Head Trauma in the ED Lecture Powerpoint Flashcards
Intracranial pressure (ICP)
Pressure exerted by fluids such as CSF and blood inside the skull (rigid nonexpandable box) on prain tissue, normal is 7-15 mmHg (average 10mmHg), for supine adult, >20 is abnormal, >40mmHg is severe, sustained increased ICP leads to decreased brain function and poor outcome
Compensated state of ICP
When an individual has a brain bleed (or enlarging mass), CSF and venous volume decrease to maintain normal ICP in a compensatory manner (brain mass and arterial volume unaffected) if overwhelmed see drop in arterial volume leading to ischemia of the brain or herniation of brain tissue
ICP monitoring types (3)
- Intraventricular (can be used to drain CSF as well - therapeutic as well)
- subdural
- intraparenchymal (in the brain tissue itself)
Cerebral perfusion pressure (CPP)
Difference between mean arterial pressure (avg between systolic and diastolic) and intracranial pressure, a net pressure gradient that drives oxygen delivery to brian tissue but not actually a measure of cereral blood flow, normal range 60-70 mmHg (CPP=MAP-ICP), if CPP too low can raise blood pressure or decrease ICP, requires ICP monitor placement first
Primary vs secondary brain injury
-Occurs at time of impact vs occurs at some point after moment of impact, often preventable and very important to control in emergency setting (hypotension, hypoxia, hypoglycemia, hyperthermia, hypocapnia)
Systolic blood pressure value in head injury patients need in order to prevent secondary injury
90mmHg
Do intracranial bleeds cause hypotension?
No because of the rigidity of the cranium - if hypotensive might have some other type of shock going on
Cushings triad
Seen as result of and indicates increased ICP
- hypertension
- bradycardia
- irregular respiration
Labs to draw on suspected head trauma patient*** (5)
- CBC
- CMP
- Coags***
- ABG
- tox screen
Minimum required radiologic studies for head injury patient (2)
- Head CT w/o IV contrast
- cervical spine CT w/o IV contrast
Closed vs open brain injury
Skull not broken, fractured, or penetrated vs sees dura and brain tissue communicating with outside world
Traumatic brain injury severity classification (TBIs) (3)
- Mild, synonymous with concussion (GCS 13-15 and some kind of mechanism of injury, can see confusion, amnesia, stumbling)
- Moderate (GCS 9-12, similar symptoms to mild, need admission to ICU and administration of antifibrinolytic tranexamic acid (TXA))
- Severe (GCS 3-8, minimally responsive, need admission to ICU and managed with TXA but not nearly as effective, same principles of eliminating secondary brain injury)
How to determine who with a mild TBI gets a head CT criteria? (10)
- retrograde amnesia >30min
- suspicion of skull fracture
- suspicion of basilar skull fracture
- 2 or more episodes of vomiting
- use of any anticoagulant
- age >60
- seizure since episode of injury
- neurologic deficits
- high impact mechanism
- intoxication or abnormal behavior
Return to learn and return to play protocol for mild TBI/concussion
- may return to school once able to concentrate on a task and tolerate visual and auditory stimulation for 30-45 min
- return to play over 6 stage course of non contact activity gradually increasing to normal level, may need referral if symptoms persist 21 days or longer or if uncertain diagnosis of concussion
Diffuse axonal injury (DAI)
traumatic shearing of the axons that occur when head is rapidly accelerated/decelerated and by secondary biochemical cascades, occurs in white and grey matter and majority end up in post traumatic coma as result, may have relatively normal head CT but exam with severely diminished GCS, generally confirmed by MRI, death rare as has no effect on brainstem
General principals for TBI treatment (4)
- Involve neurosurgery
- head of bed 30 degrees
- Pharm DVT prophylaxis from stable repeat head CT
- keppra for seizure prophylaxis
Epidural hematoma
Collection of blood between dura and skull, 80% of skull fractures, an arterial bleed affecting middle meningeal arteries and can lead to herniation if untreated, see initial brief loss of consciousness then rapid neuro deterioration, fixed dilated pupil on unilateral side
Subdural hematoma
More common than epidural hematoma, occurs from shearing force on venous bridging veins between dura and arachnoid, commonly due to acceleration or deceleration injuries, space occupying lesion causing concave hematoma, can be acute or chronic and many relatively asymptomatic, causes midline shift of structures to one side due to the space occupying lesion
Traumatic subarrachnoid hemorrhage
Venous bleeding in subarachnoid space between arachnoid and pia mater, usually associated with other hemorrhage, not space occupying, may increase ICP and block outflow of CSF from ventricles, if isolated may be aneurysmal in origin
Cerebral contusion
Bruise of brain tissue that primarily occurs in cortical tissue when the brain collides with bony protuberances on inside surface of the skull, frontal/temporal lobes most commonly affected, frequently associated with edema which can be a cause of elevated ICP, sometimes mislabeled as an intraparenchymal/intracerebral hemorrhage
Coup vs contrecoup injury
Coup is at the site of impact with an object, contracoup is on the opposite side of the area the object was hit, can occur individually or together
3 types of skull fractures
- Linear (extends thru full thickness, most common, often without significance unless cross middle meningeal artery groove which then causes a lot of bleeding)
- Depressed (leaves impression on skull, often involves brain parenchymal injury)
- Basilar (fracture thru posterior or anterior skull base, most often petrous portion of temporal bone or occipital bone, can cause CSF leaks, increased risk of meningitis)
