26-09-23 - Applied physiology - The Clinical Management of Traumatic Brain Injury

Question 1

Learning outcomes

Answer 1

• To gain insight into the epidemiology of head injury
• To understand the concept of primary and secondary head injury
• To be able to apply the Glasgow Coma Scale
• To understand the Monroe-Kellie doctrine
• To describe the effects of systemic BP, pO2 and pCO2 on cerebral perfusion
• To recognise common intracranial haematomas on CT

Question 2

Traumatic brain injury (TBI) epidemiology

Answer 2

• Traumatic brain injury (TBI) epidemiology
• 1998 and 2009 there were 208,195 recorded episodes of continuous hospital care in Scotland as a result of TBI.
• 47% Falls
• Peaks different age groups.
• TBI is a major mortality , morbidity Head injury commonest cause of death and disability in 1-40 years old UK
• 1,4 million patients per year in Wales and England
• 33-50% of these attending are children
• 90 -95% are mild injuries
• In Scotland estimated 6.6% of ED are head injuries
• UK 200.000 admissions per year.
• Death incidence 0.2% of all patients attending ED
• Males 1.5 / 1Female
• Under 0-4years , 15-19 and over 75s
• Falls, Road Traffic Accidents (RTA) and Assaults are the major cause

Question 3

Global Burden of diseases (GBD) of TBI

Answer 3

• Global Burden of diseases (GBD) of TBI
• Prolonged Effects of injury
• Over 50 million TBI / year internationally
• High income countries numbers of TBI in elderly increases
• TBI deaths are 30-40% of all injury related deaths
• Neurological injury is the most important cause of disability related to neurological diseases
• TBI costs US$400 billion annually
• EU 2-5 million new cases occur each year

Question 4

What causes a TBI?

What are 4 examples of TBIs?

Answer 4

• A TBI is caused by external forces that cause damage
• 4 examples of TBIs:

1) Fracture

2) Haemorrhage
* A hemorrhage is profuse bleeding from a ruptured blood vessel or copious blood loss.

3) Haematoma
* A hematoma is localized bleeding outside of blood vessels. A bruise (also called contusion) is an example of a type of mild hematoma

4) Axonal injury

Question 5

What is primary brain injury?

What does its variation depend on?

Is it treatable?

Answer 5

• Primary brain injury is the instant injury and occurs at the moment of impact
• The pattern & extent of damage depends in nature of impact
• Primary brain injury is not treatable, with there only being target prevention (public health issue) to reduce their occurrence

Question 6

What causes shaken baby syndrome?

When does it usually occur?

Answer 6

• If a baby is forcefully shaken, their fragile brain moves back and forth inside the skull.
• This causes bruising, swelling and bleeding – shaken baby syndrome
• Shaken baby syndrome usually occurs when a parent or caregiver severely shakes a baby or toddler due to frustration or anger

Question 7

What is a contrecoup injury?

What causes a coup-contrecoup injury?

Answer 7

• A contrecoup brain injury means the brain has been injured directly opposite the point of trauma.
• For example, if a motorist is rear-ended, the force would push them into their seat and their head away from the steering wheel, into the headrest.
• Coup-contrecoup brain injuries occur when a head injury results in damage to 2 sides of the brain (the side of the trauma and the opposite side of the brain).

Question 8

What are 3 stages in the early management of a head injury?

Answer 8

• 3 stages in the early management of a head injury:

1) Prehospital management
* Immediate management of the scene

2) Assessment in the ER

3) Investigating pre-emptive investigations

Question 9

What are 2 parts in the prehospital management of TBI?

What is optimised?

What should be done if there is a suspected C-spine injury?

Describe the Glasgow coma scale (in picture).

What is GCS used for?

What GCS score is for mild, moderate, and severe TBIs?

Answer 9

• 2 parts in the prehospital management of TBI?

1) Airway, Breathing, Circulation (ABC)
* Optimise oxygenation:
* When assessed pre admission SpO2 < 90% in 50% of cases
* Open the airway, but if a cervical spine injury is suspected, immobilise the C-spine using a rigid collar while intubating

2) Glasgow Coma Scale (in picture)
* Assesses disability and degree of head injury:
* E4V5M6 - GCS 15/15
* Mild 13-15
* Moderate 9-12
* Severe 8 or less
 

Question 10

What 7 pieces of information should be mentioned when sending a patient to hospital?

Answer 10

• 7 pieces of information should be mentioned when sending a patient to hospital:
  1) Under 5 years old and over 65-year-olds
  2) Amnesia
  3) Loss of consciousness
  4) High Energy injury
  5) Vomiting
  6) Seizure
  7) Bleeding / Clotting disorders

Question 11

What is secondary brain injury caused by?

What are 6 factors that can cause secondary brain injury?

Answer 11

• Secondary brain injury is caused by the Secondary processes which occur at the cell & molecular level to exacerbate neurological damage.
• 6 factors that can cause secondary brain injury:
  1) Neurotransmitter release (glutamate)
  2) Free radical generation
  3) Calcium mediated damage
  4) Inflammatory response
  5) Mitochondrial dysfunction
  6) Early gene activation

Question 12

What are 5 ways to reduce secondary brain injury?

Answer 12

• 5 ways to reduce secondary brain injury:

1) Optimise Oxygenation
* Need to intubate and give oxygen, also have to let patient have enough blood circulating using hypertonic solutions

2) Optimise Cerebral Perfusion

3) Blood Glucose
* Do they have diabetes?
* Do they have hyperglycaemia?
* Try to get this in normal range

4) Hypocapnia / Hypercapnia

5) Body Temperature
* Give paracetamol for pyrexia

Question 13

What is the Monro-kelli doctrine?

Describe the Monro-kelli doctrine for a normal brain, compensated brain, and uncompensated and raised ICP (intracranial pressure) brain (in picture)

Answer 13

• The Monro-Kellie doctrine, or hypothesis, is that the sum of volumes of brain, CSF, and intracranial blood is constant.
• An increase in one should cause a decrease in one or both of the remaining two.
• Monro-kelli doctrine for a normal brain, compensated brain, and uncompensated and raised ICP (intracranial pressure) brain (in picture)

Question 14

How can we monitor intracranial pressure (ICP)?

What 6 conditions will increase ICP?

Describe the formula for cerebral perfusion pressure CPP (in picture)

Answer 14

• Intracranial pressure (ICP) can be monitored using interventricular measurement
• 6 conditions will increase ICP:
  1) Bleeding in the brain
  2) Tumor
  3) Stroke
  4) Aneurysm
  5) High blood pressure
  6) Brain infection.
• Formula for cerebral perfusion pressure CPP (in picture)

Question 15

Pathophysiology of primary and secondary brain injury flow chart (in picture)

Answer 15

Question 16

What are 4 PMH features that suggest an increased risk of intracranial mass.

What are 3 examination signs that suggest an increased risk of intracranial mass?

Answer 16

• 4 PMH features that suggest an increased risk of intracranial mass:
  1) High impact injury
  2) Significant retrograde amnesia
  3) History of coagulopathy
  4) Post traumatic seizure
• 3 Examination signs that suggest an increased risk of intracranial mass:
  1) GCS 12/15 or less
  2) GCS 13/15 or 14/15 and failing to improve within 2 hours of injury
  3) Clinical signs of skull fracture

Question 17

What are 4 red flags concerning TBIs?

Answer 17

• 4 red flags concerning TBIs:

1) Loss of consciousness, drowsiness, confusion, fits

2) Painful headache which doesn’t settle, vomiting or visual disturbance

3) Clear fluid from ear or nose, bleeding from ears, new deafness (CSF rhinorrhoea test for glucose or beta 2 transferrin)

4) Problems understanding or speaking, loss of balance, difficulty walking or weakness in arms or Legs

Question 18

What 4 factors should we consider for Breathing with TBIs?

How should we investigate the C-spine?

What drug may be given for a suspected TBI?

Answer 18

• 4 factors we should consider for Breathing with TBIs:
  1) Administer oxygen
  2) Monitor SpO2
  3) Monitor ABGs
  4) GCS < 8 intubate
• For C-spine, offer a plain x-ray investigation of choice, often CT cervical spine
• Tranexamic acid (sometimes shortened to TXA) is a medicine that controls bleeding, and can be given for suspected TBIs

Question 19

How can CO2 affect CBF (cerebral blood flow) and cerebral vessel diameter?

What is the target for PaCO2?

What happens if PaCO2 increases?

Answer 19

• Cerebral vessel diameter (and CBF – cerebral blood flow) changes over a wide range of PaCO2
• The target fir PaCO2 is 4.5 -5.0kPa with target directed therapy
• If PaCO2 increases, vasodilation occurs, because tissues want more oxygen, Oxygen increases, ICP increases, and oedema increases

Question 20

What should we prioritise and minimise?

How common are convulsions in severe head injuries?

How do we treat this?

How does temperature affect brain metabolic rate?

What else should we also consider?

Answer 20

• We need to optimise oxygen supply and minimise demand
• Convulsions (rapid involuntary muscle contractions) occur in 15% of severe head injuries
• Treat with phenytoin in early head injury to stop fits
• Brain metabolic rate increases 6-9% for every degree rise in temperature, so we must treat this with an anti-pyretic
• We should also think about sedation (propofol / midazolam)

Question 21

What 7 pieces of information are needed when contacting a neurosurgeon?

Answer 21

• 7 pieces of information are needed when contacting a neurosurgeon:

1) Mechanism of injury

2) Age of patient

3) Respiratory and cardiovascular status

4) GCS score & pupil response
* No pupillary response means the patient is deteriorating rapidly and near death

5) Alcohol/drugs

6) Associated injuries

7) Results of CT scan

Question 22

What are 8 parts of the ICU Management of Intracranial Hypertension?

Answer 22

• 8 parts of the ICU Management of Intracranial Hypertension:

1) ICP monitoring

2) Osmolar therapy
* E.g with hypertonic solutions such as mannitol

3) Decompressive craniotomy

4) Hypothermia (?)
* Causes vasoconstriction, so oedema wont increase but circulation will decreases, so cerebral perfusion pressure will also be less (don’t want this)

5) Venous Thromboembolism Prophylaxis (treatment given or action taken to prevent disease.)

6) Stress ulcers

7) Prophylaxis Seizure

8) Prophylaxis Nutrition

Question 23

Tier ranking based on severity of injury (in picture)

Answer 23

Question 24

If the patient is ventilated, how can we decrease patient’s arterial PCO2?

Answer 24

• If a patient is ventilated, we can decrease the patient’s arterial PCO2 by increasing the ventilation rate

Question 25

What is the optimum target for blood glucose after traumatic brain injury?

Answer 25

* In the first week (acute stage) of TBI, a blood glucose target of 90-144 mg/dL (5-8 mmol/L) was associated with reduced mortality rate and decreased intracranial pressure (ICP) compared to a blood glucose target of 63-117 mg/dL (3.5-6.5 mmol/L).

Question 26

What can Peri-orbital bruising indicate? What needs to be done in this situation?

Answer 26

* Peri-orbital bruising is associated with anterior cranial fossa fracture * We need to ask for a consultation from the neurosurgeon in this case

Question 27

What is Battle’s sign a sign of?

Answer 27

* Battle’s sign is associated with Petrous temporal bone fracture * Bruising might take time to develop

Question 28

In what 7 scenarios should a request a CT scan immediately following TBI?

Answer 28

* 7 scenarios should a request a CT scan immediately following TBI: 1) GCS<13 on initial assessment. 2) GCS<15 2 hours after injury 3) Open or suspected depressed skull 4) Any sign of Basal skull injury (risk of infection/meningitis 5) Post traumatic seizure 6) 1 or more episodes of vomiting (3 in kids) 7) Amnesia for events more than 30 mins before impact

Question 29

Extradural hematomas (aka epidural haematomas) How common are extradural haematomas (aka epidural haematoma)? What are they strongly associated with? What artery/veins commonly cause extradural haematomas? What is a lucid interval? What is the likely outcome of extradural haematomas if treated? Do extradural haematomas pass the sutures? What shape can extradural haematomas have on CT?

Answer 29

* Extradural Haematoma (aka epidural haematoma) * Relatively uncommon * Strongly associated with skull fracture * Extradural haematomas are usually due to Middle meningeal artery, with 1/3 due to venous bleeding * There is classically a lucid interval, which is the period of time between regaining consciousness after a short period of unconsciousness, resulting from a head injury and deteriorating after the onset of neurologic signs and symptoms caused by that injury * Extradural haematomas have good outcomes if treated * Extradural haematomas don’t pass the sutures, as the dura is fixed t the sutures * Extradural haematomas can have a biconvex shape on CT scans

Question 30

Subdural haematoma. How common are these? What % of head injuries do they complicate? What are subdural haematomas caused by? What groups are they more common in? How does their prognosis compare to that of extradural haematomas? Do they cross the suture lines? What shape do subdural haematomas have on CT?

Answer 30

* Subdural haematoma * Subdural haematomas are more common as they happen more easily * They complicate 20-30% of head injuries * Subdural haematomas are caused by Rupture of the veins travelling from the brain surface to the sagittal sinus * In the elderly, bridging veins are more fragile and more prone to haemorrhage * In chronic drinkers, the brain can shrink, making the veins more prone to haemorrhage * The prognosis of subdural haematomas is worse than that of extradural haematomas * Subdural haematomas can cross suture lines * Subdural haematomas can have a crescentic shape on CT  

Question 31

Subarachnoid haemorrhages. What are subarachnoid haemorrhages associated with? What are they more commonly caused by?

Answer 31

* Subarachnoid haemorrhages * Subarachnoid haemorrhages are associated with a ruptured aneurysm * They are more commonly associated by head injury

Question 32

Scalp haematoma CT scan (in picture)

Answer 32

Question 33

Intracerebral Haemorrhage. What type of injury is Intracerebral Haemorrhage? What are they caused by?

Answer 33

* Intracerebral Haemorrhage * Intracerebral Haemorrhages are an axonal injury, usually due to stretching & shearing * They are caused by impact on the side of the skull and often are a contre coup injury, but can also happen in shaken baby syndrome

Question 34

What are 3 clinical signs of herniation? How fatal is cerebellar tonsillar herniation? Why is this?

Answer 34

* 3 clinical signs of herniation: 1) Dilated or unreactive pupil(s) * Likely already too late 2) Extensor posturing * Also known as extensor posturing, decerebrate rigidity is a term that describes the involuntary extensor positioning of the arms, flexion of the hands, with knee extension and plantar flexion when stimulated as a result of a midbrain lesion. 3) Decrease in GCS of 2 or more points (even just a decrease in 1 point) * There is a compensating time in the brain, but when decompensation occurs, everything can deteriorate every quickly * Cerebellar tonsil herniation is often very fatal * It usually occurs along with ascending or descending transtentorial herniation. * Acute herniation can compress the posterior inferior cerebellar arteries, vertebral arteries, and their branches or the origin of the anterior spinal artery, which can lead to ischemia of brainstem, tonsils, and lower cerebellum.