Stroke Flashcards
Where is the weakest point of the skull?
The pterion
frontal, sphenoid and parietal bone meets here
thinnest bone
contains anatomical structures such as the middle meningeal artery
How much does the brain weigh?
1.3kg
The brain receives ____% of the cardiac output
15
What are the main parts of the brain?
cerebrum
cerebellum
brainstem
The brain is covered by the meninges. Name them
Dura mater
Arachnoid mater
Pia mater
The first 3 minutes of trauma to the brain are the most significant. What is the consequence if blood flow is not resolved in this time?
permanent brain damage
The cerebrum is divided into…
cerebral hemispheres
Each cerebral hemisphere is divided into 4 lobes. Name them
Frontal lobe
Temporal lobe
Parietal lobe
Occipital lobe
What connects the cerebral hemispheres of the brain?
the corpus callosum
List the sub-cortical structures of the brain
Limbic system- hippocampus, amygdala, olfactory
thalamus (relay centre)
hypothalamus (homeostasis) and pituitary
epithalamus
subthalamus
metathalamus
ventricular system
Any depression in the brain is referred to as …
a sulcus
A raise on the side of each sulcus of the brain is referred to as …
gyrus
What is the function of the central sulcus
separates the frontal lobe from parietal lobe
separates the pre-central gyrus from the post-central gyrus
The pre-central gyrus is known as the …
motor cortex
face, arm, leg and trunk
The post-central gyrus is known as the …
sensory cortex
The sylvian fissure is also known as the …
lateral sulcus
What is the function of the sylvian fissure?
to separate the temporal lobe from the parietal and frontal lobes
Brocas area is involved with…
speech
(excessive speech)
Wernickes area is involved with …
hearing
The prefrontal cortex (gyrus) is involved with …
conscious intellect
personality
Where is brocas area located?
usually located in the dominant hemisphere
the left cerebral hemisphere is usually the dominant hemisphere
What is the supplementary motor area involved with?
head and eye turning
What is the paracentral lobule and what is its function?
continuation of pre and post central gyrus
causes the inhibition of bladder and bowel voiding
What are the components of the frontal lobe?
precentral gyrus
brocas area
supplementaty motor area
prefrontal gyrus
parecentral lobule
What are the components of the temporal lobe?
auditory cortex
middle and inferior temporal gyri
limbic lobe
Visual pathways (optic radiations)
What is the auditory cortex involved in ?
hearing language
hearing sounds, rhythm and music
What are the middle and inferior temporal gyri involved in?
learning
memory
The limbic lobe is linked to …
olfaction
emotion
connects them all
links smells to memory
What are the main parts of the parietal lobe?
postcenrtral gyrus
supramarginal and angular gyri
What is the function of the post central gyrus?
sensory cortex
touch, pressure etc
What is the function of the supramarginal and angular gyri?
wernickes area (hearing, receptive understanding of speech)
ability to construct shapes
numerical skills
optic radiation fibres- deep
The occipital lobe is made up of the visual cortex. What is the function?
perception of vision
Where is the cerebellum located?
located in posterior cranial fossa (formed by the floor of the cranial cavity)
The cerebellum is seperated from the cerebrum by…
the tentorium cerebelli
The cerebellum is made up of 2 hemispheres. What midline structure is present between and connects the two hemispheres?
the vermis
What is the function of the cerebellum?
maintenance of gait
modulation of motor skills
maintenance of balance
What is the function of the brain stem?
connects the brain with the spinal cord
What are the components of the brainstem?
midbrain, pons, medulla oblongata
What is the function of the midbrain?
acts as a conduit for the motor cortex to the rest of the body and carries sensory information to the sensory cortex
What is the function of the brainstem?
sensory and motor functions of face and neck (CN)
breathing, cardiovascular, sleeping and eating
transmission of sensory and motor signal from CNS to the rest of the bod
Where are the cranial nerves located ?
brain
and brainstem
CN2- thalamus (subcorticla structure)
CN3 &4 - midbrain
CN5- pons
CN6,7,9,10,1112- medulla
CN I is the _______ nerve
olfactory nerve
CN II is the ________ nerve
optic nerve
CN III is the _______ nerve
State the muscles it innervates
oculomotor nerve
innervates all oculomotor nerve except lateral rectus and superior oblique muscle
pupillary activity
CN IV is the _______ nerve
State the muscles it innervates
trochlear nerve
innervates the superior oblique muscle
CN V is the _______ nerve
state the muscles it innervates
trigeminal nerve
sensory supply to face
innervates muscle of mastication
CN VI is the _______ nerve
State the muscle it innervates
Abducens nerve
Lateral rectus muscle
CN VII is the _______ nerve
state muscle it innervates
facial
innervates muscles of facial expression
CN VIII is the _______ nerve
vestibulocochlear
hearing
CN IX is the _______ nerve
glossopharyngeal nerve
soft palate sensation
taste of posterior 1/3 of tongue
CN X is the _______ nerve
vagus
swallowing
speech
CN XI is the _______ nerve
State what muscles it innervates
accesory
trapezius and sternocleidomastoid
CN XII is the _______ nerve
State what muscles it innervates
hypoglossal
innervates muscles of the tongue
Where does the dura matter attach itself to?
the calvaria of the bone
Where is CSF found?
subarachnoid space
Anterior circulation to the brain is supplied by the…
internal carotid artery
The internal carotid arises from the ___________
common carotid
What are the 4 divisions of the internal carotid blood vessel?
opthalamic
middle cerebral
anterior cerebral
anterior communicating
Posterior circulation to the brain is provided by the …
vertebrobasilar system
The vertebrobasilar system is comprised of …
Basilar arteries
Vertebral arteries
The vertebral arteries arise from subclavi and fuses to form the basilar arteries
The internal carotid artery supplies what portion of the brain?
the anterior 2/3
The vertebrobasilar system supplies what portion of the brain?
the posterior 1/3
What are the divisions of the vertebrobasilar system?
posterior inferior cerebellar
anterior inferior cerebellar
superior cerebellar
posterior cerebral
posterior communicating
Where is the circle of willis located?
sits beneath the surface of the brain but is attached
What is the circle of willis?
an anatomical structure that provides anastomotic connection between the anterior and posterior circulations
What is the circle of willis comprised of?
2 anterior cerebral arteries (including the anterior communicating artery)
Middle cerebral arteries
the posterior communicating arteries
What is the internal capsule?
it is a white matter structure of the brain
it is where the motor and sensory nerves are packaged
it allows communication between the cerebral cortex and areas of the brain stem
The cerebral veins offer superficial and deep drainage. Where do cerebral veins drain into?
sinuses
Where are the sinuses located?
space between the arachnoid and dura
Where are most cerebral veins located?
between the arachnoid and dura
Dural venous sinuses drain into …
internal jugular vein
An orbital infection can drain into …
the cavernous sinus
What is the function of a neuron?
transmit electrical impulses
What is the function of glial cells?
protect neurons
form myelin (insulation)
supply nutrients to neurons
Give examples of glial supporting cells
astrocyte
oligodendrocyte
ependymal cells
microglia
What are astrocytes?
specialised glial cell
form a protective layer (physical barrier) with processes which attach to blood vessels
the control blood homeostasis and neuronal metabolism
What are microglial cells?
specialised macrophages
offer immune protection within the confines of the brain
What is white matter?
myelinated axons
What is grey matter?
neuronal cell bodies
What is a stroke?
an acute neurological deficit lasting more than 24 hours and caused by cerebrovascular aetiology (vessel in the brain)
What is the main type of stroke ?
Ischaemic stroke (85%)
What are the types of strokes?
ischaemic stroke
haemorrhagic stroke
subarachnoid haemorrhage- little aneurysms
central venous thrombus
vetebral/carotid dissection- this occurs when the vessels split-“hole in the wall” of the vessels
vasculitis (lupus?)
What is an ischaemic stroke?
a stroke that occurs when blood supply in cerebral vascular territory is critically reduced due to occlusion or critical stenosis of a cerebral artery
What are the pathologies of an ischaemic strokes?
thrombotic pathologies- atherosclerosis of cerebral vessels; directly reduces cerebral perfusion
Embolic pathologies- atrial fibrillation, carotid atheroscleosis; leads to cerebral arterial occlusion due to embolism- clot originating from a clot that was formed in an atheroma
Hypoperfusion- e.g. shock leading to global hypoperfusion of the brain- failing heart, failure to pump blood; leading to too little blood in the brain
Sudden stroke onset presents as:
visual loss
weakness
aphasia (speech problems)
impaired co-ordination (ataxia)
The FAST acronym is used to help with the detection of symptoms of a stroke. What does it stand for?
Face drooping
Arm- can they raise arms?
Speech- slurred speech?
Time- time to call 999
What are the risk factors of a stroke?
older age
family history
previous stroke
HTN
smoking
diabetes
atrial fibrillation
carotid artery stenosis
dyslipidaemia
What clinical investigations are used to diagnose an ischaemic stroke?
CT
MRI
What is the management a stroke with a presentation of <4.5 hours with no contraindication to thrombolysis?
altephase (6% risk of intracranial haemorrhage) - thrombolysis
aspirin 24 hours after thrombolysis (300mg)
endovascular treatment (pulling a clot out?)
swallowing assessement- if you cant swallow, you will inhale; puts lungs at risk
VTE prophylaxis - this is a heparin injection
What is alteplase?
biosynthetic form of tissue plasminogen activator (tPA)
plasmin breaks down fibrin clot- fibrinolysis
dissolves clot to restore blood flow to brain
What is a contraindication for alteplase and aspirin use?
risk of haemorrhage
What is a transient ischaemic attack (TIA)?
Transient episode of neurological dysfunction
What is the cause of a TIA?
Caused by ischaemia without infarction
There is cell death in a stroke
same as a stroke but symptoms only last for a short amount of time ?
has the same aetiology as an ischaemic stroke- commonly an embolic body
How long do majority of TIA take to resolv?
1 hour
What is the management for TIAs?
antiplatelet therapy
lipid lowering agent
anti HTN therapy
lifestyle modification
carotid endarterectomy/stent (for cases where there is >50% occlusion of vessel)
What is a haemorrhagic stroke?
this is a disruption to blood flow due to intraparenchymal haemorrhage
- this is where there is bleeding into the functional tissues of the brain
blood flow is interrupted as blood is leaking into parenchymal tissue
thus not enough blood is reaching other parts of the brain
What are the causes of a haemorrhagic stroke ?
cerebrovascular changes- induced by long standing HTN- endothelial injury
amylloid angiopathy - often in elderly patients
Briefly outline the pathophysiology of a haemorrhagic stroke
expanding haematoma (clot) shears neighbouring arteries with leads to further bleeding and clot expansion
clot growth is then halted by haemostasis and increased pressure
haemorrhage may rupture into subarachnoid space or the intraventricular space
there is a high mortality which is a result of direct destruction or compression of critical areas- leads to circulatory arrest
The mortality of a haemorrhagic stroke is increased with intraventricular haemorrhage (hydrocephalus). True or false
true
there is a build up of fluid in the brain
How are haemorrhagic strokes managed?
consider ITU admission
Supportive measures:
-airway protection
-swallow assessment (for lung protection)
-neurological observation
Reversal of coagulopathy - try and promote clotting
blood pressure control
surgery- raised intracranial pressure, hydrocephalus (fluid in brain)
What is the most common cause of a subarachnoid haemorrhage?
intracranial aneurysm (non traumatic- not a result of trauma e.g. hit to head)
What are the symptoms of a subarachnoid haemorrhage ?
classic thunder-clap headache
+/- neurological impairment
nausea
seizures
collapse
How are subarachnoid haemorrhages diagnosed?
head CT
CT angiogram (vessels)
lumbar puncture
What is the pathology of a subarachnoid haemorrhage?
raised ICP
toxic effects of blood on parenchyma
cerebral vessels vasospasm
What is an aneurysm?
dilation of the vessels
bulge in blood vessel caused by weakness in blood vessel wall
What circulatory structure in the brain has an increased risk of developing aneurysms and why?
circle of willis
this is because of the “twists and turns”- structure
How are subarachnoid haemorrhages managed?
admission to neurosurgical unit
secure aneurysm (endovascular treatment IR or surgery)
maintain blood pressure
nimodipine (fast acting calcium channel blockers) 60mg QDS for 21 days; used to control blood pressure
What does the rule of thirds for a subarachnoid haemorrhage refer to?
1/3 die
1/3 have long term disability
1/3 return to normal
What is venous sinus thrombosis?
this is where there is an acute thrombus in dural (dura mater) venous sinuses
What are the symptoms of venous sinus thrombosis?
headache
visual disturbance
+/- weakness
+/- seizures
What are the risk factors for venous sinus thrombosis?
overweight
females on oral contraceptives
How are venous sinus thombi diagnosed?
CT head
CT venogram (veins)
MRI
What is the pathology of venous sinus thrombosis?
congestion of blood leading to reduced blood supply to parenchyma (functional tissue)
cerebral oedema (fluid build up)
raised ICP
What is the management for venous sinus thrombosis?
anticoagulation (heparin then warfarin)
What is a carotid/vertebral dissection?
mainly traumatic injury, can sometimes be spontaneous
this is where the layers of these arteries are spontaneously seperated
this leads to a reduction in blood flow
What are the symptoms of a carotid/vertebral dissection?
headache/neck ache
ischaemic symptoms
How is a carotid/vertebral dissection diagnosed?
CT head/neck
MRI head/neck
What is the pathology for a carotid/vertebral dissection?
haemorrhage in tunica intima (innermost layer of the artery)
leads to an expanding clot in the tunica intima
blood flow is disrupted
turbulent flow in artery can then lead to thrombus/embolism
How is a carotid/vertebral dissection managed?
anticoagulation therapy (heparin then warfarin)
aspirin
angioplast +/- stenting
What are the dental considerations for a stroke?
medications
carers
communication
poor dental hygiene
paralysis of oro-facial muscles- food residues
reduced sensation
How should a stroke be manage in dental surgery?
give oxygen
call 999
