Brain & Traumatic Injury Flashcards
What are the three components within the cranium according to the Monro-Kellie Doctrine?
Brain tissue, cerebrospinal fluid (CSF), and blood.
What is intracranial pressure (ICP)?
The pressure exerted by CSF on the brain tissue (normal: 7–15 mmHg).
What is cerebral perfusion pressure (CPP)?
CPP = MAP – ICP; it reflects pressure required to perfuse the brain (normal: 50–70 mmHg).
What is the physiological mechanism maintaining constant cerebral blood flow?
Cerebral autoregulation through vasodilation and vasoconstriction.
Name some factors that affect cerebral autoregulation.
Blood pressure, CO₂ levels, O₂ delivery, blood viscosity, pharmacological agents.
What are the two types of primary TBI?
- Focal 2. Diffuse
Give examples of focal primary brain injuries.
Skull fractures, contusions, lacerations, intracranial haemorrhages, penetrating injuries.
What is a diffuse axonal injury (DAI)?
Generalized damage to white matter caused by rotational forces or rapid deceleration.
What are two categories of skull fractures?
Vault and basal skull fractures.
What intracranial bleed presents with a lentiform (biconvex) shape?
Extradural haematoma (EDH).
What vessel is commonly involved in EDH?
Middle meningeal artery.
What is a key feature of subdural haematoma (SDH)?
Crescent-shaped bleed due to tearing of bridging cortical veins.
What type of bleed can push the ventricles and cause midline shift?
Subdural haematoma.
What is an intracerebral haemorrhage (ICH)?
Bleeding into brain parenchyma, often from lacerated vessels during contusion.
What is an intraventricular haemorrhage (IVH)?
Bleeding within the ventricles, often associated with severe TBI.
What is a subarachnoid haemorrhage (SAH)?
Bleeding into the subarachnoid space, potentially causing hydrocephalus.
What is a coup injury?
Injury at the site of impact.
What is a contrecoup injury?
Injury opposite to the site of impact.
What types of forces cause coup-contrecoup injuries?
Acceleration-deceleration or rotational forces.
Name the 3 classifications of TBI.
- Closed 2. Penetrating 3. Explosive
What is a concussion?
Temporary neurological dysfunction due to brain deformation; a mild DAI.
What are symptoms of a concussion?
Headache, dizziness, confusion, amnesia, visual changes, emotional shifts.
What causes secondary brain injury?
Ongoing cellular damage after the primary injury due to metabolic and inflammatory processes.
What are consequences of reduced cerebral blood flow?
Ischaemia, ionic pump failure, calcium/sodium influx, excitotoxicity, free radical damage.
What neurotransmitter is heavily involved in excitotoxicity?
Glutamate.
What is the role of the inflammatory response in secondary injury?
Unclear, but believed to worsen damage.
What is the Monro-Kellie Hypothesis?
The skull is a fixed volume. If one component (brain/CSF/blood) increases, another must decrease.
Causes of raised ICP?
Tumours, haemorrhages, oedema, hydrocephalus, idiopathic causes.
Classic triad of raised ICP?
Headache, vomiting, papilledema.
What is the danger of ICP >40 mmHg?
Risk of brain herniation, ischaemia, and death.
What is brain herniation?
Displacement of brain tissue due to raised ICP—can be fatal.
What are routes of brain herniation?
Falx cerebri, tentorium cerebelli, and foramen magnum.
What is Cushing’s triad?
Hypertension (with wide pulse pressure)
Bradycardia
Irregular respirations (e.g. Cheyne-Stokes)
What are the GCS score ranges for TBI?
Mild: 13–15
Moderate: 9–12
Severe: <9
What does a drop in GCS from 15 to 14 suggest?
Doubles the risk of neurosurgical findings on CT.
GCS score associated with 40% mortality?
Severe TBI (GCS <9).
How is mild TBI managed?
Observation, supportive care, CT if anticoagulated or symptomatic.
Initial steps in severe TBI?
Follow ATLS guidelines: ABCDE approach, stabilize airway and circulation.
When is a CT head indicated?
Any drop in GCS, signs of fracture, anticoagulants, focal neuro signs.
How to reduce ICP?
Elevate head 20–30°
Hyperventilation (temporary)
Mannitol/diuretics
Drain CSF
Sedation, barbiturates, or hypothermia
When is ICP monitoring indicated?
GCS <9 or if patient needs general anaesthesia.
Name common complications of traumatic brain injury.
Venous thromboembolism (VTE)
Focal neurologic deficits
Hydrocephalus
Seizures
Infections (esp. penetrating injuries)
Post-concussion syndrome
Which brain bleed is classically associated with a lucid interval?
Extradural haematoma.
What is a hallmark feature of diffuse axonal injury?
Axonal shearing from rotational forces → coma or persistent vegetative state.
What imaging is used first for TBI?
Non-contrast CT scan of the head.
How does hyperventilation lower ICP?
Causes vasoconstriction from ↓ CO₂ → ↓ cerebral blood volume.
What osmotic diuretic is commonly used to reduce ICP?
Mannitol.
What is the goal of elevating the head in TBI?
To facilitate venous drainage and reduce ICP.
What is a closed TBI vs. a penetrating TBI?
Closed = no skull breach; Penetrating = object breaches skull/brain (e.g., GSW).
What cascade is triggered by low CBF after TBI?
Ionic pump failure → Na⁺/Ca²⁺ influx → excitotoxicity (glutamate/aspartate) → cell death.
What factors contribute to reduced cerebral blood flow post-TBI?
Oedema, haemorrhage, raised ICP, hypotension, hypoxia.
What is the normal range of ICP?
7–15 mmHg.
