How to pick the right treatment of intracranial aneurysms.

17 Pages·2017·1.05 MB·English

To coil or not to coil? How to pick the right treatment of
intracranial aneurysms.
Poster No.: C-2777
Congress: ECR 2018
Type: Educational Exhibit
Authors: E. Y. A. Palkhi, K. Anand, J. Zhong, H. Nejadhamzeeigilani, T.
Patankar, T. Goddard; Leeds/UK
Keywords: Hemorrhage, Aneurysms, Stents, Embolisation, CT-Angiography,
CT, Neuroradiology brain, Interventional vascular, Arteries / Aorta
DOI: 10.1594/ecr2018/C-2777
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Page 1 of 17
Learning objectives
1. To gain insight into the factors to consider when deciding to treat intracranial
aneurysms (ICA) and how to select the most suitable device.
2. To review all endovascular devices used for treating intracranial aneurysms
3. To discuss the types of complications that may result from each treatment
Background
Endovascular techniques for treating intracranial aneurysms are now making treatment
increasingly safer and more effective with multiple new devices and treatment
combinations available. This can present a conundrum for the neuro-interventionist for
selecting the best treatment option.
Findings and procedure details
Endovascular options should be considered based on anatomic considerations such as
aneurysm geometry and morphology, peripheral access, and parent vessel anatomy.
Clinical presentation, patient medical history and comorbidities, as well as operator
experience are other important factors that must be evaluated.
Endovascular treatment with coiling of saccular aneurysm with a favourable neck has
been accepted as a safe procedure with better outcomes than surgical clipping as per
the international subarachnoid haemorrhage trial (ISAT). However, treatment of complex
aneurysms such as large, wide neck and fusiform ones remains technically challenging
for coiling, with a poor occlusion and high recurrence rate of up to 80%.
The use of novel devices including flow diverter devices (FDD) which include intra-
saccular devices within the aneurysm and endoluminal devices placed in the parent
vessel at the aneurysm neck has greatly increased the scope of treatment of ICAs to
those with more complex anatomy where coiling or clipping on their own are difficult or
impossible.
The indications and contraindications to ensure that endovascular treatment is the most
suitable initial or overall treatment must be carefully considered and are broadly covered
in Fig. 1 on page 8 .
Page 2 of 17
Fig. 1: Indications and contraindications for endovascular treatment of intracranial
aneurysms
References: E. Palkhi
SECTION 1: Anatomic and clinical considerations
A) Anatomic considerations
1) Peripheral vascular anatomy, aortic arch and great vessel anatomy
Access is commonly via the transfemoral route (transbrachial and transradial routes less
commonly used), followed by navigating the aortic arch and selection of the desired
carotid and vertebral artery.
i) Aortic arch and great vessels: Increased tortuosity of the great vessels and aberrant
branching patterns from the arch can make catheter access difficult
II) Cervical portion of the carotid and vertebral arteries: high-grade cervical stenosis and
excessive tortuosity may limit access and increase the risk of complications
iii) Intracranial vessel anatomy: individual variability is high and therefore careful planning
by the use of biplane angiography and roadmapping is necessary to increase procedural
safety and reduce the risk perforation. Increased tortuosity within a closed configuration
carotid syphon in the context of anterior circulation aneurysms, can also make catheter
tracking challenging.
2) Route of access
Most direct route available via ipsilateral carotid or vertebral artery, however it is important
to assess the patency of the circle of Willis to consider potential alternative routes based
on aneurysmal orientation and size; this is especially important in emergency situations
where there is loss of access from the ipsilateral side during treatment.
3) Aneurysm anatomy
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Aneurysms are often located branching points of parent arteries and where the course
of a vessel takes a curve.
I) Morphology and Geometry of the aneurysm
• Size: measured by maximum diameter dimension of the aneurysm dome
(small, large, giant)
• Shape: Saccular (most common) or fusiform, presence of irregularities,
presence of a daughter sac
• Neck size: wide neck >4mm or aspect ratio<2 (dome height to neck width).
The aspect ratio helps determine the need for adjuncts
• Geometric ratios: Increased Aspect ratio (dome height to neck width) and
size ratio (aneurysm size to parent artery size) are associated with a higher
risk of rupture.
II) Location and direction of the aneurysm relative to the parent artery
This has important implications for strategy used to access the inside of the lesion.
• Major vessel bifurcation aneurysms (carotid or basilar) are usually entered
o
with a straight or 45 angled microcatheter.
• Smaller branch vessel bifurcation (posterior communicating or ophthalmic
o
artery) often require 90 or J-shaped microcatheter access.
III) Presence of branch arteries in proximity to the aneurysm
• Branch vessel arising from parent artery or base of neck are usually safer to
treat with caution
• Branch vessels arising from higher up the neck base or dome are
associated with a high risk of ischaemic complications or with ineffective
treatment with poor occlusion grades.
B) Clinical considerations
• Patient comorbidity, age and performance status
• Presentation: ruptured or unruptured aneurysm (presence of SAH) or
symptomatic
SECTION 2: Types of Endovascular techniques, devices and delivery systems
Page 4 of 17
Reconstructive techniques involve direct occlusion of the aneurysm using coils, bridging
devices (balloons and stent remodelling) and novel standalone flow diverter devices
(FDD). Deconstructive techniques are far less commonly utilised and involve parent
artery occlusion hence stopping inflow at the origin of the aneurysm with or without
revascularisation.
1) Coiling
Used independently in treatment of saccular, narrow necked aneurysms with simple
anatomy. They are often utilised in the emergency setting as well.
Aneurysm occlusion is achieved by using gradually decreasing coil sizes. An adequate
frame is initially obtained by careful selection of the first coil corresponding to the size
of the aneurysm.
The early and late complications of endovascular coiling are summarised in Fig. 2 on
page 8 .
Fig. 2: Early and late complications of endovascular coiling
References: E. Palkhi
2) Assistive/bridging neck devices
These are not routinely used in ruptured aneurysms as they increase procedural duration
and complexity, risk of complications and often require antiplatelet medication.
i) Balloon remodelling
These are used to assist in coiling of wide necked aneurysms. A temporary occlusion
balloon is inflated across the aneurysm neck while embolization coils are introduced.
The balloon offers may advantages including control of coil and catheter which prevents
coil prolapse into the parent vessel, moulding of neck and origin of bifurcation, and rapid
inflation of the balloon in front of the aneurysm also limits bleeding in the context of intra-
procedural rupture. Balloon remodelling is technically challenging, requires many steps
and is associated with high morbidity and mortality.
ii) Intracranial stenting
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These help to provide support for coils even after their introduction into the aneurysm as
opposed to balloon remodelling. They are also used in increasingly complex lesions such
as those with a very wide neck or no neck, such as dissecting aneurysms and 'blister
like' aneurysms. They are associated with a relatively increased risk of thromboembolic
complications (requiring long term dual antiplatelet) and haemorrhagic complications.
3) Flow Diverter Devices
These can be broadly categorised into Endoluminal and Intra-saccular devices
i) Endoluminal devices
Endoluminal flow diverter devices are self-expanding, low porosity (high-mesh density
metal coverage stents) devices deployed across the aneurysmal segment within the
parent vessel with the intention of immediate change in regional circulation with diversion
of blood away from the aneurysm. The resultant aneurysmal stasis promotes thrombosis
within the aneurysm. Examples of endoluminal FDD are listed in Table 3.
Endoluminal flow diverters avoid access into the aneurysm thus reducing risk of intra-
procedural aneurysm rupture. They also provide better neck reconstruction and reduced
long-term recanalisation. Other advantages over endosaccular coiling are the ability to
treat the weakened abnormal arterial wall by providing a scaffold for neoendothelialisation
to occur. These devices have demonstrated superior results with good long term
compared to other treatment options for wide neck, complex aneurysms.
ii) Intra-saccular devices (flow disrupter devices)
Flow disrupters are flexible intrasaccular mesh devices suitable for treating complex
aneurysms of the bifurcations with a wide neck. The first available flow disruptor device
is the Woven Endobridge device (WEB) which is a self-expanding oblate braided mesh
of nitonol wires that is deployed into the aneurysm sac itself. Once deployed, the WEB
device induces thrombosis within the aneurysm.
The initial WEB device had dual layer (DL) design with inner and outer braids, however
this has since evolved to a single layer (SL) device with a higher density nitonol wires
achieving similar flow disruption effects. Additional modifications to the WEB device
include a spherical subtype (SLS) and enhanced visualisation due to platinum-coated
nitolol wires (EV). Furthermore, miniaturisation of the WEB devices (WEB 17 and WEB
21) has enabled delivery of these devices through smaller catheters.
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The advantages of intra-saccular device is the combination of an endosaccular approach
with flow diversion thereby eliminating the need for dual antiplatelet therapy and therefore
extending their use to the emergency setting of a ruptured aneurysm. One drawback of
the WEB device is that it does not involve neck reconstruction. Examples of intra-saccular
devices are listed in Fig. 3 on page 9 .
Fig. 3: Summary of types of FDD devices and novel neck reconstructive devices
References: E. Palkhi
Fig. 4: Case of a basilar artery aneurysm treated solely with an intra-saccular WEB
device (blue arrow) with successful post-treatment occlusion. Illustrations of the WEB
single and spherical subtype are also shown (right, Courtesy of Sequent Medical, see
References)
References: Leeds Teaching Hospitals NHS Trust - Leeds/UK
Fig. 5: CONTOUR device (blue arrow), an intra-saccular device currently offered on a
trial basis in the UK. 3D rotational angiography pre-treatment and post-treatment DSA
images show a case of basilar tip aneurysm (red arrow). Illustrations of the CONTOUR
devices shown (right image, Courtesy of Cerus Endovascular, see References)
References: Leeds Teaching Hospitals NHS Trust - Leeds/UK
Fig. 6: Case of a basilar artery tip aneurysm (red arrow) treated with coiling (yellow
arrow) and a pCONUS adjunctive device (blue arrows) with successful occlusion post-
embolization. pCONUS illustration on the far right image (Courtesy of Phenox, see
References)
References: Leeds Teaching Hospitals NHS Trust - Leeds/UK
Fig. 7: Case of a basilar tip aneurysm (light green arrow) treated with coiling (yellow
arrow) with a barrel stent (blue arrow). 3D rotational angiography (Left), DSA images of
approach with corresponding part of the barrel stent (middle) and post-treatment DSA
images with successful total occlusion demonstrated. (See references for illustration).
References: Leeds Teaching Hospitals NHS Trust - Leeds/UK
Fig. 8: A case of an elective right supraclinoid internal carotid artery aneurysm (red
arrow) treated with a pulserider stenting device (blue arrows) and 8 coils (yellow arrow)
with complete occlusion demonstrated. Pulserider device illustration (image on far right,
see references)
References: Leeds Teaching Hospitals NHS Trust - Leeds/UK
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Fig. 9: A case of an incidental partially thrombosed basilar tip aneurysm (red arrows)
treated with T-stenting using low profile self-expandable (LEO Baby stent, blue arrows)
and coiling (yellow arrows). Pre-treatment, approach, post-treatment DSA images are
demonstrated. No evidence of recurrence demonstrated at 2-year follow up. Illustration
of the LEO baby stent demonstrated on image on the right (See References)
References: Leeds Teaching Hospitals NHS Trust - Leeds/UK
Images for this section:
Fig. 1: Indications and contraindications for endovascular treatment of intracranial
aneurysms
© E. Palkhi
Page 8 of 17
Fig. 2: Early and late complications of endovascular coiling
© E. Palkhi
Fig. 3: Summary of types of FDD devices and novel neck reconstructive devices
© E. Palkhi
Page 9 of 17
Fig. 4: Case of a basilar artery aneurysm treated solely with an intra-saccular WEB device
(blue arrow) with successful post-treatment occlusion. Illustrations of the WEB single and
spherical subtype are also shown (right, Courtesy of Sequent Medical, see References)
© Leeds Teaching Hospitals NHS Trust - Leeds/UK
Page 10 of 17