Endovascular Treatment of Multiple Aneurysms Involving thePosterior Intracranial Circulation

Tarik F. Massoud, Guido Guglielmi, Fernando Vinuela, and Gary R. Duckwiler

Summary: The results of surgery on multiple intracranial aneu-rysms that involve the vertebrobasilar circulation are poor, andassociated patient mortality remains high. We describe the en-dovascular treatment of four patients with multiple aneurysmsthat involved the posterior intracranial circulation. Satisfactoryocclusion of all aneurysms was achieved by using electrolyticallydetachable coils, and all patients had a good clinical recovery.Our early experience suggests that endovascular coil occlusionmay be a particularly suitable method for treating this high-riskcondition.

Index terms: Aneurysm, embolization; Aneurysm, intracranial;Interventional instruments, coils

Intracranial saccular aneurysms are the maincause of nontraumatic subarachnoid hemor-rhage, and are responsible for about 22% to 25%of all deaths relating to cerebrovascular events(1). The presence of multiple intracranial aneu-rysms, especially when involving the posteriorintracranial circulation, represents an evenhigher risk than does a single aneurysm, be-cause there is a higher associated mortality inpatients with multiple lesions (2, 3). In addition,the risk of rebleeding from the original aneu-rysm is higher and occurs earlier in this group ofpatients (4). Unfortunately, the literature sug-gests that there is no clear-cut strategy regard-ing the optimal management of multiple intra-cranial aneurysms (3).In recent years, endovascular treatment of

intracranial aneurysms has gained acceptancefor poor surgical candidates or difficult/inoper-able aneurysms. The occlusion of intracranialaneurysms by use of Guglielmi electrically de-tachable coils (Target Therapeutics, Fremont,Calif) and electrothrombosis has recently beenintroduced as a safe and controllable therapeu-tic method via the less invasive endovascular

route (5). The endovascular treatment of mul-tiple intracranial aneurysms by using simplecoils has been reported previously in one pa-tient (6). We describe our experience in theocclusion of eight aneurysms in four patientsusing Guglielmi electrically detachable coilsand highlight the benefits of this technique fortreating this particular subset of patients. Case 2has been reported previously (7).A detailed description of the mechanical

structure of the electrically detachable coils hasalready been published (8). Recently, improve-ments to this device have been made (9).Briefly, the main components include a 175-cmstainless steel core soldered to a very soft plat-inum coil varying in length from 4 to 30 cm (upto 40 cm previously). The latter has a circularmemory that allows it to be deposited in thedome of the aneurysm without traumatizing thefragile wall. The diameter of the detachable coilcan be 0.025 or 0.038 cm (0.010 or 0.015 in),and it is manufactured to be used in conjunctionwith a special version of Tracker 10 or 18 mi-crocatheters (Tracker microcatheters with twomarkers manufactured by Target Therapeutics,Fremont, Calif). Most procedures are performedwith the patient awake under neuroleptic anal-gesia and with systemic heparinization. Via thetransfemoral route, a Tracker microcatheter isadvanced coaxially through a 6F guiding cath-eter and into the aneurysmal sac. After checkangiography, a 1.0- to 1.5-mA/2.0- to 3.1-Vpositive direct electrical current is applied to theproximal end of the stainless steel delivery wire.The negative ground pole is connected to aconductive pad positioned on the patient’s skin.In 2 to 6 minutes the current dissolves the stain-less steel immediately proximal to the platinum

Received October 26, 1994; accepted after revision June 30, 1995.Presented at the 32nd Annual Meeting of the American Society of Neuroradiology, Nashville, May 1994.From the Department of Radiological Sciences, Endovascular Therapy Service, University of California at Los Angeles Medical Center.Address reprint requests to Tarik F. Massoud, MD, Endovascular Therapy Service, Department of Radiological Sciences, University of California at Los

Angeles Medical Center, 10833 Le Conte Ave, Los Angeles, CA 90024.

AJNR 17:549–554, Mar 1996 0195-6108/96/1703–0549 q American Society of Neuroradiology

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Fig 1. A–E, Left vertebral arteriograms show a midbasilar artery aneurysm (A) and delivery of the larger first coil (B), which acts asa nest for the subsequent coil. A right internal carotid arteriogram (C) shows an aneurysm of the posterior communicating artery and coilsin an occluded aneurysm of the basilar artery. After successful embolization of both aneurysms, as seen on a left vertebral arteriogram(D) and a right internal carotid arteriogram (E), a small residual aneurysmal neck is seen in the basilar artery aneurysm on the frontalview.

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coil by electrolysis, allowing the platinum coil todetach within the aneurysm. The delivery wire isthen withdrawn. More coils can be introducedand detached according to the size of the aneu-rysm. At the end of the procedure, the micro-catheter is removed and an angiogram is ob-tained to assess aneurysmal occlusion andparent vessel patency. A repeat angiogram isobtained in 3 to 5 days.

Case Reports

Case 1

A 41-year-old woman sustained a subarachnoid hem-orrhage after a 2-year history of occipital headaches. An-giography revealed an aneurysm of the right posteriorcommunicating artery and another aneurysm of a mid-basilar artery fenestration. Both aneurysms were occludedby using Guglielmi electrically detachable coils (Figs 1A–

E), the posterior communicating artery aneurysm with 30cm of platinum and the basilar artery aneurysm with 18cm of platinum (leaving a tiny neck remnant). After em-bolization, the patient had a right-sided ischemic event,most likely resulting from an embolism from the rightposterior communicating aneurysm, which occurred dur-ing treatment. However, the symptoms resolved totallywithin a few days, and the patient remains well.

Case 2

A 30-year-old woman was admitted for embolization ofaneurysms of the posterior circulation. Over the previous 6months she had suffered moderate occipital headachesand one episode of sudden transient diplopia. She had nonausea, vomiting, or syncope. Examination revealed thepresence of cerebral aneurysms and a minor subarachnoidhemorrhage. She had a long-standing history of hyperten-sion resulting from renal artery stenosis, which had re-quired a right-sided nephrectomy 7 years earlier. Her

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blood pressure was, however, well controlled by antihy-pertensive medication. No abnormality was found onphysical examination. Three-vessel angiography was per-formed before embolization. Right vertebral artery injec-tion showed a 7-mm basilar tip aneurysm and a 1-cmaneurysm of the P1 segment of the right posterior cerebralartery. There was no filling of the P2 segment of the rightposterior cerebral artery. Collateral flow into the anteriorand middle cerebral territories was noted on the left. A leftcommon carotid artery injection showed diffuse narrowingthroughout the internal carotid course, with external tointernal carotid collaterals. A right internal carotid arteryinjection showed segmental narrowing of the cavernousinternal carotid artery. The right middle and anterior cere-bral distributions were normal. The angiographic diagnosisof moyamoya disease associated with cerebral aneurysmswas made. By means of a Tracker microcatheter, thebasilar tip aneurysm was occluded with one 20-cm andtwo 8-cm Guglielmi electrically detachable coils and theright P1 aneurysm was occluded with one 40-cmGuglielmi electrically detachable coils.

A postembolization angiogram showed a tiny residualneck in the basilar tip aneurysm and 95% obliteration ofthe P1 aneurysm. No parent vessel occlusion was identi-fied. The patient remained well, and a repeat angiogram 4days later showed no change in the basilar tip aneurysmand complete obliteration of the P1 aneurysm resultingfrom progression of intraaneurysmal thrombosis. The pa-tient was asymptomatic upon discharge the next day. The12-month follow-up angiogram showed complete occlu-sion of both aneurysms. She was symptom free at the2-year clinical follow-up examination.

Case 3

A 49-year-old woman with a grade I subarachnoid hem-orrhage was referred for embolization of intracranial aneu-rysms. Ten days earlier, she had suffered a subarachnoidhemorrhage for which she underwent a craniotomy. It waspresumed at the time that an aneurysm of the right pos-terior communicating artery had bled. At surgery, how-ever, this aneurysm was found to be unruptured but un-clippable (wide-necked). Preembolization angiographicassessment showed an additional aneurysm of the leftposterior inferior cerebellar artery. Endovascular emboli-zation of the posterior communicating artery aneurysmwas first undertaken, and complete occlusion achievedwith a 10-cm Guglielmi electrically detachable coil. Next,the aneurysm of the left posterior cerebellar artery wasembolized with two 8-cm coils. During delivery of thesecond coil, the aneurysm ruptured and the patient be-came comatose. She was intubated and ventilated, andcontinued delivery and detachment of the second coil re-sulted in occlusion of the aneurysm. A postembolizationCT scan confirmed the presence of a large subarachnoidhemorrhage. The patient required a ventriculostomy, andensuing severe vasospasm was treated within a few hoursby intracranial angioplasty. She gradually recovered, andangiography at 18-months follow-up showed persistent

occlusion of both aneurysms. She was well at the 2-yearclinical follow-up examination.

Case 4

A 42-year-old woman had a grade I subarachnoid hem-orrhage. Angiography revealed two aneurysms of the ver-tebrobasilar junction, one pointing anteriorly and the otherposteriorly. A suboccipital craniotomy was performed sev-eral days after hemorrhage, with partial clipping of theanterior aneurysm. Both aneurysms were subsequentlyoccluded with Guglielmi electrically detachable coils, thelarger posterior aneurysm with a total of 14 cm of platinumand the smaller anterior aneurysm with 4 cm of platinum.The larger aneurysm was completely occluded, and a tinywedge remnant was seen along the superior aspect of thesmaller aneurysm. The patient remains well.

Discussion

The average reported frequency of multipleintracranial aneurysms in clinical studies is 15%to 20% when these are defined as the combina-tion of at least one ruptured and one or moresilent aneurysms (3). Importantly, many of thestudies reporting these figures were conductedwithout routine four-vessel angiography. Also,aneurysms of a few millimeters in diameter areeasily missed on preoperative angiograms (10).Careful use of cerebral panangiography mayreveal a frequency of multiple intracranial an-eurysms of close to 45% (2). Naturally, thereare cases of multiple aneurysms without anyrupture, so the actual frequency of multiple in-tracranial aneurysms may be even higher thanreported previously. Necropsy studies reportinga frequency of 50% (11) lend support to thissuspicion. Therefore, the not infrequent pres-ence of multiple intracranial aneurysms in pa-tients with aneurysmal subarachnoid hemor-rhage may add considerably to existingtherapeutic problems for these patients.A correlation between the natural history and

the surgical risk in patients with multiple intra-cranial aneurysms has been established byBaena et al (12), who found that untreated un-ruptured aneurysms bled at a rate of 3% peryear, with a cumulative mortality rate of 20%.Other accounts place the annual risk of rupturefrom an intact aneurysm in the presence of mul-tiple intracranial aneurysms at 1% per year andthe mortality rate at 4% over a 5-year period(10). In one series, 83% of patients with inoper-able multiple intracranial aneurysms died within1 year of the initial subarachnoid hemorrhage.

Therefore, the view that such aneurysms (in-cluding those unruptured) should be activelytreated has recently become dominant (13).Opinions regarding surgical strategy for mul-

tiple intracranial aneurysms have been divided.These have varied from nonintervention for un-ruptured aneurysms to operation only on thoseunruptured aneurysms that can be reached viathe same craniotomy as for ruptured aneu-rysms. More recently, Mizoi et al advocated sur-gery for all multiple intracranial aneurysms in aone-stage operation whenever possible, or evenby a second operation if this were necessary toclip the unruptured aneurysms (13). Adoptionof such a strategy has resulted in one-stagesurgical treatment in 78% of patients, two-stagetreatment in 7% of patients, and partial treat-ment (unruptured aneurysm left untreated) in15% of patients.In one large series (13), patients with multiple

intracranial aneurysms were classified into fourgroups according to the location of the aneu-rysms: the first three groups were composed ofpatients with various combinations of anteriorcirculation aneurysms; the fourth group in-cluded patients with vertebrobasilar artery an-eurysms. Only 42% of patients in group 4 couldbe treated by one-stage operations, comparedwith 60% to 90% in the other groups. Further-more, the surgical results in group 4 were poor,with a mortality rate of 27%, compared with 6%to 8% in the other groups. This poor outcome inpatients with multiple intracranial aneurysmsinvolving the posterior circulation was mainlythe result of bleeding from untreated vertebro-basilar aneurysms, which were thought to beunruptured aneurysms preoperatively. Of noteis the relatively high overall frequency (25%) ofposterior circulation aneurysms in patients withmultiple intracranial aneurysms as comparedwith the frequency of 8% in those patients withonly a single aneurysm, further emphasizing theneed for complete preoperative diagnostic an-giography (2). However, despite careful panan-giography and computed tomography or mag-netic resonance imaging (14), and even in lightof surgical findings, it is not always possible todetermine which aneurysm has bled (13).Although the surgical risk of direct operation

for multiple intracranial aneurysms is onlyslightly worse than for single aneurysms (13),several factors adversely affect the outcome af-ter surgery in these patients. As explainedabove, problems remain with regard to one-

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stage operations in patients with aneurysms lo-cated in the posterior circulation. Misdiagnosisof the location of a ruptured aneurysm amongmultiple intracranial aneurysms also results in apoorer outcome (15). Aneurysms located inmultiple sites, requiring multiple craniotomies/surgical approaches during the acute stage, re-sult in a worse outcome than obtained with mul-tistaged surgery. However, multistaged surgerycan be performed with low morbidity and mor-tality only if the ruptured aneurysm (with theassumption that this was diagnosed correctly)has already been clipped. Nemoto et al (15)have reported that the size of unruptured aneu-rysms among multiple intracranial aneurysmsis also a significant prognostic factor. Postoper-ative morbidity in patients with aneurysms lessthan 5 mm in diameter was 1%, whereas it was20% with aneurysms measuring 10 mm ormore. In addition, the increasing rate of occur-rence of multiple intracranial aneurysms withadvancing age presents a therapeutic dilemmain that although the risks of rebleeding in thesepatients is higher, so are the associated risks ofsurgery (2). Therefore, in one series comprising105 patients with multiple intracranial aneu-rysms (15), surgery for unruptured aneurysmscaused 2% morbidity in patients 28 to 55 yearsold and 18% morbidity in patients over 56 yearsold. A larger series of patients reported byInagawa (16) also confirms a poorer surgicaloutcome in patients older than 60 years.The optimum treatment of an intracranial an-

eurysm is its total occlusion with preservation ofthe parent artery, and with minimal morbidityand mortality related to the procedure. Sincethe early 1970s, endovascular treatment in se-lected cases of intracranial aneurysms hasemerged as a therapeutic alternative to directsurgery. Many of the aneurysms considered forendovascular treatment have been surgicallyinaccessible or difficult to treat. As outlinedabove, the presence of multiple intracranial an-eurysms conveys a higher risk to patients andcan offer neurosurgeons particular therapeuticchallenges and difficulties. Upon careful consid-eration of these difficulties, the less invasiveendovascular approach may seem an attractivealternative to surgery for patients with multipleintracranial aneurysms.The endovascular approach to aneurysmal

occlusion has progressed considerably over thelast decade. Previously, such treatment hadbeen limited to balloon embolization. This tech-

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nique, however, carries the significant risk ofaneurysmal rupture during balloon inflation, thefrequent occurrence of posttreatment aneurys-mal remnants, and late balloon deflation. Treat-ment with Guglielmi electrically detachablecoils has been recently developed as a less trau-matic and more controllable endovascularmethod of aneurysmal occlusion. These de-vices have three main advantages: 1) they arevery soft and less traumatic to the aneurysmwall; 2) they are detachable by application ofelectric current, which is also believed to inducethrombosis by attraction and accumulation ofnegatively charged blood elements; and 3) theyare retrievable before detachment, which allowssafe and accurate placement within the aneu-rysm. It is possible with this technique toachieve complete occlusion in aneurysms withsmall necks. Complete occlusion is more diffi-cult to achieve in wide-necked aneurysms be-cause of the risk of coil deposit in the parentartery. Careful angiographic follow-up of pa-tients with wide-necked subtotally occluded an-eurysms is mandatory to check for potentialaneurysmal regrowth and rupture.Single aneurysms in the posterior fossa gen-

erally pose difficult surgical problems, whichmay be accentuated by the presence of multipleintracranial aneurysms, with their higher pro-pensity for posterior circulation distribution.Therefore, an alternative endovascular tech-nique would be of particular benefit in this groupof patients. The results of using Guglielmi elec-trically detachable coils in 43 aneurysms of theposterior fossa have been reported previouslyby Guglielmi et al (9), who showed an associ-ated low morbidity and mortality rate, espe-cially for patients in Hunt and Hess grade III orbetter. Complete occlusion was achieved in 13of 16 small-necked aneurysms in this group.This initial experience suggests that Guglielmielectrically detachable coils are both safe andeffective in the treatment of aneurysms of theposterior fossa.A further benefit of the endovascular ap-

proach for treatment of multiple intracranial an-eurysms is the elimination of the hazard of mis-diagnosing and thus not treating the aneurysmresponsible for hemorrhage. Instead, by usingthis technique, all aneurysms (ruptured and un-ruptured) may be endovascularly occluded atthe same time. This technique also eliminatesthe problems associated with multiple craniot-omies/surgical approaches that may be neces-

sary in some cases. Furthermore, multistagedtreatment can be performed, even within rela-tively short intervals of follow-up after the initialtreatment. Retreatment may be necessary forwide-necked aneurysms that exhibit coil com-paction caused by persistent exposure to thecirculation. Finally, the avoidance of generalanesthetic, craniotomy, brain retraction, andsurgical vessel manipulation may be particu-larly advantageous in elderly patients, who havea greater preponderance of multiple intracranialaneurysms and who are also at higher surgicalrisk because of their age (16). Notwithstandingthese advantages, ischemic and hemorrhagiccomplications do occur with the use ofGuglielmi electrically detachable coils for em-bolization of aneurysms. In 140 consecutive pa-tients treated at our institution, 14 had ischemiccomplications (five resulting in permanent def-icits; nine transient ischemic attacks) and fiveaneurysmal ruptures (two patients who were inHunt and Hess grade IV and V died, and threepatients in grades I to III are well). The compli-cations encountered in two of the cases in thisreport were transient and the patients’ out-comes were good.Further accumulation of experience (clinical

and angiographic) in use of the Guglielmi elec-trically detachable coils for treatment of bothsingle and multiple intracranial aneurysms,along with critical comparative studies with sur-gery, will aid in verifying the long-term efficacyand true role of this recently developed tech-nique. Our early experience with Guglielmielectrically detachable coils in the treatment ofmultiple intracranial aneurysms, particularlythose involving the vertebrobasilar system, sug-gests that it may be a particularly suitable ther-apeutic method for this high-risk condition.

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