Vascular disturbances Flashcards
How much of the telencephalon and diencephalon are supplied by the a) internal carotids; b) vertebral arteries
- 80% from internal carotids
* 20% from vertebral arteries
don’t forget to revise the blood supply to the brain images
don’t forget to revise the blood supply to the brain images
don’t forget to revise the venous drainage of the brain images
don’t forget to revise the venous drainage of the brain images
What is cerebrovascular disease?
- pathology affecting blood vessels (mostly arteries)
* common cause of neurological disease in Western countries
What are the consequences of ophthalmic artery lesion?
ipsilateral mono-ocular vision loss
What are the consequences of anterior cerebral artery lesion?
producing contralateral weakness and sensory loss primarily in the leg
What are the consequences of middle cerebral artery lesion?
- contralateral weakness and sensory loss most in face and arm and bit to leg
- contralateral homonymous hemianopia
- aphasia
What are the clinical features of lesions of the carotid arterial system?
Combinations of: • hemiparesis • hemisensory deficit • monocular visual loss • homonymous hemianopia • aphasia
What are the consequences of lesions of the branches to the brain stem?
- loss of brain stem function
- cranial nerve abnormalities
- maybe hemiparesis and hemisensory deficits
What are the consequences of lesions of the branches to the cerebellum?
ataxia and disequilibrium
What are the consequences of lesions to the posterior cerebral artery?
unilateral or bilateral hemianopia
What are the clinical features of lesions of the vertebra-basilar arterial system?
Combinations of: • diplopia • dysarthria • dysphasia • disequilibrium • hemiparesis • hemisensory deficit • homonymous hemianopia
What is a cerebrovascular accident?
- CVA
- common
- clinical manifestation of cerebrovascular disease
- sudden, non-convulsive focal neurological deficit
- minimal or severe symptoms
What is a stroke?
- broad term for cerebrovascular accident
* refers to both ischemic and hemorrhagic lesions
What is a cerebral infarct?
area of necrosis within the brain due to vascular occlusion
What are transient ischaemic attacks?
- TIA
- sudden focal neurological dysfunction, followed by complete recovery (in 5-30min)
- no infarction, no permanent
• emboli obstructs then breaks up prior to neural damage
What is global hypoxic ischaemic encephelopathy?
- generalised reduction in blood flow to brain
- gradual loss of cerebral activity
- blunted intellectual function
- motor deficits
- increasing dementia
- bilateral tract symptoms
- especially bulbar palsy
- dysarthria
- dysphagia
List the causes of ischaemic cerebrovascular disease?
- atherosclerosis
- thrombosis
- collagen diseases and vasculitis
- embolism
- systemic hypotension
What is the most important disease process responsible for thromboembolism?
atherosclerosis
What are causes of thrombosis?
- vasculitis
- meningitis
- encephalitis
- periarteritis nodosa
- polycythemia
- dehydration
- mechanical obstruction by masses
What vessels are mostly affected by thrombosis?
- cervical portion of carotid
- cerebral
- basilar
- vertebral aa.
- watershed area between anterior and middle cerebral artery
- middle cerebral artery
Where are embolisms from? where do they mostly occlude?
- heart (valvular lesion, arrhythmias, bacterial endocarditis)
- aorta, carotid vessels
• occlude middle cerebral artery
What is systemic hypotension?
- haemodynamic failure of circulatory system
* causes diffuse ischaemia and infarction (anoxic encephalopathy)
What is the biggest risk factor for hemorrhagic cerebrovascular disease?
hypertension
What are the predisposing factors of ischaemic cerebrovascular disease?
- age > 40yrs
- diabetes mellitus
- hypertension
- cigarette smoking
- medication
- obesity
- oral contraceptives
- chronic heart failure (by embolus and thrombus)
- hyperhomocysteinaemia
- atrial fibrilation
- polycythaemia and thrombocythaemia
- bleeding tendency
- illicit drug use
What is a lacunar infarct?
- “micro-infarct”
- < 1cm diameter
- due to thickening of vessel wall (from smoking, diabetes mellitus, hypertension)
- usually in pons, basal ganglia, internal capsule
What mechanisms cause a thrombus?
- changes to vessel wall
- turbulent blood flow
- change in blood constituents
List the causes of ischaemic strokes?
- thrombosis
- embolism
- vasculitis
- occasionally trauma
What are the stages of development of a cerebral infarct?
1) Acute
• architecture preserves, softening, discolouration
2) Organising
• day 3, parenchyma soft and friable, architecture lost
3) Remote
• cystic lesion, gliosis at periphery
What artery is involved in a patient with hemiplegia of face, arm and leg on one side, dysphasia?
branch of the middle cerebral artery
What artery is involved in a patient with hemiplegia (leg more than arm), apraxia, motor dysphasia, disturbance in micturition?
branch of the anterior cerebral artery
What artery is involved in a patient with contralateral homonymous hemianopia and occasionally diffuse burning pain on one side of body?
branch of contralateral posterior cerebral artery
What artery is involved in a patient with severe headaches, vertigo, ataxia, vomiting, diplopia, nystagmus?
vascular lesion in brain stem
List the haemorrhage cerebrovascular diseases?
- subarachnoid
- intracerebral
- epidural
- subdural
List the causes of hemorrhagic cerebrovascular diseases?
- hypertension (#1)
- intracranial arterial aneurysms
- coagulation disorders
- vascular malformations
- anticoagulant meds
- illicit substance abuse
What are the effects of hypertension on the cerebral circulation?
- acceleration of atherosclerosis
- weakening of blood vessel walls
- reductio of blood flow
- formation of micro aneurysms
- if malignant hypertension - dilated segments of intracranial blood vessels with loss of endothelial integrity -> leak of proteinaceous fluid +/- abc out of vessels -> oedema in brain
Where are intracranial arterial aneurysms mostly located?
- bifurcation of vessels
- anterior half of Circle of Willis
- internal carotid / post. communicating artery junction
- anterior cerebral and ant. communicating artery junction
- middle cerebral artery junction
What is the aetiology of intracranial aneurysms?
- congenital (berry)
- mycotic (from bacterial)
- atheroma
- hypertension
- associated with polycystic disease of kidneys
What is the pathogenesis of intracranial arterial aneurysms?
- ballooning of intima + defect in medial and internal elastic lamina
- 1mm to 10mm
What are the clinical features of intracranial arterial aneurysms?
- asymptomatic prior to rupture
- maybe headache on effort
- may cause pressure on cranial nerves 3-6
- if rupture -> subarachnoid haemorrhage
List the vascular malformations that may cause intracranial arterial aneurysms?
- arteriovenous malformations
- cavernous haemangioma
- capillary telangiectasia
- venous angioma
What is arteriovenous malformation?
- developmental abnormality
- often in young
- defective communication btw arteries, capillaries and veins with dilation of one or more vascular elements
- forms tortuous meshwork
- produce chronic ischaemic state
List the types of haemorrhagic stroke?
- intracerebral
- sub-arachnoid
- sub-dural
- epidural
What is an intracerebal haemorrhage?
- blood accumulation within substance of the brain
- focal mass lesion
- acts as space occupying lesion
- if clots -> intracerebral hematoma
- massive or small
- if smaller: steady progression of symptoms
Compare a massive hemorrhage to a smaller hemorrhage?
Massive:
• rupture into ventricles
• rapidly fatal
Smaller:
• causes headache of increasing intensity, vomiting, mental confusion, convulsion, impairment of consciousness, focal signs
• presents abruptly
• brought on by physical exertion
What is a subarachnoid haemorrhage?
- occurring in sub-arachnoid space
- # 1 cause is rupture of cerebral artery aneurysm
- sudden extreme headache, starting at back of skull
- neck rigidity, fever
- mostly in 20-40yr olds
What are the causes of meningitis?
- bacterial meningococcal meningitis
- subarachnoid bleed
- supratentorium tumour
What is a sub-dural haemorrhage?
- blood btw dura and arachnoid
- acute or chronic
- often from head injury
- often extensive because of loose attachment to membranes
- often with subarachnoid hemorrhage and contusions
- blood clot increases in size by osmosis (because greater density than CSF)
- raises ICP
Why is atherosclerosis a risk factor for thrombotic stroke?
- platelets can bind on atherosclerotic plaque and block flow
- thromboembolic stroke: a piece of plaque can break free and travel until blocks smaller artery
- VBI: narrowed vessels mean not enough flow
- TIA: emboli breaks down in under 30min
What is a lacunar infarct?
- occlusion of a single small perforating artery
- effects deep cerebral white mater, basal ganglia or pons
- small area of necrosis
What is the relationship between hypertension and haemorrhage stroke?
- acceleration of atherosclerosis (hard risk factor)
- weakening of blood vessel walls
- formation of micro-aneurysms (may rupture)
- reduction of blood flow
- if malignant hypertension (dilated segments of intracranial blood vessels with loss of endothelial integrity -> leak of proteinaceous fluid +/- RBC out of vessels -> oedema in brain
What is an example of vasogenic oedema?
when malignant hypertension causes dilated segments of intracranial blood vessels with loss of endothelial integrity -> leak of proteinaceous fluid +/- RBC out of vessels -> oedema in brain
What is the relationship btw aneurysms and haemorrhage stroke?
- aneurysms are at risk of rupturing
- atherosclerosis weakens walls
- wall weakening
- aneurysm is weakest point that rupture if stressed
What changes occurring in the blood vessel are associated with aneurysm formation?
wall weakness or destruction
What are the risk factors for a stroke?
Uncontrollable:
• family Hx, od age, male
Atherosclerosis factors: • hypertension (#1) • smoking • diabetes mellitus • high blood cholesterol • obesity • increased age
What is the pathophysiological basis for right sided weakness in a patient that had a stroke?
left cerebral hemisphere lost blood supply
What is the pathophysiological basis for slurred speech in a patient that had a stroke?
middle cerebral artery occlusion -> brocas or wernickes areas
