Topic 9 - Head Injuries Flashcards
(36 cards)
Describe the development of an intracranial haematoma
Following head injury, blood can gather between the meninges or within the brain - no true space in normal anatomy, increases potential space
Describe the ability of the CNS to recover
- CNS neurons have limited ability to recover in comparison to PNS neurons
- Substantial functional recovery occurs due to neural plasticity
- Potential for brain to change structure and function - rewiring of neurons
- Greater exposure to particular stimulis means more neurons are dedicated to that stimulus (+ vice versa)
List the types of brain injuries
- Primary injury - result of initial trauma
- Secondary injury - evolving pathophsysiological consequences of the primary injury
Describe the development of a subdural haematoma
- Venous blood
- Collects between dura and arachnoid mater
- No limitation of blood flow, spreads more evenly
Describe the appearance of a subdural haematoma on a CT
- No limitation of blood flow, blood can spread more evenly
- Less clear on CT, crescent shape
List the clinical signs of displacement of the cingulate gyrus under the falx cerebri
- May have no clinical signs
- May be confused, drowsy or show contralateral weakness
- Pressure on motor cortex or compression of anterior cerebral artery)
When does recovery from brain injuries occur?
Fastest recovery occurs in the first 6 months, continues for 2 years
Describe normal and abnormal flexion in the motor response section of the Glasgow coma scale
Normal - elbow bends, arm moves away from body
Abnormal - elbow bends, arm moves over body
Why does brain herniation develop after head injuries?
Brain is not compressible - as mass expands causes displacement (herniation)
Explain the clinical usefullness of a Glasgow Coma Score
Numbers from each section can be added to give score, not accurate representation of patient’s condition
Describe the appearance of an extradural haematoma on a CT scan
- Characteristic lens shape - blood collects in one area because the dura is fixed to the skull at sutures so it can’t spread
- Causes midline shifting - loss of ventricles
- Fresh blood appears white, turns more grey with time
List the categorisation of GCS scores
Mild = 13-15
Moderate = 9-12
Severe = 8 or less
List types of secondary head injuries
- Cerebral oedema
- Increased intracranial pressure
- Haemorrhage
- Herniation
- Seizures
- Ischaemia
List the behavioural consequences of brain injury
- Period of confusion, disorientation
- Attention and learning ability lost
- Agitation, agression, frustration
- Nervousness, restlessness
- Sleeping pattern disrupted
- Overreaction to stimulation
- Inconsistent behaviour
Describe the affect of downwards herniation of the brain on brainstem functions
- Coma
- Altered respiratory rate
- Altered HR
- Altered BP control
- Death from cardiorespiratory arrest
Explain the effect a head injury will have on CPP
- ICP increases after injury, decreasing the CPP
- Blood flows from high to low pressure, raised ICP decreases the pressure gradient favouring blood flow to the brain
- Normally the brain autoregulates bloodflow regardless of pressure by changing the resistance of vessels, but after injury these homeostatic mechanisms fail
- Increasing ICP leads to decreasing CPP and ischaemic damage
Describe the stages of brain herniation
- Displacement of cingulate gyrus from one hemisphere to another under the falx cerebri
- Brain moves downwards (uncle herniation)
- Brainstem affected
List the types of primary injury and give examples
- Focal - localised to site of impact
- Fracture
- Haematoma - localised bleeding outside blood vessels
- Polar
- Cerebral contusions - multiple microhaemorrhages, small blood vessels leak into brain tissue
- Usually occur coup (adjacent to site of impact) or contre coup (diagonally opposite)
- Diffuse - movements of the brain within the cranial cavity causing widespread neurol damage
- Diffuse axonal injury - ‘stretching’ injury to the neurons + axons throughout the brain
Describe the Glasgow Coma Scale
- Eye opening
- Spontaneous - 4
- To sound - 3
- To pressure - 2
- None - 1
- Verbal response
- Oriented - 5
- Confused - 4
- Words - 3
- Sounds - 2
- None - 1
- Motor response
- Obey commands - 6
- Localising to pain - 5
- Normal flexion - 4
- Abnormal flexion - 3
- Extension - 2
- None - 1
Define the Glasgow Coma Scale
A standardised test developed for assessing the level of consciousness in acutely brain injured individual
How is CPP used clinically?
As a surrogate marker for cerebral blood flow
Describe an intracerebral haematoma
Blood within substance of brain
List the types of intracranial haematomas
- Extradural/epidural
- Subdural
- Intracranial
- Subarachnoid
How is ICP measured clinically?
- Can be measured directly - invasive so not usually done
- Neurological observations used to detect increasing ICP after head injuries
- GCS
- Vitals - pulse, BP, temperature
- Pupil responses
- Motor/sensory response
- Every 15 minutes
