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Small Animal Medicine > Traumatic Brain Injuries > Flashcards

Traumatic Brain Injuries Flashcards

1
Q

What are the 2 types of head trauma?

A
  1. primary injury - associated with impact
  2. secondary injury - sequelae of primary injury that can be avoided with proper intervention (hemorrhage, edema, oxidative damage)
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2
Q

How does primary injury affect the brain? What are some examples?

A

physical disruption of the parenchyma and vasculature beyond the control of the clinician

  • contusions
  • lacerations
  • diffuse axonal injury
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3
Q

What is the most common reason for surgical intervention following brain trauma?

A

intracranial hemorrhage

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4
Q

What determines cerebral perfusion pressure? Intracranial pressure?

A

MAP - ICP

as intracranial volume increases, pressure also increases

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5
Q

What are 4 determinants of ICP?

A
  1. CSF production - fairly constant, minimally affected by increased ICP
  2. fluid storage capacity or compliance system (V/P)\
  3. resistance to CSF flow
  4. absorptive resistance (dural sinus)
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6
Q

What is the difference between compliance and elastance?

A

change in V / change in P

change in P / change in V

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7
Q

What is CSF pathway outflow resistance?

A

resistance to fluid flow through CSF pathways and arachnoid villi

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8
Q

What is the final resistive element to CSF flow?

A

dural sinus pressure = exit pressure of the system

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9
Q

What are the 2 major contributions to ICP at steady state?

A

10% - CSF outflow resistance and production

90% - dural sinus pressure

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10
Q

What is the Monroe-Kellie Doctrine?

A

an increase in volume of one intracranial compartment (blood, brain, CSF) must be compensated by a decrease in one or more of the other compartments so that the total volume remains fixed

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11
Q

What is a compliance curve?

A

exponential curve showing the decrease in contractibility with increasing volume

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12
Q

What is the pressure/volume curve?

A

as volume increases, compliance decreases resulting in smaller increases in volume creating larger increases in pressure

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13
Q

What are 5 compensatory mechanisms of the brain?

A
  1. decrease production rate of CSF
  2. shunt CSF out of skull
  3. increase rate of CSF absorption into the dural sinuses by opening arachnoid villi
  4. decrease cerebral blood volume by autoregulation (vasoconstriction)
  5. hyperventilation —> vasoconstriction
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14
Q

Where in the brain are lesions especially dangerous?

A
  • temporal
  • obstruction of foramen magnum = removes 1/3 of buffering capacity which increases pressure
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15
Q

What is the Cushing reflex?

A

physiological nervous system response to acute elevations of ICP, resulting in widened pulse pressure (increasing systolic, decreasing diastolic), bradycardia, and irregular respirations

  • likely a resetting of sympathetic tone with reflex vagal response
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16
Q

What are 4 parts of the upper motor neuron system for sympathetic innervation?

A
  1. medullary rostral ventrolateral reticular nucleus (RVL)
  2. caudal ventrolateral medulla (CVL)
  3. solitary tract (ST) and nucleus (NTS)
  4. baroreceptors and chemoreceptors
17
Q

Where is the rostral ventrolateral reticular nucleus (RVL)? What does it do? What are its afferents and efferents?

A

medulla oblongata - NTS site for baro/chemoreceptor termination

sympatho-excitatory tonicity - senses decreased HR and BP and increases them

  • AFFERENT - from NTS
  • EFFERENT - to spinal cord pre-ganglionic sympathetic neurons
18
Q

What is the function of the caudal ventrolateral medulla (CVL)? Where does it get imput?

A

inhibits sympathetic RVL region

  • NTS
  • baroreceptor reflex arc
19
Q

What are RVL neurons especially sensitive to?

A

ischemia - output increases with local ischemia resulting in peripheral vasoconstriction to increase BP and vagally induced reflex bradycardia

20
Q

What fluids are recommended for treating patients in a shock state with brain injuries?

A
  • crystalloids
  • hypertonic saline
  • hetastarch
  • ANY —> need to treat hypotension and can worry about edema later with Furosemide
21
Q

What additional treatment is recommended for patients with brain injuries?

A

oxygenation/hyperventilation by face mask, nasal, or transtracheal

  • hyperventilation especially in patients at risk for hypercarbia
22
Q

What secondary assessments are done after patients with head trauma are stabilized?

A
  • damage to other organ systems
  • spinal trauma
  • complete neurologic exam
  • imaging, CT preferred
23
Q

What is CT preferred for head trauma patients?

A
  • better visualization of bone
  • acute hemorrhage is readily apparent
  • faster than MRI
24
Q

What medical therapy is recommended for patients with head trauma?

A

Mannitol —> can cause minor hypothermia!

(glucocorticoids probably not warranted)

25
Q

What is the purpose of giving head trauma patients Mannitol? What 4 effects does it have?

A

decreases ICP

  1. reflex vasoconstriction*
  2. osmotic diuresis
  3. reduced CSF production
  4. scavenges free radicals
26
Q

What are some concerns associated with Mannitol therapy in brain trauma patients?

A
  • monitor serum osmolality —> hyperosmolarity
  • exacerbation of hemorrhage
  • reverse osmotic shift
27
Q

Why is glucocorticoid therapy not commonly done for head trauma patients?

A
  • no evidence of efficacy for head trauma
  • potential for deleterious effects
28
Q

Why is it recommended to induce moderate hypothermia in head trauma patients?

A

may decrease release of glutamate and inflammatory cytokines

29
Q

What are 5 indications for surgical treatment of head trauma?

A
  1. depressed skull fractures
  2. open skull fractures
  3. contaminated material in parenchyma
  4. intracranial hemorrhage
  5. poor response to medical therapy
30
Q

What is the most common post-trauma development in the brain?

A

hemorrhage —> needs to be removed before it becomes fatal

31
Q

When is decompressive therapy recommended in head trauma patients?

A

patients that are refractory to medical therapy

  • controversial, but shown to decrease ICP
32
Q

What management principles are recommended in head trauma patients?

A
  • keep head elevated 30 degrees
  • adequate padding
  • frequent turning
  • nutritional support
  • physical therapy
33
Q

What is the prognosis of patients with head trauma? What 5 complications affect prognosis?

A

guarded to poor

  1. pneumonia
  2. DIC
  3. diabetes insipidus
  4. sepsis
  5. seizures

Small Animal Medicine (52 decks)

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