RESPONSES TO THE BRAIN IN TRAUMATIC INJURY Flashcards
What is the tentorium?
a tough connective tissue that separates the hemispheres of the brain from the brainstem and cerebellum
how do we measure the severity of a brain injury?
glasgow coma scale
post traumatic amnesia
loss of consciousness
what does it mean if a lesion is extra-axial?
within skull but outside brain parenchyma
what are intra-axial lesions?
lesions within the brain parenchyma
what is a coup injury?
brain damage that occurs directly under the point of impact
what is a countrecoup injury?
occurs on the opposite side of the brain from where the head is struck
what are some symptoms of brain injury?
vomiting, pain, dizziness, loss of consciousness, amnesia
outline the natural history of a brain injury?co
primary brain injury
progressive damage
secondary injury
functional outcome
what are some focal brain injuries?
contusion, haemorrhage, skull fracture, penetrating jead injury
what are some examples of progressive damage in the brain after primary injury?
mechanoporation calcium flux oxygen free radical formation lipid peroxidation axotomy
how is cerebral blood flow usully autoregulated?
through vasoconstriction and vasodilation
how are intercranial haemorrhages initially compensated for?
venous constriction and absorption of CSF into the spinal cord
what is the monro-kellie doctrine?
the sum of volumes of brain, CSF, and intracranial blood is constant so an increase in 1 means a decrease in the others
what is raised ICP?
> 20mmhg
what is severe ICP increase?
> 40mmHg
what are the 4 stages of increasing ICP?
Stage 1 - compensatory reduction in CSF and blood volume so no rise in ICP
stage 2 - when volune continues to increase beyond the point of compensation, the ICP increases
‣ may feel drowsy and have a headache
stage 3 - sustained increased ICP with dramatic changes in ICP and small changes in volume, decreasing cerebral perfusion pressure
‣ deteriorating conscious level, intermittent elevations in bp and bradycardia
stage 4 - cerebral perfusion pressure caeses, widespread necrosis begins and compression of brainstem respiratory centres lead to respiratory arrest and death
‣ coma, fixed dilated pupils, death
outline the volume pressure curve during raised ICP?
As haematoma volume increases, initially the ICP doesnt rise but pass the point of decompensation we get exponential rise in ICP
the time from pont of decompensation and herniation is relatively small compared to haematoma growing time so you must treat urgently!
what are some symptoms and signs of raised ICP?
headache vomiting without nausea ocular palsies altered level of consciousness back pain papilloedema
what is Cushing’s reflex?
if ICP rises, the body responds by releasing endogenous steroids and mean blood pressure will increase which is impprtant to maintain cerebral perfusion pressure
whats the equation for the cerebral perfusion pressure?
mean blood pressure - intercranial pressure
what do extradural haematomas look like on CT?
white lens shape
what does a subdural haematoma look like on CT?
bi-convex shape
whats a craniotomy?
taking a patch of bone off the skull and removing the blood causing pressure
