Traumatic Brain Injuries Flashcards
What is the leading cause of morbidity and mortality following trauma? (3)
Head Injury
- Almost half of all trauma deaths are from head injury
- Drugs and alcohol are etiologic 70% and confound the examination
What is a primary brain injury?
Initial insult. Not much you can do except try to prevent it
What is a secondary brain injury?
Examples include: bleeding, edema, movement of the brain. These symptoms can be managed, some are preventable and some are treatable
What are the 3 mechanisms of primary injury?
- Concussion-compression (direct blow)
- Sudden deceleration (brain squishes into skull)
- Rotational acceleration (causes axons to tear)
Concussion-Compression
- Directly from localized impact
- If compressive force exceeds elasticity of the skull, skull will fx
- Initial force is transmitted to the intracranial contents causing localized tissue damage
Sudden Deceleration (4)
- Abrupt deceleration of a rapidly moving head
- Sudden halt causes brain to collide with the inner surface of the skull
- Shearing forces happen d/t acceleration and rebound
- Contusions and lacerations result
What does tearing of the bridging veins on the side opposite to the area of impact result in?
Subdural Hematoma (contrecoup)
Rotational Acceleration (7)
- Parenchymal tearing
- Axonal disruption
- Hemorrhage
- Brain edema
- Focal shear/strain damage tends to occur in axons btw grey and white matter (common in frontal,temporal, and corpus collosum)
- Shows up well on MRI, not CT
- Microhemorrhages may show up as it progresses
“Talk and Deteriorate” Cases
- “Lucid intervals” pt has a temporary moment of improvement and they think they are ok, then they die
- Can be save with prompt intervention!
- Cause of deterioration is an expanding intracranial mass lesion (subdural or epidural hematoma)
What are 3 Secondary traumatic brain injuries?
- Systemic insults
- Intracranial insults
- Cerebral ischemia-reperfusion injury
What are the 2 most frequent systemic insults causing secondary brain injury?
- Hypoxemia
- Hypotension
What are 6 systemic insults of secondary brain injuries?
- Hypotension
- Hypoxemia
- Anemia
- Electrolyte disturbances
- Hypo/hyperglycemia
- Hyperthermia
Hypoxemia (4)
- systemic insult
- results from hypoventilation
- Brainstem movement at time of injury causes loss of consciousness and its responsible for respiration
- other possible causes include: airway obstruction, flail chest, hemo/pneumothorax, pulmonary contusion
Hypotension (5)
- Leads to decreased end organ perfusion
- Systolic<90
- Increases mortality
- Impairment of auto regulation of cerebral blood flow
- Restoration of arterial blood flow improves neurological status
Intracranial insults (2)
- Subdural hematoma can occur, needs to be operated ASAP, >4hrs increases mortality rate a lot
- Prolonged elevated ICP is a/w poor outcomes
What happens to ICP if large intracranial hematomas are not removed promptly?
Rise rapidly d/t further bleeding and edema
What increases if subarachnoid hemorrhage is seen on CT?
Pt developing cerebral vasospasms
Cerebral Ischemia-Reperfusion Injury (4)
- Transmembrane shift of Na & Ca into the cell and K out of the cell
- Oxygen radical formation
- Lipid peroxidation
- All leads to cell death, worse neurological outcomes
Histological and Biochemical Changes in Brain Injuries (4)
- Change in Ca homeostasis
- Production of free radicals
- Release of excitatory amino acids
- Alterations in intercellular magnesium
GSW to the Brain (4)
- Energy dissipated in the brain by a bullet is proportional to the impact velocity squared
- Rifles are the worst
- Shell fragments and handgun fragments are not as bad
- Explosively increased ICP produces direct brainstem damage in experimental models
What are the different types of Primary Traumatic Brain Injuries? (8)
- Scalp injuries
- Skull fx
- Penetrating injuries
- lacerations
- Concussions
- Contusions
- Diffuse axonal injury
- Intracranial hematoma
Scalp Injury (3)
- Mild bruising to complete avulsion
- **A major scalp laceration can cause hemorrhagic shock
- Scalp injuries can overlie a penetrating skull injury that can cause meningitis or a brain abscess
Skull Fx
- Most are linear
- Stellate (star) occur with more force
- Depressed fx occur with even more force
- Skull fx greatly increase the likelihood of underlying brain injury
Basilar Skull Fx (3)
- Cause injury to cranial nerves
- Cause injury to bv’s traversing the foramina at skull base
- If it extend to the paranasal sinuses or mastoid air cells, it can cause CSF to leak from the nose
Battle’s Sign
- bruising behind the ear
- indicative of basilar skull fx
Penetrating Injuries (4)
- At risk for meningitis or brain abscess
- Stab wounds to orbit or nasal cavity are prone to enter the cranium
- Causes vascular injuries
- And Neurological deficits
Lacerations (2)
- Occur after severe blunt head trauma from a shear/strain injury
- Pontomedullary junction is prone to this type of injury following hyperextension of the head on the neck (whiplash)
Concussion (4)
- Transient loss of consciousness that may result from temporary dysfunction of either cortical hemispheric neurons bilaterally or reticular activating system
- Little or no apparent tissue damage but often amnesia
- Retrograde amnesia
- Memory of event still intact
- Decreases in cerebral blood flow for a couple hrs
- Mild ICP for several days
What are cerebral concussions regarded as?
- Mild head injuries BUT
- there may be extensive subclinical damage
Contusions (4)
- Some tissue injury (capillary damage & interstitial hemorrhage)
- Can produce neurological deficits
- Usually act as a place for hemorrhage to occur
- Or a place for swelling/ post traumatic epilepsy to occur
What are the 3 types of contusion?
- Coup
- Intermediate
- Contrecoup
Diffuse Axonal Injury (5)
- Result from strain/shear forces
- Pathogenesis is poorly understood
- Magnitude and distribution reflect morbidity of injury, esp. in pts who do not have mass lesion
- May have petechial hemorrhaging between gray and white matter
- MRI is preferred but can be seen with CT
What is the Triad of Damage in Diffuse Axonal Injury?
- Corpus callosum
- Dorsal lateral quadrant of the midbrain
- Microscopic damage w/in subcortical white matter
Intracranial Hematomas (4)
- Intracerebral hematoma
- Subdural hematoma
- Epidural hematoma
- Subarachnoid hemorrhage
Intracerebral Hematoma (4)
- Hemorrhage in to brain parenchyma
- Caused by shear/strain forces rupturing bf’s
- Small ones treated non-surgically (control ICP, maintain perfusion
- Surgical decompression for: large ones, if pt is severely impaired, deteriorating pts
What decreases ICP? (2)
- Hyperventilation
- Mannitol
3 Types of Subdural Hematoma
- Acute
- Subacute
- Chronic
What are subdural Hematomas caused by?
- Tears in the bridging veins
- Limited by the falx!!
Acute Subdural Hematoma
- Treated by prompt craniotomy and evacuation
- Poor prognosis d/t underlying brain damage
Subacute/Chronic Subdural Hematoma
- Treated with burr hole evacuation
What is the magic number for midline shift?
3mm
What do you do if midline shift is more than 3mm?
Call a Neurosurgeon!!
Epidural Hematoma Cause
Tearing of the middle meningeal artery, usually a/w temporal bone fx. Not limited by the falx!
Clinical Picture of Epidural Hematoma (3)
- Loss of consciousness
- Followed by period of lucidity
- Followed over several hours by headache, loss of consciousness and progressive neurological deterioration
Tx of Epidural Hematoma
- If pt losses consciousness a 2nd time or stays unconscious, neurologic deterioration may progress rapidly
- Emergency craniotomy and evacuation
- IV mannitol (buys time)
- Hyperventilation to PCO2 of 25-35 (buys time)
How do you manage cerebral blood flow?
- Elevate head of bed (decreases ICP)
- Mannitol
- Hyperventilation
How does mannitol manage cerebral blood flow?
- increases intravascular volume, SBP, CPP
- ICP decreases
- Osmotic effects
- Hemodilution (decreases blood viscosity)
- Don’t give to rapidly or it can cause hypotension
How does hyperventilation manage cerebral blood flow? (5)
- causes alkalosis
- decreases ICP (constricts arterioles)
- Have to be careful! Follow ABG’s
- Can cause increase vessel reactivity which leads to hypoxemia and severe damage
- prolonged alkalosis can cause decrease in 02 available to tissues
Increased ICP (3)
- 10-20 needs careful monitoring
- over 20 should be treated urgently
- 30-50 a/w poor prognosis
Indications for ICP monitoring (4)
- When its important to determine ICP
- If there is a chance ICP is elevated
- When tx is needed for increased ICP
- When accurate assessment of neurological status is not possible
Herniation of the medial portion of the temporal lobe through the tentorium cerebelli causes?
- brain herniation
- midbrain compression
- LOC
- Decerebrate rigidity
Herniation of the medulla through the foramen magnum causes? (3)
- brain herniation
- reduced blood flow to the central medulla
- Cushing response (systemic HTN, bradycardia, respiratory irregularities)
Herniation of the cerebellar tonsils through the foramen magnum can cause? (3)
- brain herniation
- further brain stem compression
- medullary ischemia
Herniation of the cerebellum upward through the tentorial hiatus can cause? (2)
- Bilateral decerebrate rigidity
- Can be precipitated by release of fluid from the lateral ventricles
What is important to assume with major trauma?
Assume there is a head injury and a c-spine fx until proven otherwise!
Glasgow Coma Scale GCS consists of what categories?
- Eye opening
- Verbal response
- Best motor response
Eye Opening of the GCS (4)
4= spontaneous 3= on command 2= in response to painful stimuli 1= closed
Verbal Response of the GCS (5)
5= coherent speech 4= confused speech 3= speaks with inappropriate words 2= makes incomprehensible sounds 1= no response
Best Motor Response of the GCS (6)
6= obeys commands 5= purposeful movements to painful stimuli 4= withdraws from pain 3= decorticates to painful stimuli 2= decerebrates after painful stimulus 1= no response
What are 2 types of ventilatory patterns with brain injury?
- Central neurogenic hyperventilation
- Phasic respiratory patterns
Central Neurogenic Hyperventilation happens with? (4)
- severe cerebral acidosis
- localized hypoxia
- pontine damage
- tentorial herniation
Types of Phasic Respiratory Patterns (3)
- Cheyne Stokes Variant (no apnea)
- Cheyne-Stokes
- Ataxic ventilation
Criteria for ventilatory assistance (9)
- Abnormal rate
- Rate of >30, <10
- Abnormal ABG
- Absence of motor response to pain
- Repeated convulsions
- Signs of aspiration pneumonia, pulmonary edema
- Rising ICP
- Required for potent analgesics
- Concurrent severe pulmonary, cardiac or abd. injury
What do you use to control agitation and seizures? (5)
- Sedatives
- Paralytics
- Avoid electrolyte imbalance, hypoxia, fever
- Dilantin
- Diazepam
Immunizations (2)
- Tetanus toxoid
- If contaminated and deep, tetanus IgG, abx, and cleaning in OR
Abx Prophylaxis (2)
Opened depressed skull fx and penetrating wounds
- antistaph PCN or 1st generation cephalosporin
GSW
- same as above
- + gram - and anaerobe coverage
What do Barbiturates do? (4)
- reduce ICP
- Reduce cerebral metabolism and O2 requirements
- prevent intravascular coagulation
- reduce free radical damage to brain cells
“Phenobarb Coma” (2)
- Useful in reducing brain damage in patients with persistently high ICPs despite max therapy
- Neurologic status is monitored by evoked potentials
Complications of Severe Brain Injuries (5)
- Neurogenic pulmonary edema
- SIRS
- Cardiac complications
- GI bleed
- Coagulopathy
Spinal Cord Injury
- From blunt or penetrating trauma
- Can present with a variety of deficits or none
- Stable and unstable fx
- Absence of a distracting injury
- GCS of 15, not intoxicated or medicated
How do you deal with a spinal cord injury?
- Immobilize the spine in trauma patients!!!
- Clear the C-spine
- X-ray flexion/extension
- CT/MRI
- Careful neurologic exam
- Tx involves fixation
SCIWORA
- Spinal cord injury without radiographic abnormality
- Results from blunt injury, hyperextension/flexion
- Normal x-ray and CT
- May be MRI evidence of injury
- Most common in children
