Traumatic Head and Spinal Cord Injury and Raised Intracranial Pressure Flashcards
What are the direct effects of trauma?
Scalp - Lacerations - Bruises Skull - Fractures Meninges - Vascular injury - Lacerations Brain/spinal cord - Contusions - Lacerations - Diffuse axonal injury - Diffuse vascular injury
What are contusions?
Bruises on surface of brain
How many vessels does diffuse vascular injury in the brain involve?
Single vessel or multiple tiny ones
What is concussion?
Clinical term Instantaneous loss of consciousness Temporary respiratory arrest Less of reflexes Possible seizure Follows sudden change in momentum of head - Direct blow - Decceleration Pathogenesis uncertain - Maybe effect at brainstem level
What is the Glasgow coma scale?
Scale of neurological status
Enables standardisation between different groups of patients
- Therapies and outcomes can be assessed
Indicates level of brain injury
What three aspects are taken into account in the Glasgow coma scale?
Eye opening
Best verbal response
Best motor response
What is the maximum score that you can get on the Glasgow coma scale?
15 > okay
What is a penetrating injury?
Direct disruption of tissue
What is a closed injury?
Movement and compression of neural and vascular structures within bony confines
What are the secondary effects of traumatic head injury?
Ischaemia Hypoxia Cerebral swelling Infection Epilepsy
When do secondary effects of traumatic injury happen?
Delayed
Can contribute to immediate clinical outcome
When does infection occur in traumatic head injury?
Later in clinical course if patient survives
What does it mean if infection takes place after a traumatic head injury?
Brain or CSF breached
When does epilepsy occur in traumatic head injury?
Late in clinical course
Describe skull fractures
Radiate from point of impact
Can be depressed - bone pushes down on underlying brain
Important to diagnose because indicator of high energy transfer injury - brain has also moved around inside skull
What is the difference between an open and closed skull fracture?
Open if communicates with surface, but closed if it doesn’t
What is a comminuted skull fracture?
Bone splinters
Can chop away at brain tissue
What does blood and/or CSF from the nose and/or ears indicate?
Basal fracture
What most commonly ruptures in an extradural haematoma?
Middle meningeal artery
Why is an extradural haematoma much more likely to happen in a younger patient than an older one?
As people age, dura becomes increasingly adherent to skull
So in younger people, dura not attached > high pressure bleed not compressed
What ruptures in a subdural haematoma?
Subdural veins
What kind of subdural haematomas are there?
Acute
Chronic
Why are subdural haematomas more common in older patients?
As you age, brain shrinks and dura adheres to skull
Veins entering sinuses under more tension
More vulnerable to rupture
Can get from quite low energy transfer
What is the most common injury to brain tissue?
Contusions
Where do coup injuries happen?
At impact site
Where do contrecoup injuries happen?
Opposite side of brain to site of impact
Where do stereotypical contusions tend to occur?
Base of brain
- Inferior frontal lobes
- Inferolateral temporal lobes
What can directly damage brain tissue?
Force itself
Torn blood vessels
What reactive process do contusions involve?
Haemorrhagic necrotisation
Where must force be applied for contusions at the base of the brain to occur?
Anywhere
Why do people sometimes develop anosmia with contusions to the base of the brain?
Olfactory bulb pulverised
What happens to a contusion if the person survives?
Contusion resolves
Damaged tissue phagocytosed
Visible shrinkage of brain in these areas
How does the brain get lacerated?
Penetration by foreign body or skull fragments
How do missile injuries cause damage to brain tissue?
Via shock waves
Where is a particularly vulnerable site where cerebral tissue can tear?
Ponto-medullary junction Particularly in children Very rare Happens in severe brain trauma Accompanies other injuries
What are diffuse forms of brain injury?
Traumatic/diffuse axonal injury (TAI/DAI)
Diffuse vascular injury
Secondary injury
What is TAI/DAI?
Axons torn
What is diffuse vascular injury?
Little blood vessels torn
How do neurochemical alternations due to trauma exert toxic effects?
Brain tissue as it’s damaged releases neurotransmitters and other substances that can cause further damage to surrounding brain tissue themselves
What happens to the axons in DAI?
Bulbous swelling and complete interruption of axon
Axonal transport continues from cell body and collect in swelling
Axon beyond that dies
What are the long term effects of DAI?
Decreases white matter
Corpus callosum thins
Ventricles dilate to compensate for tissue loss
Patient severely neurologically impaired
Describe cord-compressive acute traumatic injury
Toothpaste effect
Soft cord tissue squeezed along adjacent spinal cord both proximally and distally
Tissue being pushed = necrotic
Can be pushed towards brainstem and cause damage there
What are the longer term sequelae of brain trauma?
Infections
Hydrocephalus
Epilepsy
Chronic traumatic encephalopathy
What can potentially be breached to cause an infection?
Scalp
Skull
Meninges
Brain tissue
What causes epilepsy after brain trauma?
Number of conditions, including:
- Tumours
- Infarcts
- Haemorrhages
- Trauma
What is chronic traumatic encephalopathy?
Brain atrophy due to neuronal loss
Abnormal deposition of tau protein
Often diffuse deposition of A-beta plaques in cortex
How much blood and CSF is in the brain?
150 mL each
What is the initial response to an expanding brain lesion?
Expulsion of as much CSF and venous blood as possible
What happens after as much CSF and blood has been squeezed out from the brain in response to an expanding lesion?
Intracranial pressure rises
Where does herniation of brain tissue occur?
Through dural openings
What happens as ICP approaches MAP?
Brain perfusion ceases
Death occurs a bit before this though
What are some potential causes of raised ICP?
Trauma Tumour Infarction Haemorrhage Infection Cerebral oedema Overproduction, or obstruction of flow or absorption of CSF
What can cause an overproduction of CSF?
Choroid plexus papilloma
What are the two main subtypes of cerebral oedema?
Vasogenic
Cytotoxic
What is a vasogenic cerebral oedema?
Due to BBB disruption with increased vascular permeability
Predominantly involves white matter
Fluid between cells
Quite sensitive to treatment; eg: steroid therapy
What happens in cytotoxic cerebral oedema?
Increased IC fluid secondary to neuronal, glial, or endothelial cell membrane injury Cells can't pump out water anymore Common in cerebral infarction Involves grey and white matter Not steroid responsive
Where does CSF come out from the brain?
Foramenae at brainstem level
What is the route that CSF takes?
Out of brain
Into subarachnoid space
Down into spinal cord
Up and around cerebral vessels
Where is CSF absorbed into venous circulation?
Arachnoid granules that project into sinuses
What happens to CSF absorption with age?
Can decrease
Can cause raised ICP > has to be drained another way
In what order to herniations occur because of a subdural haematoma?
Subfalcine herniation of cingulate gyrus
Distorted lateral ventricles
Transtentorial herniation of medial temporal lobe
Displacement and distortion of brainstem
Tranforaminal herniation of cerebellar tonsil
What happens in a subfalcine herniation of the cingulate gyrus?
Brain tissue forced under falx cerebri
What problems do distorted lateral ventricles cause?
None
What happens in a transtentorial herniation of the medial temporal lobe?
Part of temporal lobe goes through same space as brainstem
Constriction of blood vessels
Occulomotor nerve close to here - eventually, compression can cause fixed dilated pupil on ipsilateral side
What has happened by the time the cerebellar tonsil herniates?
Patient on respirator or dead
What type of lesions cause a transforaminal herniation of the cerebellar tonsil earlier?
Posterior fossa expanding lesion
What causes brainstem haemorrhages with brainstem herniation?
Blood supply of brainstem fixed
Tissue has been pushed down but vessels can’t move
Vessels tear
