Head trauma Flashcards
CSF production, circulation and reabsorption
Produced by choroid plexus in lateral, 3rd and 4th ventricles
Reabsorbed by arachnoid granulation in superior sagittal sinus
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3 layers of meninges
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Which blood vessels are responsible for extradural bleed
Meningeal arteries, especially middle meningeal artery
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Which blood vessel responsible for subdural bleed
Bridging veins
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Which blood vessels are responsible for intra-cerebral bleed (subarachnoid haemorrhage)
Major blood vessels at the base of the brain
Brainstem parts
Midbrain
Pons
Medulla
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Function of midbrain and upper pons
Reticular activating system (state of alertness)
Function of medulla
Cardiorespiratory centre
Tentorium cerebelli
Separates intracranial cavity into supratentorial and infratentorial
Midbrain passes through tentorial hiatus
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Which nerve could be compressed against the tentorium
Oculomotor leading to a blown pupil (carries PSN, if impaired, eye only gets sympathetic)
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Which part of brainstem herniates through tentorium due to raised ICP
midbrain
Which part of brain herniates through tentorium due to raised ICP
the medial part of temporal lobe known as uncus
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Sx of uncus herniation
Ipsilateral pupillary dilatation (PSN fibers of CN3)
Contralateral hemiparesis (corticospinal tract of the midbrain)
Reduced GCS (reticular system)
Normal ICP
10mmHg
What sustained ICP is associated with poor outcome
>22mmHg
Monro-kellie doctorine
Total volume of intracranial content is constant
Total volume = Venous volume + arterial volume + brain + CSF
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Cerebral perfusion pressure (CPP) formula
CPP = MAP - ICP
At what MAP is cerebral blood flow autoregulated (constant)
MAP of 50-150 mmHg
GCS depending of severity of traumatic brain injury (TBI)
Mild 13-15
Moderate 9-12
Severe 3-8
When calculating GCS and there’s discrepancy between left and right side, which score do you use
The best motor response (the higher score)
Types of skull vault (roof) fracture
Linear vs stellate
Depressed vs non-depressed
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Clinical signs of basilar skull fracture
Periorbital ecchymosis (raccoon eyes)
Retroauricular ecchymosis (Battle’s sign)
Rhinorrhoea (CSF from nose)
Otorrhoea (CSF from ear)
CN7,8 dysfunction
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Classic epidural haematoma presentation
Lucid period before deterioration
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Which region of the brain often affected by epidural bleed
Temporoparietal
Further investigation after CT showing contusion
Repeat CT within 24 hours to look for change in the pattern of injury (20% of patients will end up having enough mass effect requiring evacuation)
Definition of mild traumatic brain injury
GCS 13-15
witnessed loss of consciousness, definite amnesia or witnessed disorientation
High risk indications for CT head for pt with mild traumatic brain injury
Any one of high risk or moderate risk:
GCS<15 for 2 hrs post-injury
Suspected open or depressed skull
Signs of basilar skull fracture
Vomiting more than 1 episodes
Age >65
Anticoagulation
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Moderate risk indications for CT head for pt with mild traumatic brain injury
LOC for 5 mins
Amnesia before impact >30mins
Dangerous mechanism (pedestrian struck, ejected out of the car, fall from more than 3 feet or 5 stairs)
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Initial management of moderate traumatic brain injury
Neurosurgery evaluation or transfer required
Initial management of severe traumatic brain injury
Urgent neurosurgery consultation or transfer required
Admission criteria for mild traumatic brain injury
- CT:
- not available
- skull fracture
- CSF leak - Focal neurology
- GCS does not return to 15 after 2 hrs
Secondary management of severe traumatic brain injury with raised ICP
Mannitol
Brief hyperventilation (reduces CO2, vasoconstriction)
Hyperosmotic saline
Surgery
Barbiturates
PCO2 aim for hyperventilation
No less than 25 mmHg - 30 mmHg (3.3 to 4.7kPa)
PCO2 aim for severe traumatic brain injury
<35mmHg
Blood pressure aim in brain injury
SBP<100 between 50 to 69
SBP <110 between 15 to 49 and older than 70
ICP goal for TBI
5-15mmHg
Reversal agent for morphine
Nalaxone
Reversal agent for benzos
flumazenil
How much shift of midline structures indicate the need for surgery
A shift of 5mm or more
Reversal for antiplatelet agents eg aspirin
Platelets
(may need repeat or desmopressin)
Reversal for warfarin
Vit K and Prothrombin complex
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Reversal for heparin
protamine
Reversal for LMWH
protamine
Reversal for direct thrombin inhibitors (eg dabigatran)
Idarucizumab (praxbind)
Reversal for rivaroxaban
none
Use of mannitol
Osmotic diuretic
For the acute neurological deterioration of pt under observation (A bolus of 1g/kg, over 5mins before transferring to CT)
Contraindication to mannitol use
Hypotension (SBP <90)
Mannitol does not lower ICP in hypovolaemia and is an osmotic diuretic, leading to a further drop in BP, and cerebral ischaemia
Monitoring with Mannitol
ICP monitor, keep <320mOsm
Use of hypertonic saline for raised ICP
IN concentrations of 3% to 23.4%
Preferable agent in hypotension as doesn’t act as a diuretic, however, equally ineffective in hypotension
Use of barbiturates in raised ICP
Only used after other measures both surgical and medical have failed
Long half-life, so needs monitoring for longer (before declaring brain death)
Don’t use in hypovolaemia or hypotension
Use of anticonvulsants in TBI
Can inhibit brain recovery, so only use when essential
No evidence for late epilepsy prevention
Factors increasing the risk of late epilepsy post-TBI
Seizures occurring within the first week
Intracranial haematoma
Depressed skull fractures
Which anticonvulsants used for post TBI seizures
Phenytoin +/- diazepam/lorazepam
If not, general anaesthesia
Dosing of phenytoin for post TBI seizure
Loading on 1g given at 50mg/min
Maintaining on 100mg/8hrs
Management of scalp depression
Generally need operative elevation eg when
- open contaminated
- degree of depression > thickness of adjacent skull
In less severe depression, just closure of scalp over suffices
Indication for use of prophylactic abx in TBI
Penetrating brain injury
Open skull fracture
CSF leak
Management of objects that penetrate the intracranial compartment or infratemporal fossa that remain partially exteriorised
Must be left in place until the possible vascular injury has been evaluated and definitive neurosurgical management established
Surgical management of intracranial mass lesions
If in remote areas/no access to imaging or neurosurgery: Burr hole craniotomy
Otherwise, bone flap craniotomy
Definition of brain death
no possibility of recovery of brain function
Criteria for brain death
GCS=3
Nonreactive pupils
Absent brainstem reflexes (eg oculocephalic, corneal and gag reflex)
No spontaneous ventilatory effort on formal apnoea testing
Absence of confounding factors such as alcohol, drug intoxication or hypothermia
Investigations that could help establishing brain death
Electroencephalography
CBF studies
Cerebral angiography
Oculocephalic reflex
AKA doll’s eye reflex
If brainstem affected eyes move with the head
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