PNP WK7 Flashcards
Nervous system disorders (34 cards)
What is the definition of an intercranial cause to loss of consciousness?
Related to the direct impact on anatomical structures of or within the cranium
- Head injury, hemorrhage etc.
What is the definition of an extracranial cause to loss of consciousness?
related to secondary causes from issues outside the cranium
- Hypoxia, hypo/erglycaemia-tension.
What is a persistent coma?
- unconsciousness
- no sleep/wake cycle
- focal damage at brain stem/thalamus
What is locked-in syndrome?
- brain stem injury that affects transmission of motor function
- awareness of surroundings but cannot respond to stimuli
What is a vegetative state?
- Follows sleep/wake cycles
- Roused by stimuli but cannot show awareness of surroundings
What is the criteria for brain death?
- Cessation of brain function
- Absence of brain stem responses
- Absence of spontaneous respirations
- Irreversible brain damage
What is intercranial pressure?
- the forces exerted within the cranium and thus the brain
- is determined by vol of brain tissue, cerebrospinal fluid and intravascular blood
What is cerebral perfusion pressure?
- The pressure of blood flow (o2) to brain tissue
- CPP= Mean Arterial Pressure (blood entering cranium)- Intercranial Pressure (blood leaving cranium)
What is the Monro-Kellie doctrine?
the components exist in volume equilibrium, so an increase in any of the 3 cerebral components will increase ICP and must be compensated for by decreasing the overall volume of the other two cerebral components
What are the early steps the body takes to deal with an increased ICP?
- shifts CSF to spinal cavity to increase venous return from brain (briefly effective)
- Resulting hypoxia triggers arterial vasodilation to improve CPP to brain (briefly effective and adds fluid in brain)
If ICP increases, what is done to critically supply the brain with O2?
- Cerebral ischemia
- Systemic vasoconstriction to force blood into brain
- Baroreceptors cause bradycardia
- Chemoreceptors respond to low CO2 levels and decrease resp. rate
CUSHING REFLEX (widened bp, bradycardia and irregular resps)
What is the result of damage to the upper motor neurons (corticospinal tract)?
- Weakness/paralysis to opposite side of body (due to crossover at medulla oblongata)
- Muscle tone/reflexes increased due to no inhibitors sent to site
What is the result of damage to the lower motor neurons (corticospinal tract)?
- Weakness/paralysis to same side of body
- Muscles are flaccid and reflexes reduced
What is the difference between decorticate and decerebrate (two involuntary motor responses from brain damage)?
Decorticate: rigid flexion in the upper limbs, lower limbs extended, caused by severe damage in cerebral hemispheres
Decerebrate: upper and lower limbs are extended, body is arched, caused by CNS depression or brain stem legions
What are local/focal effects?
- signs related to the specific area of damage to the brain or spinal cord
- e.g. paralysis of right arm from damage to left side of frontal lobe
What happens the vision if the
- Optic chiasm
- Optic nerve
- Optic tract
is disrupted?
Chiasm: Field of vision in both eyes is disrupted
Nerve: Field of vision in eye on same side is disrupted
Tract: info on the lateral same side, and medial other side will be damaged
What is the difference between expressive, receptive and global aphasia?
Expressive: Cannot speak or write fluently
Receptive: Unable to understand language
Global: Cannot express self or comprehend others’ language
What is the definition of a seizure?
an episode of inappropriate neuronal electrical discharge resulting in disordered brain activity in the cerebral cortex
What is a TIA (transient ischemic attack)?
- Temporary localised reduction in blood flow to the brain
- Caused by partial occlusion, embolus, spasm
What is a Cerebrovascular accident (CVA)?
- A stroke, sudden lack of blood supply to certain parts of the brain due to plaque build up in artery that breaks off
- Ischemic: sudden blockage to cerebral artery causing necrosis as a result of a thrombus (clot) or embolism (moving clot)
- Haemorrhagic: cerebral artery ruptures and there is a brain bleed, loss of blood supply and increased ICP, can be caused by hypertension
What is a cerebral aneurism?
- localized dilation in an artery from a rupture in the artery wall
- blood, along with CSF causes an inflammatory response, vasospasm and increased ICP
What is the pathophysiology of a malignant primary brain tumour?
- no well-defined margins, are invasive, have a layer of inflammation surround adding to the pressure
- increasing mass can lead to herniation
- don’t normally metastasize out of the CNS
What are the different types of partial seizures?
- Simple Partial: Only one hemisphere involved, no LOC
- Complex Partial: Temporal lobe, consciousness is impaired, automatism and post-ictal present
What are the types of generalised seizures?
Absence : lapse in consciousness for 10 seconds
Atonic: sudden loss of muscle tone
Myoclonic: sudden uncontrolled jerking of 1+ limbs
Tonic-clonic: immediate LOC, tonic phase involves muscle contraction and body stiffening, clonic phase involves flexion spasm then muscular relaxation
