Head Injury Flashcards
equation for cerebral perfusion pressure (CPP)
CPP = mean arterial pressure (MAP) - intracranial pressure (ICP)
what is the goal CPP, MAP and ICP after head injury
CPP = >60mmHg MAP = >80mmHg ICP = <20mmHg
signs of anterior cranial fossa skull base fracture
raccoon/panda eyes
CSF rhinorrhoea (contains glucose)
subconjunctival bruising
signs of middle cranial fossa injury
battle sign over mastoid area
bleeding from EAM or CSF otorrhoea
what is the difference between primary and secondary brain injury
primary - occurs on impact
secondary - due to the consequences of the injury (neuronal damage, haematoma, swelling, ischaemia, infection)
what are the types of haematoma
extradural
sub dural
intracranial
what is a common cause of indirect brain damage in haematoma
tentorial or tonsillar herniation
common site of extradural haematoma
temporal/temporoparietal regions
what are the different types of brain herniation
subfalcine herniation
lateral tentorial herniation
central tentorial herniation
tonsillar herniation
what is a subfalcine herniation
displacement of brain under falx cerebri (usually first herniation to occur)
what is the first radiological sign of a space-occupying haematoma
mid-line shift
after subfalcine herniation, what type of herniation occurs next
lateral tentorial
what is lateral tentorial herniation and what does it cause
herniation of medial temporal lobe through tentorial hiatus
causes midbrain compression and damage
what does lateral tentorial herniation lead to
central tentorial herniation
what does central tentorial herniation lead to
tonsillar herniation - herniation of cerebellar tonsils through formen magnum
what is a long-term complication of dural tear
infection (meningitis or cerebral abscess)
clinical effects of lateral tentorial herniation
deterioration of consciousness
limb weakness on same side of lesion
pupil dilatation with failure to react to light (CNIII compression)
clinical effects of central tentorial herniation
loss of upward gaze
deterioration of consciousness
pupils initially small, become moderately dilated and fixed to light
diabetes insipidus (pressure on pituitary and hypothalamus)
clinical effects of tonsillar herniation
may cause upward cerebellar herniation
neck stiffness and head tilt
depressed consciousness
respiratory irregularities (leads to respiratory arrest)
why does cerebral ischaemia often occur after head injury
autoregulation (which should cause vasodilatation) is defective
results in hypotension and reduced ICP leading to decreased cerebral perfusion
results in hypoxia and ischaemia
when should a head CT be requested in head trauma
suspected skull fracture
disorientated patient (GCS <13 on admission or <15 after 2 hours)
patient on anti-coagulation
focal neurological signs
post traumatic seizure
vomiting > once
loss of consciousness and age>65/dangerous mechanism of injury/anterograde amnesia>30 mins
what vessels are affected in subdural haemorrhage
bridging veins between cortex and venous sinuses causing bleeding between dura and arachnoid
causes of subdural haemorrhage
trauma (up to 9 months ago)
decreased ICP
dural metastases
anticoagulation
symptoms and signs of subdural haematoma
fluctuating levels of consciousness physical/intellectual slowing sleepy headache personality change unsteadiness seizures local neurological symptoms (hemiparesis, unequal pupils) - late
what does subdural haemorrhage look like on CT
crescent shaped collection of blood around one hemisphere
midline shift
management of subdural haemorrhage
evacuation (1st line)
craniostomy (2nd line)
causes of extradural haematoma
fractured temporal or parietal bone
trauma to temple
clinical manifestations of extradural haemorrhage
deterioration of consciousness (no initial loss of consciousness) lucid interval if has been drowsy severe headache vomiting confusion fits brisk reflexes upgoing plantar hemiparesis
What does extradural haematoma look like on CT
‘lens’ rounded shape
midline shift
possible dilated contralateral 4th ventricle
management of extradural haemorrhage
clot evacuation
what are late effects of head injury
epilepsy
CSF leak into nose/middle ear
cognitive problems
what is a depressed head fracture
skull trauma which blows bones inwards depressing brain segments
difference between simple and compound depressed skull fractures
simple - no laceration, no need to remove bone fragments (does not reverse neuronal damage)
compound - overlying laceration, risk of infection
what is NOT a clinical feature of depressed bone fracture
loss of consciousness
typical cause of depressed bone fracture
blow from a sharp object
investigation for depressed skull fracture
head CT
