Traumatic brain injury
Types of injury:
- Open head injury: skull fracture that results in brain exposure
- Increased risk of infection
- Closed head injury: no skull fracture or exposed brain
- Increased risk for intracranial pressure
Pathophysiology:
- Local brain injury
- Damage to a specific region of the brain due to bruising, bleeding, laceration, or swelling
- Coup-countercoup injury
- Injury in which the brain is damaged due to the point of impact and the opposite side due to rebound forces
- Diffuse axonal injury
- Tearing of axons and small vessels due to the acceleration of the brain in the skull, leading to neuronal death
- Edema
- Swelling of brain tissue after injury (vasogenic or cytotoxic edema), which raises intracranial pressure
- Hypoxic-ischemic injury
- Loss of cerebral circulation, typically due to compromise of the cardiovascular and respiratory systems
Stratification of brain injury:
Brain injuries can be stratified into three categories: mild, moderate, and severe based on symptomatology present. Stratification can be done with the use of the Glasgow Coma Scale (GCS):
- Mild TBI (i.e., concussion)
- GCS score: 13-15
- Loss of consciousness: 0-30 minutes
- Alteration of consciousness: brief; up to 24 hours
- Post-traumatic amnesia: <1 day
- Imaging: normal
- Recovery: full recovery of physical and cognitive function, with the patient seen in an outpatient setting
- Moderate TBI
- GCS score: 9-12
- Loss of consciousness: >30 minutes; <24 hours
- Alteration of consciousness: >24 hours
- Post-traumatic amnesia: 1-7 days
- Imaging: normal or abnormal
- Recovery: potential to have full recovery of physical and cognitive function with intense rehabilitation in an inpatient rehabilitation or skilled nursing facility
- Severe TBI
- GCS score: 8 or less
- Loss of consciousness: >24 hours
- Alteration of consciousness: >24 hours
- Post-traumatic amnesia: >7 days
- Imaging: normal or abnormal
- Recovery: permanent physical and cognitive impairment; typically in a nursing home setting or home setting with total care
Behavioral stratification of traumatic brain injury:
Rancho Los Amigos Cognitive Scale is utilized to classify behaviors through a predictable sequence. Individuals progress through levels in sequence but can plateau at any point. Level of behavior:
- Level I: No response
- Cognitive assistance needed: total assistance with all cognitive functions
- Response to stimuli: no response to sounds, sights, touch, or pain
- Single-step commands: unable to follow single-step commands
- Characteristics of level: individuals are typically in a comatose state
- Level II: Generalized response
- Cognitive assistance needed: total assistance with all cognitive functions
- Response to stimuli: inconsistent, non-purposeful, generalized response to stimuli
- Single-step commands: unable to follow single-step commands
- Characteristics of level: individuals in a vegetative state
- Level III: Localized response
- Cognitive assistance needed: total assistance with all cognitive functions
- Response to stimuli: localized response to stimuli
- Single-step commands: unable to follow single-step commands
- Characteristics of level: individuals within a minimally conscious state; able to inconsistently track objects and respond to their name
- Level IV: Confused, agitated
- Cognitive assistance needed: maximal assistance for cognitive function
- Response to stimuli: localized response
- Single-step commands: unable to follow single-step commands
- Characteristics of level: confused, combative, easily agitated, hypersexual behavior
- Level V: Confused, inappropriate
- Cognitive assistance needed: maximal assistance for cognitive function
- Response to stimuli: localized response
- Single-step commands: able to follow simple commands consistently; difficulty with complex commands
- Characteristics of level: confused, inappropriate behaviors (combative and hypersexual behaviors have subsided), severely impaired memory
- Level VI: Confused, appropriate
- Cognitive assistance needed: moderate assistance for cognitive function
- Response to stimuli: localized response
- Single-step commands: able to follow single-step commands
- Characteristics of level: confused but behaviors are appropriate (goal-directed); no combative characteristics
- Level VII: Automatic, appropriate
- Cognitive assistance needed: minimal assistance for cognitive function
- Response to stimuli: localized response
- Single-step commands: able to follow single-step commands
- Characteristics of level: improved carryover with activity, minimal assistance for learning new tasks, increased awareness of deficits
- Level VIII: Purposeful and appropriate
- Cognitive assistance needed: stand-by assistance for cognitive function
- Response to stimuli: localized response
- Single-step commands: able to follow single-step commands
- Characteristics of level: able to integrate new and old memory into making decisions, able to make adjustments to behavior in social interaction with minimal assistance