Head Injury

Question 1

Head Injury

Common causes

Answer 1

RTC (bulls-eye, damage to helmets)
Direct blows to the head
Falls from height
Sports related injury

Question 2

Head Injury

Signs and symptoms

Answer 2

Lacerations, contusions or haematomas to the scalp
Boggy areas when palpating the scalp
Visible fractures or deformity of the skull
Battle’s sign or ‘panda eyes’ (not apparent for several hours)
Dizziness
Nausea and vomiting
Abnormal pupils and/or pupil reaction
Visual disturbances (double or blurred vision, seeing ‘stars’)

Ambulance Care Practice p327
Cerebrospinal fluid and/or blood leaking from the nose or ears
Severe headache
Altered level of consciousness
Perseveration (repeatedly asking the same questions)
Amnesia
In the later stages of traumatic brain injury, the cardiovascular centre in the medulla becomes ischaemic.

Question 3

The Cushing reflex is triggered

Answer 3

The Cushing reflex is triggered, resulting in peripheral vasoconstriction and a rise in systolic blood pressure.

This in turn, leads to reflex bradycardia.

Respirations are also affected, leading to irregular respirations.

Ambulance Care Practice p328

Question 4

Intracranial contents

Answer 4

Brain
Blood
CSF

Question 5

Autoregulation

Answer 5

The ability of a tissue to automatically adjust the blood flow through it to match its metabolic demand for O2 and nutrients and the removal of wastes is called autoregulation.
Total blood flow through the brain remains almost constant, regardless of the degree of physical or mental activity.
In systemic circulations, blood vessels dilate in response to low O2 levels.
Tortora & Grabowski 9thEd p686

Question 6

Physiology brain injured

Answer 6

In the traumatically injured brain, autoregulation starts to fail and affected areas of the brain become pressure passive, relying on higher than normal mean arterial pressures to maintain cerebral blood flow.
If a cerebral oedema or haematoma develops, CSF is displaced and the level of venous blood in the cranium is reduced. In the early stages of rising intracranial pressure (ICP), blood pressure will be fairly stable.

Question 7

MAP = Diastolic + 𝟏/𝟑[ [pressure

Answer 7

Cerebral Perfusion Pressure
(CPP)

Mean
Arterial Pressure
(MAP)

Intracranial Pressure
(ICP)

Question 8

Coup injury

Answer 8

Brain impacts on skull on hitting ground

Question 9

Contra-coup injury

Answer 9

Transmitted forces cause brain to rebound and impact on opposite side of skull

Question 10

Pathophysiology head injury

Answer 10

Primary brain injury occurs at the time of injury.

Prevention strategies, including the wearing of motorcycle and cycle helmets, the use of airbag restraint systems (e.g. seatbelts and airbags) and public education.

Question 11

Pathophysiology head injury 2nd

Answer 11

Secondary brain injury occurs following the primary event as a result of hypoxia, hypercarbia or hypoperfusion
Numerous studies have demonstrated the correlation between arterial hypoxaemia and poor prognosis following traumatic brain injury (TBI).

Some demonstrate increased mortality up to 50% following only one brief episode of desaturation.
A reduced level of consciousness may lead to airway obstruction or inadequate ventilation resulting in poor oxygenation, carbon dioxide retention and acidosis.

Airway obstruction or aspiration are major and often preventable causes of death in patients with severe traumatic brain injury.

Question 12

Hyperventilation reduces what does what

Answer 12

Hyperventilation reduces arterial CO2, leading to vasoconstriction of the cerebral vasculature, worsening both cerebral hypoxia and oedema.

Question 13

Hypoventilation increases what does what.

Answer 13

Hypoventilation increases arterial CO2, causing vasodilation of cerebral blood vessels, which increases intracranial volumes (and subsequently ICP).

Question 14

Treatment goals for adults and children differ.

Answer 14

Treatment goals for adults and children differ.

For adults, keep SBP >90mmHg.

For children, there are age specific SBP targets.

Question 15

Management

Answer 15

Some evidence suggests that placing the patient in a 30o head up position reduced the effects of raised ICP in patients with TBI.
The patients GCS should be calculated, as this can be an important prognostic indicator and is useful for monitoring injury progression over time.

Question 16

Complications

Answer 16

A number of age related structural changes in cerebral architecture leaves elderly people at increased susceptibility to intracranial haemorrhage following what may be a an apparently minor head injury.
It is estimated that up to 10% of TBIs are complicated by cervical spine injury.

There is strong evidence rigid collars create a detrimental rise in ICP (probably due to compression of the jugular veins of the neck).

It is estimated that up to 10% of TBIs are complicated by cervical spine injury.

There is strong evidence rigid collars create a detrimental rise in ICP (probably due to compression of the jugular veins of the neck).
Current practice is to loosen the collar once extrication is complete and the patient is secured in a position of neutral alignment with conventional head and body immobilisation.

Pain can lead to patient agitation, which itself leads to further cerebral hypoxia.

(The administration of opioids in severe TBI is problematic due to the potential to exaggerate respiratory depression, hypoventilation, hypercapnia and increased ICP.)

Question 17

Maxillofacial injury

Pathology

Answer 17

Maxillofacial injury (i.e. involving the maxilla and/or face) is common, with an estimated 500,000 facial injuries occurring each year.

Ambulance Care Practice p 328