TBI Pathophysiology Flashcards
What is a TBI?
A brain injury caused by a hit to the head that ranges from mild to severe depending on the amount of change to mental status and the length of time a patient is unconscious
What are the most common causes of a TBI?
Falls (48%)
Unintentionally struck (17%)
MVAs (13%)
What are some ways you classify a TBI?
- Chronicity of Injury (acute vs. chronic)
- Mechanism of Injury
- Severity of Injury (mild to severe)
- Level of Cognition Currently (Rancho Scale of Cognitive Function)
- Level of Arousal at Time of Injury (Glasgow Coma Scale)
What type of head Injury occurs from Direct Contact?
- Concussion
- Contusion (coup/counter-coup)
- Hematoma (epidural intracerebral or subarachnoid)
What type of head Injury occurs from a Penetrating Injury?
What type of head Injury occurs from a Blast Injury?
What type of head Injury occurs from a Heart attack or near drowning?
Invasive injury to neuronal and vasculature tissue
Diffuse Axonal Injury
- Anoxia
- Hypoxia
What type of head Injury occurs from an Acceleration/Deceleration Injury?
- Concussion
- Hematoma (subdural)
- Diffuse Axonal Injury
What is a head contusion?
How are they identified?
How are they differentiated from a hematoma?
Swollen brain tissue where there is vascular and tissue damage which can be a response to the brain moving within the skull
Identified by a CT scan and appears as a hemorrhagic lesion
differentiated from hematoma in that blood is intermixed w/ brain tissue
What is a cranial hematoma?
What are the 3 different types?
Damage to major blood vessels in the head or heavy bleeding into or around the brain
Epidural (bleeding between skull and dura)
Subdural (bleeding between dura and arachnoid)
Subarachnoid, Intracerebral (bleeding within brain)
What is a diffuse axonal injury?
Are they identified on CT scans?
torsion or shearing of long axons
However not every axonal injury is a diffuse injury, diffuse injuries interrupt axonal transport and have axonal swelling
Not identified on CT and sometimes not on MRI’s either
What is a primary blast injury?
Occurs following high order over-pressurizing shock wave moving through the body, affects gas-filled organs such as the lungs, GI tract, and middle ear
What is a secondary blast injury?
caused by bomb fragments and other objects propelled by the explosion resulting in penetrating injuries
What is a tertiary blast injury?
Results from the blast wind throwing the victim and include bone fractures and amputation
What is a quaternary blast injury?
includes injuries not included in first three levels such as burns, crush injuries and respiratory injuries
What is normal intracranial pressure (ICP) and what would be considered excessive ICP?
What can excessive ICP cause?
What are signs of excessive ICP?
typical ICP=10-15 mm Hg in supine and -10 in standing
excessive ICP= over 20-25 mm Hg and can cause papilledema, herniation, brain tissue damage, stroke, etc.
signs include decreased pulse rate, change in conciousness, agitation, and coma
What is Cushing’s Triad?
What would the opposite of the triad indicate?
Three primary signs that often indicate increased ICP
they include:
increase systolic BP
Decreased pulse and respiration
These signs are the exact opposite for Shock
How do you calculate cerebral perfusion pressure?
(mean arterial pressure) - (Intracranial Pressure)
What types of Injuries are identified using an x-ray?
Which are identified using a CT scan?
MRI?
X-ray: identifies skull fractures
CT Scan: contusion and hematoma
MRI: some DAIs
What is the goal of surgical intervention for hematomas?
What surgical interventions are used for an epidural hematoma?
What surgical interventions are used for a subdural hematoma?
reduce pressure
craniotomy and evacuation
burr holes
What pharmacologic interventions are indicated for cerebral edema?
What drugs are sued for delirium?
Drugs for seizures?
glucocorticoids (vasogenic edema), mannitol (osmotherapy), or induced hypothermia
Sedatives
Phenytoin, valproate, phenobarbital, felbamate
What signs for TBI lead to better prognosis?
- Less than 1 year of symptoms
- focal severity rather than diffused
- 8/10 cognition on Rancho scale
- 13-15 level of arousal time on glasgow scale
- less than 2 weeks in coma
- less than 2 months of amnesia duration
- less than 40 yrs. old
How is the eye opening response graded on the glasgow coma scale?
4 points- spontaneous eye opening before stimuli
3 points- eyes open to verbal stimuli
2 points- eyes open to physical stimuli
1 point- no opening at any time and no interference
0 points- non testable due to interfering factor
How is the verbal response graded on the glasgow coma scale?
5 points- orientated and correctly answers cognition Q’s
4 points- confused conversation, but coherent
3 points- words are intelligible but inappropriate
2 points- sounds only, no words
1 point- no response and no interference
0 points- non-testable due to interference
How is the motor response graded on the glasgow coma scale?
6 points-obeys commands for movement
5 points- purposeful movement to stimulus
4 points- withdraws in response to pain
3 points- flex. in response to pain (decorticate posture)
2 points- ext. in response to pain (decerebrate posture)
1 point- no response and no interfering object
0 points- non testable due to interference
How would you classify a head injury using the glasgow coma scale?
Severe= GCS of 3-8
Moderate= GCS of 9-12
Mild= GCS of 13-15
Describe each level of altered consciousness:
Coma
Stupor
Obtunded
Delirium
Coma-unconcious and no sleep wake cycles; may have reflexive movement
Stupor-general unresponsiveness; requires repeated stimuli
Obtunded- reduced alertness; slow to respond to stimuli
Delirium- disorientated; fearful and misinterpret stimuli
Describe each level of altered consciousness:
Persistent Vegetative State
Minimally Conscious State
PVS- unconscious; but has sleep wake cycles; withdraws to noxious stimuli; occasional non-purposeful movement; brief orientation to sound or an object
MCS- partially conscious; localize noxious stim and sounds; inconsistent following commands
Describe levels 1-5 of the Rancho Los Amigos Scale for Cognitive Function
Level 1: No response (total assistance): unconscious/comatose with no reaction to stimuli
Level 2: Generalized Response (total assistance): reaction inconsistent/without purpose
Level 3: Localized Response (Total assistance): more specific reaction, i.e may turn head in direction of voice
Level 4: Confused/Agitated (Max assist): active; bizarre behavior; may react in hostile manner 2* of confusion
Level 5: Confused, Inappropriate non-agitated (Max assist): less agitated/more consistent but still confused/inappropriate
Describe levels 6-10 of the Rancho Los Amigos Scale for Cognitive Function
Level 6: Confused, Appropriate ( Mod Assist): context-appropriate, goal-directed responses, require direction
Level 7: Automatic, appropriate (min assist for ADLs): follow routine, but judgement/problem-solving are impaired
Level 8: Purposeful, Appropriate (Stand by assist): orientated; independent with familiar tasks, may need assistance to manage routines and planning of daily personal household, community, etc.
Level 9: Purposeful, appropriate (stand by assist on request): independent w/ tasks for longer period, may still request assistance for routines
Level 10: purposeful, appropriate (modified independent): able to handle multiple tasks simultaneously, accurately estimates abilities and independently adjusts to task demands. irritability/low frustration tolerance when sick, fatigued, or under emotional stress
