C10 - Head Trauma Flashcards
What is the blood supply to the scalp? Where are these branches derived from?
‘Some Scary Sharks Overeat People’
- Supraorbital = ICA
- Supratrochlear = ICA
- Superficial temporal = ECA
- Occipital = ECA
- Posterior auricular = ECA
What signs may be present upon examination if a patient has a skull fracture?
- ‘Racoon eyes’ = bilateral eye bruising
- ‘Battle sign’ = bleeding behind the ear
- Haemotympanum = bleeding behind ear drum in canal
- CSF leak = clear fluid dripping from nasal passages
How does the Glasgow Coma Scale assess a patient on their eye opening response?
1: None = no opening at any time
2: To pressure = after finger tip stimulus
3: To sound = after spoken or shouted request
4: Spontaneous = open before stimulus
How does the Glasgow Coma Scale assess a patient on their verbal response?
1: None = no audible response
2: Sounds = only moans/ groans
3: Words = intelligible single words
4: Confused = not orientated but communicates coherently
5: Orientated = correctly gives name, place and date
How does the Glasgow Coma Scale assess a patient on their motor response?
1: None = no movement in arms/ legs
2: Extension = extends arms at elbow
3: Abnormal flexion = bends arm at elbow, but clearly abnormal
4: Normal flexion = bends arm at elbow, features not abnormal
5: Localising = brings hand above clavicle to stimulus on head neck
6: Obeys commands = obeys a 2-part request
How is the Glasgow Coma Scale score rated?
13-15 = mild
9-12 = moderate
3-8 = severe
What is the normal value of intracranial pressure?
5-12 mmHg (anything >20 is concerning)
What is cerebral pefusion pressure and how is it calculated?
Net pressure gradient causing cerebral blood flow to the brain
CPP = MAP - ICP
How is the brain injured following a blow to the head? (step process)
1: Impact - blow sends shockwaves through brain, damaging patches of neurons
2: Deceleration - swings cerebrum on brainstem, tears reticular formation and corticospinal tracts
3: Rotation: stretches connections (axons) between the 2 hemispheres
4: Vibration: resonance after impact bruises the underlying cortex
What is the final common pathway of acute brain injury?
Ca2+ enters cell, leading to swelling.
Increases intracranial pressure
Decreases cerebral perfusion pressure
Cerebral ischaemia
Provokes further acidosis, glutamate and free radical release
What NT is responsible for acute epilepsy?
Glutamate
What is prosopagnosia? What can it be caused by?
Difficulty recognising faces (interpreting visual information)
Can be caused by damage to the temporal lobe
What is temporal lobe epilepsy and what symptoms may present?
Focal seizure in the temporal lobe
De ja vu, unprovoked fear, visual distortions
What is cytotoxic oedema?
Initial oedema, refers to cellular swelling. Gluid is retained in the cytoplasm and theres a loss of Na+-K+ ATPase. Glutamate-gated Ca2+ channels are open and Ca2+ draws water in. This raises ICP
What is vasogenic oedema?
Delayed oedema (48hr). Breakdown of blood brain barrier leads to protein and fluid extravasation into the parenchyma
How would oedema (and thus raised ICP) be treated/ managed?
- Elevate head to 30 degrees
- Intubate and hyperventilate (short periods)
- IV mannitol
- Ventricular drainage
Why would you intubate and hyperventilate a patient that had raised ICP? Why is it only performed for short periods?
Causes vasoconstriction so can lower cerebral blood flow = thus lower ICP
For short periods to avoid causing cerebral ischaemia
What can raise ICP?
Oedema
Hydrocephalus
Vasospasm
Microvascular pathology
Idiopathic intracranial hypertension
What are some signs of raised ICP?
- Headache: straining, worse on bending over and worse in the morning
- Vomiting
- Loss of consciousness
- Papilloedema - swelling of disc at back of eye
- Cushing’s triad: wide pulse pressure, irregular breathing, bradycardia
What is the point of decompensation?
TO maintain ICP at an appropriate level, the brain can lose extra CSF and blood. The point that this works up to is ‘the point of decompensation’, above which the pressure in the skull increases exponentially
How can a patient lose their pupillary response with raised ICP?
Increased ICP can lead to transtentorial herniation, where the brain herniates downwards and places pressure on the brainstem. As the oculomotor nerve sits near here, it can lead to fixed dilated pupils
What is the investigation of choice for raised ICP?
- CT scan
- Invasive ICP monitoring: catheter in lateral ventricle of brain to monitor pressure
How can CSF be removed?
- Repeated lumbar puncture
- Drain from intraventricular monitor
- Ventroperitoneal shunt (hydrocephalus)
What is an extradural haematoma? What is its common cause/ location?
Collection of blood between the dura mater and the skull.
Common cause = trauma, collection of blood often found in temporal region at pterion (overlying middle meningeal artery) as bone is very thin here
How does an extradural haematoma present?
Patient intially loses consciousness, then briefly regains it (lucid), then loses consciousness again
How is an extradural haematoma treated?
Craniotomy - evacuation of haematoma
What is a subdural haematoma?
Collection of blood deep to the dural layer of the meninges, due to rupture of bridging veins
What are some symptoms of a subdural haematoma?
headache, nausea, vomiting, confusion, drowsiness, poor balance
How do subdural and extradural haematomas present on a CT scan?
Extradural = lemon shape
Subdural = crescent shape
What is a subarachnoid haemorrhage and how can it be caused?
Collection of blood within the subarachnoid space, deep to the subarachnoid meninges
Most common cause = head injury, or brain aneurysm (usually secondary to HTN)
How might a patient present with a subarachnoid haemorrhage?
Headache: ‘thunderclap’, occipital region, sudden onset
Nausea and vomiting
Meningism - photophobia (sensitive to light), neck stiffness
Coma
Seizures
If you suspect a subarachnoid haemorrhage but the CT is negative, what test might you perform and why?
Lumbar puncture - test for RBC’s to see if blood has leaked into CSF
What is a seizure? What 2 processes can lead to one?
Sudden uncontrolled electrical disturbance in the brain
- Increased glutamate activity at NMDA receptors
- Reduced GABA or GABA receptor expression
= uncontrolled action potentials in the brain
What can cause seizures?
Epilepsy, infections, electrolyte imbalance, toxins, drugs, febrile seizures (in children when they have a temperature)
What are the 2 types of seizures?
Generalised = involves both cerebral hemispheres, typically lose consciousness
Focal = limited area of cortex (usually temporal), level of awareness can vary
What can a focal seizure lead to?
If in an area of the motor cortex = clonic movement of limb
If sensory cortex = triggers abnormal sensation
What investigations might be done for a seizure?
EEG
MRI
How would generalised seizures be treated?
Sodium valproate - males only
Lamotrigine