Head Trauma

Question 1

Describe the different types of haemorrhage that can occur in head trauma

Answer 1

Extradural - torn meningeal arteries rupture between endosteal dural layer and calvarium

Subdural - usually after a blow that causes the brain to move within the skull: veins rupture within subdural space

Subarachnoid - blood collects beneath arachnoid layer of meninges (if blood gets into CSF or aneurysm rupture)

Intracerebral - rupture of a vessel within the brain

Question 2

What are the characteristic features of raised intracranial pressure?

Answer 2

Follows pathway of localising signs, decreasing levels of consciousness, coma then death

Question 3

What are the current diagnostic and management approaches for head trauma?

Answer 3

ATLS guidelines - assess whether damage is focal/diffuse
Is there a skull fracture?
Aim to prevent secondary brain damage by reduced cerebral perfusion (prevent hypoxia and hypotension)
Monitor ICP -> treat when rises above 25mmHg but maintain CPP
CT/MRI scans and GCS

Question 4

What are the 3 key areas of the brain mainly affected by raised ICP?

Answer 4

Cingulate gyrus - herniates under the falx cerebri (falcine herniation)

The Uncus - herniates over the tentorium cerebelli (damages midbrain)

The Cerebellar Tonsils - herniates through foramen magnum to give tonsillar herniation

Question 5

Outline ATLS

Answer 5

Advanced Trauma Life Support
Acute control of airway, breathing, circulation
Prevent hypoxia and hypotension
GCS/Neuro exam

Question 6

Why are patients with head trauma kept normovolaemic?

Answer 6

Prevent hypotension -> reduced cerebral perfusion

Prevent hypertension -> SIRS/MOF

Question 7

What is decompressive craniotomy surgery? When might it be used?

Answer 7

To open up part of the skull to allow the brain to swell outside and therefore relieve pressure - often used as a last resort and often in intracerebral haemorrhages

Question 8

Shape-wise how can you tell the difference between an extradural and subdural haematoma?

Answer 8

Extradural are lemon shaped

Subdural are banana shaped - more crescent long and thin

Question 9

What’s the normal ICP? At above what pressure is it usually treated?

Answer 9

0-10 mmHg

Treated above 20 mmHg (or 25)

Question 10

What’s the equation for cerebral perfusion pressure?

Answer 10

CPP = MAP - ICP

usually 50-70 mmHg

Question 11

In neurocritical care patients, why should free water not be administered?

Answer 11

Will decrease plasma osmolality and therefore increase water content of the brain tissue (as BBB is semi permeable membrane) further increasing ICP

Question 12

Why are elevated blood sugar levels associated with worsening of ischaemic injury?

Answer 12

Ischaemic brain metabolises glucose into lactic acid, lowering tissue pH and exacerbating injury

Question 13

What are the 5 glasgow outcome scores?

Answer 13

1 Dead
2 Vegetative state (sleep/wake cycle but not sentient)
3 Severely disabled (conscious but dependent)
4 Moderately disabled (independent but disabled)
5 Good recovery

Question 14

What are some mental sequelae that can occur following head trauma? Why are these problematic?

Answer 14

Personality disorders
Memory disorders
Reduced reasoning power
Apathy, lack of drive
Temper tantrums
Family disruption

= patients lack motivation and capacity to cope with therapeutic programmes without constant prompting

Question 15

Which cranial nerve is most commonly damaged in head trauma and what are its symptoms?
What other brain damage might persist?

Answer 15

CN VIII
Vertigo, Nausea, Nystagmus

Hemispheric sequelae, cranial nerve palsies, anosmia

Question 16

What’s the monro-kellie hypothesis?

Answer 16

The skull is a constant fixed volume, within it lie the brain, CSF and blood

Vtotal = Vbrain + VCSF + Vblood + Vmass

Brain uses that equation to maintain itself over a broad range of pressures, but once exhausted it rapidly and exponentially increases leading to rapid deterioration and death if not treated quickly

Question 17

What’s the initial mechanism of the brain to cope with increased pressure?

Answer 17

CSF shunted into cisterns surrounding base of brain and spinal cord - particularly lumbar cistern and cisterna magna

Question 18

What are the signs of raised ICP and why?

Answer 18

Papilloedema (optic disc appears to be bulging due to increased CSF surrounding optic nerve)

Fixed dilated pupil due to loss of parasympathetic supply to that eye because CN III can become compressed at the tentorial notch

Question 19

What are the 4 main types of brain herniation?

Answer 19

Subfalcine herniation: below falx cerebri

Uncal herniation: uncus pushes into tentorial notch of tentorium cerebelli (trapping CN III)

Tonsillar herniation: cerebellar tonsils through foramen magnum

Coning: forced movement of brainstem through foramen magnum

Question 20

Why is coning a medical emergency?

Answer 20

Forces brainstem through foramen magnum = cardiovascular, respiratory and conscious centres are at risk

Question 21

What’s a transcalvarial herniation and how may it be used beneficially?

Answer 21

Extrusion of brain tissue through vault in the skull

Used in neurosurgery to reduce raised ICP and impact of swelling

Question 22

What’s a Chiari malformation?

Answer 22

Congenital disorder where cerebellar tonsils project into foramen magnum

Question 23

What’s Kernohan’s notch?

Answer 23

Fold in the cerebral peduncle of the midbrain, that forms as a result of tissue moving from one side of the skull to the other, causing the tissue to fold on itself
Seen on contralateral side to lesion

Question 24

What type of blood collects between which two structures in an extradural haemorrhage?

Answer 24

Meningeal arteries rupture so arterial blood collects between dural endosteal layer and the calvarium

Question 25

What type of blood is a subdural haemorrhage?

Answer 25

Vein

Question 26

Where does blood collect and what type of blood in a subarachnoid haemorrhage?

Answer 26

Arterial blood - usually from mico aneurysm rupture

Collects in CSF beneath arachnoid layer of meninges

Question 27

What type of damage causes DAI?

Answer 27

Twisting/rotational force applied to axons eg car crash - small lesions usually at border of grey and white matter

Question 28

Why should free water/dextrose solutions NOT be administered to critical care head injury patients?

Answer 28

Decrease plasma osmolarity and therefore increase water content on the brain
Elevated blood sugar levels can worsen injury as ischaemic brain metabolises glucose to lactic acid = lowers pH and exacerbates injury