Nervous system: Head trauma

Question 1

What is cerebral contusion?

Answer 1

‘Bruising’ of the brain where blood mixes with cortical tissue due to microhaemorrhages. Occurs as a result of direct trauma, and the areas affected are where the brain can hit a bony prominence

Question 2

What is coup contrecoup injury?

Answer 2

Coup is when the brain is injured at the site of impact, contrecoup is the injury that occurs at the opposite side, from where the brain is pushed back onto the skull

Question 3

What is the definition of concussion?

Answer 3

Head injury with temporary loss of brain function, it is a milder from of diffuse axonal injury

Question 4

What is the pathophysiology of concussion?

Answer 4

Trauma occurs which stretches and injures the axons, causing impaired neurotransmission, loss of ion regulation and reduction in cerebral blood flow. As a result there is temporary brain dysfunction.

Question 5

What is the definition of diffuse axonal injury?

Answer 5

Shearing of the interface between grey and white matter following trauma acceleration/deceleration or rotational injury damaging the intra-cerebral axons and dendritic connections

Question 6

What is the pathophysiology of diffuse axonal injury?

Answer 6

There is trauma which shears the grey and white matter interface causing axonal cell death. There is cerebral oedema which raises ICP. Commonly fatal

Question 7

What are the clinical signs of a basilar skull fracture?

Answer 7

• Racoon eyes from venous sinus bleeds
• CSF rhinorrhoea
• CSF otorrhoea from perforated ear drum
• Battle sign
• Haemotympanum

Question 8

How is a basilar skull fracture managed?

Answer 8

• Need to look for other injuries as it takes significant force to break the base of the skull
• depressed fractures may need to be elevated
• persistant CSF leak may need surgery

Question 9

How are head injuries classified into mild, moderate and severe?

Answer 9

Mild: GCS 13-15, post-traumatic amnesia <1 day, LOC 0-30 minutes
Moderate: GCS 9-12, post-traumatic amnesia 1-7 days, LOC 30m-24hrs
Severe: GCS 3-8, post-traumatic amnesia more than 7 days, LOC >24 hours

Question 10

What are the urgent CT head criteria?

Answer 10

Urgent CT is within 1-3 hours.
- GCS <13 at any point, <14 2 hours after injury
- suspected skull fracture
- 2 discrete episodes of vomiting
- seizure
- LOC with any of:
65 and over, coagulopathy, dangerous mechanism of injury, amnesia >30 minutes

Question 11

What is the site of an extradural haemorrhage?

Answer 11

Between the inner surface of the skull and the periosteal dura mata.

Question 12

What is the cause of an extradural haemorrhage?

Which patient groups are most common?

Answer 12

90% cases is a severed artery, commonly the middle meningeal artery.
50% of cases happen in young patients under the age of 20, this is because the dura are firmer in older patients, and younger patients tend to do more risky activities.

Question 13

What is a supratentorial extradural haemorrhage?

Answer 13

The haemorrhage occurs above the tentorium cerebelli (95% of cases)

Question 14

Describe how the conscious level of patient with an extradural haemorrhage will change with time

Answer 14

The patient will initially present with LOC as a result of the impact of initial injury
40% then experience a ‘lucid interval’ where they have transient recovery with an ongoing headache
As the haematoma enlarged ICP will raise causing a rapidly deteriorating level of consciousness.

This can all happen in a few hours so need urgent CT and pressure relieved

Question 15

What is the management of an extradural haemorrhage?

What is the prognosis?

Answer 15

Small EDH can be observed and managed conservatively
Large EDH need referral to neurosurgery for craniotomy and clot evacuation
Prognosis is very good with early diagnosis and intervention.

Question 16

How does an extradural haemorrhage appear on CT scan?

Answer 16

Lemon shaped.

Cannot extend past the sutures because the dura are continuous through the suture lines

Question 17

What is the site of a subdural haemorrhage?

Answer 17

Between the meningeal dura mata and the arachnoid mata

Question 18

What is the cause of an subdural haemorrhage?

Which patient groups are most common?

Answer 18

Usually occurs as a result of shearing of the bridging veins (the veins which drain the brain into the venous sinuses). Most often due to trauma but could be spontaneous.
Can occur in any age group however spontaneous bleeds are more common in cerebral atrophy (older pts) because there is more tension on the bridging veins.

Question 19

How does a subdural haemorrhage appear on CT?

Answer 19

Banana shaped, the falx prevents blood crossing the hemispheres.
Acute bleeds (due to trauma) appear hyperdense - brighter than brain tissue.
Chronic bleeds (in elderly, may have vague history of head trauma such as falls) appear hypodense - darker than brain tissue.

Question 20

What is the management of a subdural haemorrhage?

Answer 20

Acute SDH need immediate neurosurgical intervention to relieve raised ICP
Chronic SDH can either be monitored with imaging or treated via burr holes.
Prognosis is poor compared to EDH, full recovery only achieved in 20% of patients

Question 21

What is the site of a subarachnoid haemorrhage?

Answer 21

Bleed between the arachnoid and pia mata

Question 22

What is the cause of an subarachnoid haemorrhage?

Which patient groups are most common?

Answer 22

Vast majority occur spontaneously secondary to a ruptured berry aneurysm, but can also be traumatic.
Most common presentations occur in patients 40-60

Question 23

How do patients with a subarachnoid haemorrhage present?

Answer 23

• thunderclap headache
• meningism, blood irritates the meninges
• N+V
• fever
• focal neurological defects
• LOC

Question 24

How is a subarachnoid haemorrhage managed?

What is the prognosis?

Answer 24

Management: stabilise the pt, prevent rebleeding (they are at greater risk), treat cerebral vasospam from irritation from the blood, surgery if large bleed.
Prognosis is very variable 30-90% mortality, there is less blood in a SAH but it is more catastrophic

Question 25

What are the risk factors for berry aneurysms?

Answer 25

• family hx
• hypertension
• heavy alcohol consumption
• smoking
• abnormal connective tissue eg ehlers danlos, marfans

Question 26

What are the common sites for berry aneurysm formation and why?

Answer 26

Points of bifurcation on the circle of willis (95% is anterior circ)
This is because there is rapid changes of blood direction and therefore turbulence, this causes a weakness in the wall.