Raised Intercranial Pressure Flashcards
Give the classification of injury given according to the structure involved for head and spinal injury
Scalp: lacerations
Skull: fractures (may be linear, depressed, etc)
Meninges: vascular injury, lacerations
Brain/cord: contusions, lacerations, diffuse axonal injury (DAI), diffuse vascular injury
What is concussion?
Instantaneous loss of consciousness, temporary respiratory arrest and less of reflexes following a sudden change in the momentum of the head
What structure is hypothesised to be involved in the pathogenesis of concussion?
Brainstem, particularly the reticular activating system
What is the difference between a penetrating and closed injury?
Penetrating injury involves direct disruption of tissue
Closed injury involves movements and compression of neural and vascular structures within bony confines
List 5 secondary effects of traumatic injury
Ischaemia Hypoxia Cerebral swelling Infection Epilepsy
What is the difference between an “open” and “closed” skull fracture?
Open communicates with surface (i.e. breaks through the skin), closed does not
What is a comminuted skull fracture?
A skull fracture in which the bone splinters
What clinical symptoms may be seen with a basal fracture?
Blood/CSF draining from nose and/or ears
What is the blood vessel typically damaged in an epidural/extradural haematoma?
Middle meningeal artery
Which blood vessels are damaged in a subdural haematoma? What is the typical course of a subdural haematoma?
Subdural veins are damaged
May be acute or chronic
What are contusions and what are their 2 classifications?
Haemorrhagic necrosis (bruising) May be coup (at impact site) or contrecoup (occur when head is not immobilised at the time of injury and the opposite side of the brain is bruised)
Where do contusions tend to occur?
At the base of the brain (site of many protuberances), particularly the inferior frontal lobes and inferolateral temporal lobes
Why do the sites of cerebral contusions stain orange?
Macrophages phagocytose blood and necrotic tissue, leaving haemosiderin behind
What is DVI?
Diffuse vascular injury, in which small blood vessels tear to produce small sites of haemorrhage
What are the histological findings in DAI?
Areas of swelling due to transection of axons
Axonal “spheroids” can be observed within a few hours of injury and are visualised using a silver stain
List 3 long term sequelae of brain trauma
Infections
Hydrocephalus
Epilepsy
Chronic traumatic encephalopathy
What are the pathogenic factors underlying chronic traumatic encephalopathy following brain trauma?
Brain atrophy due to neuronal loss
Abnormal deposition of Tau protein
Often diffuse deposition of A-beta plaques in cortex
How many mLs of blood and CSF are in the cranium?
~150mL each
What is the initial response to an expanding brain lesion?
To expel as much CSF and venous blood as possible
When does brain perfusion cease in raised ICP?
When ICP > arterial pressure
List 7 potential causes of raised ICP
Trauma Tumour Infarction Haemorrhage Infection Cerebral oedema Overproduction, obstruction to flow or absorption of CSF
Distinguish between the 2 main subtypes of cerebral oedema and their causes
Vasogenic: due to BBB disruption with increased vascular permeability
Cytotoxic: due to increased intracellular fluid secondary to neuronal, glial or endothelial cell membrane injury (e.g. in stroke)
What is the difference between vasogenic and cytotoxic cerebral oedema in terms of the affected areas and therapies?
Vasogenic predominantly involves the white matter and can be treated with steroids
Cytotoxic involves both grey and white matter and is not responsive to steroids
What are the 3 main types of herniation?
Subfalcine (herniation of cingulate gyrus under falx cerebri)
Transtentorial/uncal (herniation of medial temporal lobe through the tentorium cerebelli)
Transforaminal/tonsillar (herniation of cerebellar tonsils through the foramen magnum)
List 5 major sites of CSF block
Interventricular foramen (foramen of Monro)
3rd ventricle
Cerebral aqueduct (aqueduct of Sylvius)
Medial aperture (foramen of Magendie) and lateral apertures (foramen of Luschka)
Basal cisterns/subarachnoid spaces
