W14 47 head injuries Flashcards
What is TBI?
Traumatic brain injury is a form of acquired brain injury, occurs when a sudden trauma causes damage to the brain
What is the classification of TBI?
Severity - mild (13-15), moderate (8-12), severe(3-7) (GCS scale)
Closed/penetrating (left=penetrating, right=closed)
Mechanism
Go to pg458 and review the anatomy images
Review pls
What often occurs in head injury?
Often the problem is something being there that shouldn’t eg a blood clot. This can cause brain structures to push or herniate out of their normally anatomically confined base.
What might cause one pupil to appear larger than the other?
Uncal herniation, putting pressure on the oculomotor nerve
What is subfalcine herniation?
Happens usually form tumours and can be from blood clots, causing strokes
What is transcalvarial herniation?
Where there might be a skull fracture where this is a hole, and part of brain starts herniating out of the gap
Why does herniation occur?
Herniation occurs due to the skull being closed and fixed volume of different components: brain/parenchymal tissue, CSF, vasculature (venous and arterial volume)
What is the balance between brain components in a normal state? (IMG PG458!)
‘Tap’ on on the CSF end and vasculature end, not brain
Maintains normal brain volume, which is about 2L, and about 80% of this is brain, 10% each is vasculature and CSF
What is the balance between the brain components in a compensated state? (PG 458 IMG!)
Compensated state where there is some sort of mass eg a blood clot:
Brain switches on the two and let’s the fluid drain out from either end to maintain intracranial pressure to a certain extent
CSF tends to be pushed down into the lumbar cisterns (biggest collection of CSF outside the brain)
What is the balance between the brain components in a decompensated state? (PG 458 IMG!)
Decompensated state:
Maxed out the CSF drainage without causing strokes
Mass can expand and cause really raised intracranial pressure
What happens when all of the compensatory mechanisms fail? - GRAPH PG459!
When all of the mechanisms fail there is an exponential increase in intracranial pressure which can lead to herniation syndrome and worse neurological outcomes
Relates to cerebral perfusion pressure = CPP
What is cerebral perfusion pressure, CPP?
CPP = MAP - ICP
What is MAP?
Mean arterial pressure - average pressure from diastolic and systolic pressure
What is perfusion pressure?
Percentage of brain being perfused but blood - if reduced then a chance of cell death, ischaemia, stroke etc
What approach should you take to the head injured patient?
ATLS principles
- ABCD (neuro) primary survey - GCS, pupils, gross limb power
- secondary survey - more refined
CT needed?
What importance background is it useful to know for assessing head injured patients?
Anticoagulation/antiplatelets? TXA - might make it worse eg warfarin might need to use medications like vit K to reverse this
Concurrent spinal/systemic injuries? Could also confound the neurological examination
Scalp lacerations? Can cause major haemorrhage eg in children.
What difficult cases might there be?
Orbital/facial injuries
What should you do to examine a pt with a head injury?
Take a history
General examination to exclude systemic injuries
Limited neurological examination
Cervical spine and other x-rays as indicated
Blood-alcohol level and urine toxicology screen
CT scan of the head is indicated if criteria for high or moderate risk of neurosurgical intervention are present
When should you admit or transfer to appropriate faculty?
Abnormal CT as an
All penetrating head injuries
History of prolonged loss of consciousness
Moderate to severe headache
Significant alcohol/drug intoxication
Skull fracture
CSF leak: rhinorrhoea or otorrhea
Significant associated injuries
No reliable companion at home
Abnormal GCS score (<15)
Persistent focal neurologic defects
When should you discharge pt with head injuries from the hospital?
Patient does not meet any of the criteria for admission
Discuss need to return if any problems develop and issue a ‘warning sheet’
Schedule a follow-up visit
What can improve results in minor head injuries?
Giving tranasamic acid within 3 hours can improve results in minor head injury
What is GCS?
Glasgow coma scale - measure of consciousness. Tells us how awake a patient is. E.g., eye-opening, verbal response, best motor response
What is MRC?
MRC power tests strength of power in the arms and legs
Who should we do a CT scan on according to the NICE head guidelines?
(People over 16 with following criteria within 1hr of head injury):
- a GCS score of 12 of less on initial assessment in the emergency department
- a GCS score of less than 15 at least 2 hours after the injury on assessment in the emergency department
- suspected open or depressed skull fracture
- any sign of basal skull fracture
- post-traumatic seizure
- focal neurological deficit
- more than 1 episode of vomiting
What are signs of basal skull fracture?
Haemotympanum, ‘panda eyes’, cerebrospinal fluid leakage from the ear or nose, Battle’s sign)
For people 16 and over who have had some loss of consciousness or amnesia since the injury, do a CT head scan within 8 hours of the head injury, or within the hour in someone presenting more than 8 hours after the injury, if they have any of these risk factors:
- age 65 or over
- any current bleeding or clotting disorders
- dangerous mechanism of injury
- more than 30mins retrograde amnesia of events immediately before the head injury
What should you do in moderate/severe TBI?
Conservative/medical
Improve venous return (raise bed to 30° and consider loosening a cervical collar)
Anti-epileptics, intubate/ventilate/sedate
Euthermia, eucarbia (may decrease pCO2 temporarily) (if refractory) hyperosmolar therapy (+/- CSF diversion)
Thiopentone coma (+/- decompressive craniectomy)
What surgical management can you do for head injuries? - img pg463/4
ICP monitor - can guide ICU management if pt kept asleep
CSF diversion (external ventricular drain)
Decompressive craniectomy Hemicraniectomy bifrontal craniectomy - cutting open the skull to release pressure
What considerations must you make for base of skull fractures?
Might have fluid coming out of ears, panda eyes, mastoid tenderness/swelling
Pneumovax vaccine to reduce risk of meningitis from any CSF leak
No evidence for Abx (antibiotics), only if develop meningitis
What considerations must you make for AED (anti epileptic) prophylaxis in head injuries?
No evidence
What considerations must you make for Anticoagulation in head injuries?
Prophylactic - mechanical for all, pharmacological per senior decision. Leg compression devices eg.
Pre-existing - senior-dependent. Anticoagulants/antiplatelets, no guidelines for when to restart medications
What considerations must you make for venous sinus thrombosis in head injuries?
Suspect when fracture going through cranial venous sinus/refractory raised ICP
