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55 Cards in this Set

  • Front
  • Back
What is cerebrovascular accident also known as?
Stroke
What is the purpose of the cerebral blood vessels?
To provide oxygen and glucose to neuronal tissue
To remove toxic waste
What causes stroke?
Disease that impairs the cerebral blood vessels
What are the two main types of stroke?
Haemorrhagic: bleeding from a blood vessel
Occlusive: closure of a blood vessel
How often does Haemorrhagic stroke occur?
20% of all strokes
What is the likely hood of a patient dying from Haemorrhagic stroke?
~60% of patients die within 12 months
How many types of haemorrhage strokes are there?
2 types
What types of haemorrhagic strokes are there?
Subarachnoid haemorrhage
Intracerebral Haemorrhage
What is intracerebral haemorrhage?
It is when the blood escapes directly into the brain tissue and destroys localised brain tissue
Causes relatively localised neuronal damage
Nature of cognitive impairment depends on region of brain affected
What is parenchyma?
The functional tissue of an organ as distinguised from the connective and supproting tissue
What is subarachnoid Haemorrhage?
It is when blood bursts from a blood vessel into the subarachnoid space and has no direct contact with neuronal tissue.
It essentially squashes the brain
Results in diffusive damage to the whole brain
Cognitive impairment is generalised, with dampening of all systems including intellect.
What is the cognitive impairment of intracerebral haemorrahage?
Nature of impairment depends on area of brain affected
What is the cognitive impairment of subarachnoid haemorrhage?
Generalised impiarment of brain, with dempening of all systems including intellect.
What is the most common type of stroke?
Occlusive stroke
80% of all strokes
How does occlusive stroke occur?
It occurs when there is a closure of a blood vessel
It causes losss of blood supply to the surrounding tissue
If loss of blood supply occurs for long enough then infarction results. i.e. death of neuronal tissue.
What is ischaemia?
The loss of blood supply tosurrounding tissue
What is infarction?
Death of neuronal tissue
Ho many types of occlusive strokes are there?
2
What are the types of occlusive stroke?
Cerebral thrombis
Cerebral Embolism
What is cerebral thrombosis?
A type of occlusive stroke
Local narrowing of a blood vessel
Most commonly due to atherosclerosis i.e. the deposition of plaques pf fatty material along the inner walls of the vessel.
What is cerebral embolism?
Fragments of fatty tissue from larger vesseld that break off and become lodged in narrower arteries such as blood vessels.
What is atherosclerosis?
The accumulation of fatty tissues on the blood vessel inner walls
How many types of head injury are there?
3
What are the different types of head injury?
Penetrating head injury
Crushing head injury
Closed head injury
What are the different types of primary injuries in closed head injury?
Diffuse axonal injury
- strecthing and shearing of brain
- widspread damage
- reticular formation area of brain heavily involved in attention and arousal
Arteries and veins may be torn
Haemorrhagic lesions at site of impact
What area of the brain is the most common site of surface contuson of closed head injury?
The frontal & temporal lobes
Why is the frontal & temporal lobes the most common site for sriface contusions in closed head injuries?
It is because they are adjacent to the sphenoidal ridge. This is a bony ridge protruding from the skull toward the brain
Why so secondary injuries occur in closed head injury?
Due to a result of system complications
Name the secondary injuries found in closed head injury?
Brain swelling
Infection
Intracranial haematoma
Damage to the brain due to hypoxia/ischaemia
What is hypoxia?
Deficieny in the amount of oxygen reaching the tissues
What are the delayed complications of closed head injury?
Post-traumatic epilipsy
Hydocephalus
What is hydicephalus?
A condition in which spinal fluid accumalates in the brain
What does PTA stand for?
Post traumatic amnesia
What is PTA?
A period of time where a injured person is unable to process information in their environment
This is due to diffuse axonal injury causing severe distruption of the attention system
Occurs in individuals with moderate to severe closed head injury
What types of behaviour and cognitive deficits are found after moderate to severe closed head injury?
Soical inappropriate behaviour, slef centred, irritable
Changes in affect with elevated or depressed mood, reduce emotional control
Attention difficulties and fatigue
Impaired planning and problem solving, abstraction difficulties, lack of insight
What types of memory deficits are encountered after moderate to severe closed head injury?
Retrograde memory impairments
Anterograde memory impairments
New learning impairment
Delayed recall impairment
COnfabulation
Achronogenesis
What are the mechanisms of recovery for closed head injury?
Resolution of temporary dysfunction
Re-organisation
- Regeneration
- Plasticity
What types of brain damage occurs from closed head injury?
Diffuse brain damage
Whatt is EEG good at determining?
It has a high temporal resolution which means it is good at recording the time at which a stimulus occured in the brain
What causes the electrical signals recorded in EGG experiments?
The electrical signals generated by the neurons in the brain
What does EEG record?
It records the combined eleectrical potentials (i.e. voltage) generated by millions of neurons
What type of neurons does the EGG record?
Electrical signals from neurons in the cerebral cortex
Why are neurons from the cerebral cortex recorded by EEG?
Because the electrodes pick up signals from this site of the brain as it is closest to the electrodes.
What are the limitations of EEG?
EEG signals are biased to signals generated in superficial layers of the cerebral cortex on the gyri.
Signals in sulci are harder to detect and ofetn masked by the signals from the gyri
The menigis, cerebrospinal fluid and skull smear the EEG signa;
Primary limitations is its poor spatial resolution
What are gyri?
A ridge or fold between two clefts of the cerebral surface in the brain
How many electrodes are used in EEG?
20-256
In EEG recording what are the factors that will increase the EEG signal?
Conducting gel
Scalp is lightly abraded
Some electrodes fail to pick up reliable EEG signals and so removed from subsequent analysis
What is the most popular method of arranging the electrodes in an EEG recording?
10 -20 system
What does the EGG record?
Compare the potential difference on the voltage between two electrodes
Compare the activity of an electrode relative to a common reference
Compare the activity of an electrode to the average of many electrodes
How are EEG signals processed?
The signals have a typical amplitude of 10microV to 100 micro V
They are amplified by a factor of 1,000 to 100,000
The signal is digitalised by a sample frequency between 256-512 Hz
Remove the really low & high frequencies
Also notch filter at 50Hz to remove the current from the mains
What is the minimum number of electrodes required in an EEG experiment?
2
Why do you need at least 2 electrodes in an EEG experiment?
It is because an electrode cannot measure the signal at a single point
The electrodes measure the voltage between the two electrodes.
Why are reference electrodes essential in EEG experiments?
To provide a point of comparision
What are the clinical usuages of EEG recording?
Used to monitor depth of anaesthesia
An adjunct test of brain death
To monitor non- convulsive seizures
To distinuish between epileptic seizures and non-epileptic seizures
To help individual interact with computers
What is an Event Related Potential ERP?
It is an EEG signal caused by the presentation of a stimulus