Week 3 Flashcards
What are the two leading causes of brain injury?
- cerebrovascular accidents (CVAs)/stroke
- traumatic brain injury
What are some causes of brain damage?
- cerebrovascular accidents/stroke
- traumatic brain injury
- tumours
- anoxia/hypoxia
- infections
- neurotoxins
- neurological diseases
What percentage of body weight does the brain represent?
2%
What percentage of the body’s oxygen is provided to the brain?
25%
How much cardiac output of the body does the brain require?
15%
Which animal can survive for hours without oxygen supply to the brain
turtles
Loss of consciousness occurs within how many seconds of interrupted blood supply to the brian?
10 seconds
What happens after 20 seconds without blood supply to the brain>
electrical activity ceases
What happens without a blood flow to the brain after 2-3 minutes?
Irreversible brain damage occurs.
Arterial supply involves two pairs of vessels, what are these?
- internal carotid arteries
2. vertebral arteries
What are the two main divisions of the internal carotid system?
- middle cerebral artery
2. anterior cerebral artery
What are the two main divisions of the vertebral - basilar system?
- Basilar artery
2. posterior cerebral arterites
What is the circle of willis?
interconnection of all the arteries which supply blood to the brain
What is one benefit of the circle of willis?
- If one artery is blocked, blood can still be supplied to that area.
- If an artery is blocked on one side, if can be transferred over via the communicating artery
The anterior cerebral artery supplies blood to which part of the brain?
medial
frontal
parietal
The middle cerebral artery supplies blood to which part of the brain?
lateral surface of the hemispheres
Posterior cerebral arteries supply blood to which part of the brain?
medial part of the occipital lobe
inferior surface of the temporal lobe
What is CVA? (stroke)
vascular disorder which results in brain injury
What is ischaemia? (stroke)
insufficient or lack of blood flow to the brain
What is an infarction? (stroke)
tissue death due to inadequate blood supply
What is infarct? (stroke)
area of damaged or dead tissue from infarction
What is penumbra? (stroke)
tissue surrounding infarct which may recover or die
What is excitotoxicity? (stroke)
Excess activity in glutamate signalling pathways (NMDA receptors) resulting in cell death.
What is oedema? (stroke)
swelling of brain
What are some signs of a stroke?
- weakness/numbness
- hard to speak or understand
- loss of balance
- loss of vision
- headache
- difficulty swallowing
What are some factors involved in stroke recovery?
- type of stroke
- size of blood vessel
- remaining intact vessels
- premorbid factors (age)
- location
Which kind of stroke is often associated with poorer recovery?
hemoragic stroke
If stroke is restricted to one area:
Outcome may be better as blood flow via alternative route
What are the two main types of stroke?
- obstructive (ischaemic) stroke
2. hemorrhagic stroke
What occurs in an obstructive stroke?
reduction of blood flow or complete blockage of a blood vessel (often fatty plaque)
What occurs in a haemorrhagic stroke?
result from bleeding into brain tissue (rupture of blood vessel)
often fatal
In obstructive strokes, what are the two main causes?
- thrombosis blood clot
2. embolism (part of a broken thrombus which blocks a blood vessel in the brain)
What does onset of obstructive stroke look like?
-cann occur suddenly, often takes 30 minutes to developed
What is recovery like for obstructive strokes?
- 80% show significant improvement
- 50% significantly disables
- around 3 months there is usually little further improvement
Most thrombotic strokes occur where?
In internal carotid or vertebral-basilar arteries
What are some cognitive and behavioural effects of obstructive stroke? (3)
- unilateral effects on function
- prominent acute effects, become less prominent over time
- signs of bilateral or diffuse damage in acute stages (confusion) which resolve as brain swelling diminishes
What are some examples of unilateral effects on obstructive stroke?
- hemiparesis
- hemiplegia
- aphasias (left)
- unilateral neglect (often right)
What is hemiparesis?
weakness in vertical half of the body
What is hemiplegia?
Complete paralysis of vertial half of body
What is aphasias (left)?
language disorders (speech fluency returns within one months if at all)
What is hemispatial neglect?
failure to attend to space at opposite side of lesion
What are transient ischaemic attacks?
episode of temporary obstruction of a blood vessel lasting less than 24 hours, many lasting only minutes, and 50% lasting <1 hour
What are the two types of TIAs (transient ischaemic attacks)?
- those lasting less than 45 minutes with no evidence of infarct on a CT
- those lasting more than 45 minutes and show radiological evidence of infarction
Within the first months of TIA, what percentage will develop a full blown stroke?
about 30%
What percentage of strokes are haemorrhage strokes?
10-20% of all strokes
What mortality rate do those with haemorrhagic strokes have within the first 30 days?
35-52%
What are 3 risk factors for hemorrhagic strokes?
- hypertension/high blood pressure (greatest risk)
- chronic use of aspirin
- cocaine and or excessive alcohol use
What are the two primary mechanisms that cause arterial haemorrhage?
- weakening of vessel
2. rupture associated with vascular abnormality, such as aneurysm etc
What is an aneurysm?
weak area in artery wall that causes area to balloon out
What are some risk factors for anerurysm rupture?
- women and older patient
- symptoms predict it
- basilar artery aneurisyms
What are the symptoms of an aneurysm?
- severe headaches, vomiting
- loss of consciousness
- can be immediately fatal
What do haemorrhagic strokes often effect?
-mostly affect thalamus, basal ganglia and brainstem
Haemorrhages associated with hypertension (high blood pressure) tend to involve:
blood vessels at the base of the verebral hemisphere
What is the outcome of a hypertensive haemorrhage?
- mortality rate of 65-80%.
- Survivors can be in a near vegetative state to a relatively good return.
- Motor symptoms prominent
What is arteriovenous malformations? (a type of haemorrhagic stroke) which accounts for 1% of all strokes
Tangled masses of arteries and veins which grow, usually gradually, more like a tumour. Born with these malformations.
What is locked in syndrome?
- rare disorder caused by ischaemic or haemorrhagic stroke in the basilar artery
- loss of all motor functions with the exception of eye movement
- cognition and consciousness remain fully in tact.
What is a traumatic brain injury?
an insult to the brain caused by an external force, may produce altered consciousness, may result in impaired cognitive abilities of physical functioning
What are the two types of traumatic brain injury?
- closed head injury
2. penetrative head injury
What is penetrating head injury?
the skull is fractured, exposing the brain and allowing the entry of foreign matter
What is a closed head injury?
Non-penetrative blow to the head. Common causes assaults, falls and sports.
what are the two stages of brain injury?
- primary injury
2. secondary injury
What are contact forces in a closed head injury?
static injury, where head is still and receives a blow. q
What are inertial forces?
movement of the brain within the head
What is translational acceleration, as one type of inertial force:
head moves in straight line with brain in centre of gravity
What is rotational acceleration, as a type of inertial force?
brain rotates around centre of gravity
What is angular acceleration, as a type of interial force?
Combination of translational and rotational forces
What is a coup injury?
injury site of initial impact
What is a contre-coup injury?
The brain rebounds against opposing side of skill causing further damage
What is a diffuse axonal injury?
Rapid deceleration forces lead to widespread damage through the brain. Axons get torn, twisted etc,
What is an intra cranial haemorrhage?
large blood vessels may be torn on impact, which create haematomas (or bruise) within the skill
What are the two different types of haematomas?
- epidural
2. subdural
A brain injury can cause many secondary injuries. What may these include
- cell death
- brain swelling
- reduced blood flow (hypoxia)
- dysregluation of blood brain barrier
Cerebral oedema is quite a common secondary injury following a brain injury. What is it?
excess fluid in the brain leading to swelling of the brain and inter cranial pressure.
What are the two types of cerebral oedema?
- vasogenic
2. cytotoxic
What is vasogenic oedema?
occurs when damage to the brain leads to increased extracellular fluid
What is cytotoxic oedema?
Occurs when a brain cell membrane pump fails, leading to increased intracellular fluid
What might happen in cerebral oedema surgery to reduce fluid?
part of the skull is removed
When a cell dies, there are two types of process that occur, necrosis and apoptosis. What are these two things?
necrosis: passive death of cells as a result of damage
apoptosis: programmed death that occurs when cell is damage
What is the apoptotic process (active self destruction)?
- the cell shrinks
- material is divided into vesicles
- scavenger cells clean up the debris
What are three indicators of severity in traumatic brain injury?
- length of loss of consciousness
- depth of coma, measured by Glasgow coma scale
- length of post traumatic amnesia
Why is length of consciousness hard to measure?
What is consciousness? When is someone conscious or not?
What is considered a mild score on Glasgow’s coma scale?
14-15
What is considered a moderate score on Glasgow’s coma scale?
9-13
What is considered a severe score on Glasgow’s coma scale?
3-8
What is post traumatic amnesia?
period of time following a brain injury which the person is incapable of learning new information, remains confused and disorientated
What are some limitations of assessing TBI severity?
- time of assessment (GCS)
- reliability of information
- medical interventions (painkillers)
- drug/alcohol use
- elderly, dementia?
What are some TBI outcomes?
- cognitive
- behavioural
- psychosocial
- clinical outcomes
TBI can result in increased risk of
- substance abuse
- homelessness
- violence
- relationship breakdowns
- job loss
- social isolation
How do we predict TBI outcomes?
- severity
- performance on neuropsychological measures
- premorbid characteristics
