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11 Neurointerventions Including Aneurysm Interventions
109
Table 11.3 Endovascular aneurysm treatment techniques
1. Endosaccular lling
a. Simple coiling
b. Balloon-assisted coiling
c. Stent-assisted coiling
d. Combined balloon and stent-assisted coiling
2. Flow diversion and vessel wall healing
a. Parent artery occlusion
b. Stent graft
c. Flow diverter
3. Combined/hybrid
a. Intra-aneurysmal ow disruptors
11.3.8 Endovascular Techniques
Historically, endovascular treatment of aneurysms has
evolved along two lines: (i) lling the aneurysmal lumen
with embolic materials for which detachable coils have
evolved as the most suitable ones; and (ii) diverting the ow
away from the aneurysm thereby promoting aneurysmal
thrombosis and healing of the neck. Endovascular aneurysm
treatment techniques are summarized in Table11.3.
11.3.9 General Technical Guidelines
• Access: The most common access used is a transfemoral
or transradial access with a 8F/6F puncture. The choice
between transfemoral and transradial access depends on
the patient’s anatomy, the procedure being performed, the
requirement of a coaxial or triaxial system, and the preferences of the operator.
• Approach/tortuosity: In patients with tortuous anatomy, it
is very crucial to have a stable positioning of the guide
catheter. The triaxial system with most possible distal
placement of the guide catheter (up to cavernous ICA)
provides enhanced support and stability.
• Antiaggregation [11]: Any procedure which requires an
intracranial stent will incite an inammatory response
with platelet activation and clot formation. To prevent
this, adequate antiplatelet priming at least for 3–5days is
to be done. The optimal dose and treatment regimen varies from operator to operator. The most commonly used
regimen is aspirin (150mg/day) and clopidogrel (75mg/
day) orally. Other drugs available in the market are prasugrel and ticagrelor. In emergent situations, the loading
dose of aspirin + clopidogrel (300mg each) or the infusion of abciximab or tiroban infusion is advocated.
• Aneurysm morphology: Saccular aneurysms are classied into narrow and wide-necked aneurysms. Narrow
neck aneurysms (<4mm) are more favorable for endosaccular lling. Wide neck/bifurcation aneurysms often
require scaffold/assistance to contain the coils within the
aneurysmal sac. For minimally wide-necked aneurysms
(4–7 mm), balloon assistance (i.e., inated across the
neck) would sufce; while very wide neck aneurysms
require the assistance of a stent or a ow diversion technique. The fusiform/dissecting aneurysms require ow
diversion and vessel wall repair techniques to heal.
11.3.10 Simple Coiling
• The discovery of detachable coils by Gugilemi revolutionized the aneurysm management. Simple coiling is
particularly suitable for narrow neck aneurysms
(neck<4 mm) and remains a widely used treatment
method at many centers.
• The procedure begins with proling the aneurysm and its
neck in an appropriate position followed by safe placement of microcatheter inside the aneurysm.
• Shaping of the microcatheter tip is important, and the
same is dictated, in a given case, by the aneurysm morphology, location, and parent artery curvatures. For
instance, S shape is preferred to cannulate superior
hypophyseal artery aneurysm.
• After microcatheter placement, the aneurysm is lled progressively by tiny platinum coils. The rst coil is the
framing coil (3D coil), the largest possible one, chosen
based on the aneurysm dimensions measured followed by
lling coils and nishing coils, which are usually soft 2D
coils (Fig.11.1).
• There are various types of coils available, including bare
coils, coated coils, and bioactive coils. Bare coils are simple platinum coils. Bioactive coils have a coating of
thrombogenic materials (like nitinol, hydrogel, or
polyglycolic- polylactic acid) over the coils.
• The complications encountered during the procedure
include aneurysmal rupture and coil extrusion, coil prolapse, and coil stretching.
11.3.11 Balloon-Assisted Coiling
• The advent of balloon microcatheters helped extend coiling to relatively wide necked (4–7mm) aneurysms, especially in acute SAH settings (Fig.11.2).
• Balloon microcatheters are either double lumen or single
lumen and are compliant or extra compliant to conform
with the parent vessel/aneurysmal neck.
• The balloon is inated across the neck of the aneurysm
during coiling to prevent coil prolapse.
• Dilute contrast (usually 50%) is used to inate the balloon. Utmost attention is required during the balloon
preparation as per the vendor guidelines for ensuring
110
L. J. D. Sebastian and N. G. Reddy
Fig. 11.1 Simple coiling in
ruptured PCOM aneurysm
In A, sentinel hematoma in right
parasellar location with SAH
extensively in basal cisterns
In B, lobulated right PCOM
aneurysm is noted
In C, after the stable position of
the microcatheter, progressive
coiling is done
In D, check run shows complete
packing with obliteration of the
aneurysm
a
c
b
d
good visibility, avoiding mixture of gas bubbles and to
prevent overination during the procedure.
• The ination time of the balloon is to be kept to minimum
to prevent ischemia and thromboembolic complications.
(ideally <3min).
• Inated balloon can also serve as a temporary tamponade
in case of intraprocedural aneurysmal rupture.
11.3.12 Stent-Assisted Coiling
• Stent-assisted coiling is useful in the treatment of widenecked aneurysms (Fig.11.3).
• The stent is placed in the parent artery such that it straddles the neck of the aneurysm, creating a scaffold that
supports and retains the coils within the aneurysm. It also
helps promote neointimal growth and ow diversion (to
some extent).
• Stents are classied as open- and closed-cell stents based
on cell shape. They are divided into laser cut and braided
stents based on make. They are either fully or partially
retrievable.
• Antiaggregation priming is needed for a minimum of
3days in elective procedures, and loading dose is administered in emergency situations. There is also a need for
long-term dual antiplatelet therapy to prevent stent
thrombosis.
11 Neurointerventions Including Aneurysm Interventions
111
a
d
b
e
c
f
Fig. 11.2 Balloon assisted coiling in ruptured terminal ICA aneurysm
In A, a large aneurysm is seen in the left suprasellar location with SAH
and IVH
In B and C, lateral and AP proling shows large aneurysm with a
pseudolobule
• The delivery microcatheter sizing is different for different
stents and makes. The coiling catheter is either jailed or
placed through the struts of the stent. Pre-planning
includes appropriate sizing of the stent and determining
the landing zones.
• Complications include foreshortening of the stent and
poor apposition with the parent wall.
In D, after the stable position of microcatheter, coiling is begun
In E, a 4×20mm balloon protective device was placed from ICA to M2
MCA
In F, nal check run showing near complete obliteration of the
aneurysm
11.3.13 Flow Diverter/Braided Stents
• Braided stents are closed cell stents, which are used both
in stent-assisted coiling and as standalone procedures.
Flow diverters are braided stents with higher metal density and smaller individual cell sizes and shapes
(Fig.11.4).
112
L. J. D. Sebastian and N. G. Reddy
Fig. 11.3 Solitaire assisted
coiling in a cavernous ICA
aneurysm
In A, lateral view, a paraclinoidal
aneurysm is noted
In B, after jailing the microcatheter in the aneurysm, solitaire
(4×30mm) stent is deployed
from terminal ICA to cavernous
ICA
In C, progressive coiling through
the microcatheter was achieved
In D, nal check run showing
obliteration of the aneurysm
a
c
b
d
• The introduction of ow diverters has shifted the focus
from aneurysm lling/occlusion to promoting vessel wall
healing in the management of aneurysms. The mechanism of action is by altering the wall shear stress and creating a scaffold for endothelial cell growth.
tional to its porosity. Porosity is the fraction of metal-free
area per total stent surface area. Pore density is the number of pores per unit area. Low porosity offers greater
ow reduction into the aneurysm with better ow diversion; however, it limits the exibility of the device.
• Pre-planning involves decision-making and proper positioning with good landing zones (avoiding the perforator
branches) and good apposition to prevent endoleak and
thrombus formation.
• As there is high metal density, antiplatelet priming is of
utmost importance to prevent stent thrombosis.
11.3.14 Stent Graft
• Stent grafts are balloon-mounted covered stents, which
offer cost-effective solutions in large extradural aneurysms (Fig.11.5).
• However, their intracranial use is off label due to their
stiff, rigid nature, and covered nature; Hence, it is used
mainly in the straight segments such as the arteries of the
neck. They are not used in intradural arteries as they have
multiple delicate tiny perforators.
• They provide reinforcement and sealing of weakened vessel walls with complete exclusion of the aneurysm.
• Complications include less conformability in tortuous
arterial segments with few long-term follow-up cases
showing asymptomatic vessel occlusion.
11 Neurointerventions Including Aneurysm Interventions
113
Fig. 11.4 Flow diverter in a
large cavernous ICA
aneurysm
In A and B, a large aneurysm
from the petro-cavernous ICA is
noted
In C, deployment of the FD is
seen
In D, check run shows decreased
lling with stasis in the aneurysm
a
c
b
d
11.3.15 Parent Artery Occlusion
• Parent artery occlusion (PAO) or feeder artery occlusion
(FAO) is a technique where the artery supplying blood to
the aneurysm is intentionally occluded—either for sealing the aneurysm or to create a ow reversal/diversion.
Reversal of the direction of blood ow in the parent arterial segment that harbors the aneurysm promotes healing
of the neck and shrinking of the aneurysm. Coils/detachable balloons are used to occlude the artery (Fig.11.6).
• Patency of the circle of Willis should be assessed before
planning PAO. Similarly, the site of origin and size of
various important branches in the feeder artery and any
variant anatomy thereupon are to be borne in mind.
Hence, pre-planning includes balloon occlusion tests for
checking the adequacy of collateral ow and other aspects
explained above. The site of PAO should be carefully
selected such that adequate ow reversal is ensured.
• PAO proves very useful in the treatment of large/giant dissecting aneurysms of the posterior circulation, which are
otherwise very difcult to treat.
• PAO may also be considered for giant dissecting aneurysms of ICA as a last resort.
11.3.16 Endosaccular Devices
• Endosaccular ow disruptors create intra-aneurysmal
ow disruption and remodeling at the aneurysm-parent
artery interface. The entire device is deployed in the aneurysm and disrupts blood ow entering and exiting the
aneurysm. The mesh across the neck can act as a scaffold
for neoendothelial growth. Bifurcations aneurysms like
MCA bifurcation and basilar top aneurysms are more
suitable for their use.
• Presently available devices are WEB, Contour, LUNA,
and Medina devices.
114
L. J. D. Sebastian and N. G. Reddy
a
e
Fig. 11.5 Stent graft placement for the treatment of giant dissecting
aneurysm at right lacero-cavernous ICA
In A, giant dissecting aneurysm at right lacero- cavernous ICA
In B, the guiding catheter was placed distal to the aneurysm
In C, stent-graft was placed
b
f
c
g
In D, native image showing kinking in mid-segment
In E, good cross ow is noted from the contralateral ICA
In F, the balloon is expanded
In H, a follow-up scan shows complete exclusion of the aneurysm
d
h
• WEB: Woven endobridge is an endosaccular nitinol
braided cage used in wide-necked bifurcation aneurysms.
WEB sizing is based on the maximal diameter of the
aneurysm.
• Medina: It is a self-expanding mesh containing multiple
leaets (petals) that help with ow diversion. It is a hybrid
system combining the design of a detachable coil and
endosaccular ow disruptor.
• LUNA: It is a self-expanding, mechanically detachable,
ovoid ow disruptor.
• Contour: This device has a cup-like conguration and
conforms to the shape of the lower half of the aneurysm
and the aneurysm neck. Sizing is based on the maximum
diameter of the aneurysm.
• While ow disruptors offer advantages in terms of their
targeted approach, and a reduced need for long-term antiplatelets, a limitation is their high cost.
11 Neurointerventions Including Aneurysm Interventions
115
a
e
b
f
c
g
d
h
Fig. 11.6 Parent artery occlusion of RVA for treating the dissecting
aneurysm from proximal basilar and terminal left vertebral arteries
involving left PICA origin
In A and B, dissecting aneurysm is noted from proximal basilar and
terminal left vertebral arteries involving left PICA origin
In C, the right prominent PCOM is noted. Left vertebral artery is hypoplastic (not shown)
In D, a detachable balloon is inated in distal right V3 segment
In E, right ICA run, post-occlusion of RVA by detachable balloons,
reveals lling of basilar artery through PCOM
11.4 Management ofSubarachnoid
Hemorrhage
Aneurysmal Subarachnoid hemorrhage (SAH) is a lifethreatening emergency. Understanding its pathophysiology,
complications and management is a must for any
neurointerventionist.
11.4.1 Pathophysiology
Aneurysm rupture is a complex pathophysiologic event.
Following aneurysmal SAH, there is sudden increase in
intracranial pressure (ICP), reduced cerebral blood ow
In F, native image shows an inated balloons occluding V2–V3
segment
In G, follow-up DSA after 3months shows occlusion of the right vertebral artery
In H, right ICA run reveals lling of basilar artery with no opacication
of aneurysm. Patient was asymptomatic at 3 month follow up
(Note: detachable gold ball balloons were cost- effective alternatives to
coils and were used in high-ow stulas like CCF and in PAO.How
ever they are no more available in India)
(CBF), decreased tissue oxygen supply, and impaired cerebral autoregulation. Systemic abnormalities such as
decreased total systemic blood volume, hyponatremia, activation of the coagulation and brinolytic system, and cardiopulmonary dysfunction also ensue.
11.4.2 SAH-Evaluation andImmediate
Management
Sudden severe headache, often described “thunderbolt headache” or “headache of life,” is highly suggestive of
SAH.Headache can be followed immediately by vomiting,
various extent of focal neurological decits, altered senso-
116
L. J. D. Sebastian and N. G. Reddy
Table 11.4 Modied Fischer’s grading in SAH
Category Criteria
Grade 0 No SAH or IVH
Grade I Minimal/thin SAH (<1mm in thickness) with no IVH
Grade II Minimal/thin SAH (<1mm in thickness) with IVH
Grade III Dense/thick SAH (>1mm in thickness) with no IVH
Grade IV Dense/thick SAH (>1mm in thickness) with IVH or
associated with ICH
rium, and loss of consciousness. In some patients, the symptoms can be milder or different, e.g., acute onset third nerve
palsy.
Whenever SAH is suspected, non-contrast head CT
(NCCT) is the imaging modality of choice for conrming the
diagnosis and grading its severity. Modied Fisher grade
(Table11.4) is widely used for grading of SAH on NCCT as
it has high prognostic value; higher grades are associated
with subsequent complications of SAH, especially vasospasm. Different clinical scoring systems are also available
to stratify these patients at presentation. World Federation of
Neurological Surgeons (WFNS) and Hunt and Hess scale are
popular ones [12, 13].
Acute SAH patients must be clinically stabilized, and
basic life support should be ensured and ABC approach (airway, breathing, circulation) applies in this regard. Some of
the other aspects of acute management before securing the
aneurysm are listed as follows:
1. Fluid management: Large bore IV line/ preferably central
line is needed to maintain euvolemia.
2. Patients are generally kept nil orally till the culprit aneu-
rysm is secured.
3. Hydrocephalus: CSF diversion is generally preferred
after securing aneurysm. However, hydrocephalus with
rapid deterioration may warrant immediate procedures
like EVD.
4. BP management: High BP can precipitate aneurysm rup-
ture, while hypotension can compromise cerebral perfusion. Hence, maintaining BP in higher-normal range is
preferred before securing an aneurysm.
5. Prophylaxis for cerebral vasospasm using calcium chan-
nel blockers (e.g., Nimodipine) is generally administered.
However, blood pressure should be maintained in optimal
range as described above.
6. Anticonvulsants: Any seizure event can precipitate aneu-
rysm rupture. Hence, prophylactic anticonvulsants are
instituted in SAH patients, even though no denite evidence exists for this practice [14].
After initial stabilization, the next immediate goal should
be denite management of the aneurysm, which can either
be surgical (clipping) or endovascular. The next section deals
with the management of immediate and delayed complications that may ensue.
11.4.3 Management ofComplications
Endovascular (or surgical) treatment of aneurysm is just one,
though essential, component of SAH management, as these
patients are prone to a variety of complications, the extent
and severity of which depend on the initial grade.
Nevertheless, these complications and the ability to treat
them or otherwise decide the nal outcome of the SAH
management.
Cerebral Vasospasm It is one of the most dreaded complications of SAH, which occurs between 4 and 14days of
ictus, peaking at 7days. The diagnosis is by the combination of clinical and imaging ndings. Any unexplained
clinical deterioration, especially in the period mentioned
above, should raise the suspicion of cerebral vasospasm.
CT or MRI may show multifocal or sometimes territorial
developing infarcts. Perfusion studies (CTP/ASL) will
demonstrate areas of decreased cerebral perfusion.
Angiographically visible cerebral arterial narrowing may
or may not accompany these changes. There are many different treatment regimens proposed in the literature for the
management of SAH related vasospasm. We describe one
of the common protocols which is also followed in our
institution:
1. Prophylactic calcium channel blockers, e.g., intravenous
nimodipine is started in all patients on admission.
2. Oral nimodipine is proven to be effective [15]. Hence, it
is imperative to change to oral nimodipine as early as possible after aneurysm treatment. It can also be administered through a nasogastric tube.
3. In patients not responding to the above, intravenous milrinone can be started.
4. After securing the aneurysm, blood pressure should be
elevated so as to raise the cerebral perfusion. Intravenous
nor=adrenaline infusion may be started to maintain high
B.P.
5. Adequate hydration should be maintained. Central venous
pressure monitoring is useful to maintain euvolemia.
6. Intra-arterial nimodipine is given in patients deteriorating
in spite of the above treatment. Frequent intra-arterial
administration—daily or every 12h—may be required in
some patients [16]. In some centers, the femoral sheath is
left in situ for a few days.
7. Magnesium sulfate and papaverine are some of the alternate drugs useful in vasospasm. Superior cervical ganglion block is also used in some centers.
8. Use of balloon angioplasty and stents is reserved for
symptomatic patients with recalcitrant vasospasm [17].
Delayed Cerebral Ischemia
spasm although microcirculation thrombosis is implicated.
This is closely related to vaso-
11 Neurointerventions Including Aneurysm Interventions
117
Apart from vasospasm treatment, IV heparin or low molecular weight heparin or aspirin are believed to improve cerebral
ischemia [18, 19].
Hydrocephalus Patients should be closely monitored for
increase in hydrocephalus. CSF diversion in the form of
EVD or VP shunt may be needed.
Hyponatremia Regular monitoring of electrolytes is
part of the routine management of SAH.Hyponatremia is
very common in the rst 2weeks. Syndrome of inappropriate secretion of antidiuretic hormone (SIADH) and
cerebral salt wasting are important causes [20]. Urinary
sodium and osmolality will help in the differential diagnosis of these conditions and institution of appropriate
treatment.
Hypokalemia Patients with potassium level less than
3meq% may need either oral or IV replenishment.
Infections Prophylaxis Routine broad-spectrum antibiotics are started in patients needing ventilatory support and
those with multiple in-dwelling catheters.
Ventilation Care/Early Tracheostomy Patients requiring
prolonged ventilatory support should be monitored for
ventilator associated pneumonia (VAP). It is better to go for
an early tracheostomy.
Miscellaneous If the patient is expected to be bedridden for
more than 7 days, DVT prophylaxis should be started.
Appropriate bedding and proper nursing care are essential to
prevent bed sores. Oral hygiene should be maintained.
Physiotherapy and Rehabilitation Patients discharged
with residual decits should be guided for appropriate physiotherapy and rehabilitation programs.
11.5 Follow-Up andMonitoring
All patients who have undergone an endovascular procedure are advised to undergo check angiogram after
3–6months to conrm the aneurysm occlusion. Aneurysm
can regrow secondary to coil compaction, extension of arterial dissection, or de novo new aneurysm formation. Larger
aneurysm recurrences require repeat treatment, whereas
small neck compactions can be followed up with serial
imaging. Follow-up angiogram are also important in downstepping antiplatelet agent once aneurysm/parent artery has
healed.
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