Head injuries

Question 1

Brain metabolism

Answer 1

20% total body oxygen
25% total body glucose
uses almost all aerobic metabolism due to damaging effects of lactate
doesn’t store oxygen/glucose - tightly coupled to cerebral blood flow

Question 2

CBF

Answer 2

cerebral blood flow
controlled by local concentration of CO2
Active brain area produces CO2: cerebral capillaries/arterioles vasodilate
–> active area gets more blood flow

Question 3

Cerebral perfusion pressure

Answer 3

CPP = Mean arterial pressure - ICP

Question 4

Cerebral autoregulation

Answer 4

keeps cerebral blood flow constant despite a wide range (50-130 mmHg) of cerebral perfusion pressures
brain not bombarded by minor fluctuations in systemic blood pressure
Autoregulation lost following trauma

Question 5

ICP

Answer 5

Normally ~10 mmHg
>20 abnormal
>40 potentially lethal

Question 6

Monroe-Kelly doctrine

Answer 6

Skull is a rigid structure that cannot expand
Initially CSF/blood inside large veins are shunted outside
eventually compensation exhausted, pressure rises dramatically

Question 7

Primary brain injury

Answer 7

occurs at time of trauma
permanent
no therapy

Question 8

Secondary brain injury

Answer 8

delayed
preventable
include:
hypoxia, hypotension, infection, seizure, electrolyte abnoramlities and raised ICP (herniations/local hypoperfusion)

Question 9

GCS eyes

Answer 9

spotaneous 4
to voice 3
to pain 2
none 1

Question 10

GCS best verbal response

Answer 10

oriented, converses 5
disoriented, converses 4
inappropriate words 3
incomprehensible sounds 2
none 1

Question 11

GCS best motor response

Answer 11

obeys 6
localizes to pain (eg cross midline) 5
withdraws 4
flexion 3
extension 2
none 1

Question 12

GCS severity

Answer 12

3-7 severe brain injury
8-12 moderate
13-15 mild
intubate

Question 13

Uncal herniation

Answer 13

also: trans-tentorial
temporal lobe swells and presses medially onto CN III (dilated pupil), cerebral peduncle (contralateral plegia), reticular activation centre of brainstem (coma)

Question 14

Tonsillar herniation

Answer 14

whole brain squeezed downwards into foramen magnum
compresses tonsils of cerebellum against medullar
–> respiratory arrest, death

Question 15

Cushing’s response/triad

Answer 15

cardiovascular response to elevated ICP
increased body BP –> reflexive bradycardia
–>respiratory iregularities due to medullary hypofusion

Question 16

head injury - airway management

Answer 16

intube if:

• airway needs protection (unconscious, airway damage/facial smash)
• ventilation is inadequate

Question 17

head injury - breathing management

Answer 17

ventilate if:

• low PaO2
• high PaCO2 (could vasodilate and cause increased ICP –> secondary injury)

Question 18

Head injury deficit assessment

Answer 18

mini-neuro exam
LOC - GCS
lateralizing findings: pupils; if bilateral blown pupils –> death
motor

Question 19

Head injury diagnostics

Answer 19

most useful - CT scan

Question 20

Epidural bleed

Answer 20

lens-shaped
initially no primary injury
if treated, no secondary injury

Question 21

Subdural bleed

Answer 21

torn vein, big potential space
crescentic hematomas
chronic subdural –> kind of looks like water
–> happens to the elderly (brain smaller so not as noticeable clinically_

Question 22

Intracerebral bleed

Answer 22

diffuse axonal injury

high speed MVA

Question 23

Brain injury treatment

Answer 23

Craniotomy (remove blood clots)
External ventricular drain (drain CSF)
osmotic diuretic/Mannitol (reduce brain vol)
Hyperventilation (reduce blood volume by v/c, too much can be dangerous)
Barbiturate coma/cooling (reduce metabolic demand)

Question 24

Acceleration/deceleration injuries

Answer 24

contusions
subdural hematoma
axon/vessel shearing
mesencephalic hematoma

Question 25

Coup

Answer 25

damage at site of blow

Question 26

contrecoup

Answer 26

damage at opposite site of below

Question 27

Coup-contrecoup

Answer 27

acute decompression causes cavitation followed by a wave of acute compression

Question 28

Mild brain injury outcomes

Answer 28

GCS13015
Post-concussive symptoms: headache, fatigue, dizziness, nausea, blurred vision, diplopia, memory impairment, tinnitus, irritability, low concentration
50% at 6 weeks, 14% at 1 year

Question 29

Moderately traumatic brain injury outcomes

Answer 29

GCS 9-12
Proportional to age and CT findings
60% good recovery, 26% moderately disabled, 7% severely disabled, 7% vegetative/dead

Question 30

Late complications of head/brain injury

Answer 30

Seizures

• 5% of head injury patients
• increased with local brain damage/intracranial hemorrhage

Meningitis - CSF leak
Hydrocephalus - acute or delayed