Blood Supply of the Brain and Spinal Cord Flashcards
Name some of the major arteries of the brain.
Anterior circulation
- Internal Carotid Artery (ICA)
- Middle Cerebral artery (MCA)
- Anterior Cerebral Artery (ACA)
- Posterior Communicating Artery
Posterior circulation
- Basilar artery (BA)
- Vertebral Artery (VA)
- Posterior Cerebral Artery (PCA)
How is the internal carotid artery segmented?
Into 7 segments Cervical Petrous Lacerum Cavernous Clinoid Ophthalmic Communicating
What are the branches of the internal carotid artery?
Ophthalmic artery (supplies whole orbit) Posterior communicating artery Anterior choroidal artery (supplies internal capsule, thalamus and optic chiasma)
Tell me about the middle cerebral artery.
Direct continuation of ICA
Supplies 2/3 of brain convexity
Lateral aspect of frontal/parietal/occipital lobes
Lateral striate arteries supply basal ganglia
Most strokes occur in MCA territory
Tell me about anterior cerebral artery.
Smaller branch of ICA
Supplies medal surface and adjacent convexity (frontal and parietal lobes)
Joined by anterior communicating artery
Tell me about the vertebral artery.
Arises from subclavian arteries Tortuous course Largest branch - Posterior cerebellar artery (PICA) Other branches - spinal arteries
Tell me about the basilar artery.
Overlies the pons
Supplies most of the brainstem
Superior and anterior inferior cerebellar arteries
Bifurcates into 2 PCA’s
Tell me about the PCA.
Bifurcation of BA
Goes around midbrain
Supplies the midbrain, thalamus, temporal and occipital lobes
Define a stroke.
Clinical syndrome of abrupt loss of focal brain function lasting > 24 hours (or causing death) that is due to either spontaneous haemorrhage into brain substance or inadequate blood supply to a part of the brain (thrombosis, embolism)
Includes SAH (Subarachnoid haemorrhage)
Define a TIA.
Transient Ischaemic Attack Sudden onset Focal disturbance of brain function (ocass. global) Presumed to be of vascular origin Resolves completely within 24 hours
How can intracerebral haemorrhage be classified?
Primary - no structure lesion
Secondary - e.g. tumour
How can cerebral infarcts be caused?
Large vessel atheroma/embolism Cardiac embolism Small vessel disease/lacunae Non atheromatous arterial disease (arteritis) Blood disorders
Other known aetiologies
Cryptogenic (no cause id)
How can intracerebral haemorrhages be caused?
Hypertensive - microaneurysms/lipohyalinosis (40%)
AVM’s (arteriovenous malformation) or aneurysms (15%)
Amyloid angiopathy (10%)
Haemostatic anticoagulant, thrombolytic, thrombocytopenia (10%)
Other - cocaine, amphetamines, tumour, venous
thrombosis
What are the symptoms of a frontal lobe stroke?
Motor area (pre-motor and motor cortex) Broca's area (expressive dysphagia) Prefrontal cortex (personality/behaviour)
What are the symptoms of parietal lobe stroke?
Primary sensory cortex
Non dominant lesions - visuospatial issues
Optic radiation (superior)
- Inferior quadrantanopia/hemianopia
What are the symptoms of temporal lobe stroke?
Central representation - Auditory/vestibular function - Taste and smell Wernicke's area (receptive dysphagia (incomprehensible) Memory circuits Optic radiation (inferior) Superior quadrantanopia
What are the symptoms of occipital lobe stroke?
Visual cortex
What are the symptoms of cerebellum/brainstem?
Motor + sensory tracts
Cranial nerve nuclei
Cerebellum - balance coordination
What are the different strokes according to the OCSP?
Oxfordshire Classification of Stroke Project
TACS - Total anterior circulation stroke (20%)
PACS - Partial anterior circulation stroke (35%)
LACS - Lacunar stroke (20%)
POCS - Posterior circulation stroke (25%)
Tell me about a TACS. (Aetiology, Clinical presentation and relevance)
Total anterior circulations stroke
Aetiology
Proximal occlusion (ICA or proximal MCA)
Large volume infarct
Superficial and deep territories
Clinical presentation
Contralateral hemiparesis (+/- hemianaesthesia)
Contralateral hemianopia
Higher cerebral dysfunction (cortical signs: dysphagia, dyspraxia (fine coordination)
Relevance
High mortality
Tell me about a PACS. (Aetiology, Clinical presentation and relevance)
Partial anterior circulation stroke
Aetiology
Occlusion of MCA branch
Restricted infarct
Clinical presentation
2 or 3 of a TACS symptoms
OR restricted motor deficit (face OR arm OR leg only)
OR isolated cortical signs
Relevance
High early recurrence rate
Tell me about LACS. (Aetiology, Clinical presentation and relevance)
Lacunar stroke
Aetiology
Single perforating artery
Basilar ganglia/pons
Clinical presentation Pure motor Pure sensory Sensorimotor Ataxic hemiparesis
Relevance
Silent
Underdiagnosed
Tell me about a POCS. (Clinical presentation and relevance)
Posterior circulation stroke
Clinical presentation
Brainstem
Cerebellar or
Occipital involvement
Relevance
Complex presentation
Thrombosis
What are some relevant history when diagnosing a stroke?
Symptom onset
When exactly??
Speed of onset
Progression of symptoms
Neurological symptoms (localisation and characterisation)
Body part affected
Modalities involved
Positive vs negative symptoms important
Stroke is always negative - they lose functions
Other symptoms
Suggesting bleeding: headache, seizure
Suggesting raised ICP: headache, vomiting, drowsiness
Suggesting aetiology: Cardiac symptoms
Atypical presentations
Delirium, confusion, collapse, incontinence
What are some vascular risk factors of stroke?
Non-Modifiable
Age, gender, genetic, family history, previous stroke/TIA
Lifestyle
Smoking, sedentary lifestyle, Heavy alcohol intake, diet
Medical
Hypertension, hypercholesterolemia, diabetes, arrhythmia
What are some differential diagnosis of stroke?
Hypoglycaemia (other metabolic disturbances) Migrainous aura Epilepsy SOL (secondary vs primary tumour, others) Demyelination Labyrinthine disorders Others - Retinal Bleeds, or infarcts (not defined as a stroke) - Peripheral neuropathy - Myopathies - Delirium - Hyperventilation (usually transient) - Functional or Psychological
What are some of the neurological deficits of a stroke?
Unilateral hemiparesis/monoparesis
Unilateral facial palsy (upper vs motor MNL)
Unilateral sensory deficit (+ modalities)
Dominant cortical (dysphagia, dysgraphia, dyslexia) Nondominant cortical (visuospatial disorder, neglect) Hemianopia/quadrantanopia (both eyes involved)
Cranial nerve signs
Cerebellar signs
What are some initial investigations when a stroke is suspected?
BM stat (blood glucose measurement) Haematological: FBC, INR Biochemical: U+E, LFT, TFT, glucose, lipid ECG Radiological: CXR where indicated
What imaging is used in a suspected stroke?
Urgent when thrombolysis is an option
Indications
- Look for the bleeding (ICH, SDH, SAH, bleed into tumour)
- Screen for stroke mimics (tumours, other rarities)
- May visualise infarct
Most early CT scans (
What extra do you do in a younger or cryptogenic stroke?
Full coagulation profile Thrombophilia screen - Protein C/S ATIII, FV Leiden, P20210A Antiphospholipid antibodies - Anticardiolipin, lupus anticoagulant Autoimmune screen Fasting plasma homocysteine Blood cultures TFT, Syphilis serology, HIV serology
What is the treatment of an acute stroke?
Intravenous thrombolysis (alteplase)
- Only if ischaemic, and given within 4.5 hours of onset
Early aspirin therapy (where not thrombolysed)
Management in the Acute Stroke Unit
Specialist rehabilitation therapists
Routine carer involvement
Education and training programs
How can stroke be prevented?
Antithrombotic meds Medical risk factor treatment - Treat hypertension - Treat hypercholesterolemia - Carotid surgery (if significant carotid stenosis) - Treat diabetes Lifestyle changes Medication compliance
