Blood Supply and Stroke Flashcards
Describe features of the vertebral artery
- First branch of the first part of the subclavian artery which ascends in the foramina in transverse processes of the upper 6 cervical vertebrae and enters the skull through foramen magnum and pierces the meninges to enter subarachnoid space.
Describe features of the basilar artery
It is formed by the union of both vertebral arteries at the pontomedullary junction. It then ascends to anterior pons and terminates as bifurcation into posterior cerebral arteries.
What are the branches of the basilar artery? what do they supply?
- Anterior inferior cerebellar artery, labrinthine artery, pontine arteries and superior cerebellar artery. These arteries wrap posteriorly to supply the cerebellum
Describe features of the internal carotid artery
- Passes into the skull via carotid canal in the temporal bone, passes through the cavernous sinus and perforates dura mater at the anterior clinoid process and enters the subarachnoid space. It divides into anterior and middle cerebral arteries and gives off posterior communicating artery.
What are the different segments of the internal carotid artery?
C1 - Cervical segment.
C2 - Petrous segment.
C3 - Lacerum segment (it doesn’t ravel through but travels above).
C4 - Cavernous segment (when its passing through the cavernous sinus)
C5 - Clinoid segment (peirces dura mater)
C6 - Ophthalmic segment.
- Communicating segment (origin of posterior communicating artery
What is the anterior and posterior supply of the circle of willis?
Anterior supply - Internal carotids become the middle cerebral artery and the anterior cerebral artery.
Posterior supply - Vertebral arteries become the basilar artery which bifurcates as the posterior cerebral artery. Add uncovered pic
What is the function of the posterior/anterior communicating arteries
Posterior - connects anterior and posterior supply of the circle of willis.
Anterior - Connects the anterior cerebral arteries.
What can occur if there is an aneurism of the PCA?
It can compress the 3rd cranial nerve which can lead to a palsy
What arteries supply the areas of the brain?
What cause a rise in intracranial pressure?
Increased CO2 (this leads to vasodilation which will increase pressure), Hypoxia and increased temperature.
Define what a stroke is
A clinical syndrome characterised by sudden onset of rapidly developing focal/global neurological disturbance which least more than 24hours or leads to death.
What is a transient ischaemic attack?
Neurological dysfunction caused by focal brain/spinal cord or retina ischaemia without evidence of acute infarction
What are some of the causes of ischaemic strokes?
Thrombosis, embolism or hypoperfusion (hypoperfusion leads to watershed areas which are between main supply areas which will be affected by hypoperfusion first)
What is the penumbra
Area of ischaemia which is not yet infarcted but will if not perfused quickly
What is a total anterior circulation stroke (TACS)? and what is needed for a diagnosis?
Large cortical stroke affecting areas supplied by middle and anterior cerebral arteries. All three os the following must be present; Unilateral weakness (and/or sensory deficit) of the face arm and leg. Homonymous hemianopia (defect of half of visual field) and higher cerebral dysfunction
What is a partial anterior circulation stroke (PACS)? And what is needed for diagnosis?
Less severe TACS, where only part of the anterior circulation has been compromised. Two of the following must be present; Unilateral weakness (and/or sensory deficit) of the face arm and leg. Homonymous hemianopia (defect of half of visual field) and higher cerebral dysfunction.
What is a posterior circulation syndrome (POCS) and what is needed for a diagnosis?
It is damage to area of the brain supplied by posterior circulation (brainstem or cerebellum.) On of the following must be present; Cranial nerve palsy and contralateral motor/sensory deficit. Bilateral motor/sensory deficit. Conjugate eye movement disorder (inability to move both eyes together). Cerebellar dysfunction or isolated homonymous hemianopia
What is a lacunar stroke and what is needed for a diagnosis?
This is subcortical stroke, there is no loss of higher cerebral functions. One of the following must be present; Pure sensory stroke or pure motor stroke, sensori-motor stroke or ataxic hemiparesis
What occurs in an anterior cerebral artery ischaemic stroke?
There will be contralateral leg weakness and/or sensory loss. Insert pic
How will a middle cerebral artery stroke present?
- Contralateral hemiplegia (arm>leg),
- Cdontralateral hemisensory loss,
- Conjugate eye deviation (looking towards side of lesion)
- Contralateral hemianopia.
- There can be language deficit if on dominant hemisphere (wernikes aphasia or broca’s aphasia),
- can have Hemineglect
What is hemianopia?
Where half of your visual field is lost
How will a posterior cerebral artery stroke present?
- Hemianopia,
- If in dominant hemisphere then can have alexia without agraphia (write but cannot read) and visual agnosia (difficulty naming objects)
- If in non-dominant hemisphere then prosopagnosia (difficulty recognising faces)
- Bilateral cortical blindness
How can a basilar artery occlusion present?
Very rare but can present with quadriplegia, diplopia and bulbar symptoms (facial weakness, dysphagia, dysarthria or dysphonia) Can have locked-in state
What are the stroke mimics?
The 5 ‘S’s;
- Seizures,
- Sepsis,
- Syncope,
- Space occupying lesions,
- Somatisation (phycological)
Describe the appearance of a stroke on ADC-MRI at acute, subacute and chronic stages
Acute - Hypointense,
Subacute - Return to near baseline then hyperintense
Chronic - Hyperintense
Describe the appearance of a stroke on DWI at acute, subacute and chronic stages
Acute - Marked hyperintense,
Subacute - Hyperintense,
Chronic - Hypointense
What is the treatment of an acute stroke?
- Use non-enhanced CT immediately to rule out intracranial haemorrhage.
- Give oxygen therapy and blood sugar control (4-11mmol/L) (also do blood tests so FBC, U+Es and coag screen),
- If ischaemic stroke then can do thrombolysis (Alteplase), thrombectomy (best treatment), theraputic hypothermia, BP control, Aspirin, Antiplatelet/anticoag treatment if complex presentation
What is the secondary prevention for strokes?
- Anti-thrombotics (clopidogrel or aspirin and dipyridamole),
- If in AF then warfarin or DOACs,
- Control BP, want to make sure systolic is <130mmHg. Use CCB, or diuretics or ACE inhibitors
- Control cholesterol with statins if total cholesterol is above 4mmol/L
What is the typical presentation of a subarachnoid haemorrhage
It tends to be described as being hit on the back of the head/worst headaches of life there can also be sudden LOC or almost immediate death. Poor prognosis. They are most often caused by aneurysm
