structural damage
• Symptoms may include weakness, speech problems, memory loss, and behavioral changes

Severe TBI

• Extended loss of consciousness or coma
• Significant brain damage visible on imaging
• Long‑term or permanent physical, cognitive, or emotional impairments are common

Closed (blunt) head injury

• The skull remains intact
• Brain is injured by rapid movement inside the skull
• Common causes: falls, car accidents, sports injuries

Open (penetrating) head injury

• An object breaks through the skull and enters brain tissue
• Common causes: gunshot wounds and shrapnel injuries
• Often causes focal, localized brain damage

Acceleration–deceleration Injury

• Brain shifts rapidly due to sudden stopping or rotation
• Common in high‑speed motor vehicle crashes
• Often associated with diffuse axonal injury

Blast injury

• Caused by pressure waves from explosions
• Common in military and industrial settings
• May involve a combination of blunt, penetrating, and oxygen‑related injuries

These are the named injury patterns doctors frequently diagnose.

Concussion

• Concussions are the most common and mildest form of TBI
• Caused by a blow or sudden jolt to the head
• Symptoms are typically functional rather than structural

Contusion

• A bruise on the brain tissue
• Often occurs at the site of impact
• May coexist with other injuries

Diffuse axonal injury (DAI)

• Widespread tearing of nerve fibers (axons)
• Caused by rotational or shearing forces
• One of the most severe forms of TBI
• Often results in a prolonged coma

Coup–contrecoup injury

• Brain injury occurs at the point of impact (coup) and on the opposite side (contrecoup)
• Caused by the brain rebounding inside the skull

Hematomas (bleeding injuries)

• Collections of blood that increase pressure on the brain:
  • Epidural hematoma – between the skull and dura mater
  • Subdural hematoma – between the dura and arachnoid membranes
  • Intracerebral hematoma – bleeding within the brain tissue itself

Primary TBI

• Occurs at the moment of impact
• Includes contusions, lacerations, axonal injury, and bleeding

Secondary TBI

• Develops hours or days later
• Caused by swelling, reduced blood flow, lack of oxygen, or increased intracranial pressure
• Often determines long‑term outcome

• Stroke: A stroke results from either an interruption of blood flow to the brain (ischemic) or bleeding within the brain (hemorrhagic).
• Anoxic or hypoxic brain injuries: Complete absence or reduced oxygen to the brain, from causes like cardiac arrest, suffocation/drowning, respiratory failure, or carbon monoxide.
• Infections: Infections such as meningitis and encephalitis can cause brain injury by leading to swelling of the tissues around the brain or the brain itself.
• Brain tumors: Benign or malignant masses can compress or infiltrate brain structures and cause functional loss.
• Toxic/metabolic: Exposure to toxins (e.g., CO) or systemic metabolic failure (hepatic/renal) can impair brain function.

The Rancho Los Amigos Scale (Revised) describes patterns of cognitive‑behavioral recovery during rehabilitation. It includes 10 levels that help teams and families understand progress and guide therapy planning.

• Level 1: No response – patient appears to be in a deep sleep and does not respond to voices, sounds, light, or touch.
• Level 2: Generalized response – patient reacts inconsistently and non-purposefully to stimuli; may open eyes but not focus on anything in particular.
• Level 3: Localized response – patient’s responses are purposeful but inconsistent; may follow simple commands.
• Level 4: Confused, agitated – patient is in a heightened state of activity; behavior may be bizarre or aggressive.
• Level 5: Confused, inappropriate, non-agitated – patient responds to simple commands but is easily distracted; may be verbally inappropriate.
• Level 6: Confused-appropriate – patient follows simple directions consistently; some awareness of self and others.
• Level 7: Automatic-appropriate – patient goes through daily routine automatically; poor insight into condition.
• Level 8: Purposeful-appropriate – patient is alert, oriented, and capable of learning new activities; may still have deficits in judgment and reasoning.
• Level 9: Purposeful-appropriate (standby assistance) – patient can shift between tasks independently; may require assistance to anticipate problems.
• Level 10: Purposeful-appropriate (modified independent) – patient can handle multiple tasks but may require periodic breaks; irritability may persist.

The Glasgow Coma Scale (GCS) is used to measure the initial responses or lack of responses to determine the level of brain injury. It assesses three key areas:

• Best Eye Response (1-4): No eye opening to eyes opening spontaneously.
• Best Verbal Response (1-5): No verbal response to being fully oriented.
• Best Motor Response (1-6): No motor response to obeying commands.

The total score ranges from 3 to 15, with lower scores indicating more severe impairments.