Consciousness, head trauma & ICP Flashcards
What are the 2 elements of consciousness?
Awareness and arousal / wakefulness
Describe the levels of awareness and arousal in unresponsive wakefulness / vegetative state.
Normal levels of arousal but reduced level of awareness
Which frequency on the EEG is the slowest and associated with deep sleep and coma?
Delta frequency
Which system in the brainstem regulates arousal?
Ascending reticular activating system (ARAS)
What are the 3 main nuclei in the ARAS and which neurotransmitters do they each secrete?
Raphe nuclei – 5HT / serotonin
Locus coeruleus – noradrenaline
Pedunculopontine nucleus – acetylcholine
What are the 3 elements of the GCS?
Eye opening
Verbal response
Motor function
What are the levels of the eye opening element of the GCS?
1 – none
2 – to pain
3 – to sound
4 – spontaneously
What are the levels of the verbal response element of the GCS?
1 – none
2 – grunts/moans
3 – inappropriate words
4 – confused
5 – orientated
What are the levels of the motor function element of the GCS?
1 – none
2 – extends to pain
3 – abnormal flexion to pain
4 – normal flexion / withdrawal to pain
5 – localises pain
6 – normal – follows commands
What are the 3 patterns of damage in traumatic brain injury?
Contusions
Haemorrhage
Diffuse axonal injury
What are the 2 types of contusions and where would they occur?
Coup contusions and contre-coup contusions
Coup contusions occur at the point of impact, whereas contre-coup contusions occur on the opposite side of the brain to the impact point
Which type of contusion is often more severe?
Contre-coup contusions
What are 2 histological features of diffuse axonal injury?
Axonal swellings
Accumulation of beta amyloid precursor protein (-APP)
Describe the Monro-Kellie doctrine.
Because the intracranial volume is fixed, any increase in volume of the brain, blood or CSF must be compensated by a decrease in the volume of the others to prevent an increase in ICP
What measure can be used to determine whether cerebral blood flow (CBF) is impaired? Provide the equation for how to calculate this measure.
Cerebral perfusion pressure
CPP = MAP – ICP
What is a non-invasive procedure used to diagnose raised ICP and what would the finding be?
Fundoscopy – with a finding of papilloedema
In papilloedema due to raised ICP, which structure bulges?
Optic disc
What are the 3 signs of Cushing’s response resulting from raised ICP?
Irregular respiration rate
Bradycardia
Widening pulse pressure (increased systolic, decreased diastolic)
