Traumatic Brain Injury Flashcards
What are the three types of brain injuries?
- Traumatic
- Acquired (i.e. stroke, tumor, disease)
- Congenital
What are the two primary causes of TBI?
- Firearms
2. Vehicle accidents
What is the biggest cause of TBI in the elderly?
Falls
What is an important TBI differential diagnosis for soldiers?
mild TBI vs PTSD
What age group has the highest incidence of TBI?
Children and young adults -> 5-20 years old
What is meant by penetrating vs perforating versus closed? What is most common?
Perforating - object has entrance and exit wound
Penetrating - object pierces dura but remains in skull
Closed - most common, brain not exposed
What is diffuse versus focal TBI?
Diffuse - affects several areas of brain
Focal - injury restricted to a specific region of brain
What is a contusion-type injury?
An injury which leaves a bruise at the point of impact, produces an area of edema, and may have hemorrhagic progression
What is coup and countercoup injury?
Coup - contusion at site of impact
Countercoup - contusion at opposite side of impact, due to recoil of brain in cranial cavity
What causes diffuse axonal injury (DAI)?
The result of acceleration / deceleration injury that causes a shearing injury / stretch of axons. These axons will swell and axonal transport will be disrupted.
How are damaged axons revealed in DAI?
Immunostaining for beta amyloid precursor protein (Beta-APP)
How often does DAI occur and where is it found?
About 50% of brain trauma, found in cerebral cortex, especially white matter like corpus callosum, SCP. Also basal ganglia, thalamus, and rostral brainstem
What are two common causes of DAI? What will be seen on the skin?
- IED (improvised explosive device) exposure
- Shaken baby syndrome
On the skin: petechial hemorrhages
What are the clinical signs of shaken baby syndrome? What will cause death?
- Encephalopathy
- Subdural hematomas
- Retinal hemorrhages
Death causes
HIE - hypoxic ischemic encephalopathy
Increased ICP
What is the normal cause of epidural hemorrhage? What symptoms are associated?
Tearing of middle meningeal artery, associated with skull fracture.
Biconvex (lens-shaped) hemorrhage as the bleeding is contained by suture lines in the skulll, and “talk-and-die” -> lucid period before getting worse
What increases risk for subdural hemorrhage?
Brain atrophy, as emissary / bridging veins are already stretched
What type of hemorrhage is associated with terrible headache?
Subarachnoid hemorrhage -> blood can be found in CSF
What causes intraparenchymal hemorrhage? why is this a problem?
Usually from hemorrhagic stroke or penetrating injuries. Can increase ICP but also BLOOD IS VERY TOXIC TO BRAIN
What are two diagnostic signs of basilar skull fracture?
- Battle’s sign -> bruising near mastoid process
2. Raccoon eyes
What does PTA stand for?
Post-traumatic amnesia
What are the three measures tested by the glasgow coma scale? What are the score ranges?
- Eye opening
- Verbal response
- Motor response
3-15
What are the GCS numbers which define mild, moderate, and severe TBI?
Mild: 13-15 -> represents 75% of all TBI
Moderate: 9-12
Severe: 3-8
What is chronic traumatic encephalopathy?
Brain injury caused by repeated mild TBI which become additive. Prominent in football players / soccer players
Prominent defects in memory and executive function as well as tau-immunoreactive neurofibrillary tangles
What is Dementia pugilistica?
Condition of boxers where goal of sport is to produce concussion, produces chronic encephalopathy
What is primary vs secondary injury?
Primary - result of direct forces on brain that affect axons / dendrites / blood vessels and cause immediate cell death
Secondary - The sequellae -> breakdown of BBB, cerebral edema, ischemia, hypoxia, free radical production, Ca+2 influx, increased ICP, glutamate excitotoxicity
What is glutamate excitotoxicity?
One of the secondary results of TBI, it is general depolarization from ATP depletion from constantly activated glutamate neurotransmitter. The Ca+2 which leaks through NMDA / AMPA channels will cause activation of proteases which degrade the cytoskeleton
Where is cytotoxic cerebral edema most common?
In astrocytes, which Na/K/Ca pumps are disrupted and water enters through aquaporins
What are cerebrovascular alterations?
Loss of autoregulatory capacity of cerebral microvessels due to chronic hypoperfusion and chronic vasoconstriction. Will lead to ischemia and loss of metabolites in brain tissue
What is Cushing’s triad and what is it diagnostic of?
Slow heart rate, high blood pressure, and irregular breathing. Diagnostic of high ICP
What are the mild treatments of high ICP?
Drainage of CSF, and osmotherapy with mannitol or hypertonic saline
What are the extreme measures to treat high ICP?
- Barbiturate coma
- Hypothermia
- Decompressive craniotomy
How is cerebral perfusion pressure calculated? What is normal?
CPP = MAP - ICP
Normal is between 50 and 150 mmHg
How are MAP and ICP found?
MAP = 1/3 systolic + 2/3 diastolic
ICP = measured using barometer
What are some reasons why TBI clinical trials failed?
- Clinical heterogeneity - TBI’s are different from person to person
- Poor animal models
- Lack of sensitive biomarkers
- Difficult to know when to apply therapies based on animal models alone
- Insufficient preclinical studies
