n many ways, giant proximal carotid artery aneurysms arethe prototype for all giant aneurysms. They frequentlyanifest with mass effect, their neck may be calcified, and
heir wall may be heterogeneous and thick. Proximal occlu-ion of the cervical internal carotid artery (ICA) does notliminate filling from cavernous-carotid branches or the oph-halmic artery. Proximal exposure may be difficult to obtainnd requires careful removal of bony skull base structures.btaining distal control of the ICA is difficult when an aneu-
ysm is large and the posterior communicating artery (PCoA)ust be exposed. An aneurysm is rarely obliterated with one
lip, and fenestrated clips are frequently required.Successful repair of giant ICA aneurysms requires signifi-
ant microvascular experience as well as multimodality pre-perative imaging and testing. Rotational angiography and-D computed tomography (CT) angiography are useful innderstanding the vascular morphology. Magnetic resonance
maging (MRI) helps to determine the true size of the lesionnd to evaluate the condition of the surrounding brain and
onathan White, MD, Department of Neurological Surgery, The Universityof Texas Southwestern Medical Center at Dallas, Dallas, TX.
ddress reprint requests to Jonathan White, MD, Assistant Professor, De-partment of Neurological Surgery, The University of Texas SouthwesternMedical Center at Dallas, 5323 Harry Hines Blvd., Dallas, TX 75390-
he relationship of the aneurysm to structures such as theptic nerve.Endovascular expertise also must be available to treat these
esions. Preoperative trial balloon occlusion can determinehe patient’s tolerance of temporary occlusion and the feasi-ility of permanent proximal arterial sacrifice. Endovascularacrifice of the parent vessel may avoid the need for openurgery, and in a few lesions coil embolization may be anffective therapy.
In many ways giant ICA, particularly carotid-ophthalmicneurysms, are the prototype for giant intracranial lesions.hey often become symptomatic with vision loss related toass effect on the optic nerve. The aneurysmal neck is often
alcified, and the tissue is frequently thick and heteroge-eous. Their size makes obtaining proximal and distal con-rol difficult. The proximal carotid is one of the most com-on sites for giant aneurysms and accounts for almost one-
hird of the lesions in our series. Common types includephthalmic aneurysms, PCoA aneurysms, and broad-basedefects of the posterior carotid wall. In contrast, the shorteck and absence of calcium of a giant ICA aneurysm arising
ust distal to the ophthalmic artery (Figs. 1 and 2) make theepair more straightforward.
This article presents the evaluation and preoperative plan-ing for repair of these lesions. Treatment options include
Microsurgical and endovascular treatment of ICA aneurysms 79
rapping of the aneurysm either with or without prior bypass,nd surgical or endovascular sacrifice of the parent vessel.he choice of treatment primarily depends on the morphol-gy of the aneurysm as determined by preoperative studies,he patient’s general health, the presence or absence of symp-omatic mass effect, and the mode of presentation. Technicaletails regarding trial balloon occlusion, vascular sacrifice,tent-assisted coiling, and direct surgical reconstruction iseviewed.
reoperative Evaluationubarachnoid hemorrhage is one mode of presentation ofiant ICA aneurysms. These patients typically undergo CT atheir initial presentation. As with smaller aneurysms, reviewf the patients’ medical condition, evaluation for hydroceph-lus, and evaluation of airway control in obtunded patientsre primary. Often even a noncontrasted CT scan shows aiant aneurysm and identifies calcification of the lesion,hich can significantly increase the difficulty of clip recon-
truction. CT helps to determine the relationship of the lesiono the anterior clinoid process and frontal sinuses.
MRI is useful for identifying intraluminal thrombus. Aarge discrepancy in the size of lesions on MRI and angiogra-hy is because of debris within the aneurysm, which leavesnly a residual portion filling. Almost always these lesionsust be emptied of their contents before clipping. MRI alsoay help determine the location of an aneurysm when it isnclear from angiography alone. MR angiography (MRA) andT angiography (CTA) can be useful adjuvant studies. Inarticular, CTA allows three-dimensional reconstruction ofhe vessels and can help identify vessels arising from the neckr, rarely, from the dome.Angiography is essential in the evaluation of proximal ca-
otid lesions. Their relationship to the ophthalmic arteryelps determine whether a portion or even an entire aneu-
igure 1 Giant aneurysm arising distal to the ophthalmic artery.
ysm is in the cavernous sinus. Anterior-to-posterior projec- S
ions provide the best understanding of the relationships tohe carotid bifurcation. Angiography also provides evidencebout the presence of thrombus within the dome of the an-urysm and helps to identify the rare fusiform lesion.
For asymptomatic patients or those presenting with massffect and no hemorrhage, careful review of the diagnostictudies can help estimate the risk of surgical treatment, and toome degree, the risk of rupture. Once these studies are com-lete, it is possible to decide if the aneurysm should bereated and, if so, what form of treatment is best.
alloon Test Occlusion (BTO)he goals of BTO in patients with a giant aneurysm are toetermine the patient’s tolerance for temporary arterial oc-lusion during the vascular reconstruction of these lesionsnd to determine if permanent parent vessel sacrifice is aossibility if the lesion cannot be clip-reconstructed ade-uately.1-3
In interpretation of a BTO results, we consider both neu-ological changes and cerebral blood flow (CBF) as demon-trated by single photon emission computer tomographySPECT).4 Even mild asymmetries in CBF are clinically rele-ant. In this situation, sacrifice of a vessel places the patient atsignificant risk for stroke. If a perfusion defect is seen when
he balloon is inflated, a second baseline study with no bal-oon is obtained on another day. A fixed perfusion defectelated to an old stroke or injury is not an indication of aailed BTO. A reversible defect seen only when the balloon isnflated suggests that sacrifice of the vessel will not be toler-ted.
natomic Difficultieseveral features shared by giant ICA aneurysms and otheriant lesions make their repair difficult. The neck may be
igure 2 Postoperative angiogram of the giant aneurysm in Figure 1.
hort neck and absence of calcification facilitated its repair.
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road along the parent vessel, and the origin of the distalessels may be extended some distance along the neck. Theresence of calcium makes it difficult for the clip to com-letely occlude the neck, forcing the clip blades down ontohe normal parent artery. Furthermore, the heterogeneousature of the neck may allow residual filling even when thehick walls of the neck appear to be in apposition.
Other difficulties are unique to the ICA location. Its prox-mity to the skull base seldom allows proximal intracranialontrol of the carotid artery. The cervical ICA may need to bexposed. Furthermore, the anterior clinoid process and optictrut often need to be removed to allow sufficient visualiza-ion of the proximal carotid artery. The ophthalmic artery cane difficult to identify, thereby allowing the aneurysm toontinue to fill during the opening, evacuation, and repair.roximity to the optic nerve can also be a problem. Thistructure is often draped thinly over the dome. The PCoAay be obscured by the large aneurysm mass, and fetal PCoA
an eliminate trapping as a repair option. The anterior cho-oidal artery also frequently adheres to the aneurysmal dome,articularly lesions of the more distal ICA. This end vesselauses significant neurologic deficit if sacrificed, and its areaf supply poorly tolerates protracted temporary occlusion.
ndovascular Technique foriant Carotid Aneurysmse must reiterate our preference for surgical clip-reconstruc-
ion of giant intracranial ICA. This technique is the best wayo eliminate the mass effect typically associated with theseesions. Endovascular treatment often ameliorates mass effectxerted on cranial nerves III, IV, and VI by cavernous aneu-ysms,5 but its results in treating optic nerve compression isore suspect.6 In fact, we have had to remove the coils fromreviously treated aneurysms because of the deterioration ofpatient’s vision (Fig. 3). Rates for the preservation of the
phthalmic artery are poor with endovascular techniques,articularly when the intracranial ICA is sacrificed. Ophthal-ic artery occlusion can cause blindness, although estimates
igure 3 Intraoperative view of a previously coiled ophthalmic arteryneurysm. Visual deterioration led to surgical decompression of theptic nerve.
f this risk vary from 0 to 20%.7 n
The recanalization rates associated with giant aneurysmsreated with bare platinum coils are high8 although this prob-em may improve as newer technologies become available.herefore, we reserve endovascular therapy for patientshose poor medical condition or particularly unfavorable
natomy makes them poor candidates for direct surgical re-onstruction such as those with a heavily calcificed or veryroximal aneurysmal neck. Two endovascular options areossible: endovascular occlusion or parent vessel sacrifice.
ndovascular Occlusionhis basic technique of stenting and coiling is detailed in therticle “General Endovascular Techniques” in this issue. Briefly,microcatheter large enough to accommodate the full size-
pectrum of coils (Excelsior 10-18, Boston Scientific Neuro-ascular, Fremont, CA) is navigated under road-mappinguidance into the proximal one-third to one-half of the an-urysm fundus. Coils are placed sequentially, starting withhe largest and stiffest coil, to form an outer basket just insidehe wall of the aneurysm. Coiling proceeds with successivelymaller and softer coils to fill the remaining spaces as com-letely as possible. These aneurysms often have quite longecks. We frequently place an intracranial stent across theeck of these lesions to help insure that the aneurysm is filledompletely while the parent vessel is preserved (Fig. 4).
arent Vessel Sacrificehis technique requires the patient’s tolerance of a priorTO, both clinically and by blood flow measurements. If theatient fails the BTO according to either criterion, a bypassrocedure must be performed before the vessel is sacrificed.ypically, a high-flow saphenous vein graft or radial artery issed for the bypass.Under full heparinization, a Meditech 8.5-mm balloon
atheter is navigated over a 0.038� exchange wire to a distalosition in the cervical ICA. The balloon is attached to aontinuous heparinized saline flush solution. An angio-raphic run is performed for road-mapping guidance. At thisuncture it is critical to inspect the angiogram and confirmhat a sufficiently long perforator-free distal vessel is availableor safe coil placement. A microcatheter (Excel 10-18, Bostoncientific Neurovascular, Boston Scientific, Fremont, CA) isavigated over a microguidewire (Agility 14, Cordis Neuro-ascular) distal to the aneurysm. The proximal balloon is
igure 4 Intracranial stenting allows endovascular repair of broad-
ecked aneurysms.
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Microsurgical and endovascular treatment of ICA aneurysms 81
nflated for the duration of the vessel sacrifice to halt ante-rade flow and to prevent potential distal thromboembolihrough the developing coil mass.
Coiling then proceeds distally to proximally, starting withmaller coils sized to the distal vessel. As successive coils areeployed, the microcatheter gradually rebounds proximally
nto the aneurysm. A larger coil to match the aneurysm ishen required. The aneurysm and parent vessels are thenccluded with coils in a manner similar to endovascular oc-lusion. After the aneurysmal segment is completely oc-luded, we reinforce the coil mass by placing smaller coils inhe carotid artery proximal to the aneurysm. We find thatydrocoils (Microvention) are particularly effective for vessel
acrifice. Their swelling characteristics rapidly occlude ves-els with fewer coils than other types of coils.
Postprocedurally, patients remain heparinized for 48ours with a prothrombin time of 50 to 70 seconds. Aspirin325 mg/day) is initiated immediately after the procedure toinimize emboli. Decadron (4 mg) is administered every 6ours to minimize the temporary development of increasedass effect, which frequently accompanies the formation of
hrombus in giant aneurysms. Close monitoring of the pa-ients in the intensive care unit (ICU) is critical because ade-uate collateral circulation develops over time. A central ve-ous catheter is placed to monitor central venous pressurend administer vasopressive agents if needed. Patients areept euvolemic and normotensive. Initially, they are kept flatfter the procedure. The head of bed is only gradually ele-ated over 1 to 2 days as tolerated. Despite preoperativeolerance of BTO, some patients require a more prolongedtay in the ICU because of their temporary need for hyper-ensive hypervolemic therapy.
urgical Techniqueervical Carotid Exposure
efore opening the dura, proximal control of the internalarotid artery is obtained by exposing the cervical carotid in
igure 5 Typical incision for a pterional craniotomy.
he neck. A linear incision is made along the medial boarder t
f the sternocleidomastoid muscle, and the platysma is di-ided using electrocautery. A transverse incision provides aore cosmetically appealing scar but has the disadvantage of
imiting exposure of the carotid.9 A self-retaining retractor islaced to expose the cervical fascia, which is divided sharplylong the medial boarder of the sternocleidomastoid muscle.
The carotid sheath is opened and the internal jugular veins identified. The common facial vein, which usually markshe level of the carotid bifurcation, is identified. This vein cane ligated and divided to facilitate exposure. The commonarotid artery (CCA), external carotid artery (ECA), and ICAre then identified. The ECA is characterized by its lateral-ost location, its smaller size and, most importantly, by theresence of cervical branches.The hypoglossal nerve crosses the carotid artery in the
igure 7 Aggressive resection of the sphenoid wing and smoothingf the floor of the anterior cranial fossa facilitate exposure and limit
he need for an orbitotomy.
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egion of the bifurcation and should be identified to avoidnjury. The vagus nerve runs in the carotid sheath but isypically deep to the vessels in the dissection and does noteed to be mobilized. A vessel loop is placed around the ICA,hich is where the temporary clip is placed. If the ICA is to be
acrificed, it is best done by stick tying the vessel twice. Theessel is then cut between the ties as flush to the CCA andCA as possible. The proximal stump is oversewn with a.0-prolene suture.
raniotomyor most giant ICA aneurysms, the head is rotated 20 to 40egrees with lateral flexion and extension to allow the frontalnd temporal lobes to naturally fall away from the cranialossa floor. A standard frontotemporal scalp incision begins 1m anterior to the tragus at the level of the zygoma and isontinued superiorly in a straight line 8 to 10 cm to theuperior temporal line. The incision curves gently anteriorlyo the midline at the level of the hairline (Fig. 5). The scalpap and temporalis muscle are elevated in a single layer andeflected with self-retaining retractors. Expanding the expo-ure via this use of an orbital or zygomatic resection is com-on, but we have rarely found these maneuvers helpful. A
hree or four-holed craniotomy is performed with the flapxtended as low as possible to the orbital roof (Fig. 6).
After the bone flap is elevated, a generous subtemporalraniectomy is performed as inferiorly as possible into theemporal fossa, to allow adequate retraction of the temporalobe. A critical aspect of the exposure is an aggressive resec-ion of the lateral aspect of the sphenoid ridge,10 typicallyith a high-speed drill and rongeurs. A thin cortical layer of
he superior and lateral posterior orbital bone is left. Thenner table of the frontal bone is removed over the supraor-ital exposure to flatten all bony protuberances on the floorf the anterior cranial fossa as well as along the sphenoiding (Fig. 7). The anterior clinoid process can be drilled in an
xtradural fashion by continuing the drilling medially andlevating the temporal lobe dura from the dura of the cavern-us sinus. We do not remove the clinoid in this fashion;ather, we resect it intradurally as follows.
The dura is opened in a curvilinear fashion based on thephenoid wing and retracted against the bony craniotomyefect to minimize epidural bleeding. Waiting until this point
n the procedure to perform a ventricular puncture allowsemoval of CSF and provides excellent assistance in achiev-ng brain relaxation. Landmarks to puncture the frontal hornf the lateral ventricle have been previously described.11
The operating microscope is now brought into the operat-ng field and is used for the remainder of the operation untillosure.
ntradural Dissectionor most giant lesions it is helpful to open the sylvian fissure.oing so is most easily accomplished by beginning distallylong the sylvian fissure and entering the fissure deeply. Dis-ection is continued in a distal-to-proximal fashion. Distaliddle cerebral arteries (MCAs) are identified and dissection
ontinues toward the MCA trunk. Once the M1 trunk haseen reached, dissection continues into the carotid and optic
isterns. If the lesion is large enough, it may be necessary to t
btain control distal to the carotid bifurcation by identifyinghe anterior cerebral artery in addition to the MCA. Smalleins crossing the fissure can be coagulated and divided toncrease the field of view dramatically.
Continued dissection onto the distal ICA is possible. Thenterior choroidal artery is identified on the lateral aspect ofhe ICA followed by identification of the PCoA. The PCoAust be occluded temporarily to trap the aneurysm com-letely because it is rarely possible to place a temporary cliproximal to the origin of the PCoA when dealing with a giantneurysm.
The proximal neck of the aneurysm is seldom well visual-zed because the large aneurysmal mass and anterior clinoidrocess obstruct the view. This bony structure is removed bypening the flap of dura covering the protrusion and drillingt with a high-speed diamond drill. The optic strut, a bridgef cortical bone from the clinoid to the lateral wall of thephenoid sinus, also should be removed. The roof of the opticanal is formed partially by overlying dura known as thealciform ligament. It should be cut to minimize compressionf the nerve during manipulation of the carotid artery. Aortion of the bony roof of the optic canal, which is very thin,lso may need to be removed. Drilling medial to the roof ofhe optic canal should be avoided because it allows entry intohe sinus air spaces and can result in a CSF leak that isifficult to repair.Before clipping it is often necessary to trap the aneurysm
ompletely to open the dome and remove the thrombus fromithin. Proximal control has already been established in theeck, but control of the ophthalmic artery, PCoA, anteriorhoroidal artery, and distal ICA is necessary to accomplishhis debulking. For proximal lesions that are not enormous,he distal temporary clip can be placed on the ICA proximalo the anterior choroidal artery. This placement is ideal be-ause the anterior choroidal artery is an end vessel that poorlyolerates prolonged temporary occlusion. Often the size ofhe lesion or a more distal location of the aneurysm neckrevents placement of the temporary clip proximal to thehoroidal artery. In some situations there is no room on theCA for the temporary clip. Then distal control must be ob-ained by placing clips on the anterior cerebral artery and
CA just distal to the bifurcation of the ICA. Even withemporary clips on the cervical ICA, ophthalmic artery,CoA, A1, and M1 back bleeding from the cavernousranches of the carotid artery can cause continued filling ofhe aneurysm if the dome is opened. The use of retrogradeuction through the cervical ICA can deflate the lesion beforet is opened and facilitate clipping.12
igure 8 Suction aspiration of a proximal giant aneurysm by aspira-
ion of the cervical ICA.
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Microsurgical and endovascular treatment of ICA aneurysms 83
etrograde Suction-ecompression Technique
fter adequate surgical exposure of the carotid bifurcationas been obtained, vessel loupes are placed around the CCA,CA, and ICA. The preoperative arteriogram is inspected toonfirm absence of plaque in the area desired for puncture,ypically the proximal ICA. If significant plaque is present, wese the CCA as the puncture site and temporarily occlude theCA.Burst suppression anesthesia is induced with thiopen-
athol, and a bulldog-style vascular clamp is placed on theervical ICA. Temporary clips are then placed on the distalntracranial vessels, typically the distal ICA and PCoA. Doingo usually softens the aneurysm, but cavernous ICA branchesend to keep it persistently full. To overcome this problem, a6-gauge angiocatheter needle is inserted into the cervicalCA. Suction is applied with either a 10 mL syringe or walluction (Fig. 8). Feedback from the surgeon observing theneurysm is critical. Inadequate suction-decompression canccur with suboptimal placement of the angiocatheter, re-uiring its repositioning.
eck Dissection and Clip Applicationnce proximal and distal control has been obtained, it isossible to complete the dissection of the neck. As described,
f the lesion contains little thrombus, it can be made moreanageable by retrograde suction and deflation. This defla-
ion is facilitated by circumferential dissection of the aneu-ysm dome. Clip application is also facilitated by freeing theome of its attachments to the surrounding brain and opticerve. An attempt should be made to complete as much ofhe dissection as possible before temporary arterial occlusion,ncluding removal of vessels adherent to the aneurysm dome.or an ophthalmic lesion, multiple periods of proximal oc-lusion can be used to identify the origin of the ophthalmicrtery when the tense, blood-filled dome of the aneurysmbscures it. For large ophthalmic and particularly PCoA le-ions, the PCoA must be identified. In this case, a short pe-iod of proximal occlusion can be used to soften the aneu-ysm. In the case of giant PCoA aneurysms and thosenvolving the posterior carotid wall, the anterior choroidalrtery is often adherent to the dome of the aneurysm. Thisessel must to be mobilized carefully to avoid injury duringlip application.
Many giant aneurysms are at least partially filled withhrombus that must be removed to permit accurate and ef-ective clip placement. With practice the aneurysm can bevacuated within 5 to 10 minutes of temporary local circula-ory arrest. After application of temporary clips, the domehould be incised at least three clip breadths distal to theneurysm’s neck in a direction parallel with the long axis ofhe parent artery. This orientation provides ample room forermanent clip placement and permits amputation of thentire distal fundus, if necessary, to mobilize the aneurysmeck for clipping. A long linear incision is made, and theltrasonic aspirator should be used to evacuate only throm-us in the neck and proximal fundus of the aneurysm. Theoal is to fashion a suitable neck for clip placement as quickly
s possible. The remaining bulk of the aneurysm can be dealt o
ith, if necessary, after the neck is closed and blood flow haseen restored.Once all proximally located thrombus has been evacuated,
he neck should be gently approximated with fine forceps. Ifasily accomplished, the surgeon can proceed directly to per-anent clip application. If the neck resists closure, the fundal
ncision should be extended in a circumferential fashion,ffectively forming a cuff that is free from the remainder of theome. The walls of this cuff can then be approximated first byhe forceps and then by permanent clips.
The neck of most giant aneurysms will have an orifice thatxtends several millimeters along the parent vessel. For thiseason, application of the clip in parallel to the long axis ofhe vessel is least likely to cause a tear at the aneurysmal neckr to produce stenosis of the parent vessel. After the initiallip is placed, brisk continued filling of a giant lesion is com-on. This filling may occur because the first clip fails to span
he entire neck, which is common with proximal lesionshen the clip extends toward the skull base. This problem
an be treated by application of a second, longer clip inandem. Another possible explanation for persistent filling ishat the heterogeneous wall of the aneurysm is too thick toermit clip closure. Alternatively, it allows a thin portion ofhe neck to remain tented open between thicker portions ofhe neck. This problem can be overcome by applying a seriesf clips in tandem until no dome filling is seen. A fenestratedlip also can be used in this situation. The closing force ofhese clips is greater than that of a long straight clip. Thehicker wall of the dome can be incorporated into the fenes-ration with the distal blades closing on the thinner aspect ofhe neck, which is still patent.
Many giant lesions have a broad-based, expansive necknd often lie on the opposite side of the vessel from surgicalerspective. In such cases, a series of fenestrated clips can ben excellent way to close the neck (Fig. 9). In placing a stackf clips the first clip must span the proximal neck of theneurysm. If residual filling is present at the end of placinghis construct, the first clip placed is often the culprit. Be-ause the cervical carotid artery is already exposed, an intra-
igure 9 Intraoperative view of a series of stacked, fenestrated clipsbliterates the neck of a giant aneurysm projecting from the deepspect of the exposure.
perative angiogram is readily obtained and helps avoid in-
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dvertent parent vessel occlusion or significant residualneurysm.
ntraoperative Angiographyn intraoperative angiogram is performed after the aneurysm
s clipped and all temporary clips have been removed. Theptimal angiographic angle achieved in the operating rooman be obtained by inspecting the best projection on thereoperative angiogram and approximating this view withhe C-arm. After complete aneurysm occlusion and proximal/istal parent vessel patency is confirmed, one additional an-iographic study is obtained. It is centered on the cervicalarotid artery to inspect for possible vessel injury or dissec-ion.
esultsiant ICA aneurysms are a heterogeneous group of difficult-
o-treat lesions. Clinical outcomes in this patient populationre related to patient-specific issues (eg, neurologic statusnd medial comorbidities), aneurysm-specific issues (eg,eurologic status and medial comorbidities), aneurysm-spe-ific issues (eg, size, exact location, contents, morphology,nd collateral circulation), and finally, the treatment modal-ty employed.
Although direct surgical reconstruction with complete an-urysm obliteration and preservation of both afferent andfferent vasculature with avoidance of local or distal ischemias the ideal outcome, it is often impossible to accomplish. Inseries of 312 giant aneurysm (all locations) at our institu-
ion, good clinical outcomes were seen in 64% of patients.owever, some degree of residual aneurysm was evident on0% of routine postoperative angiograms. Occlusion or ste-osis of one arterial branch was seen in more than 10% ofases. Postoperative subarachnoid bleeding occurred in 2.2%f patients.Before the introduction of BTO, Hunterian ligation of the
CA was associated with a 49% incidence of ischemic com-lications and angiographic evidence of aneurysm thrombo-is in 75% of paraclinoid aneurysms and on fewer than 50%f supraclinoid lesions.
onclusioniant ICA aneurysms are the single most common family ofiant lesions and can be divided into cavernous, ophthalmic
egment, and posterior carotid wall lesions.13 The proximity
f ophthalmic segment lesions to the skull base often requireservical-carotid exposure and even retrograde suction to re-air the lesion. While cavernous lesions make excellent en-ovascular candidates, intracranial lesions seldom do be-ause of their tendency to manifest with optic nerve massffect, the presence of a large neck, and the presence of in-ralumenal thrombus that allows for coil compaction. Thedvent of intracranial stenting has been a significant advancen the endovascular treatment of the lesions. BTO allows theurgeon to determine whether prolonged temporary occlu-ion or vessel sacrifice can be tolerated. It can therefore allowhe utilization of selective cerebral bypass. Proximal ligationlone carries the highest subsequent risk of hemorrhage ands rarely needed at these locations.2
eferences1. Taki W, Sakai N, et al: Circulatory arrest with profound hypothermia
during the surgical treatment of large internal carotid artery aneurysm:Case report. Neurol Med Chir (Tokyo) 38:725-729, 1988
2. Drake CG, Peerless S J, Ferguson GG: Hunterian proximal arterialocclusion for giant aneurysms of the carotid circulation. J Neurosurg81:656-665, 1994
3. DeVries EJ, Sekhar LN: A new method to predict safe resection of theinternal carotid artery. Laryngoscope 100:85-88, 1993
4. Mathews D, Waler BS: Brain blood flow SPECT in temporary balloonocclusion of carotid and intracerebral arteries. J Nucl Med 34:1239-1243
5. Kazekawa K, Tsutsumi M: Internal carotid aneurysms presentingwith mass effect symptoms of cranial nerve dysfunction: Efficacyand imitations of endovascular embolization with GDC. Radiat Med21:80-85
6. Malisch TW, Guglielmi G: Unruptured aneurysms presenting withmass effect symptoms: Response to endovascular treatment withGuglielmi detachable coils: Part 1. Symptoms of cranial nerve dysfunc-tion. J Neurosurg 89:956-961, 1998
7. Shaibani A, Khawar S: Temporary balloon occlusion to test adequacy ofcollateral flow to the retina and tolerance for endovascular aneurysmalcoiling. AJNR AM J Neuroradiol 25:1384-1386, 2004
8. Standard SC, Guterman LR: Endovascular management of giant intra-cranial aneurysms. Clin Neurosurg 42:267-293, 1995
