TBIs Flashcards
TBI def
alteration/malfunction of brain function from external force
TBI is a process, not an event!
Secondary injury can be more damaging than primary injury
i.e. hit head and occlude airway–>airway occlusion has most sev. effects
main mechs of brain injury
Brain Contusion
Increased intracranial pressure ( ICP)
Diffuse Axonal Injury
primary injury
Irreversible cellular injury as a direct result of the injury
Prevent the event (wear helmet)
secondary injury
Damage to cells that are not initially injured-“watershed”
Occurs hours to weeks after injury
Prevent hypoxia and ischemia (hypotension)
brain contusion
cell death accompanied by hemorrhage (leakage of blood)
The soft brain tissue is vulnerable to contusion in head trauma
The contusion often occurs at a site distant from the point of impact
(coup and counter-coup)
volume of intracranial vault
80% brain tissue 10% blood 10% cerebrospinal fluid *An increase in the volume of any of these causes increased ICP* ha, AMS, coma
inc. IC pressure
The brain can swell (edema), but little room esp. in young adults (more room in infants, old ppl)
Excess blood can accumulate due to hemorrhage
Cerebrospinal fluid can accumulate due to blockage of outflow
key ICP concepts
The intracranial vault is a fixed volume –> Bone does not expand!
There is only one way out of the intracranial vault –> the opening at the base of the skull known as the foramen magnum
When the brain is squeezed through the foramen magnum (herniation), the brainstem is compressed, the patient stops breathing, and the patient dies
Diffuse Axonal Injury
Occurs in up to 1/2 of traumatic brain injuries1
Is a diffuse form of injury, meaning that damage occurs over a more widespread area than in focal brain injury
Involves the shearing of axons in the white matter tracts
DAI manifests
Is one of the major causes of unconsciousness and persistent vegetative state after head trauma.
Over 90% of patients with severe DAI never regain consciousness (those that do wake up often remain significantly impaired)
Head Injury-Normal Physiology
Brain consumes 20% of total O2 Receives 15% of Cardiac Output Brain tissue perfusion CPP versus CBF CPP=MAP-ICP MAP=(SBP-DBP/3) + DBP
Autoregulation
(CPP) 50-150 mm Hg
ICP measurements
Normal
ICP physical findings of inc. ICP
Neurologic deterioration (know dermatomes)
Unilaterally dilated pupil
Hemiparesis
Posturing
TBI pks in who
Peak male 15-24 years MVA, assault
Peak male > 65 years falls
falls>unknown>MVA>struck>assault
TBI key hx
Mechanism of Injury Patient’s condition prior to incident Co-morbid factors Patient’s immediate post trauma condition Patient’s current condition
other injuries w. TBI
consider mech. of injury
Always consider a spinal cord or vertebral column injury in a patient with a traumatic brain injury
(Esp in those pts that are unconscious!!) -C-scan spines, don’t want to miss
Remember: SCIWORA! (SCI w.out radiological abnormality)
TBI primary survey
Airway (while maintaining cervical spine stabilization)
Breathing
Circulation (checks all)
Disability (Neurologic assessment) AVPU—alert ;responds to verbal stimuli; responds to painful stimuli; unresponsive
Exposure
ATLS? prim. survey
prevent secondary brain injury from
Hypoxemia Hypotension Anemia hyperglycemia evacuation of mass
Airway control with cervical spine immobilization, If a definitive airway is needed..
goal??
Orotracheal Rapid Sequence Intubation
Goal of RSI is to blunt rise in ICP and maintain adequate MAP
decerebrate
extended
decorticate
flexed
Acute Neurological Examination in severe TBI
Pupil assessment
Motor gross function (posturing)
Secondary Survey
Glasgow Coma Scale
Best Eye Response. (4) 1 No eye opening. 2 Eye opening to pain. 3 Eye opening to verbal command. 4 spontaneously
Best Verbal Response. (5) 1 No verbal response 2 Incomprehensible sounds. 3 Inappropriate words. 4 Confused 5 Orientated
Best Motor Response. (6) 1 No motor response. 2 Extension to pain. 3 Flexion to pain. 4 Withdrawal from pain. 5 Localising pain. 6 Obeys Commands.
concussion
Any alteration of Cerebral Function Caused by a Force to the Head with any or one:
Brief LOC Headache Visual changes Personality change Fatigue Balance disturbances Light headed Concentration disruptions Amnesia
scalp lacerations
May lead to massive blood loss (even w. small cut)
Small galeal lacerations may be left alone
skull fx
Linear and simple comminuted skull fractures
Exploration of wound
Ppx antibiotics are controversial
Occipital fxs have a high incidence of other injury
If depressed beyond outer table-requires NS repair?
assessment for concussion
SCAT3
basilar fracture
Most common-petrous portion of temporal bone, the EAC and TM
get small slice imaging, typ. CT may miss
Basilar skull fx w. dural tear signs
CSF otorrhea CSF rhinorrhea Battle Sign Raccoon Sign hemotympanum (may be occluded) vertigo hearing loss 7th nerve palsy (facial, Bell's)
CSF testing (basilar fx)
Ring sign, glucose or CSF transferrin
(basilar) skull fx injuries should be started on…
ppx abx
Ceftriaxone 1-2 gm
specific head injuries
Epidural Hematoma
Subdural Hematoma
Subarachnoid Hemorrhage
Intraparenchymal Hematoma
ddx based on presentation, cause, imaging
epidural hematoma
Rupture of Middle Meningeal Artery
Associated with fracture of Temporal bone (or just blunt injury)
epidural hematoma asso. w. fx of temporal bone
Rapid expansion under systemic arterial pressure
“Lucid” interval (fine for a bit)
Transtentorial herniation
CN III Palsy-down and out
CT shows Biconvex disk-bulges out like lens
Subdural Hematoma
Rupture of Bridging Veins
Slow dev. due to low pressure venous system (days-wks)
Seen in elderly, alcoholics, blunt head trauma, shaken baby
Subdural Hematoma CT
Crescent-shaped hemorrhage-goes along lines of cranium
Crosses suture lines; Midline shift–>herniation
Subarachnoid Hemorrhage
Rupture of an aneurysm
Usually a Berry aneurysm or AVM
ocular nerve palsy-down and out (like epidural?)
subarachnoid hemorrhage can be traumatic or atraumatic
time course?
Atraumatic -> Hypertension, aneurysm
Traumatic -> Usually blunt head trauma
*Rapid time course
“Worst headache of life”
“thunderclap”
Subarachnoid Hemorrhage CT
subarachnoid blood
Many times bilateral or Circle of Willis
If CT negative then recommend lumbar puncture (atraumatic)
Intraparenchymal Hematoma
occurs where?
cause?
Basal ganglia and internal capsule
In trauma, can be lobar
Systemic hypertension
Also due to vasculitis, neoplasm and trauma
IP hemorrhage doesn’t usually ???
rapidly expand or cause significant edema or midline shift
Unless patient is on an anticoagulant
IP hem dx
px?
CT scan of brain
usually good
Depending upon cause (good in trauma)
Supportive care while it resolves
specific head injuries: diffuse axonal injury
Disruption of axons in white matter and brainstem
Injury occurs immediately and is irreversible
Seen after MVC or shaken baby syndrome
Usually have persistent vegetative state
CT usually normal
MRI with multiple, diffuse abnormalities
