Thursday, March 16, 2023
HomePhysical Medicine and RehabilitationTraumatic Brain Injury (TBI) - Definition, Epidemiology, Pathophysiology

Traumatic Brain Injury (TBI) – Definition, Epidemiology, Pathophysiology



Traumatic brain injury (TBI) is a nondegenerative, noncongenital insult to the brain from an external mechanical force, possibly leading to permanent or temporary impairment of cognitive, physical, and psychosocial functions, with an associated diminished or altered state of consciousness.

The definition of TBI has not been consistent and tends to vary according to specialties and circumstances. Often, the term brain injury is used synonymously with head injury, which may not be associated with neurologic deficits. The definition also has been problematic with variations in inclusion criteria.

See Posttraumatic Stress Disorder (PTSD), a Critical Images slideshow, to help recognize the symptoms of PTSD and to determine effective treatment options.

For patient education information, see the article Concussion.

Glasgow Coma Scale

The Glasgow Coma Scale (GCS) defines the severity of a TBI within 48 hours of injury.

Eye opening

See the list below:

Spontaneous = 4

To speech = 3

To painful stimulation = 2

No response = 1

Motor response

See the list below:

Follows commands = 6

Makes localizing movements to pain = 5

Makes withdrawal movements to pain = 4

Flexor (decorticate) posturing to pain = 3

Extensor (decerebrate) posturing to pain = 2

No response = 1

Verbal response

See the list below:

Oriented to person, place, and date = 5

Converses but is disoriented = 4

Says inappropriate words = 3

Says incomprehensible sounds = 2

No response = 1

The severity of TBI according to the GCS score (within 48 h) is as follows:

Severe TBI = 3-8

Moderate TBI = 9-12

Mild TBI = 13-15

Ranchos Los Amigos Scale of Cognitive Functioning

The severity of deficit in cognitive functioning can be defined by the Ranchos Los Amigos Scale.

level I = No response

level II = Generalized response

level III = Localized response

level IV = Confused-agitated

level V = Confused-inappropriate

level VI = Confused-appropriate

level VII = Automatic-appropriate

level VIII = Purposeful-appropriate

TBI defined by the Head Injury Interdisciplinary Special Interest Group of the American Congress of Rehabilitation Medicine

The Head Injury Interdisciplinary Special Interest Group of the American Congress of Rehabilitation Medicine defines mild head injury as “a traumatically induced physiologic disruption of brain function, as manifested by one of the following:

Any period of loss of consciousness (LOC),

Any loss of memory for events immediately before or after the accident,

Any alteration in mental state at the time of the accident,

Focal neurologic deficits, which may or may not be transient.”

The other criteria for defining mild TBI include the following:

GCS score greater than 12

No abnormalities on computed tomography (CT) scan

No operative lesions

Length of hospital stay less than 48 hours

The following criteria define moderate TBI:

Length of stay at least 48 hours

GCS score of 9-12 or higher

Operative intracranial lesion

Abnormal CT scan findings

The National Institutes of Health Traumatic Coma Data Bank

The National Institutes of Health (NIH) sponsored the Traumatic Coma Data Bank (TCDB).
The TCDB revealed that severe TBI is indicated when the GCS score is below 9 within 48 hours of the injury.

Simplified Motor Score (SMS)

The SMS is a 3-point scale developed to address the perceived limitations of the GCS, such as its complexity and poor interrater reliability. The points are as follows:

Obeys commands = 2 points

Localizes pain = 1 point

Withdraws to pain or worse = 0 points

A study by Thompson et al determined that in an out-of-hospital setting, the SMS was similar to the GCS score for predicting TBI outcomes.

Related Medscape Drugs & Diseases topics:

Classification and Complications of Traumatic Brain Injury

Neurointensive Care for Traumatic Brain Injury in Children

See Medscape’s Resource Center Trauma for further information.

- Advertisment -

Most Popular