Traumatic head and spinal injury Flashcards
Which structures may the direct effects of trauma be seen in? Which types of trauma affect each structure?
Scalp - lacerations
Skull - fractures
Meninges - vascular injury, lacerations
Brain/spinal cord - contusions, lacerations, diffuse axonal injury, diffuse vascular injury
What is concussion?
A clinical term to describe instantaneous loss of consciousness, temporary respiratory arrest and loss of reflexes.
What causes concussion?
Sudden change in the momentum of the head Pathology unknown (maybe RAS)
How is a head injury assessed clinically?
Glasgow coma scale
13 or above: mild brain injury
9-12: moderate brain injury
8 or less: severe brain injury
Why is the bony casing around the brain and spinal cord both a blessing and a curse?
Blessing: high energy transfer required to breach layer
Curse: Soft tissue against hard bone can cause problems
How is damage caused in penetrating injuries and in closed injuries?
Penetrating: direct disruption of tissue
Closed: movement and compression of neural and vascular structures within bony casing
What are some of the secondary effects of traumatic head injury?
Ischaemia Hypoxia Cerebral swelling Infection Epilepsy
How do skull fractures generally behave?
Radiate from point of impact
May be depressed
What are the different classes of skull fractures?
Open: communicate with surface
Closed: do not communicate with surface
Comminuted: splintering of bone
What does blood or CSF coming from the nose and/or ears indicate?
Basal skull fractures
Why is it important to diagnose skull fractures?
They are an indicator of high energy transfer energy
Therefore, potential for direct brain sequelae is high
Why are extradural haematomas less common in elderly people?
Dura becomes more adherent to the skull with age, so that blood cannot track through it
Why are subdural haematomas more common in elderly people?
Brain shrinks > veins stretched> more susceptible to rupture
Why can subdural haematomas be acute or chronic?
Can be self-limiting, as it is very low pressure blood
Can continue to accumulate unnoticed until it causes raised ICP
What are contusions?
Haemorrhagic necrosis or bruising of the brain
What are coup injuries?
Those that occur at the site of impact
What are contrecoup injuries?
Injuries that occur on the opposite side of the brain when the head is not immobilised at the time of injury
Why do contusions often occur at the base of the brain?
Many irregularities in the cranial floor which the brain may rub against
What are some common sites for contusions at the base of the brain?
Inferior frontal lobes
Inferolateral temporal lobes
Describe the appearance of old cerebral contusions?
Abnormal gyri
Collapsed brain tissue
Yellowish
Why do old cerebral contusions appear yellowish?
Macrophages have removed necrotic tissue and blood
Leave behind haemosidirin
What causes a traumatic cerebral haematoma?
Intra-cerebral haemorrhage when a large blood vessel is ruptured
Define a laceration?
Penetration by foreign body or skull fragments
Describe the damage caused by missile injuries?
Brain at either side of bullet path has shockwave effect
So, actual injury to brain can be much greater in diameter than the bullet itself
What is required for cerebral tissue to tear?
Severe enough impact with sufficient energy transfer
What is the most vulnerable site for cerebral tissue tearing?
Ponto-medullary junction
Which part of the brain is most susceptible to diffuse axonal injury?
Corpus callosum
Describe the microscopic appearance of diffuse axonal injury lesions in the corpus callosum?
Silver stain > axonal spheroids (area of swelling in axon, marker of transection)
Describe the macroscopic appearance of diffuse vascular injury?
Spotty haemorrhages
Describe the longterm effects of diffuse axonal injury?
Brain atrophy
Enlarged ventricles
Thin corpus callosum
Thin white matter
Describe the toothpaste effect in cord-compressive acute traumatic injuries?
Spinal cord squashed by bone and cartilage > cord tissue squeezed both proximally and distally
List some of the longer term sequelae after brain trauma?
Infections
Hydrocephalus
Epilepsy
Chronic traumatic encephalopathy
What is hydrocephalus?
Ventricles become dilated and brain tissue is compressed as a consequence
Why may hydrocephalus occur in the long term after brain trauma?
Exit for CSF may be blocked off by scar tissue
What are the three major components of the cranium?
Brain tissue
CSF
Blood
How much blood and CSF usually exists in the cranium
150mL each
How does the brain initially respond to an expanding brain lesion?
Expulsion of as much venous blood and CSF as possible
Where can herniations of brain tissue occur due to raised ICP?
Through dural openings
What happens as ICP approaches arterial pressure?
Brain perfusion ceases
CPP=MAP-ICP
What is a major structural sequelae of raised ICP?
Herniation of brain tissue
What are the causes of raised ICP?
Trauma Tumor Infarction Haemorrhage Infection Cerebral oedema Increased CSF
What are the two main types of cerebral oedema?
Vasogenic
Cytotoxic
Describe vasogenic cerebral oedema?
Due to BBB disruption with increased vascular permeability
Predominantly involves white matter
Responds to normal treatment
Describe cytotoxic oedema?
Increased intracellular fluid to cell membrane injury
Involves grey and white matter
Non-steroid responsive
Which three brain areas are prone to herniation with raised ICP?
Medial temporal lobe
Cingulate gyrus
Cerebellar tonsil
