Cerebral Vasculature Flashcards
Why is the brain so vulnerable?
Very vulnerable if blood supply is impaired because it is so metabolically active
What three arteries supply the brain?
Common carotid
Internal carotid
Vertebral artery
What is the benefit of the arrangement of the circle of willis?
If you have a blockage in one of the internal carotids e.g. atherosclerotic build up
Chance of compensatory flow from the other side
How does blood exit the cranial cavity?
Cerebral vains
Venous sinuses in the dura mater
Internal jugular vein
What are the layers of the brain?
Dura mater
(Inner meningeal layer and Outer periosteal layer)
Arachnoid mater
Pia mater
Is there any extradural space?
No space between the skull and the dura mater
What are the 4 types of haemorrhage?
Extradural
Subdural
Subarachnoid
Intracerebral
What are main features of extradural haemorrhage?
trauma, immediate clinical effects (arterial, high pressure)
Can strip dura away from the skull
Raised ICP
Some pts might have a lucid interval
What does a fracture to the pterion result in?
Main artery supplying the dura (middle meningeal artery) is behind the pterion
Rupture of this artery causes a extradural haemorrhage
What are main features of subdural haemorrhage?
trauma, can be delayed clinical effects (venous, lower pressure)
which is why patients are often kept overnight after a head injury
high impact injuries
Cresenteric collection on CT
If large enough can cause midline shift or herniation
What are main features of subarachnoid haemorrhage?
Ruptured aneurysms (congenital) Weaknesses in the blood vessel walls that burst and cause subarachnoid bleeds
What are main features of subarachnoid haemorrhage?
Spontaneous hypertensive
What is a CVA?
Cerebrovascualr accident (stroke)
What is the definition of a CVA?
rapidly developing focal disturbance of brain function of presumed vascular origin and of >24 hours duration
What are the two types of stroke?
Thrombo-embolic (85%)
- Ischaemic, blockage stops blood flow
- AF is common cause of emboli formation
Haemorrhagic (15%)
- Vessel bursts
- Intracerebral or Subarachnoid
What is a TIA?
Transient ischaemic attack
What is the definition of a TIA?
rapidly developing focal disturbance of brain function of presumed vascular origin that resolves completely within 24 hours
can last seconds/minutes
What is an infarct?
Degenerative changes which occur in tissue following occlusion of an artery
What is cerebral ischaemia?
Lack of sufficient blood supply to nervous tissue resulting in permanent damage if blood flow is not restored quickly
What does thrombosis mean?
formation of a blood clot (thrombus) causing a blockage
What does embolism mean?
plugging of small vessel by material carried from larger vessel e.g. thrombi from the heart or atherosclerotic debris from the internal carotid
What are the risk factors for stroke?
Age Hypertension Cardiac disease Smoking Diabetes mellitus
Haemorrhagic
- Anti-coag
- AV malformation
What are the three main cerebral arteries?
Anterior
Middle
Posterior
Which cerebral has the biggest perfusion field?
Middle cerebral artery
It also supplies many of the subcortical, deep structures of the brain
What does the anterior cerebral artery supply?
Midline structures
Perfuses all the way back to the parietal-occipital fissure
What does the posterior cerebral artery supply?
Inferior part of the temporal lobe
Occipital lobe
What are the anterior cerebral artery symptoms?
Paralysis of contralateral structures (leg > arm, face)
Disturbance of intellect, executive function and judgement (abulia)
Loss of appropriate social behaviour
What are the middle cerebral artery symptoms?
Classic stroke”
Contralateral hemiplegia: arm > leg
Contralateral hemisensory deficits
Hemianopia (loss of one side of the visual field)
Aphasia (L sided lesion)
What are the posterior cerebral artery symptoms?
Visual deficits
homonymous hemianopia
visual agnosia
How would atherosclerosis look on a specimen?
yellow discolouration in the walls of the vessels is a build-up of atheroma, fatty deposits that cause atherosclerosis or “hardening of the arteries”
How does fresh blood present on a CT scan?
White lesions
How does blood that has become a haematoma present (after time has passed)?
Black lesions
What are some RFs for subdural haematoma?
Old age
Alcoholism
What are symptoms of raised ICP?
Throbbing Headache worse when coughing, sneezing and in the morning Blurred vision (Papillodema) Feeling less alert than usual Vomiting Changes in behaviour Weakness Fatigue Irritability
What is the treatment for a subdural haematoma < 10mm in size, non-expansile without significant dysfunction?
Observation + follow up imaging Prophylactic anti-epileptics for 7 days e.g. phenytoin Correct coagulopathy Raise head of bed
What is the treatment for a subdural haematoma < 10mm in size or expansile or with significant dysfunction?
Surgery first line - Burr-hole craniotomy - Trauma craniotomy - Hemicraniotomy In addition to above
What investigations are done for a head injury?
Head CT within 1 hour if any of the following present:
GCS < 13 initially GCS < 15 at 2 hrs after injury Suspected skull fracture Post-trauma seizure Focal neurological deficit <1 episodes of vomiting
CT within 8 hours if no but on anti-coag OR loss of consciousness/amnesia + RFs
- > 65 yrs
- history of bleeding disorder
- trauma
- > 30 mins retrograde amnesia of events preceding injury
What can cause raised ICP?
Severe head injury Stroke Brain abscess Meningtis/Encephalitis Hydrocephalus AV malformation/fistula Venous sinus thrombosis
What is idiopathic IH?
Intracranial hypertension in women in their 20s/30s
Associated with: Overweight Endocrine problems Abs, steroids, COCP Anaemia or polycythaemia CKD Lupus
What investigations are done for raised ICP?
CT or MRI
Lumbar puncture
What is the medical treatment of idiopathic IH?
Weight loss Stop medications Diuretics Steroids for headaches and reduce risk of vision loss Regular LPs
What is the surgical treatment of idiopathic IH?
Shunt
Optic nerve sheath fenestration
When do you monitor ICP?
Pts with head injury:
+GCS 3-8 and abnormal CT scan
OR
Normal CT but 2 of the following
40+ yrs
Motor posturing
SBP <90mmHg
What is the gold standard for monitoring ICP?
Intraventricular fluid filled catheter transducer systems
What is the treatment for raised ICP?
CSF drainage
Head of bed elevation
Analgesia
Diuretics
What are causes of spontaneous SAH?
Intracranial aneurysm
Arteriovenous malformation
Pituitary apoplexy
Arterial dissection
What are some conditions associated with berry aneurysms?
adult polycystic kidney disease, Ehlers-Danlos syndrome and coarctation of the aorta
What are the classic presenting features of a SAH?
Headache: sudden-onset (‘thunderclap’ or ‘baseball bat’), severe and occipital
N+V
Meningism
Coma
Seizures
Sudden death
ECG changes including ST elevation may be seen
How do you diagnose SAH?
CT head - bright
LP - min 12 hours post symptoms onset, xanthochromia seen
What is the management of SAH?
Neurosurgery referral ASAP after confirmation
Treatment depends on cause
Intracranial aneurysms - Coil, some require craniotomy + clipping
Hydrocephalus - External ventricular drain
What symptoms are more likely in haemorrhagic strokes?
Decreased level of consciousness
Headache
N+V
Seizures
What is the FAST campaign?
Face - ‘Has their face fallen on one side? Can they smile?’
Arms - ‘Can they raise both arms and keep them there?’
Speech - ‘Is their speech slurred?’
Ttime - ‘Time to call 999 if you see any single one of these signs.’
What investigations are done for suspected stroke?
CT
MRI
Urgently
How do you manage ischaemic strokes?
Thrombolysis if
- pt presents within 4.5 hours of symptom onset
- pt has not had prev intracranial haemorrhage or uncontrolled hypertension
Exclude haemorrhagic ASAP and start 300mg asprin
What is treatment for a TIA?
Immediate antithrombotic therapy - Clopidogrel for secondary prevention OR Asprin 75mg
If pt has had TIA in the past 7 days or more than one:
arrange to be seen by stroke specialist urgently
Statin e.g. Atorvastatin
Consider anti-coag for AF e.g. LMWH
Carotid doppler
What is the management of haemorrhagic strokes?
Most pts not suitable for surgery Supportive Stop anti-coagulants Lower BP Early mobilisation
How do you assess storke?
ROSIER score >0 means stroke is likely
-1: Syncope and Seizure
+1: Asymmetric facial weakness, arm weakness, leg weakness, speech disturbance or visual field defect
What are possible features of TIAs?
unilateral weakness or sensory loss. aphasia or dysarthria ataxia, vertigo, or loss of balance visual problems sudden transient loss of vision in one eye (amaurosis fugax) diplopia homonymous hemianopia
