Traumatic Brain Injury

Question 1

Traumatic Brain Injury
— Primary and secondary insults
> what they lead to?

Answer 1

Primary insult
— Hemorrhage
— Damaged parenchyma
— Neuroaxonal injury
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Secondary Insult
— Ischemia
— Edema > Maximal effects at 24-48 hrs
<><><><>
This leads to increased ICP

Question 2

Initial Goals for head trauma

Answer 2

— Determine extent of injuries
— Assess brain function
— Broadly localize neurological lesion
> cortical is ‘good’, brainstem is ‘bad’

Question 3

Patient Assessment for head trauma case

Answer 3

— Level of consciousness
— Respiratory pattern / Systemic signs
— Cranial nerve examination
— Head
> Palpate for fractures
> Bleeding / Leakage of CSF – ears, nose, wounds
— Pain perception to limbs
— Motor function / Postural reactions
<><><><>
GPE with MINIMAL manipulation of the head/neck

Question 4

decreased level of mentation comes from one of these places:

Answer 4

1. Cerebrum (bilateral & severe)
2. Brain stem – ascending reticular activating system (ARAS)
   <><><><>

Question 5

Deficits in the cranial nerves indicate:

Answer 5

brain stem involvement

Question 6

Respiratory Pattern for new head trauma patient
— Markedly abnormal respiratory patterns mean what?

Answer 6

— Respiratory centers are located centrally
— Markedly abnormal respiratory patterns
> Suggest brainstem lesion
> Carry a poor prognosis

Question 7

Systemic Signs of head trauma

Answer 7

Cushing’s Reflex
— Hypertension
+
— Bradycardia

Question 8

Cushing’s Reflex - what is it? what does it mean?

Answer 8

CPP=MAP–ICP
> if our ICP goes up very high, then our MAP must rise to maintain cerebral perfusion
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To maintain cerebral perfusion pressure (CPP):
— If ICP rises, then MAP must also rise
— This increased MAP triggers a baroreceptor mediated BRADYCARDIA
<><>
Cushing’s Reflex = Systemic Hypertension + Bradycardia
> Imminent brain herniation

Question 9

Pupillary Light Reflex - what it tells us?

Answer 9

— Assesses
— CNII & CNIII
> Constriction suggests CN III is intact
— Note even fine changes
<><>
> CN 3 is at a very important segment of the brainstem

Question 10

PLR - what does this tell us?

Answer 10

• even a small change in pupil width tells us PLR and thus CN3 is intact

Question 11

Brainstem Lesion - what will this look like in the eyes? what does this mean for lesion localization and prognosis?

Answer 11

Pupils
— Dilated
— Central
— Unresponsive
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— Lack of CNIII input
— Midbrain / Pons
— Grave prognosis
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Pupils
— Asymmetry
— Ocular vs brain trauma
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— Unilateral rapid changes
— ICP

Question 12

Physiologic Nystagmus - tells us what?

Answer 12

Evaluates
— CN III, IV, VI, VIII
— Medial Longitudinal Fasciculus
<><>
— Global assessment > means we have a breadth of our brainstem that is doing well

Question 13

Decerebrate Rigidity - tells us what? what does it look like? prognosis?

Answer 13

Cortical injury
— Disconnection of the higher centres of the brain &
brainstem
— Patients are comatose, lack PLR, dilated or pinpoint pupils
— Rigidity - extension of all 4 limbs & tail, opisthotonus
— GRAVE prognosis

Question 14

Decerebellate Rigidity - tells us what? what does it look like? prognosis?

Answer 14

Cerebellar injury
— Patients are ALERT & aware
— Neck & forelimbs are in extension
— Hindlimbs are normal (or hyperflexed)
— FAVOURABLE prognosis

Question 15

Modified Glasgow Coma Score - what does it assess? what is the scale? what is its use?

Answer 15

• Motor activity, brainstem reflexes, level of consciousness
• scale goes from 6 (best) to 1 (worst) for each category, then add them up
• It is a good prognostic indicator; higher scores mean better prognosis

Question 16

Imaging for head trauma - when to do skull ultrasound

Answer 16

— puppies, tiny dogs, open skull fractures

Question 17

Imaging for head trauma - use of CT and MRI?

Answer 17

— CT preferred:
> Acute hemorrhage & bone are better visualized
<><>
— MRI
> ID more subtle lesions
> Findings ass’d with prognosis

Question 18

skull fractures - incidence with brain trauma? associated with what conditions?

Answer 18

• 46-72% incidence
• associated with Development of seizures, post traumatic epilepsy
  > Worse outcome at 3, 6, 12 months

Question 19

Factors Affecting ICP

Answer 19

Intracranial mass lesion – hemorrhage, depressed skull fracture
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Cerebral edema (aggravated by ischemia / poor brain perfusion)
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Vasodilation:
— Venous return
> Head position
> Intrathoracic / intraabdominal pressure
— Cerebral vasodilation - increased PaCO2 ; decreased PaO2
— Fluid overload
— Hyperthermia
— Venous sinus thombosis or other obstruction
— Seizures

Question 20

Emergency Management for head trauma

Answer 20

1. Airway/Breathing/Circulation
   - IV access
   - O2 Supplementation
2. Stabilize the patient
   - ie. pneumothorax, fatal arrhythmias, etc

Question 21

Treatment for head trauma

Answer 21

“make all vitals perfect”
<><><><>
- Maintain normal BP
> MAP 90-100 +mmHg
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- Resuscitate to NORMOVOLEMIA
> Maximize O2 delivery
> Minimize fluid overload
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- O2 Supplementation
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- Fluid Resuscitation
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- Pain Management
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etc…

Question 22

Fluid Resuscitation for brain trauma cases - what are our principles? primary considerations??

Answer 22

Low volume resuscitation
— Crystalloids
— Hypertonic Saline
— Colloids
— Blood
<><>
Risks of HYPOTENSION/ HYPOVOLEMIA far outweigh risks of overhydration

Question 23

indication for crystalloids for fluid resuscitation in head trauma case? rate?
what if hypotension persists?

Answer 23

Indication
— Mild hypotension
— MAP 60-80 mmHg
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Rate
— Dog – 40 ml/kg (up to max 70 ml/kg)
— Cat – 20 ml/kg (up to max 40 ml/kg)
<><><><>
If hypotension persists
— Add hypertonic saline / colloid

Question 24

O2 Supplementation for head trauma patient
- goal?
- what to avoid? why?
- hypoxemic vs hyperoxemic states and outcomes

Answer 24

— Goal – normoxia
> Pulse oximeter 95-98%
> PaO2 3 80mmHg – 105 mmHg
<><>
— Avoid nasal prongs / cannulas > we dont want sneezing
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— Hypoxemia – leads to vasodilation, increased ICP & decreased cerebral blood flow
— Hyperoxemia – also associated with worse outcomes related to ROS!

Question 25

Pain Management for brain trauma case - what to use and how?

Answer 25

Use opioids - TITRATE - Fentanyl > Short acting, easy to adjust - Methadone - Hydromorphone > TITRATE – avoid vomiting!!!!!!!!!!!!!!!! <><> - Opt for NSAIDs once animal stable

Question 26

what signs are we looking for in a head trauma case to start treatment to avoid brain herniation?

Answer 26

1. decreased Level of consciousness 2. Cushing’s reflex — Bradycardia — Hypertension 3. Loss of PLR / Rapid change in pupil size / Loss of physiologic nystagmus <><> ≥ 2 signs ..... TREAT!!!

Question 27

Elevated ICP - how to treat?

Answer 27

Hyperosmolar therapy — Mannitol — Hypertonic saline

Question 28

what is mannitol? what does it do? contraindications?

Answer 28

— Osmotic diuretic, useful for treating elevated ICP — Decreases blood viscosity — Free-radical scavenger <><> Contraindications: — Hypovolemia, CHF — Ongoing intracranial hemorrh (empirical) — IV continuous infusion not recommended

Question 29

Hypertonic Saline - use for treatment of elevated ICP? caution?

Answer 29

Hyperosmolar solution — ‘Draws’ out brain edema — Also: Improves CBF & O2 delivery <><> — Caution – maintain Na+ < 160 mmol/L

Question 30

Hyperosmolar Therapy for increased ICP - treatment plan overall, monitoring?

Answer 30

mannitol or Hypertonic Saline — Try one, if little effect, try the other! — May need to repeat <><> Monitoring q8 hr or more often — Hydration — Electrolytes

Question 31

Corticosteroids for increased ICP? what do they do?

Answer 31

— **Not Recommended** — No beneficial effect to reduce cerebral edema — May perpetuate: > Neuronal damage if ischemia present > Hyperglycemia — Standard dosing of prednisone & dexamethasone particularly unlikely to benefit

Question 32

CO2 Management for brain trauma patient? values?

Answer 32

1. Hyperventilation > decreased PaCO2 > Cerebral Vasoconstriction > Short-term only <><> — PaCO2 – 30 mmHg (No less) — ETCO2 – 35 mmHgw <><> 2. Endotracheal Intubation — Topical laryngeal lidocaine spray — Pretreat w IV lidocaine 0.75mg/kg IV prior to intubation — Induce with propofol

Question 33

Anesthetic Considerations for brain trauma - which do we prefer? why?

Answer 33

Propofol preferred ; Barbiturate alternative - Reduces cerebral metabolic rate for O2 <><> Sedation — Benzodiazepines — Alpha 2 agonists - > Ultra low doses only > Dexmedetomidine 1-2 mcg/kg/hr

Question 34

positioning for brain trauma patient

Answer 34

Improve Venous Drainage — Head elevated 30° — Avoid occlusion of the jugular veins — Maintain normal intrathoracic/abdominal pressures — *Prevent coughing/sneezing/vomiting*

Question 35

how to Prevent Hyperthermia in the brain trauma patient - how should we regulate temp?

Answer 35

— Maintain temp at low end of normal — Allow patient to rewarm passively if the patient is hypothermic on presentation — Avoid shivering > shivering using oxygen > Temp > 36.5°C (98°F)

Question 36

issues with hyperglycemia and hypoglycemia in the brain trauma patient

Answer 36

hyperglycemia: — Associated with increased cerebral lactate / acidosis & cell death — Worsening neurological outcome <><> hypoglycemia: — Worse cerebral metabolic effects <><><><><><><><> Normoglycemia is the goal

Question 37

Seizure Management for the head trauma patient - incidence? - treatment - management

Answer 37

Seizure incidence — ~ 14+% within 24 hours of injury, or within 1 week of injury — Increased incidence with skull fractures & herniation <><> Treatment — Diazepam — Levetiracetam <><> Management — *Levetiracetam* PO TID — Diazepam infusion — Phenobarbitol

Question 38

antiemetics for head trauma patient? what about hemorrhage control?

Answer 38

- yes we can try to do both <><> Antiemetic — Maropitant — Metoclopramide — Dimenhydrinate <><> Tranexamic Acid — Anti-fibrinolytic (maintain clot) — Control hemorrhage

Question 39

General Management for head trauma patient

Answer 39

— Early enteral feed — Eye care / oral care — Avoid bladder distension ---- increase ICP > Continuous drainage — Nursing care (turning patient, physio)

Question 40

Recovery for head trauma patient

Answer 40

— Time! <><> — Expectations: — Ataxia — Circling — Signs of cerebellar disease ** Markers of improvement in previously recumbent patient ** > most of the time recover well if they survive first 24 hours

Question 41

Critical Periods for head trauma patient

Answer 41

— 1st 24 hours for survival — 1st 72 hours for change in neuro status > if they make it this far, in good shape! — Thereafter recovery period

Question 42

Prognosis for brain trauma patient

Answer 42

— Non-survival (mortality ~15%) predicted by: - Modified Glasgow Coma Score - ≦ 8 associated with ~ 50% non-survival - Concurrent injuries with evidence of decreased perfusion / oxygenation (ie. Increased lactate, decreased pH, SpO2) - Need for endotracheal intubation or HTS administration <><><><> Poor outcome ass’d with: — Brain herniation — Skull fractures — Increased size of intra-parenchymal lesions

Question 43

Sequelae to brain trauma

Answer 43

— Impossible to predict at initial exam <><> Thalamocortical injury — Personality changes — Visual deficits — Circling — Weakness in 1+ limb — Late onset epilepsy - seizures within 1 year of injury <><> — Generally excellent prognosis

Question 44

brain trauma summary - things to focus on for assessment - keep in mind, what to regulate, what to watch for - overall prognosis

Answer 44

Important points — Good neurological assessment — Appropriate lesion localization <><> — Rapidity of changing neuro status — Regulation of blood pressure, O2, CO2 — Recognition of signs of imminent brain herniation <><> Excellent prognosis in many patients