Neurological Emergencies - brain

Question 1

Primary Brain Injury

Answer 1

physical damage to brain tissue - contusion, haematoma, laceration, vasogenic oedema

Question 2

Secondary brain injury

Answer 2

Associated with excitatory neurotransmitter release, inflammation and increased ICP

Question 3

Vasogenic oedema

Answer 3

Disrupted BBB - extracellular accumulation of serum proteins - oedema

Question 4

Cytotoxic oedema

Answer 4

Swelling of cells due to energy depletion - ion pumps fail

Question 5

Cerebral blood flow is dependant on

Answer 5

Cerebral perfusion pressure

= mean arterial pressure - intracranial pressure

Question 6

cerebral perfusion pressure can be reduced by either

Answer 6

Decreased MAP, increased intracranial pressure

Question 7

Blood flow in the brain is usually protected by

Answer 7

auto regulation

Question 8

Initial actions with a potential head trauma

Answer 8

Check ABC - airways breathing, circulation
Ensure adequate oxygenation - pulse ox or blood gas if available.
Check MAP

Question 9

Head trauma can lead to a temporary severe dyspnoea & tachypnoea due to

Answer 9

Neurogenic pulmonary oedema.

Doesn’t normally require specific tx

Question 10

Levels of alertness

Answer 10

Comatose - non-responsive even to noxious stimuli
Stuporous - basically asleep but rousable by noxious stimuli e.g. pinching toe
Obtunded - depressed response to normal stimulation

Question 11

Decerebellate posture

Answer 11

Extreme dorsal extension of the head and neck, thoracic limb extension and pelvic limb flexion.
Indicates cerebellar damage.

Question 12

Decrebrate posture

Answer 12

Similar to decerebellate but pelvic limbs extended and reduced mentation
Indicates more severe damage at the forebrain level

Question 13

Pupil changes seen with increased ICP

Answer 13

initial constriction followed by dilation.

Anisocaria can result from asymmetrical ICP

Question 14

Modified Glasgow coma scale takes into account

Answer 14

Motor activity
Brainstem reflexes
Level of consciousness

Question 15

Signs of elevated ICP

Answer 15

Reduced level of mentation
Altered pupil function - constricted then dilated ± unequal
Loss of vestibule-ocular reflex

Question 16

Cushing response

Answer 16

Increased MAP and bradycardia occurring simultaneously - response to end-stage, life threatening ICP
Auto-regulatory mechanisms increase MAP to try and maintain cerebral perfusion pressure - reflex bradycardia

Question 17

Investigating/monitoring head trauma

Answer 17

Modified Glasgow coma scale - esp. if done by the same person.
Monitor MAP, oxygenation, HR, RR, urine output.
CT > MRI as faster

Question 18

Treating head trauma (6 points)

Answer 18

Goal = maintaining cerebral blood flow

• elevate head 30 degrees to ensure no occlusion of jugular veins.
• may need IVFT - many animals in shock
• oxygenation - aim >95% on pulse ox
• analgesia - usually methadone
• treat any seizure activity aggressively - diazepam and phenobarbitone
• nutritional support if prolonged

Question 19

IVFT in severe head trauma

Answer 19

Hypertonic saline bolus followed by maintenance crystalloids - restore normovolaemia - restoring MAP.

Mannitol - high molecular weight osmotic diuretic diuresis - use once normovolaemia is achieved to reduce ICP

Question 20

Mannitol

Answer 20

A high molecular weight osmotic diuretic - if BBB intact can work in the brain to decrease ICP.
Risk of rebound ICP

Question 21

If there are concerns regarding head trauma and increased ICP you can administer

Answer 21

Mannitol & hypertonic saline - induce osmotic diuresis in the brain (provided BBB intact). Lowering ICP.
Also act to restore normovolaemaia improving cerebral blood flow.

Question 22

If seizure activity

Answer 22

Treat aggressively

Diazepam and phenobarbitone