Flashcards in Vascular Deck (119):
What does the recurrent artery of Heubner supply?
Anterior putamen, pallidum and internal capsule
What deficit occurs if the posterior perforators are injured from an ACom aneurysm
Septal injury resulting in akinetic mutism
Branches of PCA 1st segment?
Posterior thalamogeniculate perforators, crural perforators, long and short circumflex
Branches of the 2nd segment PCA?
Posterior medial and lateral choroidal A
Where is the anterior choroidal artery seen on an AP angiogram?
Lateral to the medial lenticulostriate perforators
Where do the Trolard group of veins drain into?
Superior sagittal sinus
What is the trans-cerebral venous system?
Cortical link between deep and superficial venous systems
What veins join to form the internal cerebral vein?
Thalamostriate, choroidal vein, septal vein and caudate vein
Where is the posterior communicating vein?
In the interpeduncular cistern connecting the basal vein of Rosthenthal on each side
What are the routes of drainage of the cavernous sinus?
Opthalmic to facial, Super and inferior petrosal to IJV, sphenoparietal sinus to SSS and basal vein of rosenthal to straight sinus
Where do the hemispheric veins of the cerebellum drain?
To the transverse sinus
Note medial veins go the BVR and straight sinus
What is a large occipital sinus associated with?
Agenesis of the transverse sinuses
What is the evidence for recannalisation in stroke?
Improved mortality and morbidity
What recannalisation strategies are there for stroke?
Thrombolysis (IV tPA) within 4.5 hours of symptom onset - better for distal vessels and less efficacious for ICA etc
Intra-arterial thrombolysis (tPA or urokinase)
Intra-arterial mechanical thrombectomy (stent retrieval)
Which patients will be best candidates for mechanical thrombectomy?
Those without underlying brain injury and extent of collateral arterial supply on 10 second delayed phase CT-A. Only perform thrombectomy on those with good collaterals.
What is the time window for endovascular stroke intervention?
What is the evidence supporting carotid endarterectomy?
NASCET study showed 17% risk reduction in the surgical arm if there is >70% stenosis
What is the significance of an ulcerated plaque for endarterectomy?
The presence of an ulcerated plaque with higher degree stenosis results in higher risk of stroke and better surgical outcomes
What is the significance of an intra-plaque haemorrhage?
Higher risk of stroke
What is the evidence for CES vs CAS (stenting)
Stenting is better for younger patients whiilst surgery was better for older patients (>68 years)
Surgery is more risky with higher degrees of stenosis whilst stenting risk remains the same.
(SPACE trial - overall no difference)
CREST - overall no difference
What is the risk for treatment of an aymptomatic carotid stenosis >70%?
3% (compared to 11% with medical therapy) - from the ACAS trial
What are the indications for by-pass surgery?
1. Flow augmentation / improvement
2. Flow preservation
What is the classical bypass surgery?
STA to M4 (proven by international EC-IC bypass study to have no benefit)
What are the collaterals in the brain?
Circle of willis
ECA-ICA through meningeal and opthalmic arteries
Pial collaterals (corticomeningeal)
What is the typical sign for exhausted cerebrovacular reserve capacity?
Low CBF but increased OEF leads to normal CMRO2
What was the COSS study?
Carotid occlusion surgery study
What was the outcome of the COSS study?
Bypass improves the haemodynamic function of the brain (OEF on PET) and patency was 96% on long term f/u, but the perioperative stroke rate was 14% so medical treatment is better
What is Moya moya?
Progressive occlusion of the ICA resulting in excessive collateralisation
What is the Jam trial?
Japanese moya moya study showed revascularisation with EC-IC bypass reduced risk of haemorrhage
What is synangiosis?
Indirect revascularisation by overlay with muscle etc. Used alone only in children but in adults only direct STA-MCA methods are used.
Would you revascularise a non-symptomatic moya moya patient?
How can DAVF and AVM be differentiated?
AVMs are fed by arteries that supply the brain but DAVFs are fed by arteries that normally supply the meninges and the shunt is in the dura not the brain
What is the risk of evolution of a benign to malignant DAVF?
What are the pathophysiology of DAVF?
Impaired venous outflow of the brain and cortical venous reflux
What is the sign of cortical venous reflux with DAVF?
Enlargement of sulcal vessels (not within the parenchyma)
What are the signal characteristics of blood with SWI?
Deoxy Hb is dark (veins) but Oxy Hb is bright (arterial)
What is the significance of confluent white matter high signal on FLAIR?
In a young patient think venous hypertension
What should be thought of in a patient with SAH/ICH and subdural in the absence of trauma?
What are the treatment options for DAVFs?
Endovascular (transarterial or transvenous)
How is a transarterial DAVF occlusion performed?
Via the meningeal (not osteodural) direct feeder to emoblise the distal artery and proximal vein
When should a DAVF be treated with transvenous endovascular approach?
If transarterial approach is not possible and only if the vein being used is not important for venous drainage
What is the annual haemorrhage rate of an AVM?
2% but up to 4-6% if associated aneurysm
What are the features of a DVA?
Dilated veins without dilated arterial feeders and no shunting
How are AVMs classified?
Surgical - Spetzler-martin
Gamma-knife - Pollock flickinger
What is the SIMVS?
Scottish intracranial vascular malformation study
How do AVMs present?
Haemorrhage 50%; Epilepsy 25% and Focal deficits, Headaches and symptomatic
What is the Lawton modification of the spetzler martin classfication?
What is the risk of AVM rupture according to the ARUBA trial?
1-4% per year
What study shows the natural history of AVMs?
Meta-analysis Gross et al 2013 Neurosurgery showed unruptured 2.2% and ruputured 4.5%
What factors of AVM are associated with higher rupture risk?
Previous haemorrhage, associated haemorrhage, deep venous drainage and deep location
What is the role of AVM intervention?
To prevent rupture risk and not seizure control
What is the obliteration rate for AVMs with gamma knife?
In the ARUBA trial what is the risk of death or stroke with intervention?
30%!! compared to 10% for medical management
What is the cure rate of AVMs with embolisation alone?
What is the Borden classification
1 - Drainage to sinus only
2 - Drainage to sinus and CVR
3 - Drainage to CVR only (highest risk of haemorrhage)
What are the branches of the supraclinoid caroid artery?
Opthalmic, PCom, Anterior choroidal
What is the prevelance of aneurysms in the population?
What is the mortality of ruptured aneurysm without treatment?
60% at 6 months
What is the re-rupture rate of an aneurysm?
6% 2 days
24% 2 weeks
40% 6 months
What are the risk factors for aneurysm ruputure?
Japanese or Finnish
What is the incidence of SAH?
7-20 per 100,000 per population
What is the risk of surgery for unruptured aneurysms?
10% in ISUIA2
What is ISUIA 2?
Prospective study showed
25 mm 40%
Posterior circ incl PCom
What are the problems with ISUIA?
Morphology of aneurysm, growth of aneurysm, smokers, female and Japanese / Finnish not taken into account
Intervention risks are too high
What is the chance of recannalisation following coiling?
What is the retreatment rate for coiled aneurysms?
Up to 13%
What factors favour clipping vs coiling?
Location e.g. basilar / SCA / intracavernous / opthalmic etc
Configuration - direction of aneurysm pointing, vessels at neck, perforators, narrow vs wide neck, bifurcation recannalise more with coiling vs sidewall aneurysm, size - very small aneurysms 15mm may compact.
Circumstances - pregnancy, kidney disease, calcification at neck, life threatening situation due to clot / hydrocephalus - fenestration of the lamina terminalis reduces shunt rate from 14% to 4%, vasospasm can be treated via endovascular means
Vessels - other aneurysms in the same surgical field or different regions, anatomical variation, vessel wall disease - marfan's syndrome due to vessel tortuosity
Age - young patients have compaction, old patients have vessel wall pathology
Etiology - Dissection better endovascular, partially thrombosed, trauma, mycotic aneurysm
What is the PHASES score?
Aid to prediction of risk of rupture of incidental intracranial aneurysms based on population, hypertension, age, size of aneurysm, previous SAH from other aneurysm and site of aneurysm
When does oxyHb become positive in SAH?
How long does xanthachromia remain 100% sensitive with spectroscopy?
2 weeks (70% at 3 weeks)
Is there choroid plexus in the occipital horn?
What is the fornicial psalterium?
The stretching out of the fornix fibre as they spread apart
How can carotid cavernous fistula be malignant?
Cavernous sinus to sphenoparietal sinus goes to supfl Middle cerebral vein and also uncal vein to basal vein of Rosenthal
What is the epsilon sign?
The characteristic venous dilatation in patient with a vein of galen malforation
How can veins drain with vein of galen malformation
Cavernous capture - causes fetus face to become veiny and blue
** there are more - look it up
What are the side effects of a vein of galen malformation?
High output cardiac failure
Arterial steal causing infarctions, encephalomalacia and melting brain (in neonates)
Haemorrhage ** very rarely if there is cavernous capture and cortical reflux
Hydrodynamic disorders - venous hypertension causes hydrocephalus (do not shunt them as it makes the vein of galen malformation worse!!)
Tonsilar prolapse due to venous hypertension
How are vein of galen malformations diagnosed?
Fetal USS shows a dilated median vein of the prosencephalon in the midline
MRI can then be done
What is the best time to embolise a vein of galen malformation?
Neonates if heart failure, otherwise 3 months as the vessels as stronger and enough contrast can be used
Inject from the artery into the vein laterally within the artery (not central part as it has highest flow)
What does the anterior communicating vein drain?
Joins the anterior BVR bilaterally (superior to the ACom)
Where is the sphenoparietal sinus?
Along the lesser wing of the sphenoid and has the superficial middle cerebral vein draining into it
Where do the lateral cerebellar hemispheric veins drain?
How are dural sinuses composed?
Multiple separate channels
What proportion of strokes are from cardiac embolus in patients with severe cartoid stenosis?
What is the definition of severe carotid artery stenosis?
What is the risk of stroke with stenosis >70%
26% with medical management
9% with carotid endarterectomy
What is vessel wall imaging?
Double inversion recovery (black blood)
If you have plaque haemorrhage in CES, what is the risk of haemorrhage within one year?
What are the features of an unstable carotid plaque?
Thin fibrous cap
What is the ICSS trial?
Showed CES surgery better than stenting. Other trials showed no differences.
What did the SPACE trial show?
Young patients better to have carotid stenting whilst elderly patients better with endarterectomy
Where are pial AVMs?
Within the brain parenchyma
Where is the shunt in a dAVF?
Within the leaflets of the dura
What is the mortality rate with a dAVF with cortical venous reflux?
What can cause a dural AVF?
What does it mean if you see a venous structure on a TOF?
Arterialisation of a vein i.e. flow is going towards the brain not away
How does TOF work?
Saturation of spins in the slab below the brain so only flow going to the head is seen
What does it mean if a patient with a DAVF notices the bruit disappears?
The DAVF has developed cortical venous reflux (very rarely it has resolved)
When do you do a venous endovascular obliteration of dAVF?
If arterial occlusion is too dangerous and
If the brain does not drain through that vein which will be occluded
What is the natural history of brain AVM?
2-4% annual haemorrhage rate
8% if there is a nidal aneurysm
6-15% if previous haemorrhage from the AVM
What are DVAs?
Developmental venous anomalies: dilated transcerebral veins without an arterial feeder (associated with cavernomas!)
What size AVM is max for SRS?
12 cm^3 (3cm diameter) unless you stage the treatment (will take 3 years to work...)
What is a pseudophlebitic pattern?
Increased caliber, number and tortuosity of pial vessels suggesting venous outflow obstruction and collateralisation
What does cerebral oedema suggest in a patient with AVM?
Venous congestion (look for a flow aneurysm!)
Which AVMs cause IVH?
Ependymal or choroidal artery fed AVMs
What is the difference between paediatric and adult cavernomas?
Paediatric cavernomas can be giant!
How do you treat a dAVF of the tentorial artery?
Disconnection of the petrosal vein through a retrosigmoidal approach
Venous endovascular embolisation is very difficult
How can you decide between a lateral supraorbital vs mini-pterional approach for an MCA aneurysm?
If within 15mm of the ICA bifuraction then lateral supraorbital. If >15 then minipterional
What is partial trapping?
A last resort where there is partial inflow obstruction to cause thrombus within the aneurysm that cannot be occluded due to perforators
Which aneurysm may be associated with Abluia?
AComm with bifrontal damage
What proportion of CT scans are positive for SAH by day 3?
How sensitive is xanthochromia for SAH at 2 weeks?
What are the types of revascularisation?
Direct - bypass
Indirect = neoangiogenesis
What is flow preservation vs augmentation?
Preservation is occlusing and bypassing a region e.g. giant aneurysm, whilst augmentation is adding supply to a compromised territory
What happens to oxygen extraction fraction when CPP falls?
OEF rises to maintain CMR02 (Cerebral metabolic rate for O2)
How can OEF be measured?
What are the methods for revascularisation in moya moya children?
What is the difference in revascularisation in adults vs children?
Adults need direct revascularisation
Should you treat a patient with previous stroke due intracerebral occlusion with reduced cerebral perfusion despite best medical treatment?
Yes - flow augmentation will reduce further strokes