Applied physiology: The Clinical Management of Head Injury Flashcards
How many attendances are there in Scotland with head injury ? in the UK ?
In Scotland 100 000 attendances /yr with head injury
In UK 1.4 M
What is the ratio of M:F who present with head injury ?
Male:Female 2:1
What are the main age groups which are concerned by head injury ?
Age: 2 peaks early 20s & early 80s
What proportion of all patients presenting with head injury are admitted ?
15%
What is the leading cause of death in <45 years old ?
Trauma (50% of these are head injury)
What proportion of adult head injuries involve alcohol ?
65%
What are the different aetiologies of head injuries ?
Falls, assaults, RTAs
Describe the change in frequency of traumatic brain injury.
Incidence of traumatic brain injury is increasing
Identify the main classifications of brain injury.
PRIMARY (neuronal damage that is done by an external force at the moment of impact. Nerves are irreparable, nothing can be done about that primary injury, can only try to prevent)
SECONDARY (secondary processes which occur at the cell and molecular level to exacerbate neurological damage, i.e. area surrounding dad tissue where blood supply may be impaired, and which may get better or worse. Focus of medical treatment)
When does primary brain injury occur ? What does pattern and extent of damage of primary brain injury depend on ?
Occurs at the moment of impact
Pattern and extent of damage depends in nature of impact
Describe the brain damages which result from acceleration deceleration injuries, and from direct blows to the head.
Acceleration deceleration injuries result in axonal shearing, with diffuse axonal injuries
Direct blows to the head result in contusions to the brain + bruising around brain
Distinguish between primary, and secondary prevention of brain injury.
PRIMARY: strategies to stop impact happening (e.g. speed limits, alcohol regulations)
SECONDARY: If impact occurs, try and minimize damage (e.g. cyclist helmets)
What is the main focus of medical intervention in brain injuries ?
Minimizing secondary brain injury, mainly by:
1) OPTIMISE OXYGENATION
2) OPTIMISE CEREBRAL PERFUSION
3) Regulating blood glucose
4) Managing hyper/hypoCapnia
5) Managing body temperature (preventing pyrexia, but in the meantime not inducing any hypothermia)
Describe the significance of the ApoE eta4 genotype for boxers.
Some genotypes have poorer outcomes when given blows to the head (i.e. should we screen boxers for ApoE eta4 genotype, which provides them with vulnerability to brain injury ?)
Identify the main secondary processes which occur at the cell and molecular level to exacerbate neurological damage (i.e. in secondary brain injury).
- Neurotransmitter release (glutamate)
- Free radical generation
- Calcium mediated damage
- Inflammatory response
- Mitochondrial dysfunction
- Early gene activation
Describe the physiological principles surrounding increases in ICP.
Monro-Kellie Doctrine:
• Skull is fixed rigid container, cannot expand. Inside it, there is venous and arterial blood, brain, and CSF.
• Normally, ICP is around 10 mmHg.
• If anything increases in that skull, it can compensate to a certain extent (e.g. due to mass such as hematoma, swelling or bruising of
the brain). This compensation means the mass can squish out some CSF and venous blood. HOWEVER, level of compensation is limited.
• After this level has occurred, if that mass continues to expand, ICP will increase exponentially. Once that happens, cerebral profusion
starts to fail and more cells start to die, and area of secondary brain ischemia expands.
Identify the main pathological features of primary brain injury.
-Activation of biomecular mediators of injury ⬇ -Neuronal damage ⬇ -Cytotoxic oedema
-Cerebral vessel damage and opening of BBB
⬇
-Increased interstitial fluid and tissue P
⬇
-Vasogenic oedema
Due to both oedemas, cerebral volume increases, ICP increases, resulting in decreased cerebral perfusion, resulting in vasodilation (to get more blood into brain), which results in further increased cerebral volume, which pushes further secondary brain injury.
Graph and explain the correlation between ICP and intracranial V.
Refer to slide 23
Expanding masses in the brain will be able to be compensated for up to critical volume (until which ICP only increases a little), after which ICP increases exponentially.
Identify the main kinds of mechanisms of injury to the brain in secondary brain injury. Which of these may contribute to the swelling of the brain ?
Hematoma
Contusion
Hypoxia/Ischemia
Diffuse Axonal Injury
First three will contribute to swelling of the brain
Identify the first measures to take, in early management of head injury.
- Assessment and identification of the patient at risk of secondary brain injury
- Pre-emptive investigation (CT scan)
- GCS
THEN
1) Optimise Oxygenation (while remembering cervical spine)
2) Optimise cerebral perfusion
3) Identify features suggesting at risk of intracranial mass
4) Identify those patients where neurosurgical intervention is required, and refer those to neurosurgery (and in the meantime, use ventilation, and drugs to buy time if needed)
5) Control glucose and provide enteral nutritional support
Which kinds of patients with head injuries do we send to hospital ?
- Extremes of age (<5years or >65years): elderly have more comorbidities, and may be on drugs including antiplatelets or anticoagulants which may increase risk of bleed (others may be at risk of clotting)
- Amnesia for events before or after injury
- Any loss of consciousness
- High energy injury
- Vomiting
- Seizure (previous neurosurgery)
- Bleeding /clotting disorder
Identify possible causes of falls in the elderly.
Cardiac arryhthmias
Simple falls
Syncope
How is GCS useful in management of head injuries ?
Useful for:
- Classification
- Initial management
- Ongoing assessment
- Determining prognosis (Best GCS post resuscitation is of prognostic value)
of patient with head injury
Identify the main scores of GCS.
1) EYE OPENING Score 4: Eyes open spontaneously Score 3: Eyes open to speech Score 2: Eyes open in response to pain Score 1: Eyes do not open Record NT: If patient is unable to open eyes due to swelling, bandages etc.
2) VERBAL RESPONSE
Score 5: Orientated
Score 4: Confused (answering appropriately but with incorrect information)
Score 3: Inappropriate words (answering with recognisable words but not making sense)
Score 2: Incomprehensible sounds (moaning and groaning)
Score 1: No response despite verbal and physical stimuli
Record NT: Dysphasic, Record T if intubated
3) MOTOR RESPONSE
Score 6: Obeys commands
Score 5: Localises to central pain (e.g. trapezius squeeze or supraorbital P)
Score 4: Normal flexion towards source of pain
Score 3: Abnormal flexion
Score 2: Extension to pain
Score 1: No response to painful stimuli
Identify questions to ask patient to assess verbal response as part of GCS.
Where are you ?
In the context of a sports match, what’s the score ? What half are we in ?
