Cerebrovascular Diseases Flashcards
3 criteria by which stroke is identified
Temporal profile
Evidence of focal brain disease
Clinical setting
Most important modifiable risk factors for stroke
Hypertension Atrial Fibrillation Diabetes mellitus Cigarette smoking Hyperlipidemia
Others include:
Systemic dses assoc with a hypercoagulable state
Use of OCPs
Atrial Fibrillation increases risk of stroke by about ____ and if with rheumatic valvular dse by about ____
6-fold
18-fold
Low levels of this electrolyte has been associated with increased stroke rate albeit through an obscure mechanism
Potassium
Low K intake and reduced serum K levels are associated with an increased stroke rate in several studies…
TIAs are generally considered more closely aligned with
A. Atherothrombotic stroke
B. Embolic stroke
A
Atheromatous plaques preferentially form at
- ICA at its origin from the common carotid
- Cervical part of the VA at their jxn to form the basilar artery
- Stem or main bifurcation of the MCA
- Proximal PCA as they wind around midbrain
- Proximal ACA as they pass ant and curve over the corpus callosum
Mechanisms through which atherothrombosis causes cerebral infarction
- Plaque or thrombus occupies lumen of a major intracerebral vessel (also watershed infarction)
- Atherothrombotic lesion in proximal vessel serve as nidus for formation of embolus (artery-to-artery embolism)
- Atherosclerotic plaque in large vessel occludes orifices of small penetrating vessels
What degree of stenosis and size of residual lumen of the carotid artery is most likely to be associated with strokes in the distal territory of the vessel?
Stenosis of >90%
Residual lumen < approx 2mm
Risk of stroke conferred by Afib according to age
<65y 1% per year
>75y 8%per year
What is the CHA2DS2-VASC score?
Heart failure or EF<35% - 1pt Hypertension - 1 Age 66-74y - 1 Age > 75y - 2 Previous stroke or TIA - 2 Diabetes -1 Coronary or peripheral vascular dse - 1 Female - 1
Predicted yrly stroke risk by total score 0 - 0% 1 - 1.3% 2 - 2.2% 3 - 3.2% 4 - 4.0% 5 - 6.7% 6 - 9.8 7 - 6.9% 8 - 6.7% 9 - 15.5%
Thickness of echogenic atherosclerotic plaques in the aortic arch found to be statistically associated with strokes.
> 4mm thickness
Migrating or traveling embolus syndrome and vessel involved
Artery-to-artery PCA occlusion from a thrombus in the proximal VA: mins or more before hemianopsia, fleeting dizziness diplopia or dysarthria from transient occlusion as clot traverses the BASILAR ARTERY
What is a paradoxical embolism
When an AbN communication exists bet R and L sides of the heart or alternative route connection via pulmonary arteriovenous fistula
Mechanism of embolism following thyroidectomy
Thrombosis in stump of superior thyroid artery extends proximally into lumen of the carotid and a portion is carried into the cerebral circulation
Clinical presentation of fat embolism
Associated to severe bone trauma
First pulmonary sx then multiple dermal (ant axillary fold and elsewhere) and cerebral petechial hemorrhages
Encephalopathy
Cerebral Air embolism may occur as a complication of the ff
Abortion Scuba diving Cranial, cervical or thoracic operations Venous catheter insertion Prev. Pneumothorax therapy
Percentage of presumed embolic strokes in which point of origin cannot be determined
20-30%
Brief ischemic attacks that precede a stroke leaving no clinical or imaging trace almost always stamp the process as
Atherothrombotic
In patients with TIAs caused by atherosclerotic dse, the 5-yr cumulative rate of fatal and nonfatal cerebral infarction is
And of myocardial infarction esp in those with carotid lesions
23% for cerebral infarction
21% for myocardial infarction
Risk of stroke over 3 yrs ff an attack of transient monocular blindness
2% if no other risk factors for atherosclerosis
24% in older pts with risk factors for atherosclerosis
What is the”capsular warning syndrome”
Escalating episodes of weakness in the face arm and leg culminating in a capsular lacunar stroke
A single transitory episode of TIA esp lasting >1hr and multiple episodes of different patterns suggest
Embolism
Brief 2-10min recurrent attacks of the same clinical pattern suggests TIA from
Atherosclerosis and thrombosis in a large vessel
TIAs induced by hyperventilation are characteristic of
Moyamoya disease
Hemodynamic changes on retinal or cerebral circulation make their appearance when lumen of ICA is reduced to:
2mm or less (normal diameter of 7mm, range of 5-10mm)
Or a 95% reduction in cross-sectional area of the vessel
Collateral vessels that may modify the effects of cerebral ischemia
- Subrachnoid interarterial anastomoses (linking MCA ACA and PCA)
- Persistent Trigeminal artery (ICA and BA proximal to circle of Willis)
- Ophthalmic artery (ICA and ECA)
- Deep cervical, thyrocervical, or occipital arteries (VA and ECA)
Cerebrovascular autoregulation through dilation and constriction of small pial vessels is operative over mean BP of approximately
50-150mmHg
Critical threshold of CBF below which functional impairment occurs
23mL/100g/min
CBF below which infarction occurs regardless of duration
Below 10-12mL/100g/min
Critical level of hypoperfusion that abolishes function and leads to tissue damage
CBF 12-23mL/100g/min
CBF that invariably leads to histologic signs of necrosis
CBF 6-8mL/100g/min
Spontaneous, recurrent or migratory venous thromboses (superficial or deep) in people with occult or recently diagnosed visceral malignant disease or hypercoagulable state associated with any malignant disease
Trousseau’s syndrome
Hollenhorst plaque
Crystalline cholesterol sloughed from an atheromatous ulcer, seen on retinal exam as emboli within retinal arteries either shiny white or reddish in appearance
Bruit loudest at
A. the angle of the jaw
B. Lower in the neck
A. Stenosis at proximal ICA
B. Common carotid or Subclavian artery
Occlusion , which occurs most frequently in the first part of the ICA immediately beyond the carotid bifurcation may be clinically silent in what percent of cases?
30-40%
Because no part of the brain is completely dependent on it
Headache on the ff locations is associated to occlusion of which artery?
A. Above the brow
B. At the temple
C. In or Behind the eye
A. Intracranial ICA
B. MCA
C. PCA
Approximate area of
A. Cortical watershed
B. Internal or deep watershed
A. High parietal and frontal cortex and adj subcortical WM (if w longstanding carotid stenosis, shifts down to perisylvian portion of MCA)
B. Subfrontal and subparietal portions of the CSO
Watershed areas in tital circulatory collapse
Sickle-shaped strip from cortical convexity of the frontal lobe through the high parietal lobe to the occipitoparietal junction
Cardinal clinical signs of stenosis, ulceration, and dissection of the ICA
TIAs
Most carotid occlusions are ____
Whereas most MCA occlusions are ______
A. Embolic
B. Thrombotic
Carotid - B. Thrombotic
MCA - A. Embolic
Percent of population wherein a persistent fetal circulation is seen with 1 PCA arising from the ICA?
Both PCA arising from corresponding ICA
20-25%
<5%
What is the thalamic syndrome of Dejerine and Roussy (clinical features, vessel involved)?
Sensory loss that includes hemibody up to the midline, which return after an interval, and pt may develop a painful paresthetic syndrome that may last for years
Thalamogeniculate branches
Sundromes of the paramedian arteries have as their main feature a 3rd nerve palsy combined with:
Weber?
Claude?
Benedikt?
Weber - contralateral hemiplegia
Claude - contralateral ataxic tremor
Benedikt - homolateral ataxia, hemiplegia with contralateral 3rd nerve palsy
Vascular cause of the amnesic Korsakoff syndrome
Occlusion of the paramedian thalamic branches to the mediodorsal nucleus
The vertebral arteries are most often occluded by atherothrombosis in what portion?
Intracranial portion
Dissection of the vertebral artery declares itself by
Cervicooccipital pain and deficits in brainstem function
Subclavian Steal
If the Subclavian artery is blocked proximal to the origin of the L VA, exercise of L arm may draw blood from the R VA and BA to L VA to distal L subclavian
Presenting with vertigo and brainstem signs with transient weakness on exercise of the L arm
Medial medullary syndrome
Medullary pyramid - Contra paralysis of arm and leg (sparing of face)
Medial lemniscus- contra loss of position and vibration sense
Hypoglossal fibers - paralysis and later atrophy of 👅
Lateral Medullary or Wallenburg syndrome
8/10 cases from Occlusion of the VA by atherothrombosis then PICA or one of the lateral medullary arteries
Usu. Infarction
1. Vestibular nuclei - vertigo, nystagmus, oscillopsia, vomiting
2. Spinothalamic tract - contra pain and temp impairment
3. Descending sympathetic trunk - ipsi Horner
4. CN 9&10 nerves - dysphagia, hoarseness, dec gag, ipsi palatal and vocal cord paralysis
5. Utricular nucleus - vertical diplopia, illusion of tilting of vision
6. Olivocerebellar, spinocerebellar, restiform, inf cerebellum - ipsi limb ataxia, falling to same side, lateropulsion
7. Descending tract and n of CN5 - pain, burning impairment of sensation ipsi face
8. Nucleus tractus solitarius - loss of taste
Rarely
9. Cuneate and gracile nucleus - ipsi numbness of limbs
Most frequent feature of Lateral Medullary syndrome
Vertigo
Though alone, it is not an indication of lateral medullary syndrome
This nystagmus feature suggests labyrinthine disease from brainstem forms of nystagmus but intfaction of the verstibular nucleus as part of the lateral medullary syndrome may also produce this sign.
Direction-changing nystagmus
Occlusion of the SCA
Middle and superior cerebellar peduncles - IPSI cerebellar ataxia
Spinothalamic tract - CONTRA loss of pain and temp
- Nausea and vomiting
- partial deafness
- static tremor of the IPSI UE
- IPSI Horner
- palatal myoclonus
AICA Occlusion
Vertigo, vomiting , nystagmus, tinnitus,
Sometimes: unilateral deafness, facial weakness, IPSI cerebellar ataxia, IPSI Horner and paresis of conjugate lateral gaze and CONTRA loss of pain and temp
Size of small arteries occluded in lacunar infarction
50-200 microns in diameter
3 mechanisms for lacunar infarction
- Local fibrohyalinoid arteriolar sclerosis that involves orifice or prox part of small penetrating blood vessel (seems to be most common)
- Atherosclerosis of a large trunk vessel that occludes origin of small vessels
- Entry of small embolic material into one of the vessels (least frequent)
Cavities of lacunes
3-15mm
Lacunes are situated in descending order of frequency:
- Putamen and caudate
- Thalamus
- Basis pontis
- Internal capsule
- Deep in the central hemispheral white matter
The relative improvement in neuro state from tPA in the NIH study came at the expense of this much risk of symptomatic cerebral hemorrhage, which is approximately ___ times the expected rate without thrombolysis
6%
Two times
Extension of treatment time for low-risk patients up to 3-4.5hrs after symptom onset is based on the following benefits
10% more achieved a good outcome
More cerebral hemorrhage seen BUT Overall Mortality was the same
What class of antihypertensive drugs was found to be a factor for occurrence of angioneurotic edema with tPA treatment?
ACE inhibitors
Special circumstance in which rapid removal of clot or repair of an intimal tear is performed more or less routinely
If vessel has closed or caused an embolus immediately after carotid endarterectomy
2 situations in which immediate admin of heparin or equivalent have drawn support from clinical findings
- BA thrombosis with fluctuating deficits
- Impending Carotid Artery Occlusion from thrombosis or dissection
But no evidence!!!
With use of heparin, bleeding into any organ may occur at a PTT of?
And at what level of PTT should heparin infusion be discontinued?
PTT >3x the pretreatment value
at PTT>100s, discontinue the infusion
Rare but dangerous complication of warfarin therapy that occur in patients with unsuspected deficiencies in protein C and S
Hemorrhagic skin necrosis
- paradoxical microthrombosis of skin vessels
One third of adults with Afib are lone fibrillators and these patients, younger than this age without additional cerebrovascular risk factors did not clearly benefit from long-term prophylactic anticoagulation.
younger than 65years
With long-term administration of warfarin, the risk of hemorrhage outweighs benefit except in the ff
Severely stenotic cerebral vessel
Atrial Fibrillation
Prosthetic heart valve
Certain blood disorders
Potential toxicity of the ff drugs A. Ticlodipine B. Clopidogrel C. Ximelagatran D. Dipyridamole E. Statin
A. Ticlodipine - neutropenia
B. Clopidogrel - thrombotic thrombocytopenic purpura
C. Ximelagatran - hepatotoxicity
D. Dipyridamole - dizziness (not well tolerated)
E. Statin - statin-induced myopathy
Vasodilators may be harmful on theoretical grounds (in tx of acute stroke) prob due to the ff
- lowering systemic BP
- dilating vessels in normal brain tissue (autoregulation lost within infarct)
- may reduce intracranial anastomotic flow
- vessels in the margin of the infarct already maximally dilated
In decompressive hemicraniectomy for patients with large MCA infarction, approximately this proportion of surviving patients will be dependent for care
One third of surviving patients will be dependent for care
Region of the carotid artery that most often lends itself to surgical management of occlusion
Carotid Sinus
Other suitable for surgical management:
Common carotid, Innominate, Subclavian
Symptomatic carotid artery stenosis includes patients with
TIAs
Large or small strokes IPSI to stenosis (some evident only on imaging)
In those with bilateral carotid disease
A. the risk of stroke after 2 years?
B. If operated?
A. Risk of stroke after 2y of 69%
B. If operated dec to 22%
Conclusion of the North American Carotid Endarterectomy Trial (NASCET) and European Carotid Surgery Trial (ECST)
Endarterectomy for sxic lesions causing stenosis >70-80%
= REDUCED incidence of IPSI hemispheral strokes
= Greater benefit with increasing degrees of stenosis
Timing of endarterectomy for maximum benefit
Within 2 weeks of TIA or minor stroke
A carotid artery stenosis of greater than 70% roughly corresponds to residual luminal diameter of
<2mm
In a pt post endarterectomy who presents, in the hrs after the procedure, with a new hemiplegia or aphasia, the patient is brought back to the OR, cause will usu be:
- intimal flap at the distal end of the endarterectomy and varying amounts of fresh clot proximal to it
BUT even after removal and repair, effects of stroke usu not improved 🙁
Hyperperfusion syndrome
Several days to a week after carotid endarterectomy
Headache, focal deficits, seizures
Brain edema, or cerebral hemorrhage
(Autoregulatory failure of cerebral vasculature in abrupt restoration of N BP and perfusion)
Most common symptom, which may also be the only manifestation of Hyperperfusion Syndrome
Unilateral severe headache
A carotid bruit generally corresponds to a reduction in luminal diameter of the artery to A mm?
But also heard in up B % of older patients with little or no stenosis
A. 2mm or less
B. 10%
This refers to continued TIAs or strokes while on low doses of Aspirin
Aspirin failure
Measures for secondary prevention of stroke as enumerated in the Adams stroke chapter
- Aspirin
- Antihypertensive agents
- Cholesterol-lowering drugs
- Smoking cessation
- During future surgical procedures, maintenance of systemic BP and O2
Accdg to the SPARCL trial, magnitude of benefit of high dose atorvastatin for secondary stroke prevention in pts with stroke or TIA in the prev 6mos
Approximately 3%
Damage produced by pure hypoxia-anoxia without hypotension
Mainly affects hippocampi
Korsakoff syndrome
Vessel most frequently involved in fibromuscular dysplasia
ICA
Radiologic picture and pathology of fibromuscular dysplasia
Radio: Series of transverse constrictions, giving the appearance of irregular string of beads or a tubular narrowing
Pathology: degeneration of elastic tissue and irregular arrays of fibrous and smooth muscle tissue in a mucous ground substance
Raeder Syndrome
Unilateral headache associated with an IPSI Horner’s syndrome in ICA dissection
Localization of severe cranial pain from intracranial arterial dissection
A. MCA
B. Basilar artery
C. Vertebral artery
A. MCA - retroorbital
B. Basilar artery - occipital
C. Vertebral artery - occipital + supraorbital
Rate of stroke in cases of cervical artery dissection
5% or less
Cervical artery dissection is usually treated with anticoagulation for several weeks or months (heparin or warfarin) except for the ff instances
(+) subarachnoid blood on CT
(+) Pseudoaneurysm within intracranial portion of the dissection
Moyamoya disease
Extensive basal cerebral rete mirabile (a network of small anastomotic vessels at the base of the brain around and distal to the circle of Willis) associated with segmental stenosis or occlusion of the terminal intracranial parts of both ICA
Genetic associations of moyamoya disease
Down syndrome
Chromosome 17q autosomal dominant with incomplete penetrance
Most common initial manifestation of Moyamoya dse in younger patients?
In older patients?
Sudden unilateral weakness of an arm, leg or both
In older patients - SAH
Characteristic of TIAs in Moyamoya
Prolonged
Induced by hyperventilation or hyperthermia
What is the rebuild EEG phenomenon?
High voltage slow waves reappear 5mins after the end of hyperventilation
Radiologic appearance of confluent areas of white matter signal change consisting of hypointense periventricular tissues possibly damaged by chronic ischemia. This probably exists in a continuum with Binswanger disease
Leukoariosis
Main features of Binswanger disease
Dementia, pseudobulbar state, gait disorder, alone or in combination
Genetic association of CADASIL (Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy)
Missense mutation on Chromosome 19 of the NOTCH 3 gene
With incomplete penetrance until after 60y of age
An autosomal recessive syndrome of early alopecia, lumbar spondylosis with white matter changes typical of CADASIL
CARASIL (Cerebral Autosomal Recessive Arteriopathy with Subcortical Infarcts and Leukoencephalopathy)
MRI CT appearance most characteristic of CADASIL
Multiple confluent white matter lesions ANTERIOR to the TEMPORAL HORNS of the lateral ventricles
Genetic association and pathology of CARASIL
Autosomal recessive mutation in the HTAR1 gene resulting in fragmentation and duplication of the internal elastic lamina of cerebral vessels with narrowing of their lumens
This treatment may prevent or retard the formation of Moyamoya and reduce risk of stroke among patients with sickle cell anemia
Exchange transfusions
Main diagnoses to consider overall among children and young adults with ischemic stroke
Carotid and vertebral artery dissection Drug abuse (mainly cocaine) Thrombosis induced by contraceptive estrogens APAS cardiac disease including PFO
Inherited prothrombotic states arise in the younger age group
Vascular lesion underlying cerebral thrombosis in women taking oral contraceptives
Nodular intimal hyperplasia of eccentric distribution with increased acid mucopolysaccharides and replication of the internal elastic lamina
The risk of cerebral infarction and ICH in pregnancy appears mainly in this period in general: A
B: timing of arterial occlusion?
C: of venous occlusion?
A. In the 6-week period after delivery
B. Arterial: 2nd, 3rd trimester and 1st wk postpartum
C. Venous: 1-4weeks postpartum
Most common sites of cerebral hemorrhage
- Putamen and adj internal capsule
- Central white matter (lobar- not hpn)
- Thalamus
- Cerebellar hemisphere
- Pons
Pathogenesis of hypertensive ICH
Segmental lipohyalinosis and formation of Charcot-Bouchard aneurysms
On EM: breaks in the elastic lamina at multiple sites almost always at bifurcations of small vessels
Targets in the management of acute ICH
PCO2
Osmolality
Na
PCO2 25-30mmHg
Osmolality 295-305mOsm/L
Na 145-150mEq
Location of intracranial aneurysm with bleeding rates many times higher compared to other locations
Vertebrobasilar and posterior cerebral artery aneurysms
Size of giant cerebral aneurysms and usual locations
By definition, greater than 2.5cm in diameter.
Mostly located on a carotid, basilar, anterior, or middle cerebral artery
Also found on vertebral artery
Dural arteriovenous fistula most at risk for bleeding
Anterior cranial fossa
Tentorial incisura
Marker, in increased amounts, associated with severe amyloid angiopathy and risk of ICH
Apolipoprotein E4 (same as for Alzheimer's disease) Also assoc is E2 allele
Distinctive pattern or location of hemorrhages in cerebral amyloid angiopathy
Subcortical, frequently posteriorly and sometimes subpial
Call-Fleming syndrome
Idiopathic widespread segmental vasospasm of cerebral vessels
Severe headache usu “thunderclap”
Fluctuating TIA-like episodes
Inflammatory diseases that Affects medium and smaller sized vessels
Polyarteritis nodosa, Churg-Strauss, Wegener granulomatosis, SLE, Behcet, hypersensitivity Angiitis, Kohlmeier-Degos, Susac
Usual neurologic symptoms of Takayasu disease
BOV esp upon physical activity
Fever, dizziness, hemiparetic and hemisensory symptoms
The presence in the blood of cytoplasmic antineutrophil cytoplasmic antibodies has been found to be relatively Sp and Sn for Wegener dse but may also be present in what other condition
Intravascular lymphoma
Criteria for the diagnosis of Antiphospholipid Antibody Syndrome
Ischemic event accompanied by detection of autoantibodies on two occasions at least 6weeks apart.
Lupus anticoagulant
Anticardiolipin
B2-glycoprotein 1
Most frequent neuro abnormality in Antiphospholipid Antibody Syndrome
TIA (often amaurosis fugax)
Most specific antibody for the Hughes Syndrome
Antibody to B2-glycoprotein 1
Arteriopathy producing deep blue-red skin lesions of livedo reticularis and livedo racemosa in association with multiple ischemic strokes
Sneddon syndrome
