10.6 Cerebrovascular Diseases Flashcards
Define stroke
- A stroke occurs when a blood vessel that carries oxygen and nutrients to the brain is either blocked by a clot or bursts (or ruptures). When that happens, part of the brain cannot get the blood (and oxygen) it needs, so it and brain cells die
WHO
Stroke was defined by the World Health Organization (WHO) more than 40 years ago as “rapidly developing clinical signs of focal (or global) disturbance of cerebral function, lasting more than 24 hours or leading to death, with no apparent cause other than that of vascular origin
Define TIA (transient ischeamic attacks)
- Acute neurological event due to a vascular cause lasting less than 24 hours
…but most resolve within an hour
What are the 3 big problems that strokes cause?
- disability (leading cause of disability)
- dementia
- mortality
Define
Oligaemia
Penumbra
Infarction
Oligaemia = ↓ blood flow, but normal function
Penumbra = neurological fallout but potentially viable tissue SNL = Selective Neuronal loss
Infarction = Neurological fallout, cells have died
Types strokes
- Obstruction in artery ➡️ Ischaemic stroke
- Rupture of blood vessel ➡️ Hemorhagic stroke (blood leaks into brain and surrounding tissue)
- Venous sinus thrombosis (thrombus in venous structure: superior sagittal sinus)
List the Causes of stroke
- Haemorrhage 20%
- Ischaemia 80%
Haemorrhage causes
- Hypertensive bleed
- Aneurysms eg SAH -> subarachnoid haemorrhage
- Vascular Malformation - AV
- Tumour
- Bleeding diathesis
- Cerebral Amyloid Angiopathy – Lobar haemorrhages (in elderly) rare
- Haemorrhagic transformation of an ischaemic OR venous infarct
Ischemia causes
Common
- Cardiac origin of emboli: 20-30%
- Atherosclerosis (thrombo-embolic): 25%
- Small vessel disease: 20% (Hypertension; Diabetes; Smoking; Alcohol)
- No cause found: 20% [younger pt]
Less common -> Virchows Triad
- Nonatherosclerotic vasculopathy: 5-10% {vessel wall}
➡️Fibromuscular Dysplasia
➡️Carotid & vertebral dissection 6-10% patients 30-50y
➡️Arteriitis: (Takayasu, isolated CNS angiitis, SLE, Wegeners, HIV, infective causes)
- Hematological causes: 5% {constituents}
➡️SC disease, Hemoglobin SC disease, PNH
➡️Polycythemia / Thrombocytosis / Leukaemia
➡️TTP / DIC / Disorders of fibrinolysis
➡️Pregnancy, Cancer, Nephrotic syndrome, acute infection,..
➡️Hypercoagulable states
➡️Antiphospholipid syndromes
- Hyperhomocysteinemia
Causes of stroke in the young
- cardiovascular myelopathy
- haemotological conditions
- drugs
Illicit drug use
- Present in up to 12%
- Varies by location and drug type
- Consider tox screen
- IV drugs can produce embolisation of foreign material or
- Endocarditis
- Drugs with a sympathomimetic effect (amphetamine, cocaine, crack) can cause ischaemic stroke through several mechanisms such as:
➡️acute hypertension
➡️enhanced platelet aggregation
➡️and rarely vasculitis (mainly related to amphetamine intake) of the periarteritis nodosa or giant cell-granulomatous types
Sources of emoboli
- Left atrium
- Left ventricle
- Aorta
- Carotid
Risk factors for strokes
- history of hypertention
- physical inactivity
- waist-to-hip ratio
- smoking
- diet risk
- cardiac causes
- diabetes
- depression
- alcohol intake
- psychosocial stress
all of them are modifiable
Cardio-Embolic stroke
Risk factors
Risk factors
- mechanical cardiac valves,
- dilated cardiomyopathy,
- myocardial infarction (AMI) within the last month left ventricular or - atrial thrombi,
- infective endocarditis
Atrial fibrillation & Stroke
- The most common arrhythmia
- 1 of 6 strokes are due to AF (1 in 3 of pts > 80)
- In patients with non valvular AF the stroke risk varies 1-14% per year
- Rheumatic heart disease patients have a 17-fold increase compared to age-matched controls
- Recent data suggests a significant proportion of cryptogenic stroke is due to paroxysmal AF
Stroke etiology
Toast classification
- atherothrombotic
- cardioembolic
- lucunar / small vessel
- other / uncommon
- cryptogenic
What is the deficit of deep lesions?
They take out all the fibres: arm, leg, face = very weak
size of lesion does not always equate the size of deficit
the deeper the lesion: ⬆️ deficit - deep = internal capsule
What deficit does cortical lesions cause?
Only take out some of the fibres: arms, face = bit weak
differential between arm and leg
Lipohyalinosis
Due to chronic hypertension
➡️ Lacune
➡️ Aneurysm
➡️ Basal ganglia bleed
Classification of strokes (4 components)
1. Cortical symptoms
- aphasia (fluency NB {pt speak faster than you write}, reading, writing) left hemisphere
- neglet (visual, auditory, tactile) -> anosognosia (denial of illness)
2. Sensory loss
3. Weakness
- cortex (anterior cerebral artery {leg}; middel cerebral artery {arm})
- deep (very big MCA stroke OR Lacunar stroke {face, arm, leg})
severe weakness = deep involvement
4. Visual flied loss
- NB!
- left homonymous hemianopia (loss vision on left side)
- lesion affect cortex (anterior or posterior circulation)
TACS - total anterior circulation syndrome
Define
Pathogenesis
- higher function fallout + sensory loss + weakness + hemianopia = TACS
- can be due to large ischemic event to hemorrhagic event
Define
At time of maximum deficit, ALL of:
- WEAKNESS - Hemiplegia or severe hemiparesis contralateral to the cerebral lesion (+/- SENSORY)
- HEMIANOPIA contralateral to the cerebral lesion
- New disturbance of HIGHER CEREBRAL FUNCTION (e.g. aphasia, visuospatial disturbance)
Pathogenesis
- proximal MCA occlusion
- Large clot, commonly cardio-embolic OR Large vessel disease
PACS - Partial anterior circulation syndrome
3 components
Define
Pathogenesis
- limited form of TACS
3 components - need 2
1. Cortical + Hemianopia
2. Motor / sensory + Hemianopia
At time of maximum deficit, 2 of the 3:
- MOTOR/SENSORY deficit
- HEMIANOPIA
- HIGHER CEREBRAL DYSFUNCTION
OR
- New higher cerebral dysfunction alone
- NOT an isolated new hemianopia
Pathogenesis
- More distal MCA occlusion = Smaller clot
Different types of strokes + their causes
- TACS (ant + big) ➡️ cardiac emboli
- PACS (ant + big) ➡️ cardiac/carotid emboli
- PoCs (post + small ➡️ various; 1/5 emboli
- LaCS ➡️ no emboli; hypertension
Lacunar syndromes
Categories
Pathogenesis
Which blood vessel occluded
Typical sites
Small vessel disease (Risk factor)
Categories:
- Pure motor stroke (PMS)
- Pure sensory stroke (PSS)
- Sensorimotor stroke (SM)
- Ataxic hemiparesis (AH)
➡️Dysarthria clumsy-hand syndrome
➡️Homolateral ataxia and crural paresis
- NO visual field deficit
- NO new disturbance of higher cortical function
- NO signs of brainstem dysfunction
- 10-25% of patients with a LACS will have a larger lesion on CT (proportion higher for Sensorimotor Stroke)
- Any of the LACS may be caused by a small haemorrhage
- Can have a small lacune in the posterior circulation
➡️Same pathology,
➡️But every lesion in the posterior circulation is called a POCS - Small deep blood vessel occluded
Typical Sites
- Basal Ganglia
- Thalamus
- Pons
- Posterior limb of the internal capsule
Small vessel disease - Risk factor
- Hypertension (Lipohyalinosis)
- Diabetes Mellitus
Posterior Circulation Syndromes
Posterior circulation supply
Posterior circulation supply
- Brainstem
- Cerebellum
- Occipital
- Cortex
- Thalamus
Cross pattern
- Cranial nerve palsy and a contralateral motor/sensory deficit
- Bilateral motor/sensory deficit
- Conjugate eye movement disorder (e.g. horizontal gaze palsy)
- Cerebellar dysfunction (e.g. vertigo, nystagmus, ataxia)
- Isolated homonymous hemianopia
Embolic POCS
Top-of-the-basilar artery syndrome
- Sudden onset hemianopia or cortical blindness
- Loss of consciousness
- Tetraparesis
Stroke mimics
present like stroke, but actually something else
- Hypoglycaemia
- Migraine
- Seizures
- Simulation
- Demyelination: ADEM (acute disseminated encephalomyelitis)
- Tumor
A left homonymous hemianopia may be due to:
- Right occipital lobe infarct
AND - Right temporal lobe infarct
