Circulation of the brain Flashcards
Brain blood supply
2 vertebral arteries
2 internal carotid artieries
ensures continuous supply of nutrients
removal of waste
internal carotid
in front of neck and divides to form middle and anterior cerebral arteries
ACA
2 anterior cerebral arteries join via the anterior communication artery forming the front section of circle of willis
Vertebral
2 vertabral arteries pass uo through the formaina in transverse process of Cx vertabrae and join infront of the brainstem at the basilar artery
Upper brain stem
basilar artery divides into 2 posterior cerebral arteries that connect to back of circle of willis by 2 small posterior communicating arteries
Circle of willis
occlusion of one internal carotid artery may not result in stroke because brain is protected from bilateral carotid occlusion through basilar supply
Middle cerebral artery
Most of the outer surface Sensorimotor cortex Basal ganglia Internal capsule Broca’s area (on left)
Anterior cerebral artery
Frontal lobe
Medial part of sensorimotor cortex
Posterior cerebral artery
Occipital lobe
Medial aspect of temporal lobe
Thalamus
Basilar artery
All of the brainstem
Cerebellum
Nuclei of cranial nerves
Disruption to blood supply
loss of consciousness within seconds
irreversible damage in minutes
Autoregulation
mean arterial bp of 60-150mmHg
BP
constriction or dilation of arterioles in brain
increase in CO2
dilation of arterioles in brain
decrease in O2
constriction of arterioles in brain
Causes of Autoregulation faliure
CNS disease: Trauma Acute stroke Tumours Inflammation
Stroke/CVA
brain attack
A stroke, also known as a cerebrovascular accident (CVA), is the rapid loss of brain function(s) due to disturbance in the blood supply to the brain. This can be due to ischemia (lack of blood flow) caused by blockage (thrombosis, arterial embolism), or a haemorrhage (leakage of blood).
Classification
Haemorrhagic stroke
Ischaemia stroke
Haemorrhagic stroke
bleeding from a cerebral artery
Subarachniod haemorrhage
bleeding into subarachnoid space
due to rupture of congenital anerysm or traume
sudden intense headache, vomiting, neck stiffness and loss of consciousness
10% die within two hours
40% die within two weeks
Aneurysm
saccular
fusiform
ruptured
treated by surgical clipping
Intracerebral haemorhage
bleeding in deeper part of brain longstanding hypertension arterial wall weaken micro-aneurysm develop rupture and bleed sever headache and vomitting
Ischaemic stroke
80% strokes due to occulsion
atherom of cerecral artery
emboli from atheromatous plaque in hear/neck vessel
Most common vessel: MCA > PCA > ACA
brainstem stroke less common but more serious
Embolic stroke
completed stroke -sudden onset
transiet ischaemic attack
repeated small emboli no infraction occurs
piece of plaque can break free and clock blood supply to the brain
artrial fibrilation
Atrial fibrillation is irregular heartbeat,blood clots are more likely to form in your heart, increasing stroke risk
thrombotic stroke
completed stroke-overnight develops over several days transient ischaemic attack sudden to full recovery 20% risk of full CVA with 4 weeks
Bamford classification
TACS – Total anterior circulation stroke
PACS – Partial anterior circulation stroke
POCS– Posterior circulation stroke
LACS – Lacunar stroke(deep penetrating arteries)
(TAC)S=stroke
(TAC)I=infarct
(TAC)H=haemorrhage
Tramatic brain injury
injury to the brain caused by external physical force,
altered state of consciousness
impairment of cognitive or physical abilities
disturbances of behaviour or emotional functioning
temporary or permanent
Mechanism of injury
Penetrating injury-risk of infection
Compression - inner cerebral traume
Deceleration- outer cerebral injury discrete cognitive deficit
Diffuse axonal injury– poor communication between brain structures, reduces processing speed, global impairment
Extradural haemorrhage
bleeding into extradural space
cause by severe trauma
sunadural haemorrhage
bleeding in subdural space
usually cause by severe trauma
maybe be delayed symptons
headache drowsiness stupor hemiparesis coma
Secondary damage of TBI
raised ICP infection ischaemic changes vasospasm complication of systemic dysfunction
Transient ischaemic attack TIA
A TIA is a sign that part of the brain is not getting enough blood, and there is a risk of a more serious stroke in future
Hemiplegia
paralysis at one side of the body
Clinical features of stroke
MOTOR
Alterations in tone
Low tone - flaccidity
High tone – spasticity
Ataxia Weakness Asymmetry Loss of normal movement patterns Loss of postural adjustments loss of balance Compensations
Pattern of spasticity
Flexor pattern in upper limb Shoulder elevation & retraction Internal rotation & adduction Elbow flexion & pronation Wrist flexion Finger flexion
Extensor pattern in lower limb Hip retraction Hip extension Knee extension Ankle plantarflexion & inversion
Clinical features of stroke
SENSORY
impaired cutaneous sensation
stereognosis
proprioceptive impairment
visual problems
Visual field loss
Homonymous Hemianopia
Clinical features of stroke
SPEECH
Expressive dysphasia
Damage to Brocas area
Usually associated with Rt hemiplegia
Loose ability to produce speech
Receptive dysphasia
Damage to Wernikes area in temporal lobe
Lose ability to understand speech
global aphasia
Clinical features of stroke
COGNITIVE
Perceptual Problems
Astereognosis Visual Agnosia Auditory Agnosia Depth perception Apraxia Anosagnosia Inattention/neglect
Agnosia
Inability to recognise objects
Neglet
more common with left hemiplegia
patients fails to attend to stimuli from the left side
poor prognosis if persists
results in many functional problems
Clinical features of stroke
Disorders of emotion Dysphagia Delay / absent swallow reflex Incontinence Secondary musculoskeletal problems Balance / Gait problems Functional difficulties Social problems
Physiotherapy treatment
prevent complications,
minimise impairments and to maximise function
Assessment Identification of problems Clinical reasoning Goal setting Objective outcomes Choice of Rx method Interdisciplinary input
Factors affecting recovery
Extent and nature of lesion Integrity of collateral circulation Pre-morbid status Age Capacity of Nervous System to re-organise Environment Motivation and Attitude of patient Patient participation Patient Experience Co-exisiting conditions Nutrition/Hydration Medication
Medical management
Treat as medical emergency MRI/CT scan Ischaemic stroke (80%)– aspirin, anticoagulants - thrombolysis SAH – surgery or endoplastic procedures SDH/EDH/ICH – treat hypertension TIA – aspirin, prevention work Other tests – Blood tests, angiography, echocardiology Other medication – osmotic agents Surgery – carotid endarterectomy
National Stroke startergy
Treat Stroke as a medical emergency
Effective assessment and treatment of vascular risk factors
TIAs assessed and scanned within 24hrs
Suspected stroke transferred to specialist stroke unit with MDT treatment and assessment
Range of services available locally to support long-term needs
Opportunity to return to work
