concussion and intercranial pressure Flashcards
what is a primary brain injury
- an injury that has already happened, usually physical
what is a secondary brain injury
- an injury that may follow a primary injury
- usually caused from reduced perfusion, inadequate oxygenation and raised intercranial pressure
what assessments need to be done on a someone with a possible brain injury
- primary survey
- diability/ neurological assessment
- AVPU
- GCS
- pupil response
- limb tones
- cranial nerve exam
- limb function
- gait
- cerebral function
what are the signs and symptoms of a concussion
- headache
- loss of consciousness
- drowsiness
- vomiting
- memory disruption
- presentation form immediate - 3 weeks
what is coup
a single impact site on the brain tissue
what is contrecoup
double impact sites on opposite sides
what is the difference between coup and contrecoup
- coup is when the skull hits the brain due to rapid acceleration of the skull
- contrecoup when the brain hits the skull from deceleration of the skull
what are the different layers of the meninges
- extradural space
- dura mater
- subdural space
- arachnoid mater
- subarachnoid space (CSF)
- pia mater (attached to brain)
where is the CSF produced
in the choroid plexus and found in the subarachnoid space
what happens if there are changes to the CSF
- it is absorbed by the arachnoid villi but if there are blood leakages into the CSF this can prevent absorption
- an increase in intracranial pressure
what are symptoms of shock
- decreased BP
- increase HR
- increased RR
what are the symptoms of increased intracranial pressure
- increased BP
- decreased HR
- decreased RR
what is the Cushing reflex
a haemodynamic response to an acutely elevated ICP
what are the stages of Cushing’s reflex
- cerebrospinal fluid pressure
- intracranial tension grows
- compression of the brain and arteries
- cut of brains blood supply
- CNS ischemic response starts and arterial pressure rises
- relieved brain ischemia
what is Cushing’s triad
- widening pulse pressure
- bradycardia
- irregular respirations (cheyne Stokes)
what are the stages of Cushing’s triad
- cushings reflex - bp and hr increase
- hypertensions persists and bradycardia
- brain stem compression = irregular breathing
why does the heart become bradycardic in stage 2 of cushing’s triad
the sympathetic nervous system is activated and then the parasympathetic system activates slowing down the HR
how is CCP calculated
CCP = BP-ICP
how does o2 treatment help the ICP
more o2 to the brain reduces the demand for greater blood flow so reducing the intracranial pressure
how does a brain injury affect blood getting to the brain and CPP
- intracranial mass lesion
- increases ICP
- reduces CPP
- leads to hypoxia/ ischemia
- induces oedema
- increases ICP
what is coning
when the brain is forced through the small gap at the base of the skull
what are the types of coning
- sub-falcine herniation
- trans-tentorial herniation
- tonsillar herniation
what is uncal herniation
- a herniation caused by an increase in intracranial pressure and the uncus slide downwards across the tentorium cerebrelli compressing the brainstem
what are the causes of uncal herniation
- expanding mass lesions within the skull
- severe head trauma leading to severe head bleeds
- hx of large ischemic strokes
symptoms of uncal herniation
- headache
- nausea
- vomiting
- changes in mental state
- Cushing’s triad
- compression of CNIII
what is sub-falcine herniation
- the hemisphere is displaced beneath falx
- cause ventricular dilation
what is tonislar herniation
- the cerebellum is pushed through teh foramen magnum
- an the inferior descent of the cerebellar tonsils
what causes tonsillar herniation
- secondary to high intracranial pressure
- stroke
- tumour
- haemorrhage
- abscess
- pons, medulla compression
how to prevent coning
- oxygenation 100%
- ensure MAP stays below 80mmHg
- saline bolus
parasympathetic pupillary reflex
- reduces incoming light
- direct reflex
- pupil constrictions
sympathetic pupillary reflex
- increases incoming light
- dilates the pupils
what is the consensual reflex
- equalising constriction between the eyes
- light into the right eye will cause the left to constrict
what is anisocoria
mismatched dilated
what is accommodation of the lenes
- the contraction and relaxation of the ciliary muscle altering lens thickness to allow refracted light from distant and far objects to fall on the fovea centralis
what happens to muscles in distance focus
- ciliary muscle relaxed
- lengthened suspensory ligaments
what happens to muscles and close focus
- ciliary muscles contract
- suspensory ligaments shortened
what is pupillomotor
can your eyes pull in and constrict
what is relative afferent pupillary defect (RAPD)
- both eyes are dilated even with a bright light on them
- damage to the optic nerve or the retina
- signal cant get to the back of the eye so there is an issue before the chiasm
what is the pupil response in increased intracranial pressure
dilated and sluggish due to increase pressure compressing vessels
sensation for corneal reflex
ophthalmic division of trigeminal (CNV) to brainstem
motor response for corneal reflex
facial nerve nuclei, bilateral (CNVII) causes contraction of orbicularis oculi
what cranial nerves aren’t working in a negative corneal reflex
V and/ or VIII
which cranial nerves aren’t working in a failed pharyngeal reflex
glossopharyngeal (IX) or vagus (x)
symptoms of vestibulo-ocular reflex impairment
- dizziness
- nausea
- loss of balance
- blurred vision
what is nystagmus
a twitch of the eye
how to test for nystagmus
- get patient to follow finger drawing an H
- pause at each of the 6 points and wait for twitching
what is papilloedema
swelling of the optic disk due to due to an imbalance of cerebral fluid and pressure in or around the brain
how does papilloedema occur
- ICP presses on the back of the eye
- optic nerve bulges into the eye
- increase the size of the optic disc
what is haemotympanum
bleeding form the ears
what is retrobulbar haemorrhage
bleeding from the eyes
what indicats a basilar skull fracture
- clear/ pale red fluid from the nose
- bruising behind the ears or eyes
what are signs of retrobulbar haemorrhage
- severe pain
- progressive vision loss
- proptosis
- fixed dilated pupils
cerebrospinal fluid leakage
- usually caused by a tear in the dura
- leads to watery discharge
- tramlining (blood on outer edges and CSF washed central blood away)
- drying drips - CSF dissipating outwards
- reservoir sign - discharge when chin on chest
