TBI and Spinal Cord Injury

Question 1

Direct TBI

Answer 1

Occurs when the head is directly struck or its motion suddenly arrested by motion.

Question 2

Indirect TBI

Answer 2

Cranial content are set into motion by forces other than direct contact. Eg. coup and counter coup

Question 3

Primary TBI

Answer 3

Mechanical damage that occurs at the time of head trauma.
Eg. brain lacerations, haemorrhages, contusions, avulsions

Question 4

Secondary TBI

Answer 4

• A facade if events proceeding primary TBI at the cellular and molecular level that continues for hours to days after the primary injury.
• Contributes to further brain injury including hypoxia, hypotension, hyperpyrexia, hyper/hypocarbia and anaemia.

Question 5

Pathophysiology of brain injury

Answer 5

• brain injury as a result of trauma, cerebral oedema, hydrocephalus, space occupying lesion,
  spontaneous bleed > increased ICP > decreased cerebral perfusion = hypoxia > ATP production > Na+/K+ pump fail > Na+ retained in cells causes cell swelling and cerebral oedema = further increase in ICP
• brain needs O2 therefore patient needs increased ventilation and perfusion pressure but increased ventilation leads to decreased CO2 which causes vasoconstriction = decreased CPP > hypoxia develops > increased CO2 > increased ICP = further damage to brain

Question 6

Patient presentation of TBI

Answer 6

• N/V
• Lacerations/contusion/haematomas to scalp
• Visible fractures or indentations to skull
• Racoon eyes
• CSF in nose/ears
• Unresponsiveness
• Confusion/disorientation
• Unequal puipls/fixed dilated
• Amnesia
• Combativeness/aggression
• numbness/tingling in extremities
• Loss of sensation/motor function
• Seizure
• Dizziness
• Visual disturbances
• Decorticate/decerebrate
• Cushings triad

Question 7

Preventing secondary head injury

Answer 7

• Maintain SpO2 >94% using non-rebreather
• EtCO2 35-40mmHg
• Maintain MAP >80mmHg for cerebral perfusion
• Head tilt 30 degrees
• Pain management (fentanyl)
• Antiemetic
• Seizure management
• Prevention of hypothermia

Question 8

Diffuse axonal injury

Answer 8

Axonal stretching leading to axolemmal disruption, ionic flux, neurofilament compaction, and microtubule disassembly, resulting in formation of retraction balls, axonal swelling and disconnection.

Question 9

Cerebral herniation

Answer 9

Occurs with increased ICP due to increased volume overwhelming neuronal compensatory mechanisms of the CNS.
- Cushings triad
Other symptoms:
- sluggish pupils/fixed or dilated, bounding HR, altered LOC.

Question 10

Cushings triad

Answer 10

• Hypertension or widening pulse pressure
• Bradycardia
• Irregular respiratory pattern (chyene-stokes) - alternating between hyperventilation and apnoea

Question 11

Monroe-Kelly Hypothesis

Answer 11

• A pressure-volume relation between ICP and CCP regarding skull contents: CSF, brain and blood.
  In case of injury where haemorrhage occurs, increasing fixed space within cranium, ICP is raised and CPP decreased. Arteries constrict to decrease intracranial volume = decreased perfusion and increased CO2 causes vasodilation. Further increase in ICP, compressed venous circulation, poor cerebral perfusion, increased swelling = brain tissue displacement and compression of brian stem.

Question 12

Decorticate posturing

Answer 12

• Injury above midbrain
• Flextion of upper extremities and extension of lower extremities

Question 13

Decerebrate posturing

Answer 13

• Arms extend abnormally and become adducted
• Clenched teeth
• Legs internally rotated

Question 14

TBI Signs and symptoms (MIND CRUSHED)

Answer 14

• Mental status change
• Irregular breathing
• Nerve changes to optic/occular motor (pupils)
• Decorticate/decrebrate posturing
• Cushings triad
• Reflex sensitivity
• Unconscious
• Seizures
• Headache
• Emesis
• Deteriorating motor function

Question 15

Intracranial pressure (ICP)

Answer 15

• Normal 5-15mmHg
• Influencing factors: CO2, O2, temp, body posturing, arterial.venous pressure

Question 16

Cerebral perfusion pressure (CPP)

Answer 16

Pressure that pushes blood into the brain
- normal = 60-100mmHg
- CPP = MAP -ICP

Question 17

Describe key management for TBI

Answer 17

1. Airway management depending on level on conscious state (suctioning, OPA/NPA, LMA.
2. Oxygenation (SpO2>94%) and EtCO2 (35-40mmHg).
3. Fluid resusitation: Maintain MAP > 80mmHg as per inadequate perfusion CPG (SCI 500ml NaCl bolus only); 20ml/kg NaCl for isolated tachycardia, and tachycardia and hypotension.
4. Analgesia as may have unrecognised pain
5. Midazolam for seizures (0.1mg/kg)
6. Glucose management if hypoglycaemic.
7. Head tilt 30 degrees.

Question 18

Describe autoregulation and effects on cerebral blood flow

Answer 18

• In response to decreasing CPP, auto regulation increases ICP to increase cerebral blood flow due to cerebral vasodilation.
• Autoregulation is efficient with a MAP of 50-150mmHg - if falls below 50mmHg cerebral blood flow becomes severely compromised and if above 150mmHg causes overstretching of cerebral blood vessels.

Question 19

Metabolic factors affecting cerebral blood flow

Answer 19

CO2 concentration (vasoconstriction)
H+ concentration
O2 concentration (vasodilation)

Question 20

Anatomy of spine: how many and types of vertebrae.

Answer 20

33 vertebrae:
- 7 cervical
- 12 thoracic
- 5 lumbar
- 5 sacral (fused)
- 4 coccygeal

Question 21

Primary SCI

Answer 21

Injury which occurs as a direct result from trauma at the time of the incident.

Question 22

Secondary SCI

Answer 22

• Injuries which occur due to cascade events following injury.
  Impacted by hypoxia, hypotension, hyperthermia and hypoglycaemia.

Question 23

Complete SCI

Answer 23

No motor/sensory function below level of injury

Question 24

Incomplete SCI

Answer 24

Motor/sensory function are both or partially present below level of injury

Question 25

Neurogenic shock

Answer 25

- Distributive shock caused by cervical or high thoracic SCI resulting in impaired descending sympathetic pathway. - PNS causes bradycardia and hypotension - Over vigorous fluid resuscitation is dangerous due to compromised CO - Max. 500mL fluid bolus.

Question 26

Neurogenic shock pathophysiology

Answer 26

- Occurs from a severe cervical or high thoracic (above T6) spinal injury causing interruption of autonomic pathways, leading to decreased systemic vascular resistance (vasodilation) and sometimes altered vagal tone (causing bradycardia). - Loss of sympathetic tone occurs below the level of injury, causing unopposed PNS stimulation and vasodilation leading to hypotension. - The lack of SNS tone results in the inability to redirect blood from the peripheries to the core circulation, also leading to excessive heat loss and hypothermia (flushed appearance below level of injury and pale above where SNS is still intact). - Relative hypovolaemia as blood volume has not changed, rather the size of blood vessels has increased, resulting in severe reduction of oxygen delivery to cells > reduced O2 delivery leads to tissue hypo perfusion = distributive shock - The higher the SCI, the more severe the symptoms - Injury above T1 has potential to disrupt entire SNS = severe - Neurogenic shock can occur from complete or incomplete SCI.

Question 27

Describe why a patient appears flushed below level of injury and pale above?

Answer 27

- The lack of SNS tone results in the inability to redirect blood from the peripheries to the core circulation, also leading to excessive heat loss and hypothermia (flushed appearance below level of injury and pale above where SNS is still intact)

Question 28

Spinal Shock

Answer 28

Temporary flaccid paralysis and loss of reflexes below the level of spinal cord lesion for 24-48 hours.

Question 29

Spinal cord injury assessment

Answer 29

- Major trauma criteria = spinal precautions - Pt who do not meet major trauma criteria require clearance. - Any one of criteria indicate spinal precautions: ○ >60 YO ○ Hx bone disease (OA, OP, RA) ○ Drugs or alcohol ○ Significant distracting injury ○ Neurological or motor deficits ○ Spinal column pain or bondy tenderness Pt cannot rotate and turn head 45 degrees left and right

Question 30

NEXUS Criteria for C-Spine immobilisation

Answer 30

If any present: * Neurological deficit present * Midline spinal tenderness * Altered level of consciousness (GCS <15) * Intoxication distracting injury - Distracting injury

Question 31

Where is the phrenic nerve located?

Answer 31

C3-5

Question 32

What are four types of skull fractures?

Answer 32

- Linear: single fracture that goes through the entire thickness of the skull - Depressed - Basilar: linear fractures through base of skull - Left (maxillary) fractures

Question 33

What are the three types of LeFort fractures

Answer 33

LeFort I: Palate fracture LeFort II: Nose and palate fracture LeFort III: entire face fracture