TBI, Edema, Hydrocephalus Flashcards
Focal head injuries include
coup/countercoup, hemorrhage, hematoma
Diffuse head injuries include
concussion, diffuse axonal injuries (these are often rotational injuries)
7 types of skull fractures
linear comminuted depressed "ping pong" open vs closed fractures of the frontal sinus growing fractures- leptomeningeal cyst
What age groups are growth fractures found in
Infants
What is the Monroe- Kellie Hypothesis
volume of the skull= brain + blood + CSF+ any mass if one is present
Which one of the physiologic factors is the least important, why
brain grows slowly
CSF can move into the spinal canal
Over what ICP do small increases in volume lead to huge changes of pressure
25 mmHg
Cerebral Perfusion Pressure=
MAP- ICP= CPP
what happens when ICP inc
when ICP increases CPP decreases
the body has two reactions–> increase systemic BP and dilate cerebral vessels.
Dilating the vessels further increases the ICP leading to a vicious cycle that culminates in cerebral ischemia leading to infraction
What is the size of the volume change that over which a small inc in volume causes a large change in pressure
100 cc
How can ICP be lowered
Hyperventilation –> CO2 is blown off and if it drops to 25 mmHg–> constriction of intracerebral vessels
mannitol diuresis, req large dose .25-1 g/kg
Neck postion can allow CSF movement
Sedation
Paralysis
Surgical: craniotomy or lobecomy
barbitutaes- lower metabolic demand
Why are barbiturates problematic for treating inc ICP
while they lower metabolic demand they can cause hypotension, they make it hard to conduct a neurological exam, and may cause a coma
Acute epidural hematoma- vessel history shape on CT tx speed
Middle meningeal artery trauma to the side of the head- may lose and regain consciousness lens shaped on CT treated with craniotomy fast bc it is arterial
Acute Subdural hematoma vessel history shape on CT tx speed
bridging veins patient is old or alcoholic= dec brain mass Crescent shaped on CT craniotomy slow b/c it is venous
Chronic Subdural hematoma
complications
what cannot be used to tx this
may cause dementia
cannot drill a burr hole to tx this
Order of mortality for chronic/ acute subudural hematomas and acute epidural hematoma
Acute subdural hematoma>acute epidural hematoma»_space; properly managed chronic subdural hematoma
What causes brain herniations
ICP gets too high
3 types of herniations
Subfalcine
Uncal
Tonsilar
Subfalcine herniation
CIngulate gyrus herniates beneath the falx cerebri
can cause compression of ACA and associated musuclar and sensory deficits
Uncal herniation
Herniation of the medial temporal lobe (uncus) through the tentorium cerebelli
causes duret hemorhages in the midbrain, CN III compression –> ipsilateral eye will be- down, out, and dilated
PCA compression- occipital or occcipitoparietal infract
Kernohans notch- contralateral side of midbrain is compressed resulting in ipsilateral hemiparesis
Tonsilar herniations
Cerebellar tonsils through the foramen magnum which compresses the medulla and causes respiratory depression
Concussion
tramatically induced alteration of mental status but without a loss of consciousness
hallmark is CONFUSION AND AMNESIA
severity of concussion is indicated by the length of post-traumatic amnesia
Other signs- delayed response, slurred speech, vacant stare, disorientation
Second impact syndrome
Post concussive syndrome
Potentially fatal condition where a second head injury is experienced within one week of the initial concussion.
the subclinical swelling still present from the original injury makes the brain more susceptible to the second injury b/c the first injury disturbs the normal auto regulatory mechanisms leading to vascular congestion and poor brain compliance.
The second injury casuses –> elevated ICP, dilated pupils, respiratory arrest, and death
Management of Concussions
ABC’s
airway management avoids hypoxia
fluid resuscitation to avoid hypotension
what imaging modality is used in diagnostic management of head injuries
CT
