Week Three - Traumatic Brain Injury & Cerebrovascular Disorders Flashcards
The brain represents what % of total body weight?
2%
How much % of normal cardiac output does the brain use?
15%
How much of the body’s oxygen consumption does the brain need?
25%
When oxygen is cut from the brain, how long do we have before irreversible damage occurs?
2-3 minutes
Where do arteries carry blood?
Away from heart to vital organs
Where do veins carry deoxygenated blood?
Back to the heart
What are the two pairs of arterial blood supply?
Internal carotid arteries
Vertebral arteries
What is the advantage of the circle of willis?
if a given artery is blocked, then other arteries can still supply blood to that area
What are the 3 main cerebral arteries in the brain?
Anterior
Posterior
Middle
What does the anterior cerebral artery supply to?
the medial, frontal, and parietal lobe
What does the middle cerebral artery supply to?
Most of the lateral surface of the cerebral hemisphere
What does the posterior cerebral artery supply to?
the medial of the occipital lobe and inferior temporal lobe
What is the circle of willis?
A joining area of several arteries at the bottom side of the brain
What do the posterior communication arteries allow? (2)
Allow joining of vertebral-basilar and carotid system.
Allows transfer of blood to the other side of brain by acting as a route of transmission
What is CVA?
Vascular disorder which results in brain injury
What is Ischaemia
Insufficient/lack of blood flow to the brain
What is Infaction?
Tissue death due to inadequate blood supply
What is Infarct?
Area of damaged or dead tissue from infarction
What is Penumbra?
Tissue surrounding infarct which may recover/die
What is Excitotoxicity?
Excess activity in glutamate signalling pathways resulting in death
What is Oedema?
Swelling of the brain
What are some signs of stroke?
weakness, numbness, paralyses
difficulty speaking
dizziness/balance issues
loss of vision
What are 5 factors involved in stroke recovery?
The type of stroke Size of blood vessel (larger = worse) Remaining intact vessels (can help with supply) Premorbid factors Location of stroke
What are the 2 main types of stroke?
Obstructive Stroke (ischaemic) Haemorrhagic Stroke
What is an Obstructive (ischaemic) stroke?
Where there is a reduction of blood flow or complete blockage of a blood vessel
Often due to fatty plaques
What is an Hemorrhagic stroke?
Results from bleeding into brain tissue (rupture of blood vessel)
Often due to weakening malformation in vessel wall (aneurysm)
What are Obstructive (ischaemic) stroke caused by? (2)
- Thrombosis (occlusion of blood vessel by a thrombosis)
2. Embolism (occlusion of blood vessel by embolism which has broken off from a thrombosis in a larger blood vessel)
How long does an obstructive stroke take to develop?
Can occur suddenly, often taking 30 min to full develop
what % show sig improvement in functioning following an OIS?
80%
What % remain significantly disabled?
50%
After an OIS, at what point are we unlikely to have further improvement?
3 months
Where do most Thrombotic strokes occur?
In the internal carotid or vertebral-basilar arteries
What are the signs of Thrombotic stroke?
Lateralised limb weakness and somatosensory changes as well as visuospatial (right) and language deficits (left)
What effect do OIS strokes have on cog and behavioural factors?
Unilateral effects on function
Prominent acte effects (but become less prominent over time)
Signs of bilateral or diffuse damage in acute stages
What are the unilateral effects in OIS?
Hemiparesis: weakness in vertical half of body
Hemiplegia: complete paralysis of vertical half of body
Aphasias: language disorder
Unilateral neglect (often right): failure to attend to space at the opposite side of lesions
often transient
What is a TIA
An episode of temporary obstruction of a blood vessel lasting less than 24 hrs
What are the two types of TIAs?
Those lasting >45 and show infarction
Those lasting <45 with no evidence of infarction
What % of people will develop a full-blown stroke following a TIA?
30%
What % of people will die following a Hemorrhagic stroke?
35-52% within the first 30 days
Risk factors for Hemorrhagic stroke?
Hypertension/blood pressure (chief risk factor)
Chronic use of oral anticoagulants
Cocaine/alcohol use
What are the two primary mechanisms that cause arterial haemorrhage?
- Weakening of a vessel due to pathological aberrations secondary to hypertension (77-88% of cases)
- Rupture associated with a vascular abnormality, such as aneurysm, AVM, tumour etc
What is an aneurysm?
Weak area in an artery wall, causing it to balloon out
Why do aneurysms occur?
May be due to:
- congenital
- born with it
- trauma/infection
The risk of having a ruptured aneurysm is more dependent on what?
The characteristics of the aneurysm as opposed to characteristics of the person
Who are some people that have an increases risk of a ruptured artery?
Women and older people
What two types of aneurysms increase the risk factor of a ruptured artery?
symptomatic aneurysm
basilar artery aneurysm
Symptoms of ruptured aneurysm?
Severe headache (nausea/vomiting)
The rupture of an aneurysm can be what?
Fatal with a 50% mortality rate in the first month
Which blood vessels/brain areas are affected by hypertensive haemorrhages?
Blood vessels at the base of the cerebral hemisphere
mostly affect thalamus, BG and brainstem
What are AVM’s?
Tangled masses of arteries and veins of congenital origin with grow gradually like a tumour - only 1% of strokes
What is locked in syndrome?
A disorder frequently caused by ischemic or hemorrhagic stroke in the basilar artery
What does locked in syndrome result in?
Loss of all motor function with the exception of eye movement
What are the 2 types of head injury?
Closed head
Penetrative head
What occurs in a Penetrative head injury
The skull is fractured, exposing the brain allowing the entry of foreign matter (eg gun shot)
What is a closed head injury?
Non-penetrative blow to the head (assaults, falls, sorts)
Brain damage in TBI typically occurs in what 2 stages?
Primary injury: Damage occurring at the time of impact
Secondary injury: Secondary effects of physiological processes initiated by the primary injury
What is a predominant cause of damage in statis injuries?
Contact forces (force of impact)
What is a static injury?
Where the head is still and receives a blow. There is an inward deformation of skull with outward deformation in adjected areas
What are inertial forces?
Movement of the brain within the head as a result of acceleration or movement
What are 3 types of inertial forces?
Translational: head moves in straight line with brain centre of gravity
Rotational: Brain rotates around centre of gravity
Angular: combination of translational and rotational forces)
What can we categorise primary injuries as? (4)
Coup: site of initial impact
Contre-Coup: brain rebounds causing further damage
Diffuse Axonal: deceleration leading to damage (axons get torn, twisted and broken)
Intra-cranial Haemorrhage: torn blood vessels resulting in haematomas (epidural and subdural)
What 3 haematomas are caused by intracranial haemorrhages?
epidural (EDH): between skull and dura matter, often due to contact injury
subdural (SDH): between dura matter and arachnoid membrane, often due to torn veins
intracerebral (ICH): frontal and temporal lobes (BG and cerebellum, often due to rupture of blood vessel
What are some secondary changes following primary injury?
swelling cell death ICP hypoxia BBB issues infection
Cerebral oedema types (2)
- Vasogenic: when damage to the brain leads to EXTRACELLULAR fluid
- Cytotoxic: when a neuron’s membrane pump fails, leading to increase INTRACELLULAR fluid
What 2 processes occur when a cell dies?
Necrosis: passive death as a result of damage, within hours of injury. Leading to damage of surrounding cells
Apoptosis: programmed death as a result of damage, may take days. No damage to surrounding cells
What are the 3 apoptotic stages?
- Cell shrinks
- Material is divided into vesicles
- Scavenger cells cleans up the debris
What are the 3 indicators to how severe an injury is?
Loss of consciousness
Depth of coma (GCS)
Length of PTA
What is post traumatic amnesia (PTA)?
A period of time following TBI in which the person is incapable of learning new information (remains confused/disoriented)
What are some problems with estimating severity of TBI? (5)
time of assessment reliability of information med interventions drug/alcohol use elderly
Physiological problems following TBI? 5
headaches fatigue dizziness nausea visual/auditory impairment
Cognitive problems following TBI? 4
Attention/concentration
Processing speed
Memory
EF
Emotional/behavioural problems following TBI? (5 - emotion)
lack of emotional control emotional lability emotional blunting lack of emotional awareness disinhibition
Psychosocial problems following TBI?
relationships - increased strain
work - reduced capacity
social activity
Clinical problems following TBI?
depression
anxiety
PD
PTSD
How do we predict outcomes of TBI? 3
severity
performance on measures
premorbid characteristics
