Ch. 4 - Head injuries Flashcards
Minimum criteria for concussion (according to text)
Period of amnesia
Which CN is easily damaged by torsion or herniation of brain?
CN6 - causes diplopia 2/2 unopposed action of medial rectus muscle
GCS score indicating severe brain injury
8 or less
Decerebrate posturing
Upper limbs adducted and internally rotated but extended at elbow; suggests upper brainstem injury
Indications for CT
- loss of consciousness >10 min
- persistent drowsiness
- persistent nausea
- lateralizing neurologic signs
- skull fracture
- CSF rhinorrhea
- injuries necessitating ventilation
- ALWAYS get plain film or CT of cervical spine
How long should you observe person with a head injury?
At least 4 hours
Why control temperature after head injury?
Elevated temps can increase ICP
If concerned about increased ICP, what is PaCO2 goal?
PaCO2 of 30-35
Signs of anterior fossa fracture
Subconjunctival hemorrhage extending to posterior limits of sclera (raccoon eyes are just subgaleal), anosmia, nasal tip parasthesia
Describe a ‘contre-coup’ injury
Sudden acceleration/deceleration force resulting in opposite ‘poles’ of brain being jammed against cranial vault
A concussion is regarded as being severe when the amnesia following the head injury lasts how long?
More than 1 day
Causes of traumatic mydriasis
Uncal herniation OR direct trauma
Describe difference between simple, depressed, and compound skull fractures
Simple – linear fracture of vault
Depressed – bone fragments depressed beneath vault
Compound – direct communication with external environment
What is the first sign of a depressed conscious state?
DROWSINESS
What does the term ‘coma’ refer to?
Patient who shows no response to external stimuli, does not obey commands, is unable to utter comprehensible words, and does not open eyes
With frontal lobe lesion, gaze will deviate to which side?
Ipsilateral to side of lesion
With pontine lesion, gaze will deviate to which side?
Contralateral to side of lesion
GCS parameters
Eye opening, best verbal response, best motor response to painful stimulus
Decorticate posturing
Upper limbs adducted and internally rotated and flexed at elbow; suggests cerebral white matter and basal ganglia injury
Pyrexia is common after head injury. What does pyrexia lasting >2 days suggest?
Traumatic subarachnoid hemorrhage or severe brainstem injury
What electrolyte abnormalities can be expected after head trauma?
Retention of sodium and water leading to mild hyponatremia + excretion of potassium
Most common sites of infection after head injury
Respiratory and urinary tracts!
What should cerebral perfusion pressure be maintained at?
Above 70 mmHg
What is the risk of epilepsy following a depressed skull fracture?
15%; continue prophylactic anticonvulsant medication for 1 year if dura was penetrated
Signs of middle fossa fracture involving petrous temporal bone
CSF otorrhea (or rhinorrhea) via Eustachian tube, deafness 2/2 CN8 or ossicular injury, hemotympanum, Battle’s sign (bruising over mastoid bone), CN7 palsy
Major concern of dural fistula
Infection; tx possible fistula with prophylactic abx (penicillin to cover Streptococcus - most common organism)
Indications for surgery in anterior cranial fossa injuries and possible dural fistula
- CSF leakage >5 days
- intracranial aerocele
- episode of meningitis
Describe tangential vs. penetrating vs. through-and-through missile injuries
Tangential - does not enter cranium but causes depressed skull fracture
Penetrating - enters cranium resulting in deposition within brain
Through-and-through - enters and exits cranium
Doubles mortality in TBI
Hypotension or hypoxia
