Week 3: Brain injury Flashcards
What are the two main causes of brain injury?
Cerebrovascular accidents(CVAs)/stroke Traumatic brain injury
What are CVAs categorised into?
- Cerebral blood flow
2. Stroke and related disorders
How much of the bodys oxygen consumption does the brain use?
25%
When oxygen is cut off from the brain, how long does it take for irreversible brain damage to occur?
2-3 minutes
Arteries carry blood…..
Away from the heart to our vital organs
Veins carry blood…..
Back to the heart (deoxygenated)
What 2 pairs of vessels are involved in arterial blood supply to the brain?
- Internal carotid arteries
2. Vertebral arteries
What are the main divisions of the internal carotid arteries?
Middle and anterior cerebral arteries
How is communication between the carotid arteries possible?
There is communication between the anterior cerebral arteries through the anterior communicating artery
Explain the vertebral-basilar system?
The vertebral arteries converge at the pons, turning into the basilar artery
This then splits into the posterior cerebral arteries (PCA)
What are the two main divisions of the vertebral-basilar system?
- basilar artery
- posterior cerebral arteries
What is the circle of willis?
The Circle of Willis is the joining area of several arteries at the bottom (inferior) side of the brain
Explain how we can see both the vertebral-basiliar and carotid system within the circle of willis…
We can see that the vertebral-basilar system joins up with the carotid system via the posterior communication arteries
What are the benefits of the circle of willis?
Allows flow of blood through an alternative route so if a certain artery is blocked or has reduced flow, the other arteries can supply blood to that area
Can also transfer blood to the other side of the brain if needed via the posterior communicating artery
Where does the anterior cerebral artery supply blood to?
The medial (middle) frontal and parietal lobes
Where does the middle cerebral artery supply blood to?
Most of the lateral surface of hemispheres (outsides)
Where does the posterior cerebral artery supply blood to?
Medial (middle) part of the occipital lobes and inferior surface of temporal lobes
What is a CVA?
Cerebral vascular accident - a vascular disorder that results in brain injury
What is ischaemia?
Insufficient or lack of blood supply to the brain
What does ischaemia typically lead to?
Infarction
What is infarction?
Tissue death due to inadequate blood supply
What is an infarct?
An area of damaged or dead tissue from infarction
What is Penumbra?
Tissue surrounding infarct which may recover or die
What is oedema?
Swelling of the brain
What is Exitotoxicity?
Excess activity in glutamate signalling pathways (NMDA receptors) resulting in cell death - toxic chain reaction from neuron to neuron
What are the signs of stroke?
Weakness/numbness/paralysis of the face, arm or leg on one side of the body
Difficulty speaking or understanding
Dizziness/loss of balance/unexplained fall
Loss of vision
Headache
Difficulty swallowing
What is the acronym for checking for stoke?
FAST
Face, Arms, Speech, time(act quickly)- call ambo
What does the size of blood vessel have to do with stroke recovery?
If it occurs in a large artery, then likely to have more devastating consequences
What do the remaining intact vessels have to do with stroke recovery?
If the stroke is restricted to a certain area, sometimes other blood vessels can supply the area
E.g. through anterior and posterior communicating arteries
What are the 2 main types of strokes?
Obstructive (ishaemic)
Haemorrhagic
What is an ishaemic stroke?
Reduction of blood flow or complete blockage of a blood vessel - often due to a fatty plaque
What is a haemorrhagic stroke?
Result from bleeding into brain tissue (rupture of a blood vessel) often due to weakening or malformation of the vessel
(often resulting in permanent brain damage or death)
What is the most common form of stroke?
Obstructive (ishaemic)
What are ishaemic strokes caused by?
- Thrombosis (thrombotic)
Occlusion of blood vessels by a thrombus (clump of cells) often a fatty plaque - Embolism (embolic)
Occlusion of blood vessels by embolism which has broken off of a thrombus in a larger blood vessel somewhere, travelling to the brain
How long does an ischaemic stroke take to develop?
30 minutes to fully develop
What are TIAs?
Transient Ischaemic attacks - common forewarning with ischaemic strokes (occur in 50-80% of cases)
Temporary obstruction of a blood vessel lasting less than 24 hours with many lasting only a few minutes
Precursor to stroke
After an ischaemic stroke, at what point is it unlikely to have little further spontaneous improvement?
3 months
Where do most thrombotic strokes occur?
In the internal carotid or vertebral-basilar arteries
What are the signs of a thrombotic stroke?
Lateralized limb weakness/paralysis and somatosensory changes
Visuospatial (right) and language (left) deficits
What kind of effects do ischaemic strokes have on cognition and behaviour?
Tend to have unilateral effects on function (arterial supply to left or right)
Prominent acute effects that become less prominent overtime (e.g. confusion, due to swelling)
Signs of bilateral or diffuse damage in acute stages, which resolve as brain swelling diminished
What kind of stroke promotes the poorest recovery?
Hemorrhagic
What are some of the unilateral effects of ischaemic strokes?
Hemiparesis: weakness in half of the body (contralateral side)
Hemiplegia: complete paralysis in half of the body
Aphasias (left): expressive and receptive language disorders (returns within 1 month - less than 25% become fluent later if not at one month)
Unilateral neglect (right parietal lobe) - failure to attend to space at the opposite side of the lesion
Unilateral neglect occurs despite any visual problems, this suggests…
Problem with attention
- Can have their attention directed towards something in the neglected area
Does unilateral neglect stick around?
It is often transient, becoming less. and less over time
Within the first months of developing TIAs, how many people have a full-blown stroke?
30%
What are the two different types of TIAs?
Those that cause infarctions that can be seen on CT scans (cerebral infarction with transient signs)
Those that don’t
Do TIAs cause any neuropsychological deficits?
They can bring subtle deficits but these are only apparent under test conditions
E.g. speed of processing, memory etc
What is a hemorrhagic stroke?
When there is a bleed in the brain due to the rupture because of weakening of blood vessels
What are the risk factors for haemorrhagic strokes?
- Hypertension/high blood pressure
- Chronic use of oral anticoagulants (aspirin)
- Cocaine use
- Excessive alcohol use
What are the two primary mechanisms that cause haemorrhagic stroke?
- Weakening of a vessel due to hypertension
2. Rupture associated with a vascular abnormality, such as an aneurysm, arteriovenous malformation (AVM), a tumor
What is an aneurysm?
Weak area in an artery wall, causing it to balloon out
Why do aneurysms occur?
Maybe congenital, be born with it
or it may be due to trauma or infection
There is a higher risk of aneurysm rupture among…
Women and older people
Those with aneurysms that are symptomatic (e.g. bodily pain)
If they are bigger
Basiliar artery aneurysms are more likely to rupture
The rupture of an aneurysm can be accompanied by severe symptoms. What are they?
Severe headache accompanied by nausea and vomiting
Neurological dysfunction
May lose consciousness
Vasospasm - when the bleed forms a clot and when the blood cells break down the nearby arteries may contract and spasm
The rupture of an aneurysm can be immediately…
Fatal
The mortality rate is 50% within the first month of the rupture
Which blood vessels are affected by hypertensive hemorrhage stroke? which parts of the brain are affected because of this
Blood vessels at the base of the cerebral hemisphere
Affects the basal ganglia, thalamus and brain stem
What does AVM stand for?
Arteriovenous malformations
What are AVMs?
Tangled masses of arteries and veins that grow much like a tumour
Are weak and very likely to rupture
How common are AVMs?
Not very common, accounting for only 1% of all strokes
How do you get AVMs?
They are typically congenital, so people are born with them
What is locked in syndrome?
A rare disorder frequently caused by ischaemic or haemorrhagic stroke in the Basilar artery
Where you lose all motor function with the exception of my movements but your cognition and consciousness remain fully intact
What is TBI?
Traumatic brain injury
An insult to the brain caused by external force that may produce diminished or altered states of consciousness resulting in impaired cognitive or physical functioning
What kind of people have the highest TBI rates?
Young adults
More likely to engage in risky activities such as driving substance use or sport
What are the two types of traumatic brain injury
Closed head injury
Penetrative head injury
What is penetrative head injury
The skull is fractured exposing the brain breaking the blood brain barrier and allowing the entry a foreign matter
What is a closed head injury
No insult to the skull
But there has been some kind of blow to the head
For example assaults falls and sports
What cushions the brain?
Cerebrospinal fluid that surrounds the brain and the spinal cord
Acts like a shock absorber but not good when force to the brain is excessive
Brain damage following traumatic brain injury typically occurs in two stages what are these stages?
Primary injury the damage that occurs at the time of impact
Secondary injury the secondary effects of physiological processes initiated by the primary injury
What is a contact force
Where the head is still and receives a blow
- status injury
Rapid inward defamation of the skull with compensatory outward defamation in adjacent areas followed by rebound affects
Results in the compression of the brain tissue and the extension
What are inertial forces?
Movement of the brain within the head as a result of acceleration or movement
What are the three types of inertial forces
Translational
Rotational
Angular
What is translational acceleration
The head moves in a straight line with brain centre of gravity
Eg. Car accident and breaking suddenly. Brain moves within the skull and hits the front of the head
What is rotational acceleration
The brain rotate around the centre of gravity
Eg. Sports type injuries
What is angular acceleration
It is a combination of translational and rotational forces
What are the different types of primary injury
Coup: injury at site of impact
Contre-coup injury: The brain rebounds against opposing side of the skull causing further damage
Diffuse-axonal injury: rapid deceleration forces lead to widespread damage throughout the brain axons get torn twisted and broken
Intracranial haemorrhage: Large blood vessels maybe torn on impact these haemorrhages create haematomas (bruise) within the skull
What are the type of haematomas intracranial haemorrhages cause
Epidural haematoma: between the skull and the dura matter often due to contact injury and most often arterial
Sub dural haematoma: between duramatter and arachnoid membrane produced by torn veins or brain surface on either side of dura
Subarachnoid haematomas: occurs between the arachnoid and the brain itself - often due to cerebral artery aneurysm
What are intracerebral haematomas?
They form within the brain usually occurring in the frontal and temporal lobe‘s but also in the Basal ganglia and cerebellum
Result from rupture of blood vessels in the brain
Associated with diffuse axon also injury’s
When does a delayed traumatic intracerebral haematoma occur
Within 72 hours post injury
What is a burst lobe
A combination of an intracerebral haematoma and a sub dural haematoma
What are some examples of secondary injury following traumatic brain injury
Brain swelling, cell death, elevated intracranial pressure, ischaemia, dysregulation of the blood brain barrier, infection
Cerebral oedema is common following TBI. What are the two types
Vasogenic oedema: occurs when damage to the brain and surrounding membranes leads to increased extracellular fluid (fluid around cells)
Cytotoxic oedema: occurs when neurons membrane pump fails and leads to increased intracellular fluid (allows fluid to rush into the cell, it bursts)
What are the two different processes of cell death
Necrosis: passive death of cells as a result of damage that occurs within hours of injury and leads to inflammation in possible damage to surrounding cells
Apoptosis: programmed death that occurs when cell is damaged (but doesn’t happen quickly) it requires significant resources and may take days no inflammation or damage to surrounding cells
What happens during apoptosis?
The cell shrinks
Material is divided into vesicles (attract clean up cells)
Scavenger cells clean up the debris
What’s three key indicators tell us how severe traumatic brain injury is
The length of the loss of consciousness
The depth of the coma
Length of post traumatic amnesia (PTA)
How do we know the depth of coma
The Glasgow coma scale
Used to assess the level of consciousness at any given time following an injury
Explain more about the post-traumatic amnesia period following traumatic brain injury
The person is incapable of learning new information and remains confused and disoriented
The most common test is the Westmead post-traumatic amnesia scale (orientation questions and memory tasks)
What are some problems that make it hard to estimate the severity of traumatic brain injury
The time of the assessment Reliability of information Medical intervention Drug and alcohol use Are they elderly and can they be impacted by things like dementia
What are some of the cognitive problems that may follow traumatic brain injury
Attention Concentration Speed of information processing Memory Executive function Word finding Speech production
What are some of the emotional and behavioural affects following traumatic brain injury
Lack of emotional control Emotional liability Emotional blunting Lack of emotional awareness Disinhibition Failure to pick up on social cues Lack of insight/awareness Change in sex drive Personality changes
What are some psycho social outcomes following traumatic brain injury
Increased strain on or total breakdown of relationships
Reduced capacity of poor decision-making surrounding work
Withdraw from activities or change in social activities
What are some clinical outcomes following traumatic brain injury
Depression, anxiety, personality disorders, PTSD
Following traumatic brain injury what are people at risk of
Substance abuse, homelessness, violence, relationship breakdown, domestic violence, unemployment, social isolation, reduced capacity for education
What can be seen with concussions
Blackouts, headache, blurry vision, balance problems, altered mood and behaviour
What is the myth surrounding concussion
That you can’t sleep after it
What is post concussion syndrome And what causes it
Where you get constant headaches and learning difficulties it is likely to develop if you return to sport too soon after injury
What are sub concussive impacts
There’s a lower impact jolts to the head there are no noticeable impact straight away but it can lead to severe degenerative brain disease is over time
May lead to chronic traumatic encephalopathy
Chronic traumatic encephalopathy?
Changes in mood and behaviour later in life can result in dementia due to the tau protein
there are damaged microtubules so tau clump together
