(Stroke. 2000;31:100.)
© 2000 American Heart Association, Inc.
Original Contributions |
Endovascular Treatment of Ruptured Posterior Circulation Cerebral Aneurysms
Clinical and Angiographic Outcomes
From the Departments of Radiology, Division of Interventional Neurovascular Radiology (T.E.L., A.M.M., V.V.H., C.C.P., P.M.M., C.F.D., R.T.H.) and Neurosurgery (V.V.H., C.F.D., R.T.H.), University of California at San Francisco.
Correspondence to Adel M. Malek, MD, PhD, Division of Interventional Neurovascular Radiology, UCSF Medical Center, Room L-352, 505 Parnassus Ave, San Francisco, CA 94143. E-mail ammalek{at}bics.bwh.harvard.edu
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Abstract |
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 Top Abstract IntroductionSubjects and MethodsResultsDiscussionReferences |
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Background and Purpose—We sought to describe the clinical outcome and angiographic results obtained in the endovascular therapy of ruptured posterior circulation cerebral aneurysms using Guglielmi detachable coils (GDC) over a 7-year period.
Methods—A retrospective analysis was performed of 112 patients evaluated at the University of California at San Francisco Medical Center between June 1991 and August 1998. The Hunt-Hess grade at presentation of treated patients was I in 26 patients (24%), II in 24 (22%), III in 27 (25%), IV in 24 (22%), and V in 8 (7%). Clinical follow-up for the total population was achieved in 104 of 109 patients (96%), with a mean duration of 13.1 months. Angiographic follow-up for the subset excluding parent vessel occlusion cases was obtained in 93% of cases, with a mean duration of 7.2 months.
Results—Technical success, defined as the ability to catheterize
and embolize the aneurysm with GDC, was achieved in 109
of 112 of cases (97%). The mean angiographic occlusion rate, or
projected area of the aneurysm occluded by the coils, for
all 110 successfully treated aneurysms was 94.6%. At latest
clinical follow-up, 81 of 109 patients (74%) achieved good recovery
with Glasgow Outcome Scale (GOS) score of I, 10 of 109 (9%) were
moderately (GOS II) and 5 of 109 (5%) were severely (GOS III)
disabled, 1 of 109 (1%) remained in a vegetative state (GOS IV), and
12 of 109 (11%) were dead. Of the subset of 77 patients with Hunt-Hess
grades I to III, 68 (88%) achieved a good clinical outcome (GOS I). A
statistically significant correlation was demonstrated between
Hunt-Hess grade at presentation and final GOS outcome score
(
2=41.4, P<0.0005). Procedure-related
permanent morbidity was 2.8% (3/109 patients). Repeated
hemorrhage was observed in a single patient (0.9%) with a
partially treated aneurysm.
Conclusions—The observed favorable outcome and low morbidity in this group of high-risk patients point to GDC embolization as an effective method for the endovascular management of patients with ruptured posterior circulation aneurysms.
Key Words: cerebral aneurysm • embolization, therapeutic • occlusion • outcome • subarachnoid hemorrhage
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Introduction |
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TopAbstractIntroductionSubjects and MethodsResultsDiscussionReferences |
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The management of patients with aneurysmal subarachnoid hemorrhage (SAH) caused by rupture of posterior circulation aneurysms presents a technically difficult problem.1 The surgical exposure needed for the clipping of aneurysms of the posterior circulation is considered comparatively more challenging than in other locations.2 The coincident presence of acute SAH with the associated cerebral edema and adhesion of aneurysm to the surrounding thrombus further compounds the challenge of accessing aneurysms located near deep brain stem structures with interposed cranial nerves and perforator arteries.3 The difficulty of treating these aneurysms in the acute phase of SAH is mirrored by the higher rate of complications and morbidity compared with lesions of the anterior circulation.4 Endovascular treatment of difficult intracranial aneurysms in patients in poor clinical condition has had an increasingly important role in the management of ruptured aneurysms. The recent advent of the Guglielmi electrolytically detachable coil (GDC) has enabled a safer and more controlled form of endovascular therapy.5 To describe the utility, safety, and intermediate-term efficacy of GDC therapy in a high-risk subset of patients, we report our experience in the endovascular treatment of ruptured posterior circulation aneurysms.
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Subjects and Methods |
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TopAbstractIntroductionSubjects and MethodsResultsDiscussionReferences |
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From June 1991 to August 1998, 112 patients with acute or subacute SAH from ruptured posterior circulation aneurysms were evaluated for endovascular treatment with the use of GDC (Target Therapeutics) at the University of California at San Francisco (UCSF) Medical Center. A retrospective analysis and review were undertaken of the hospital and outpatient charts, the operative report, and all angiographic, CT, and MR studies. This was supplemented by follow-up clinical examination and telephone interviews.
Angiographic Analysis
Quantitative measurement of aneurysm size was performed
with the use of digital subtraction angiographic projections
obtained with externally placed 1-cm reference washers to correct for
geometric magnification. Studies performed after 1996 used an on-board
angiographic digital computer (Toshiba Corporation) for measurement of
aneurysm height, width, and neck size. The analysis
included determination of aneurysm shape, degree of
aneurysm occlusion, and extent of aneurysm
recanalization. The angiographic projections of
the aneurysm used during initial treatment and subsequent
follow-up studies were separately analyzed by 2
neurointerventional radiologists to determine the rate of occlusion of
the aneurysm, which is the proportion of the projected area
of the aneurysm occluded by coil placement. A third
independent neuroradiologist was called on for arbitration in cases of
discrepancy. One hundred percent occlusion was assigned only to
aneurysms with dense packing and no contrast filling of the
aneurysm fundus or neck. Aneurysm neck remnants were
determined with respect to the total projected area of the
aneurysm.
Clinical Outcome Measures
Clinical condition at the time of treatment was determined with
the Hunt-Hess grading scheme.3 Outcome was measured with
the Glasgow Outcome Scale (GOS)6 (in which GOS I
corresponds to good recovery and resumption of normal life despite
minor deficits, GOS II to a moderately disabled but independent
patient, GOS III to a severely disabled [but conscious] patient who
is dependent on others for daily support, GOS IV to a persistently
vegetative state, and GOS V to death); the Quality of Life Outcome
Scale (QOL)7 (in which QOL 1 corresponds to a patient with
normal lifestyle, QOL 2 to a patient with minor neurological
dysfunction but who is able to perform activities of daily living
without help, QOL 3 to a patient needing assistance with daily
activities, QOL 4 to one unable to perform activities of daily living
and requiring full-time care, and QOL 5 to death); and the modified
Rankin scale.8 Members of the UCSF neurovascular neurology
team performed initial inpatient neurological examinations. Clinical
data were obtained from neurological examinations by UCSF neurovascular
neurologists during follow-up angiographic studies, from examinations
by patients’ referring neurosurgeons and neurologists, and by
telephone interviews with a neurosciences clinical nurse
specialist.
Clinical Management and Technical Complications
Additional information included the interval between SAH and
treatment, dates of retreatment, medical history and complications,
initial signs and symptoms and their progression or resolution,
rebleeding, presence or absence of vasospasm, treatment of vasospasm,
adverse events during diagnostic angiography, adverse
events during GDC embolization, and delayed complications. Adverse
events were categorized by type of adverse event, imaging
characteristics, and adverse event outcome.
Statistical Analysis
Clinical information, procedural information, follow-up, and
angiographic data of all endovascular aneurysm treatments
performed at UCSF since 1991 were maintained in a database, and
statistical analysis was performed with the SAS Institute
software package. ANOVA was used to compare outcome scores versus
presentation and treatment characteristics, and the
Tukey-Kramer honestly significant difference correction was used
for comparison as appropriate. Additionally, Pearson’s
2 test was used to determine marginal
homogeneity among nominal variables. A value of P
0.05
was considered statistically significant.
Embolization Technique
The majority of cases used relied on general
anesthesia by a dedicated neuroanesthesiology team with
neuromuscular blockade to prevent patient motion and improve control
over patient hemodynamics in the case of an adverse
event such as aneurysm perforation. A 6F or 7F vascular access
sheath (Avanti, Cordis Endovascular) was inserted in the common femoral
artery. Complete diagnostic angiography was performed
through a 5F UCSF-II (Cordis) or 7F Berenstein (USCI-Bard) catheter
with the use of biplane high-resolution digital subtraction angiography
to evaluate the presence and extent of vasospasm and other intracranial
vascular anomalies. After the optimal orthogonal view for embolization
was determined, a baseline activated clotting time was
obtained, and the patient was given a weight-based bolus of
intravenous heparin (70 U/kg body wt). A repeated
activated clotting time was obtained after the initial bolus,
and additional heparin was administered to achieve a value between 250
and 300 seconds. Maintenance heparin was administered hourly at
half the initial bolus dose. The heparin was reversed with an
appropriate dose of intravenous protamine sulfate at the
end of the procedure. After therapeutic anticoagulation was confirmed,
a 6F (Envoy, Cordis) thin-walled, straight guide catheter was placed
for vascular access. With the use of magnified real-time fluoroscopy
and digital road-mapping techniques, a microcatheter (0.010F to 0.018F)
was placed coaxially through the guide catheter and directed into the
aneurysm with the aid of a microguidewire (0.010F to 0.016F).
In cases of complex vascular anatomy, the microcatheter was
appropriately steam-shaped to accommodate complex curves. GDC
embolization of aneurysms was performed with GDC T10 (Target
Therapeutics) electrolytically detachable coils. In cases of saccular
aneurysms that had a definable neck, coils were used to
obliterate the aneurysm fundus without impinging on the parent
vessel. In fusiform ruptured aneurysms, the coils were used to
occlude the aneurysmal segment of the parent vessel. Patients
who underwent intentional parent vessel occlusion did not routinely
undergo long-term follow-up surveillance angiography after
determination of satisfactory occlusion at the end of the initial study
with documentation of complete flow arrest. This management protocol
was determined on the basis of the observation that a completely
occluded parent artery does not undergo late
recanalization9 (Figure 1
). After embolization, the patient was
transferred to the neurological intensive care unit, under the joint
care of members of the Department of Anesthesia and
dedicated intensive care specialists from the neurovascular neurology
team.
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Results |
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TopAbstractIntroductionSubjects and MethodsResultsDiscussionReferences |
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Patient Demographics and Clinical Presentation
The mean age was 52 years; age ranged from 18 to 79 years. There were 77 women (69%) and 35 men (31%). All patients in this series had an acute or subacute SAH and were classified according to Hunt and Hess.3 The median time to treatment after initial SAH was 4 days. The stratification of treated patients was as follows: grade I in 26 patients (24%), grade II in 24 patients (22%), grade III in 27 patients (25%), grade IV in 24 patients (22%), and grade V in 8 patients (7%).
Aneurysm Characteristics and Morphology
The most prevalent location was at the basilar bifurcation in 55
patients (49%) (Figure 2). Among
treated aneurysms, 40 (37%) were saccular in shape and had a
narrow neck (<4 mm), 14 (13%) were saccular and harbored a wide
neck (>4 mm), 25 (23%) were fusiform, 19 (18%) were irregularly
shaped or multilobed, and 8 (7%) were giant. Figure 3 shows a histogram distribution of the
aneurysms by neck size (Figure 3A) and largest fundus
dimension (Figure 3B).
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Angiographic and Neurological Follow-Up
Angiographic follow-up was obtained in 76 of 82 patients (93%)
treated with preservation of the parent vessel, with a mean
angiographic follow-up of 7.2 months (range, 1 day to 55 months).
Clinical follow-up was achieved in
104 of the 109 treated patients (95%). The mean duration of
neurological follow-up was 13.1 months (median, 9.5 months; range, 5.1
to 56 months).
Technical Success
Endovascular treatment was successfully performed in 109 of 112
patients (97%; Figure 4). In 3 patients (3%), the decision to abort
treatment was made after attempts to deploy the coils in the
aneurysm were not successful. In 1 case with a fusiform left
vertebral artery aneurysm and a contralateral right vertebral
artery occlusion, the coils could not be placed without compromising
flow in the parent vessel. In a second case of a fusiform basilar
artery aneurysm, coils could not be placed that did not
encroach on the parent vessel lumen. In the third case of a basilar tip
aneurysm that incorporated the posterior cerebral arteries in
the neck, no coil conformation could be found that did not encroach on
the posterior cerebral arteries.
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Angiographic Outcome
In this series of 110 aneurysms, 82 aneurysms were
treated with preservation of the parent vessel, and 76 of 82 (93%)
underwent follow-up angiography; the distribution of duration between
initial procedure and latest angiographic follow-up is shown in Figure 5A. The initial mean angiographic
occlusion rate for all 110 successfully treated posterior circulation
aneurysms was 94.6%. The mean percent occlusion at final
angiographic follow-up was 94.9%. The initial and final angiographic
occlusion rates were determined by aneurysm type for the subset
of non–parent vessel occlusion aneurysms that underwent
angiographic follow-up (n=82) (Figure 6).
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Aneurysms at the most common location, the basilar bifurcation
(n=53), showed an initial occlusion rate of 96.6% and final occlusion
rate of 95.1%. The results indicate occlusion at latest follow-up of
>90% in all locations except for lesions of the basilar trunk, which
were characterized by a wide neck and difficult morphology. Figure 7 illustrates a case of basilar tip
aneurysm.
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Overall, 54% of the non–parent vessel occlusion aneurysms
were embolized to 99% to 100%, 40% were occluded to 90% to
99%, and 6% were incompletely occluded (90%) after initial
embolization. Aneurysm neck size was found to be correlated
with a lower final percent occlusion (Figure 8A). The final occlusion rate in the
subset of aneurysms with neck size <4 mm showed
significantly higher final occlusion compared with those with neck size
of 4 to 6 mm (P<0.05) and those with neck size
>8 mm (P<0.0001). Similarly, a trend was also
identified between aneurysm fundus size and final extent of
occlusion, with aneurysms with a fundus >12 mm having a
significantly lower rate of final occlusion than those measuring 3 to 6
and 6 to 9 mm (P<0.002) (Figure 8B).
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Recanalization After Treatment
Of the 76 aneurysms with angiographic follow-up,
77.6% (59/76) showed no evidence for
recanalization, while 22.4% (17/76) did.
Analysis of the aneurysms demonstrating
recanalization revealed that 88.2% (15/17) had
either a neck size >4 mm (16 aneurysms) or were fusiform
(1 aneurysm). Two patients with initial 100% occlusions showed
evidence of recanalization on follow-up
angiography. The first showed 3% recanalization at
7 months and underwent no further treatment. The second was a patient
with a basilar tip aneurysm initially showing 15%
recanalization at 28-month follow-up who underwent
an unsuccessful attempt at retreatment. The patient returned 16 months
later with further recanalization to 25% and
underwent successful retreatment with occlusion of 99%. A follow-up
angiogram 9 months later showed no change in aneurysm
appearance.
Clinical Outcome
Clinical follow-up for >1 month was achieved in 104 of 109
treated patients (95%; mean duration, 13.1 months) (Figure 5B
).
At latest follow-up, 74% (81/109) of patients showed good recovery
(GOS I), 9% (10/109) had moderate disability (GOS II), 5% (5/109)
were severely disabled (GOS III), 1% (1/109) were vegetative (GOS IV),
and 11% (12/109) were dead (Figure 9A). Overall, 83% (91/109) of patients
had good recovery or moderate disability (GOS I and II) at the time of
final follow-up. A statistically significant correlation between
Hunt-Hess grade at presentation and final GOS outcome score
was demonstrated (2=41.4,
P<0.0005). All 26 patients presenting in Hunt-Hess
grade I had a final score of GOS I. Of the 24 patients presenting
in Hunt-Hess grade II, 88% (21/24) improved to a final score of GOS I,
4% (1/24) had a final score of GOS III, and 8% (2/24) deteriorated to
lower scores. Of 27 patients presenting in Hunt-Hess grade III,
78% (21/27) improved to GOS I, 15% (4/27) improved to GOS II, 4%
(1/27) remained at GOS III, and 4% (1/27) deteriorated to GOS V. Of
the 24 patients presenting with Hunt-Hess grade IV, 46% (11/24)
recovered to GOS I, 21% (5/24) improved to GOS II, 8% recovered
(2/24) to GOS III, 1 recovered to GOS IV (4%), and 21% (5/24)
deteriorated to GOS V status. Of the 8 patients with Hunt-Hess grade V
at presentation, 25% (2/8) improved to GOS I, 13% (1/8)
to GOS II, 1 to GOS III, while 50% (4/8) deteriorated to GOS V.
Overall, of the patients presenting in Hunt-Hess grades I to III,
88% achieved a GOS I outcome score on final follow-up.
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We used the QOL to assess the status of treated patients at final
follow-up. A statistically significant relationship between Hunt-Hess
grade at presentation and final QOL score was demonstrated
(2=54.6, P<0.00001) (Figure 9B). A similar analysis of the modified Rankin outcome
at latest follow-up established a significant correlation with
Hunt-Hess grade at time of treatment (2=71.1,
P<0.00001) (Figure 9C).
Other variables at presentation were analyzed
for their potential contribution to patient outcomes. Specifically, the
presence of vasospasm was found to be inversely correlated with final
clinical outcome as measured by GOS score
(2=15.6, P<0.008). In contrast,
patient age, sex, the presence of recanalization,
the need for subsequent retreatment, and the location of the
aneurysm were not significantly correlated with patient
clinical outcome.
Complications Associated With Endovascular Therapy
Aneurysm Rerupture
One patient suffered late rebleeding (0.9%, 1/109 patients). This
patient was a Hunt-Hess grade III with a ruptured giant fusiform distal
basilar artery aneurysm that was treated with a staged
embolization. A 90% occlusion was achieved but was complicated by an
asymptomatic dissection of the left vertebral artery that
progressed to a complete occlusion. Despite a good neurological
recovery, a follow-up angiogram 21 months later showed 15%
recanalization, but no further treatment was
attempted because of inability to access the aneurysm. The
patient suffered a recurrent SAH 3 years after initial treatment. An
angiogram after the rehemorrhage showed a stable 75%
occlusion. The patient died from complications related to recurrent
hemorrhage.
Procedure-Related Mortality and Morbidity
There were no cases of procedure-related mortality in the series.
Overall, there were 3 complications leading to permanent morbidity, for
a rate of 2.8% (3/109 cases) (Table 1).
Eight procedure-related complications were encountered that did not
lead to a neurological deficit and were transient, for a rate of 7.3%
(8/109 cases). These included 1 case of aneurysmal rupture, 1
case of asymptomatic branch occlusion successfully treated
with superselective infusion of urokinase, 3 cases of transient
nonocclusive thrombus, and 4 cases of herniation of a portion of a GDC
into the parent vessel. We encountered technical problems during coil
placement in 2 patients that necessitated coil removal by use of a
microsnare device (Microvena).
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Medical Complications
Patients in this cohort suffered concurrent medical complications,
some of which were related to SAH. One patient suffered a myocardial
infarction and aspiration pneumonia after treatment. Another patient
developed a pulmonary embolus, which was treated to an
uneventful recovery with anticoagulation. One patient with a Hunt-Hess
grade V SAH suffered a repeated hemorrhage before treatment and
subsequently developed severe vasospasm that was aggressively treated.
The patient also developed pancreatitis, candida sinusitis, and severe
fungemia. Three patients developed gastrointestinal bleeding, possibly
due to stress ulcers.
Mortality
Sixteen treated patients died (16/109, 15%) during the course of
this study. Nine of the sixteen (56%) presented
initially in Hunt-Hess grade IV or V. This subset of patients had poor
initial neurological condition, refractory vasospasm with subsequent
infarction, and comorbid medical conditions (pneumonia, sepsis,
congestive heart failure, and pulmonary edema). None of these
patients showed improvement in their neurological examination or
outcome scores after endovascular treatment and before death.
Four patients who initially presented with Hunt-Hess grade II hemorrhages died. The first patient suffered from a rare anemia and developed a coagulopathy after a blood transfusion leading to a fatal hemorrhage from a previously unruptured pericallosal aneurysm. The second patient developed a massive gastrointestinal hemorrhage associated with severe cirrhosis, which led to hypotensive shock. The third patient with Wyburn-Mason’s syndrome with an arteriovenous malformation underwent successful coil therapy of a superior cerebellar feeding artery aneurysm but suffered a massive intracerebral hemorrhage from the arteriovenous malformation and died 30 days later. The fourth patient died as a result of overwhelming congestive heart failure, pulmonary edema, and pneumonia. Two patients died of myocardial infarctions during the follow-up period after discharge from the hospital.
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Discussion |
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TopAbstractIntroductionSubjects and MethodsResultsDiscussionReferences |
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The primary goal of endovascular therapy is the prevention of repeated hemorrhage and its devastating consequences.10 The clinical experience from a series of ruptured aneurysms treated conservatively has demonstrated a 37% risk of rebleeding at 4 weeks and an overall mortality rate from repeated hemorrhage and its sequelae of 34% to 42%.11 12 In the context of this poor natural history, the results presented here for ruptured intracranial posterior circulation aneurysms indicate that GDC embolization confers a protective effect. We encountered no recurrent SAH in the acute phase after endovascular embolization. Furthermore, no aneurysm that was occluded to >75% by angiographic criteria rebled during the entire follow-up period.
The recurrent SAH rate and mortality from aneurysm repeated
rupture in this series are 0.92% (1/109 patients). This corresponds to
a yearly rebleeding rate of 0.85%/y, a rate similar to those reported
in other endovascular series (Table 2),
which range from 0%/y to 3%/y (Kuether et al,13 1.4%;
Eskridge et al,14 3%; Pierot et al,15 0%).
Tsutsumi et al16 measured the rate of recurrent SAH at
1.4% to 1.8% in a group of 220 patients treated with surgical
clipping during a follow-up period ranging from 3 to 21 years. The
cumulative risk for recurrent SAH was estimated to be 0.5%, 2.2%, and
5.5% at 5, 10, and 15 years postoperatively, respectively. All the
aneurysms in the surgical series were thought to have been
completely clipped at surgery, in distinction to our series, in which
the aneurysm that rebled was known to have been incompletely
treated from the outset.10 11 12 16
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Clinical Outcomes
The initial clinical grade of the patient at
presentation strongly predicted patient outcome. In this
series, 94% of good-grade patients (Hunt-Hess I or II) had good
recovery leading to a GOS I outcome at final follow-up.
Intermediate-grade patients (Hunt-Hess III) predictably had a lower
percentage of GOS I outcome (78%). This finding is consistent
with other series that have reported lower percentages of good outcome
for grade III patients: 55%,17 57%,18 and
100%.13 In poor-grade patients (Hunt-Hess IV and V),
fewer patients recovered to a good final outcome: only 46% of
Hunt-Hess grade IV cases and only 25% of Hunt-Hess grade V patients
achieved GOS I outcomes. All measured indices, including GOS, modified
Rankin, and QOL, showed improved outcomes after GDC embolization when
adjusted for the initial neurological condition. Late deterioration
resulted from medical problems (7.3%, 8/109), vasospasm (8.3%,
9/109), and delayed complications (1.8%, 2/109). Our overall final
excellent/good clinical outcome (GOS I/II) of 83% (91/109) is
comparable to the 69% to 91% (average of 77%) GOS I/II outcomes seen
in other series (Table 2). In the current single center study,
74% (81/109) of all treated patients recovered to a final GOS of I,
compared with 69% of the ruptured subset of the multicenter series of
150 basilar bifurcation aneurysms.14 Comparison
with other published series of endovascular treatment not limited to
the subset of ruptured posterior circulation lesions reveals comparable
outcome statistics.5 13 14 15 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 These series (Table 2) show GOS I outcome in 44% to 100% of good-grade patients,
with a mean of 79%.
Angiographic Outcome
Small aneurysms with narrow necks and saccular shape
demonstrated excellent initial and final occlusion rates. Overall, 88%
of the treated non–parent vessel occlusion aneurysms were
occluded in the 90% to 100% range, while all parent vessel
occlusion–treated aneurysms (n=28) showed complete
angiographic occlusion at the end of the treatment. In comparison, the
multicenter study of 150 basilar apex aneurysms14
noted 75% of aneurysms at 90% to 100% occlusion after GDC
embolization. Other series of posterior circulation aneurysms
treated with GDC embolization (Table 2) report complete and
near-complete (99% to 100%) angiographic occlusion in a mean of 62%
of patients (range, 42% to 85%), compared with 54% in our series. In
surgical series, Peerless et al35 reported an
87.4% rate of total occlusion by clipping, with a neck remnant seen in
5.8% and residual aneurysm body or fundus in 6.8%. Recently,
the series of Samson et al34 reported residual
aneurysm after surgical clipping in 6% of cases by
postoperative angiography. Complex aneurysm geometry was
responsible for less than complete occlusion in almost all cases. In
the present series, fully 39% of treated aneurysms
harbored a wide neck (>4 mm), and 38% measured >10 mm in
largest diameter. The difficulty in attaining complete obliteration of
these complex aneurysms is shared with surgical series, which
have similarly reported greater difficulty in complete occlusion by
clipping in this group.34 35 Incomplete aneurysm
occlusion by endovascular coil placement may still offer a measure of
protection from rehemorrhage, as shown by the low repeated
rupture rate in this and other series, although the threshold of
occlusion needed to achieve such protection is unclear.
Histopathological examination of human aneurysms treated with
GDC has shown that incompletely treated aneurysms develop an
organized thrombus along the periphery of the aneurysm,
possibly reinforcing the wall.36 37 Frank
recanalization and aneurysm growth were
noted in some wide-necked aneurysms with poor initial
occlusion, a phenomenon similar to that recently reported by Mericle et
al.38 Recent experimental modifications of the GDC, such
as ion implantation and surface coating39 with collagen or
growth factors,40 have led to improved
endothelial proliferation on the coil surface and
better aneurysm occlusion in animal studies. The possible
future incorporation of these advances may eventually yield better
intermediate and long-term angiographic occlusion in wide-necked and
large aneurysms treated from an endovascular route.
Complications
There were no cases of procedure-related mortality in our series,
compared with rates ranging from 0% to 6.4% in other endovascular
series. The permanent morbidity rate of 2.8% compares favorably with
other series ranging from 2% to 5% (Table 2). The permanent
combined morbidity and mortality in our series was 3.7% (morbidity,
mortality, and death from repeated hemorrhage). Other
endovascular series have reported combined morbidity and mortality
rates between 5% and 16.9%. A recent
meta-analysis41 of 48 eligible endovascular
studies totaling 1383 patients reported permanent complications in 46
of 1256 patients (3.7%; 95% CI, 2.7% to 4.9%).
Comparison With Surgical and Endovascular Series
Recent reports have compared endovascular and surgical treatment.
Gruber et al22 performed a retrospective study of 41
patients with basilar apex aneurysms. Of the 11 who underwent
GDC embolization after SAH, 91% had a GOS score of I or II compared
with 73% for the 15 patients who underwent surgery in the same
setting. Overall, patients who underwent GDC embolization had
significantly better outcome (P<0.001) than patients who
underwent surgery, even when poor-grade patients were excluded in that
report. The second study by Vanninen et al33
described a prospective randomized trial of surgery versus endovascular
therapy in 109 patients. Clinical outcome at 3 months showed 83% of
coil-treated patients with posterior circulation aneurysm with
GOS I and II scores compared with 60% of surgical patients. This
study, which is limited by the small number of cases, failed to detect
a statistically significant difference in final outcome. Leber et
al25 performed a retrospective study comparing
endovascular and surgical treatment of 248 aneurysms and
concluded that the clinical outcomes showed no significant difference
between the 2 methods in terms of safety and efficacy. This series
analyzed 297 aneurysms, 162 treated surgically and 134
treated by endovascular techniques. Although these 3 studies have
significant limitations, they suggest that short-term clinical outcome
of patients treated with GDC embolization are at least equivalent to
surgery. In the present study, restricted to posterior circulation
aneurysms that in most surgical series have fewer favorable
outcomes, we were able to demonstrate good outcomes (GOS I or II) in
94% of good-grade patients (Hunt-Hess I and II). This is comparable to
the clinical outcome of similar cohorts in these 3
surgical/endovascular studies (Table 2) (GOS scores of 91%,
83%, and 91%, respectively). The 3 studies also reported the
morbidity/mortality rates of the surgical versus endovascular
approaches. Leber et al25 demonstrated a 6.2% mortality
rate after surgery and 4.5% after endovascular treatment. Gruber et
al22 reported a 50% morbidity/mortality rate in the
surgical group compared with 10% in the endovascular group. Vanninen
et al33 reported an equal 6% morbidity/mortality in both
surgical and endovascular arms of their study, although posterior
circulation aneurysms constituted only 11% of cases in that
series (Table 2). Importantly, Leber et al25 found
no significant difference in morbidity between anterior versus
posterior circulation aneurysms treated with the endovascular
approach. In contrast, surgical clipping is associated with a
significantly higher morbidity and mortality in posterior compared with
anterior circulation aneurysms.42
The surgical management of posterior circulation aneurysms has evolved significantly over the past 30 years.2 35 43 44 The international cooperative study described by Kassel et al45 46 included 266 patients treated for vertebrobasilar aneurysms. This series reported an overall death rate of 31.2%, good recovery in 52.6%, and a 7.9% incidence of severely disabled/vegetative outcome. Other surgical clipping series2 35 43 44 report mortality of 6% to 11% and morbidity of 10%. The most recent published surgical series by Samson et al34 describes the results of 303 aneurysms of the basilar apex, one third of which were unruptured. At 6-month follow-up, 81% of patients were judged to be neurologically intact or to have mild nonlimiting deficits (GOS I and II). Residual aneurysm was identified by follow-up angiography in 6% of patients. No patient suffered recurrent SAH during a mean follow-up of approximately 8 years. Other large series have shown similar outcome data, with GOS I and II outcome ranging from 82% to 85%.43 44 47 48 49 Any direct retrospective comparison of endovascular and surgical results is greatly hampered by differences in clinical condition at presentation, proportion of ruptured aneurysms, and acuity of treatment after SAH, since a longer wait before treatment selects better-grade patients). For example, our study had a higher proportion of poor-grade patients compared with that of Samson et al34 (29% Hunt-Hess IV and V versus 13%).
The dependence of risk and complications on aneurysm location in surgical clipping and relative independence in endovascular treatment limits any direct comparison of results obtained with surgical and endovascular therapy. The criteria for difficulty and associated risk in treatment of an aneurysm are different. Whereas anatomic location and the required surgical exploration and exposure contribute to the morbidity of clipping, the angiographic determinants, such as neck size and aneurysm morphology, primarily affect the risk of endovascular therapy. The present study is probably characterized by a referral bias since a significant proportion of patients in the early phases of the study period were referred for coil therapy either because they were believed to be poor candidates for or had failed open surgical clipping. This partly accounts for the high proportion of fusiform aneurysms treated by parent vessel occlusion.
Despite the inherent limitations in comparing surgical and endovascular studies, the retrospective nature of this study, and potential selection and referral bias, our results of 0% direct mortality, 2.8% overall mortality, and 83% overall excellent/good outcome (GOS I and II) compare favorably with published surgical results of ruptured posterior circulation aneurysms.1 2 21 25 34 35 43 45 46 47 Our findings confirm that GDC embolization is effective in preventing repeated hemorrhage of ruptured posterior circulation aneurysms, and they also highlight the need for surveillance angiography in partially treated lesions. Future studies will be needed to determine the extended long-term outcome and efficacy of this endovascular therapy.
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Acknowledgments |
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We are thankful for the assistance of Drs D.R. Gress, W.S. Smith, and C. Johnston.
Received June 22, 1999; revision received October 6, 1999; accepted October 6, 1999.
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