describes surgical management of aneurysm and their new modalities of treatment based on global research

1. Surgical management of
Anterior Circulation
Aneurysm

2. Decision making for treatment of Intracranial
Aneurysm
• Two important goals in treatment of patients with intracranial
aneurysm:
• 1. complete, permanent aneurysmal occlusion
• 2. optimal preservation or restoration of patient’s neurological
function.

3. Factors associated with aneurysm rupture
• Aneurysm specific factors
• Size>7mm
• Irregular shape
• Posterior circulation
• Acom artery location
• Flow straight into aneurysm
• Associated with Av malformation
• High aspect ratio: dome-neck ratio> 1.6
• Previous SAH
• Wall shear stress

4. • Patient factors
• Female
• Age
• Smoking
• Hypertension
• Alcohol
• Family history of SAH

5. Neuroradiological evaluation
• Computed tomography
• MRI sequences
• CT Angiography: low sensitivity for aneurysm that are<5 mm in size
• MR Angiography
• Cerebral Angiography
• 3D rotational Angiography
• DSA is the gold standard
• 4 dimensional CTA and volume rendering and spin rotational, and 3D
DSA are used for surgical planning

6. Aneurysmal rupture risk
• Aneurysm size anterior posterior
• <7mm 0% 2.5
• 7-12mm 2.6 14.5
• 13-24mm 14.5 18.4
• 25 mm or > 40 50

7. Associated with poor surgical outcome
• Increased aneurysm size: four fold poor outcome when compared with
small aneurysm due to intimate association with small perforators, broad
aneurysm neck, intraluminal thrombosis, atherosclerosis in aneurysm neck
or dome
• Aneurysmal location: giant basilar, Acom , ICA bifurcation have greatest risk
• Calcification in aneurysm neck
• Atherosclerosis
• Aneurysm orientation and neck configuration
• Advanced patient age
• SAH
• Intracerebral haemmorhage

8. Aneurysm rebleeding
• 70-90% of patients who rebleed die
• Risk is greatest on day 1 and perhaps in first 6 hours after SAH
• It then occurs at a constant rate of 1-2% per day during subsequnent
4 weeks
• Factors associated are premorbid hypertension, poor clinical grade,
ICH, IVH, greater radhiographic severity of SAH, large aneurysm
size>10mm, and posterior circulation aneurysm
• Rebleeding reduced by administration of antifibrinolytic drugs

9. Hunt and Hess grade for SAH and associated
mortality

11. Intracerebral hemorrhage
• ICH complicates about 30% of ruptured aneurysm and increases
mortality after SAH
• Factors such as young age and better clinical grade, small ICH volume
25-50 ml and intrasylvian ICH are associated with better outcome
whereas decreasing percentage of ICH evacuations IVH and need for
EVD aggravate outcome.
• Improved patient outcome is seen when emergency ICH evacuation is
performed, particularly with simultaneous and successful aneurysm
obliteration.
• CTA obtained after head Ct is useful and can detect > 90% of
aneurysm > 3-5 mm in diameter.
• The spot sign on CTA is an indicater of active bleeding within ICH and
associated with increased risk of intraoperative aneurysm rupture.

12. Ruptured aneurysm and early vasospasm
• The cause of cerebral vasospasm still remains obscure. Several substances such as
serotonin, prostaglandins, catecholamines appear to have a vasoconstrictive effect on the
cerebral vessels.
• Recent evidence indicates that erythrocyte lysis within the subarachnoid spaces may play
a major role in the genesis of delayed clinically relevant cerebral vasoconstriction
following aneurysmal subarachnoid hemorrhage (SAH).
• The pathophysiology of brain ischemia following aneurysmal rupture, and the correlation
between angiographic vasospasm, neurological condition, intracranial pressure (ICP)
value, cerebral blood flow and CT findings. It is concluded that, at present, blood volume
expansion and/or induced hypertension, and pharmacological control of increased ICP
provide the best basis for clinical management of the cerebral ischemic complications of
SAH.
• Vasospasm is associated with poor outcome and between 10-15 % of patients will have
angiographic evidence of vasospasm within 48 hours of aneurysm rupture.
• Early surgery with aneurysm obliteration followed by immediate angioplasty (continuous
nimodipine infusion during embolization procedure) reduced the risk of poor outcome

13. Endovascular approaches to intracranial
aneurysm
Core principles are :
1. Create a stable construct: primary goal is to occlude the aneurysm from the
parent circulation while maintaining patency of parent vessels
2. Balance anticoagulation: unlike open approaches, endovascular occlusion
involves both physical occlusion and thrombus formation. And the balance can
shift depending on clinic scenario like in ruptured aneurysm, endovascular
construct selected on rapid aneurysm occlusion without the need for adjuvant
antiplatelet therapy such as primary coil or ballon assisted coil construct.
3. Promote endothelization: healing process that excludes the aneurysm from
circulation is dynamic and slow. Within the first week after coil occlusion, an
unorganized thrombus composed of cell mass and fibrin forms within coil mass
and in subsequent week collagen deposition occurs and over 3-12 months
tissue vascularization occurs

16. • Associated with better short term outcomes whereas surgical
techniques are more durable and associated with better aneurysm
occlusion and rebleeding
• Complete or >90% occlusion observed in 50-90% of small aneurysm
with narrow neck with endovascular technique
• Technical complications like intraprocedural aneurysm perforation,
distal embolization, parent vessel occlusion, coil migration are
observed
• Risk factors for thromboembolic complications are older age, MCA
location, longer procedural time, female gender, while
intraprocedural rupture risk are more asso with Acom aneurysm small
aneurysm size.
• Antiplatelet agents are required when stents are deployed and limit
the utility of stent after SAH

17. Barrow ruptured aneurysm trial (BRAT)

18. Endovascular for narrow necked aneurysm

19. • EVT is the first methodology for any narrow necked aneurysm regardless of
rupture status.
• Anterior communicating aneurysm: here, difficulties may arise from
successful catheterization of the A1 segment or may be caused by
torturosity of a1-A2 segement ( due to catheter stability) and due to
angiomorphology of aneurysm because of presence of presence of
multiple arterial branches. Well orientation of aneurysm related to parent
vessel must be delineated. Status of contralateral a1 segment influence the
choice of EVT. If the contralateral A1 segment is absent, it is paramount
that the ACoA is not impigned by the coil massin order to preserv blood
flow to distal contralateral ACA. acoA directed inferiorly or posteriorly are
difficult to treat. Selecting an angled catheter or custom steam shaping a
microcatheter decrease the kick out during coil embolization. Frequent
manipulation may increase the chances for iatrogenic perforation or
rupture of aneurysm. Ballon remodelling technique may provide distinct
advantages. Often the a1 segment providing the dominant inflow is the
best route for the approach of microcatheter. If the vessel is too torturous
to accomadate a ballon microcather, a bilateral approach is necessary.

20. • Opthalmic artery aneurysm: more readily treated with EVT. Clipping
often requires drilling of ACP and optic strut to completely delineate
the aneurysm neck and due to proximity with ICA to dural ring and
cavernous sinus, surgical exposure of carotid artery is required and
lastly the proximity with optic nerve. The origin of opthamic artery
must be identifiedto minimize chances of iatrogenic occlusion. The
risk of monocular vision loss should prompt consideration of surgical
treatment. If identified as distinct from neck of aneurysm, EVT is
ideal. The use of ballon microcatheter help in support of
microcatheter during deployment of coils. The risk of ischemic events
with ballon inflation can be mitigated by patent PcoA and AcoA.

21. • MCA aneurysm: when located at Mca bifurcation, an aneurysm may
be intimately related with M2 branches, precluding successful coil
embolization. Compromise of these branch by impringement from
the coil mass can result in significant ischemia or thrmoembolic
complications.location close to surface of brain makes surgical
treatment attractive. For EVT, it is difficult to obtain clear working
angle and distal locate makes the navigation challenging. Often the
MCA is 2 mm or less at bifurcation , increasing the chance of vessel
injury during balloon catheter inflation.
• Flow diverting stents such as PED, are used to teat distal circulation
aneurysms and small, narrow necked aneurysm. Other devices like
WEB help treat wide neck bifurcation aneurysm withoutneed for
adjunctive devices or stents

22. Wide neck aneurysm
• Necks greater than 4 mm or dome to neck ratio <2
• There is inverse relationship between increasing neck width beyond
4mm and ultimate coil packing density.
• Wide opening at neck leaves the parent artery at risk of
thromboembolic complications.
• As for ruptured aneurysm, it is better managed with EVT. But
maintain balance between risk of coil herniation associated TEC and
packing density become more difficult as CSF diversion procedure are
required in setting of SAH (dual antiplatelet therapy is required for
EVT) and SAH creates prothrombotic state and risk of TEC increases.

23. • Dual coiling catheter technique prevent coil herniation: framing coil is
advanced through one of catheters and not detatched to provide stability
during embolization. The other catheter is then advancedinto frameand
the second catheter is used to pack the frame with progressively smaller
and softer coils. The framing coil is then detatched after the other catheter
has been removed
• Balloon assisted coiling techniques: allowing the aneurysm neck to be
temporarily obstruct withballon inflation while coils are advanced. The
balloon is then deflated and if coils appears stable, it can be deattched.
• Temporary stenting technique: retrievable stent is partially deployed across
the neck of aneurysmwith second catheter jailed in aneurysm. Following
embolization, stent is resheated and removed, provided no coil loops are
herniating.
• Flow diversion: deploying stent of lower porosity in the parent artery
spanning the aneurysm neck. Luminal metal coverage is generally around
30-40% the struts distrupts the normal arterial flow into aneurysm fundus,
creating stasisand serves as scaffols for endothelization eventually leads to
thrombosis and exclusion of aneurysm
• Stent assisted coilingembolization

24. Anterior circulation aneurysm
• 85-95% of all aneurysm
• Acom and DACA (30-35%)
• MCA (20-25%)
• Pcom (25-30%)
• ICA bifurcation (5%-7%)

25. Anterior communicating artery aneurysm
• The single most common site of aneurysms presenting with SAH.
• May also present with diabetes insipidus (DI) or other hypothalamic dysfunction.
• CT scan SAH in these aneurysms results in blood in the anterior interhemispheric
fissure in essentially all cases, and is associated with intracerebral hematoma in
63% of cases
• Intraventricular hematoma is seen in 79% of cases, with the blood entering the
ventricles from the intracerebral hematoma in about one–third of these.
• Acute hydrocephalus was present in 25% of patients (late hydrocephalus, a
common sequelae of SAH, was not studied).
• Frontal lobe infarcts occur in 20%, usually several days following SAH.
• One of the few causes of the rare finding of bilateral ACA distribution infarcts is
vasospasm following hemorrhage from rupture of an ACoA aneurysm. This results
in prefrontal lobotomy-like findings of apathy and abulia.

26. • Aneurysm are situated deeply and in midline, have bilateral
anterograde arterial supply from paired A1 segments.
• Increased risk of ishemic complications stems from close proximity of
aneurysm to paired A1 and A2 segments, 2 recurrent arteries of
heubner, 2 orbitofrontal A, 2 frontopolar A, and ACoA
• Tackling of aneurysm should be done from the side of dominant A1
segment.
• Acess to AcoA junction gained through opening of 3 arachnoid
cisterns: carotid, chiasmatic and lamina terminalis
• AcoA complex is most common location of ruptured aneurysm

28. • Angiographic considerations Essential to evaluate contralateral carotid, to determine if
both ACAs fill the aneurysm. If the aneurysm fills with one side only, it is desirable to
inject the other side while cross compressing the side that fills the aneurysm to see if
collateral flow is present. Also, determine if either carotid fills both ACAs, or if each ACA
fills from the ipsilateral carotid injection.
• If additional views are needed to better demonstrate aneurysm. Try oblique 25° away
from injection side, center beam 3–4 cm above lateral aspect of ipsilateral orbital rim,
orient X-ray tube in Towne’s view. A submental vertex view may also visualize the area
but the image may be degraded by the large amount of interposed bone.
• Surgical treatment
• Approaches
• 1. pterional approach: the usual approach
• 2. subfrontal approach: especially useful for aneurysms pointing superiorly when there
is a large amount of frontal blood clot (allows clot removal during approach)
• 3. anterior interhemispheric approach contraindicated for anteriorly pointing
aneurysms as the dome is approached first and proximal control cannot be obtained
• 4. transcallosal approach

30. • Pterional approach
• Side of craniotomy: A right pterional craniotomy is used with the
following exceptions (for which a left pterional crani is used):
• 1. large ACoA aneurysm pointing to right: left crani exposes neck
before dome
• 2. dominant left A1 feeder to aneurysm (with no filling from right A1):
left craniotomy provides proximal control
• 3. additional left sided aneurysm(use shoulder roll, rotate head 60°
from vertical).
• Craniotomy (slightly more frontal lobe needs to be exposed than,
e.g. for a p-comm aneurysm).
• Lumbar drain assists with brain relaxation

31. • Microsurgical dissection
• Dissect down Sylvian fissure with gentle retraction of frontal lobe away from base of skull.
Olfactory nerve visualized first, then optic nerve.
• Open arachnoid over carotid and optic cistern and drain CSF. Elevate temporal tip, coagulate any
bridging temporal tip veins that are present, and expose ICA. Follow the ICA distally, looking for
A1 (the exposure of which allows temporary clipping in the event of rupture).
• If the A1 take-off is too high, it may be hidden and would require excessive retraction to expose.
Options to increase exposure include
• 1. gyrus rectus resection: a 1 cm long gyrus rectus corticectomy is performed just medial to the
olfactory tract. Helps find the ipsilateral A1 and often ACoA and A2. This is also helpful for
downpointing aneurysms because it permits visualization of the contralateral A1 before exposing
the dome of the aneurysm (for proximal control). May lead to neuropsychiatric deficits. A subpial
resection is performed with preservation of the small arterial branch that is consistently located
here
• 2. fronto-temporal-orbital-zygoma removal
• 3. splitting the Sylvian fissure
• 4. ventricular drainage Once found, A1 is followed until the ipsilateral A2 is identified. Then the
contralateral A2 is identified and is followed proximally until the contralateral A1 is exposed. The
a-comm is usually encountered in the process.
• Critical branches to preserve: recurrent artery of Heubner; small ACoA perforators (may be
adherent to aneurysm dome). If the aneurysm cannot be clipped, it may be trapped by clipping
both ends of the ACoA only if each ACA fills from the carotid on its own side. Post clipping, some
authors recommend fenestrating the lamina terminalis in an effort to reduce the need for post-op
shunting.

32. • Anterior interhemispheric approach
• Involves minimal brain retraction. More suitable for an aneurysm
that points straight up, but even with this proximal control is poor.
• Position: supine with the neck extended ≈ 15°.
• A transverse skin incision is made in a skin crease in the lower
forehead. This describe using a 1.5 inch trephine craniotomy in the
midline just superior to the glabella. Alternatively, better advantage of
the dural opening may be possible with a more rectangular opening.
The dural flap is hinged on the superior sagittal sinus. The depth of
the aneurysm is ≈ 6 cm from the dura. Proximal control of the A1
branch of the ACA is difficult with this approach.

33. • Distal anterior cerebral artery aneurysms
• Aneurysms of the distal anterior cerebral artery (DACA) (i.e., the ACA distal to the
ACoA) are usually located at the origin of the frontopolar artery, or at the
bifurcation of the pericallosal and callosomarginal arteries at the genu of the
corpus callosum.
• Aneurysms located more distally are usually posttraumatic, infectious (mycotic),
or due to tumor embolus.
• DACA aneurysms are often associated with intracerebral hematoma or
interhemispheric subdural hematoma since the subarachnoid space is limited
here.
• Conservative treatment of DACA aneurysms is often associated with poor results.
Unruptured DACA aneurysms have a higher incidence of bleeding than
unruptured aneurysms in other locations. These aneurysms are fragile and
adherent to the brain, which predisposes to frequent premature intraoperative
rupture. Best treated with open microsurgical treatment
• On arteriography, if both ACAs fill from a single sided carotid injection, it may be
difficult to make the important determination as to which ACA feeds the
aneurysm. Multiple aneurysms are commonly associated with DACA aneurysms.
• Treatment. Aneurysms up to 1 cm from the ACoA may be approached through a
standard pterional craniotomy with partial gyrus rectus resection.

35. • Aneurysms > 1 cm distal to the ACoA up to the genu of the corpus callosum, including those of
the pericallosal/callosomarginal bifurcation, may be approached surgically by a basal frontal
interhemispheric approach via a frontal craniotomy using a bicoronal skin incision.
• The patient is positioned supine with the neck slightly extended, positioned vertically or just a
few degrees to the left. A right sided craniotomy is preferred in most instances (exception:
aneurysm dome buried in the right cerebral hemisphere making retraction hazardous), but should
cross to the contralateral side by a couple centimeters. It must be taken all the way to the floor of
the frontal fossa to permit exposure of the anterior cerebral artery for proximal control. The
craniotomy extends ≈ 8 cm above the supraorbital ridge in order to provide way in
circumnavigating veins bridging to the superior sagittal sinus. The dural flap is based on the
superior sagittal sinus. If the sinus needs to be mobilized, it may be divided low anteriorly.
• ACA aneurysms distal to the genu of the corpus callosum may also be approached by an
interhemispheric approach using a unilateral skin incision.
• For these, the patient’s neck is not extended, and a parasagittal craniotomy is used that doesn’t
need to be as low on the frontal fossa. The cingulate gyri may be difficult to separate, and care
must be taken because excessive retraction may pull the cingulate gyrus off the dome of the
aneurysm and produce premature rupture.
• Ideally, A2 proximal to the aneurysm should be identified initially for proximal control and then
followed distally to the aneurysm. When this is not possible, dissection should follow distal ACA
branches proximally toward the aneurysm, taking care not to disturb the aneurysm. Often, a
portion of the cingulate gyrus may need to be removed and sometimes up to 1–2 cm of the
anterior corpus callosum may need to be divided

36. • Surgical complications: Prolonged retraction on the cingulate gyrus
may produce akinetic mutism that is usually temporary. The
pericallosal arteries are small in caliber and may be atherosclerotic,
which together increases the risk of occlusion of the parent artery
with the aneurysm.

37. • Middle cerebral artery (MCA) aneurysms
• The following considers MCA aneurysms of the M1-M2 junction
(referred to as “trifurcation” region, although this is not a true
trifurcation).
• Surgical treatment
• Approaches
• 1. transsylvian approach through a pterional craniotomy: this is the
most commonly used approach
• 2. superior temporal gyrus approach
• a) advantages: minimizes brain retraction, possible reduced
vasospasm from manipulation of proximal vessels
• b) disadvantages: proximal control difficult, slightly larger bone flap,
possible increased risk of seizures

39. • Microsurgical dissection
• Dissect down Sylvian fissure with major vector of retraction on tip of
temporal lobe (less on frontal lobe than in ACoA aneurysm). Open
arachnoid and drain CSF. Elevate temporal tip, coagulate bridging
temporal tip veins, and expose the ICA for proximal control in the
event of rupture. Follow the ICA distally by splitting the Sylvian fissure
to expose the M1 (again, for proximal control).
• Although exposure for proximal control is helpful to have as a
contingency, one may be able to avoid temporary clipping of the MCA
in the event of intraoperative rupture by controlling bleeding with a
large suction, and subsequent clip placement (since the blood flow
through the MCA is not as voluminous as through the ICA, and the
surgical access to these aneurysms is usually fairly unrestricted).
• Critical branches to preserve: distal MCA branches, recurrent
perforators from the origin of the major MCA branches

40. • paraclinoid aneurysms
• Applied anatomy The carotid artery exits the cavernous sinus and enters the subarachnoid space
at the dural constriction known as the carotid ring (AKA clinoidal ring). Arising from ICA Between
the roof of cavernous sinus and origin of posterior communicating artery.
• Classified as: 1.dorsal 2. ventral 3. carotid cave 4. global type.
• The supraclinoid portion of the carotid artery may be divided into the following segments
• 1. ophthalmic segment: the largest portion of the supraclinoid ICA. Lies between the take-off of
the ophthalmic artery and the posterior communicating artery (PCoA) origin. The proximal
portion of this (including the origin of the ophthalmic artery) is often obscured by the anterior
clinoid process.
• Branches include: a) ophthalmic artery: usually originates from the supracavernous ICA just after
the ICA enters the subarachnoid space. Enters the optic canal positioned inferolateral to the optic
nerve
• b) superior hypophyseal artery: the largest of several perforators supplying the dura of the
cavernous sinus and the superior pituitary gland and stalk
• 2. communicating segment: from the PCoA origin to the origin of the anterior choroidal artery
(AChA)
• 3. choroidal segment: from AChA origin to the terminal bifurcation of the ICA

42. • Ophthalmic segment aneurysms (OSAs) :
• 1. ophthalmic artery aneurysms
• 2. superior hypophyseal artery aneurysms:
• a) paraclinoid variant: usually does not produce visual symptoms
• b) suprasellar variant: when giant, may mimic pituitary tumor on CT Presentation (excluding
incidental discovery) Ophthalmic artery aneurysms Arise from the ICA just distal to the origin of
ophthalmic artery.
• They project dorsally or dorsomedially towards the lateral portion of the optic nerve.
• Presentation: 1. ≈ 45% present as SAH
• 2. ≈ 45% present as visual field defect:
• a) as the aneurysm enlarges it impinges on the lateral portion of the optic nerve → inferior
temporal fiber compression → ipsilateral monocular superior nasal quadrantanopsia
• b) continued enlargement → upward displacement of the nerve against the falciform ligament (or
fold) → superior temporal fiber compression → monocular inferior nasal quadrantanopsia
• c) in addition to near-complete loss of vision in the involved eye, compression of the optic nerve
near the chiasm may also produce a superior temporal quadrant defect in the contralateral eye
(junctional scotoma AKA “pie in the sky” defect) from injury to the anterior knee of Wilbrand
(nasal retinal fibers that course anteriorly for a short distance after they decussate in the
contralateral optic nerve15)
• 3. ≈ 10% present as both

43. • Superior hypophyseal artery aneurysms
• Originate in the small subarachnoid pocket medial to the ICA near the
lateral aspect of the sella.
• The direction of enlargement is dictated by the size of this pocket and the
height of the lateral sellar wall, resulting in two variants: paraclinoid &
suprasellar.
• Suprasellar variant may actually grow to a size large enough to compress
the pituitary stalk and cause hypopituitarism and “classic” chiasmal visual
symptoms (bilateral temporal hemianopsia).
• Angiographic considerations A notch can often be observed in the anterior,
superior, and medial aspects of giant ophthalmic artery aneurysms due to
the optic nerve.
• If additional views are needed to better demonstrate aneurysm. Try
oblique 25° away from injection side, center beam 3–4 cm above lateral
aspect of ipsilateral orbital rim, orient X-ray tube in Towne’s view. Try
submentovertex view.

44. • Surgical treatment
• Ophthalmic artery aneurysms If necessary, the ophthalmic artery may be sacrificed
without worsening of vision in the vast majority. Clipping a contralateral ophthalmic
artery aneurysm is not technically difficult, and is not uncommonly required as OSAs are
often multiple. The aneurysm arises from the superomedial aspect of the ICA just distal
to the ophthalmic artery origin, and projects superiorly. Cutting the falciform fold early
decompresses the nerve, and helps minimize worsening of visual deficit from surgical
manipulation.
• For unruptured aneurysms, drill off anterior clinoid via an extradural approach before
opening dura to approach neck; for ruptured aneurysms, this may not be as safe. In most
cases, a side-angled clip can be placed parallel to the parent artery along the neck of the
aneurysm.
• Superior hypophyseal artery aneurysms If necessary, the superior hypophyseal artery on
one side may be clipped without demonstrable deleterious effect (due to bilateral supply
to stalk and pituitary). Clipping a contralateral superior hypophyseal aneurysm is not
really feasible. With a usual pterional approach, the carotid artery is usually encountered
first, and with large aneurysms is usually bowed laterally towards the surgeon. Clinoidal
removal is usually required. The entire ICA wall may appear to be involved, and it may
necessitate temporary ICA clipping (with cerebral protection) to reconstitute the ICA
using encircling clips parallel to the parent vessel

45. Thank You