Head injury

Question 1

What is the leading cause of death in the UK for people aged < 40?

Answer 1

Head injury

Question 2

What are the 2 main classes of head injury and what are the mechanisms of injury which cause them ?

Answer 2

Open and closed head injuries.

• Open head injury, is a head injury in which the dura mater, the outer layer of the meninges, is breached. Penetrating injury can be caused by high-velocity projectiles or objects of lower velocity such as knives, or bone fragments from a skull fracture that are driven into the brain. (missle)
• Closed head injuries are a type of traumatic brain injury in which the skull and dura mater remain intact. Caused by acceleration/deceleration/rotation (non-missile)

Question 3

Explain the difference between what is meant by a head injury and a brain injury

Answer 3

• A head injury is any sort of injury to your brain, skull or scalp This can range from a mild bump or bruise to a traumatic brain injury. Common head injuries include concussions, skull fractures, and scalp wounds.
• Whereas Traumatic brain injury (TBI) is an insult to the brain from an external mechanical force, possibly leading to permanent or temporary impairment of cognitive, physical, and psychosocial functions, with an associated diminished or altered state of consciousness.

Question 4

What are the 2 main classes of traumatic brain injury ?

Answer 4

1. Primary - occurs from time of injury
2. Secondary - occurs due to consequences of injury (can be partly preventable)

Question 5

Describe the pathophysiology of traumatic brain injury

Answer 5

Following traumatic brain injury (primary) there is:

1. Release of excitatory amino acids (glutamate, aspartate) and subsequent binding to receptors (eg NMDA - type of glutamate receptor)
2. This results in release of intracellular calcium, activation of phospholipases, breakdown of cell membrane, cell swelling, activation of apoptosis.

This can then lead to secondary brain injury as it can then cause:

• Loss of blood-brain-barrier (BBB), allowing leucocyte infiltration - inflammation
• Loss of cerebral autoregulation of blood pressure - ischaemia
• Loss of cerebral autoregulation of blood flow – metabolic de-coupling – even more ischaemia causing further brain oedema

Question 6

Define what is meant by cerebral prefusion pressure

Answer 6

CPP is defined as the difference between the Mean Arterial Pressure (MAP) and the Intracranial Pressure (ICP).

CPP = MAP - ICP

This represents the pressure gradient driving cerebral blood flow (CBF)

Question 7

Define MAP and ICP

Answer 7

• MAP, is defined as the average pressure in a patient’s arteries during one cardiac cycle. MAP = [(2 x diastolic) + systolic] divided by 3.
• ICP, is a measurement of the pressure of brain tissue and the CSF that cushions and surrounds the brain and spinal cord.

Question 8

What is the normal range for ICP ?

Answer 8

9-11 mmHg

Question 9

Following head injury what should you aim to keep the CPP above ?

Answer 9

> 60 mmHg

Question 10

What clinical finding is suggestive of an anterior cranial fossa fracture ?

Answer 10

‘Raccoon’ or ‘Panda eyes’

Question 11

What clinical finding on examination would you expect to find in a patient with a skull base fracture of the middle cranial fossa ?

Answer 11

‘Battle sign’ over mastoid area

Question 12

What are the mild signs and symptoms of traumatic brain injury ?

Answer 12

Physical symptoms

• Loss of consciousness for a few seconds to a few minutes
• No loss of consciousness, but a state of being dazed, confused or disoriented
• Headache
• Nausea or vomiting
• Fatigue or drowsiness
• Difficulty sleeping
• Sleeping more than usual
• Dizziness or loss of balance
• Scalp swelling/laceration

Sensory symptoms

• Sensory problems, such as blurred vision, ringing in the ears, a bad taste in the mouth or changes in the ability to smell
• Sensitivity to light or sound
• Cognitive or mental symptoms
• Memory or concentration problems
• Mood changes or mood swings
• Feeling depressed or anxious

Question 13

What are signs/symptoms of severe traumatic brain injury ?

Answer 13

Physical symptoms

• Loss of consciousness from several minutes to hours
• Persistent headache or headache that worsens
• Repeated vomiting or nausea
• Convulsions or seizures
• Dilation of one or both pupils of the eyes (fixed dilated pupil) - Pupillary responses to light (3rd nerve palsy) - recall that CN III Innervates a number of the extraocular muscles. Parasympathetic: Supplies the sphincter pupillae and the ciliary muscles of the eye, this can be compressed by hernation and raised ICP resulting in the fixed dilated pupil
• Clear fluids draining from the nose or ears
• Inability to awaken from sleep
• Weakness or numbness in fingers and toes
• Loss of coordination

Cognitive or mental symptoms

• Profound confusion
• Agitation, combativeness or other unusual behavior
• Slurred speech
• Coma and other disorders of consciousness

Question 14

What test is done to assess someones level of consciousness following a head injury ?

Answer 14

Glasgow coma scale (GCS)

Question 15

What are the 3 main criteria assessed in the GCS ?

Answer 15

1. Eye opening
2. Verbal response
3. Best motor response

Question 16

Define what a coma is

Answer 16

• A prolonged state of deep unconsciousness, caused especially by severe injury or illness.
• A state of extreme lethargy or sleepiness.

1. Do not open eyes
2. Do not obey commands
3. Do not speak

Question 17

What GCS score indicates that a patient is in a coma ?

Answer 17

Score of equal to or < 8

Question 18

What GCS indicates mild head injury ?

Answer 18

13-15

Question 19

What is the key management in the acute situation for someone with a head injury and why is this so important ?

Answer 19

• ABC’s and possible C-spine immobilisation.
• This is very important as irreversible neuronal damage occurs within 5 minutes of circulatory arrest

Question 20

How much of the bodies CO goes to the brain and how much of the bodies overall O2 consumption is due to the brain ?

Answer 20

• 15% of the bodies CO goes to the brain
• The brain uses 20% of the bodies O2 - hence it is very susceptible to hypoxia

Question 21

When should you do a CT head scan for adults with head injury?

Answer 21

• GCS < 13 on initial assessment in the emergency department.
• GCS < 15 at 2 hours after the injury on assessment in the emergency department.
• Suspected open or depressed skull fracture.
• Any sign of basal skull fracture (haemotympanum, ‘panda’ eyes, cerebrospinal fluid leakage from the ear or nose, Battle’s sign).
• Post-traumatic seizure.
• Focal neurological deficit.
• More than 1 episode of vomiting.

Additionally do a CT in adults who have experienced some loss of consciousness or amnesia since the injury who have any of the following additional risk factors:

• Age 65 =or older.
• Any history of bleeding or clotting disorders e.g. warfarin
• Dangerous mechanism of injury (a pedestrian or cyclist struck by a motor vehicle, an occupant ejected from a motor vehicle or a fall from a height of greater than 1 metre or 5 stairs).
• More than 30 minutes’ retrograde amnesia of events immediately before the head injury.

Question 22

When should you do a CT head scan for children with head injury?

Answer 22

• Suspicion of non-accidental injury
• Post-traumatic seizure but no history of epilepsy.
• On initial emergency department assessment, GCS < 14, or for children under 1 year GCS (paediatric) < 15.
• At 2 hours after the injury, GCS <15.
• Suspected open or depressed skull fracture or tense fontanelle.
• Any sign of basal skull fracture (haemotympanum, ‘panda’ eyes, cerebrospinal fluid leakage from the ear or nose, Battle’s sign).
• Focal neurological deficit.
• For children under 1 year, presence of bruise, swelling or laceration of more than 5 cm on the head.

For children who have sustained a head injury and have more than 1 of the following risk factors:

• Loss of consciousness lasting more than 5 minutes (witnessed).
• Abnormal drowsiness.
• Three or more discrete episodes of vomiting.
• Dangerous mechanism of injury (high-speed road traffic accident either as pedestrian, cyclist or vehicle occupant, fall from a height of greater than 3 metres, high-speed injury from a projectile or other object).
• Amnesia (antegrade or retrograde) lasting more than 5 minutes

Question 23

When should you use cervical spine immobilisation for someone with a head injury ?

Answer 23

• GCS less than 15 on initial assessment by the healthcare professional.
• Neck pain or tenderness.
• Focal neurological deficit.
• Paraesthesia in the extremities.
• Any other clinical suspicion of cervical spine injury.

Question 24

What is the intensive care management of head injury ?

Answer 24

• Sedation; reduces cerebral metabolic rate, reduces cerebral blood flow, reduces ICP
• Ventilation; maintain adequate oxygenation pO2 13 - 15kPa, maintain normocapnia pCO2 4 – 4.5kPa
• BP; manipulate to maintain CPP of > 60mmHg
• Glucose; maintain normoglycaemia
• Temp; maintain euthermia

May need to use ICP monitoring

Question 25

What are some of the different methods for protecting the brain following head injury ?

Answer 25

• CSF Drainage - reduces ICP
• Mannitol - improves micro-perfusion (think this is given first over the saline)
• Hypertonic saline - may be better than mannitol

Hyperventilation - temporary effect (2-4 hrs)

Hypothermia - weak evidence for effect

Decompressive craniectomy – randomised trial underway

Question 26

What are the main types of traumatic intracranial bleeding which can occur following a head injury ?

Answer 26

Question 27

What are some of the late complications which can arise due to head injury ?

Answer 27

• Epilepsy; early (first 2 weeks), low risk late (likely to become established)
• CSF leak; into nose, into middle ear
• Cognitive problems; post-concussion syndrome (poor concentration, headache, poor memory, lethargy)