2 - Head Trauma Flashcards
(104 cards)
How is TBI classified?
Mild, moderate and severe
Based on Glasgow Coma Scale (GCS)
Most TBI (80%) are defined as?
This type of TBI is aka?
Mild - GCS 14-15
Concussion
Outcomes of moderate TBI? (GCS 9-13)
Mortality - <20%
Long disability - HIGH
Long term outcomes of sever TBI (GCS 3-8)
Mortality - 40%
Only 10% have a “good” recovery
If youre gonna die from a severe TBI when do you usually do it?
The first 48hrs
Why do brain injuries tend to cause decreased brain perfusion and cellular hypoxia?
CPP, MAP, ICP and systemic factors all work together to regulate blood flow to brain.
With brain injury these factors (autoregulation) are not working which causes the hypo perfusion to occur
CPP, MAP, ICP formula
CPP = MAP-ICP
What is the lower limit of the brains ability to autoregulate cerebral blood flow?
CPP <60mmHg
Tx for traumatic hypotension?
aggressive fluid resuscitation
Injury Leads to ischemia so you must use aggressive fluid resuscitation
If yo dont have an ICP monitor how can you ensure blood flow to brain?
maintain a MAP of >/= 80
Primary brain injuries include?
- Contusion (bruise to parenchyma)
- hematomas
- diffuse axonal injury (inj to axons)
- direct cellular damage
- loss of BBB
- disruption of neurochemical hemostasis
- loss of the electrochemical function
Types of brain hematomas?
Subdural Epidural Intraparenchymal Intraventricular Subarachnoid
What causes secondary brain injuries?
Secondary neurotoxic cascade
- a massive release of neurotransmitters (glutamate) into the presynaptic space w activation of N-methyl…propionic acid
Causes an ionic shift -> mitochondrial damage and cell death/necrosis
How long does the secondary injury last?
Apoptosis caused by the injury has been reported to occur longer than 1 yr after injury
The secondary neruotoxic cascade should not be confused with?
Secondary insults
- HOTN, hypoxemia etc
That accelerate damage
Brain edema results from 2 distinct processes and can be fatal in TBI, they are?
Cellular swelling (cytotoxic edema)
Extracellular edema (direct damage to BBB)
Pathophysiology of brain edema?
water content rises ICP increases - direct compressive tissue damage - vascular compression-induced ischemia - brain parenchyma herniation - brain death
4 major brain herniation syndromes?
Uncal transtentorial
Central transtentorial
Cerebellotonsillar
Upward posterior fossa
MC brain herniation?
Uncal herniation
- uncus of temporal lobe is displaced inferiorly through medial edge of the tentorium
What causes uncal herniation?
Expansion lesion in the temporal lobe or lateral middle fossa
Uncal herniation s/s?
Ipsilateral fixed and dilated pupil
- compression of CN III -> unopposed sympathetic tone
Contralateral motor paralysis
- compression of pyramidal tract
What causes central transtentorial herniation?
Midline lesions
Less common
Central transtentorial herniation s/s?
Bilateral pinpoint pupils
Bilateral babinski’s sign
Increased muscle tone
Then:
Prolonged hyperventilation
Fixed midpoint pupils
Decorticate posturing
What is cerebelllotonsilar herniation?
When the cerebellar tonsils herniate through the foramen magnum