CASE REPORT
Neurol Med Chir (Tokyo) 52, 439¿442, 2012

Ruptured Aneurysm With Delayed Distal Coil
Migration Requiring Surgical Treatment
—Case Report—
Hajime WADA,1 Naoki TOKUMITSU,2 Wakako SHIRAI,2
Kazuhiro SAKO,2 and Kyousuke KAMADA1
1Department of Neurosurgery, Asahikawa Medical University, Asahikawa, Hokkaido;
2Department of Neurosurgery, Nayoro City General Hospital, Asahikawa, Hokkaido

Abstract
A 64-year-old woman with subarachnoid hemorrhage manifesting as sudden onset of severe headache
visited our hospital on post-onset day 8. Diagnostic cerebral digital subtraction angiography revealed
an aneurysm located at the left internal carotid-anterior choroidal artery with diffuse cerebral arterial
spasm. Coil embolization was selected because of diffuse spasm in spite of parent artery elongation at
the extra-cranial portion. A small portion of the coil migrated to the parent artery, but coil embolization
was successfully completed. The patient developed delayed spasm, which required arterial fasudil
hydrochloride injection. After the acute phase of subarachnoid hemorrhage, the patient's symptoms
disappeared. However, on day 24 after subarachnoid hemorrhage, the patient showed right hemiparesis
and total aphasia, and skull radiography revealed that the migrated coil had moved into the M1 portion
of the left middle cerebral artery. Craniotomy was performed to retrieve the coil and clip the aneurysm
neck. However, the migrated coil could not be retrieved because of adhesion to the arterial wall.
Delayed coil migration is very rare in the chronic phase.
Key words: subarachnoid hemorrhage,
complication

coil embolization,

delayed coil migration,

clipping,

Introduction

Case Report

The International Subarachnoid Aneurysm Trial (ISAT) is
the only multi-center prospective randomized clinical trial, considered the gold-standard in study design, comparing surgical clipping and endovascular coiling of ruptured
aneurysm. The ISAT found that patients equally suited for
both treatment options achieved substantially better outcomes after endovascular coiling treatment than after surgery in terms of survival-free disability at one year.
However, the coiling technique is technically developing
and continues to carry risks of unexpected complications.
Coil migration is one of the rare complications, but might
be related to poor functional outcome. Therefore, evaluation techniques such as volume embolization ratio (VER)
and new embolization devices have been developed to improve aneurysm stability after endovascular treatment
with platinum coils.
We describe a case of bizarre coil migration in a patient
with a ruptured internal carotid-anterior choroidal artery
aneurysm treated by surgical excision of the migrated part
for rescue treatment.

A 64-year-old woman visited the emergency service of
Nayoro City Hospital because of severe headache persisting for a week. She had suffered sudden onset of headache
and nausea for 8 days. Head computed tomography (CT)
demonstrated residual clot in the subarachnoid space
(Fig. 1A, B; Fisher group 3), and the diagnosis was
subarachnoid hemorrhage (SAH) on the 8th day after occurrence (Hunt and Kosnik grade 2). Emergent angiography revealed an aneurysm at the left internal
carotid-anterior choroidal artery (4.5 × 5.4 × 3.2 mm,
neck: 3.9 mm) with severe intracranial arterial vasospasm
(Fig. 1C). In addition, the internal carotid artery (ICA) in
the cervical portion was tortuous and had a loop, which
suggested difficulty in accessing the aneurysm by the endovascular approach (Fig. 1D). However, considering the
vessel structure anomaly and vasospasm, we selected
aneurysm embolization by endovascular coils.
Under general anesthesia, a Slimguide catheter (6 Fr;
Medikit, Tokyo) with a 6-Fr sheath was inserted via the
right femoral artery and positioned at the proximal portion of the cervical ICA. An Excelsior SL-10} 45 preshaped microcatheter (Stryker Neurovascular, Fremont,
California, USA) was carefully navigated to the aneurysm
using a Synchro2 Soft 0.014 micro guidewire (Stryker Neu-

Received

April 28, 2011;

Accepted August 31, 2011

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Fig. 2 A–C: Left internal carotid angiograms, lateral view,
showing placing the 3rd coil into the aneurysm (A), but a loop
protruded into the left internal carotid artery (B). The loop was
unraveled and moved into the left internal carotid artery (C).
Then, we abandoned detaching the fourth coil. D: Post-coil
embolization subtraction image showing only a small neck
remnant, so we decided that this operation should be abandoned.
Fig. 1 A, B: Computed tomography scans on admission showing subarachnoid hemorrhage. C: Three-dimensional digital
subtraction angiogram revealing an anterior choroidal artery
aneurysm. D: Left common carotid angiogram showing coiling of the extracranial internal carotid artery (arrow).

rovascular). For the first coiling, a cage formation was
created inside the aneurysm using DCS complex fill 5 × 5
(Cordis Corporation, Bridgewater, New Jersey, USA) (Fig.
2). After successful cage formation, flexible platinum coils
were introduced such as DCS mini-complex fill 3 × 4 coils
to fill the inner cavity of the aneurysm, and moderate
aneurysm packing was confirmed. After intravenous administration of 3,000 units of heparin, GDC UltraSoft 3 ×
4 coils (Stryker Neurovascular) were inserted for complete
embolization. The last coil was too soft and redundant,
resulting in a loop which protruded into the parent artery
and pushed the microcatheter away from the aneurysm.
Although we tried to achieve complete packing using a
shorter coil (GDC UltraSoft 2 × 2), the aneurysm neck was
too wide to hold the looped coil, and coil manipulation
was severely disturbed by the cervical ICA anomaly. We
abandoned further procedures because blocking of the
blood flow into the aneurysm had been completed, and we
planned to observe the remaining coil loop. The total coil
length was 9 cm, and the VER was 17.4%.
After the endovascular treatment, the patient had no
neurological deficit. Cerebrospinal fluid was continuously
drained with intrathecal administration of urokinase
(6,000 units/day) and aspirin (100 mg/day) was orally administered to prevent deterioration of vasospasm. Two
days later (10th day after onset), she suffered right hemipa-

Fig. 3 A: Left carotid angiogram, anteroposterior view, before
arterial injection of 30 mg of fasudil hydrochloride on day 10
revealing delayed arterial spasm (arrowheads). B, C: Computed tomography scans on day 10 showing low density areas in
the left frontal lobe.

resis and aphasia, and emergent cerebral angiography disclosed narrowing of the bilateral anterior cerebral arteries
and middle cerebral arteries (MCAs) (Fig. 3A). Severe
vasospasm was considered to be the cause of the symptoms and 30 mg of fasudil hydrochloride was administered via the 4-Fr angiographic catheter. No displacement or migration of the coils in the aneurysm and
improvement of vasospasm were confirmed. The symptoms persisted until the 12th day and head CT revealed a
low density area in the left frontal region (Fig. 3B, C).
Cerebral angiography was repeated and 30 mg of fasudil
hydrochloride injected into the left ICA for symptomatic
vasospasm. The coil shape including the protrusion maintained stable. After the 3rd angiography, she gradually

Neurol Med Chir (Tokyo) 52, June, 2012

Surgery to Treat Delayed Coil Migration

441

Fig. 4 Skull radiographs, Town's (A) and lateral views (B), on
day 24 showing the migrated coil portion (arrowhead).
Fig. 6 Left internal carotid angiograms, anteroposterior view,
showing no aneurysm in the digital subtraction image (A), and
the remaining coil and clips (B).

Fig. 5 Intraoperative photographs. A: After opening the left
sylvian fissure, the migrated coil was seen through the middle
cerebral arterial wall (arrows). AN: aneurysm dome, M1: M1
portion of left middle cerebral artery. B: A clip was applied to
the neck of the aneurysm, and the cut anterior aneurysm wall
and coils were seen. The clip head was opened slightly, to try to
retrieve the migrated coil. However, the coil was adhered to the
arterial wall. When the coil was pulled, a wrinkle was caused
on the wall of the M1 artery. The coil could not be removed.
B?: Illustration of B. ICA: internal carotid artery.

recovered from the symptoms. In the early morning of the
24th day after onset, severe right hemiparesis and total
aphasia suddenly appeared. Emergent magnetic resonance (MR) imaging demonstrated no new lesion on
diffusion-weighted images except for old ischemic
changes due to the vasospasm. MR angiography showed
uncertain signal loss between the peripheral portion of the
left ICA and the proximal site of the MCA. Radiography
depicted part of the embolization coils was stretched and

Neurol Med Chir (Tokyo) 52, June, 2012

had migrated from the aneurysm neck to the MCA (Fig. 4).
Although the symptoms diminished within 6 hours
without special treatment, we decided to retrieve the
migrated part of the coils by open surgery, to avoid embolic events or arterial wall injury and aneurysm re-rupture.
The left ICA and the aneurysm were exposed by left
fronto-temporal craniotomy and part of the migrated coil
was observed between the ICA top and proximal MCA
(Fig. 5). After temporary clips were placed at the proximal
and distal sites of the aneurysm on the ICA, the translucent aneurysm sac was opened for complete removal of
the coils. However, the entire coil was impossible to
withdraw because of severe adhesion between the migrated part and the MCA arterial wall. As the coil was pulled,
a wrinkle was caused on the wall of the M1 artery. Therefore, we removed only the coils in the aneurysm, preventing further coil migration, since aggressive manipulation
might worsen arterial wall injury. Aneurysm clipping was
achieved with 2 titanium clips (Yasargil 720T; Aesculap
AG, Tuttlingen, Germany) and the coil remnant was cut at
the aneurysm neck inlet, leaving the migrated part in the
M1. Postoperative angiography demonstrated 8 mm of the
remnant coil remained between the ICA top and proximal
MCA with complete aneurysm clipping (Fig. 6). Six
months after the open surgery, she had suffered no new
neurological deficit, and the remnant coil had not migrated or caused any new ischemic event.

Discussion
The present case of SAH caused by a ruptured aneurysm
and associated with severe vasospasm initially treated
with endovascular embolization. Although serial angiography showed no deformity or dislocation of the coils
during the acute period, coil migration was found more
than 3 weeks after the embolization. The superiority of
coil embolization over clipping for ruptured aneurysms
within 2 years after onset has been proposed. In particular, the endovascular procedure causes fewer ischemic
complications during the vasospasm phase in patients
with SAH.1,7) In this case, coil embolization was appropriate to avoid re-bleeding in the acute period.
In general, migration of the coil outside the aneurysm is
caused by stopping packing while the coil partially pro-

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H. Wada et al.

trudes. Other causes are wide aneurysm neck or loose
packing of coils. We could not help ending in such a situation in the acute stage. If a little more coil can be packed
into the aneurysm tightly regardless of the coil type, this
complication would not occur. Assisting techniques with
balloon or stent are effective and used worldwide to
reduce migration of the coil. On the other hand, delayed
coil migration after embolization has been recently reported. There are two main reasons for the migration. One reason is the stent technique used with the embolization.2,4)
Although stent devices are expected to stably support embolizing coils, fine coils might escape from the stent struts
with loose mesh design. The other reason is the combination of the ultrasoft coil, which was recently developed for
better embolization, and the balloon remodeling technique.3,5,8) This technique may simply compress the
ultrasoft coils in the coil complex by the balloon. In our
case, no stent, balloon, or ultrasoft coil was used. Therefore, our endovascular strategy had less risk of coil migration than previous methods. Coil migration usually occurs
during or within a day after the embolization procedure
(acute phase). Since vessel endothelium cells might
proliferate within a week after treatment, the coils might
become stable in the subacute phase. Delayed coil migration, as experienced in the present case, is relatively rare.
Surgical removal failed to retrieve the migrated coils because of severe adhesion related to endothelial proliferation and inflammation on the arterial wall. On the basis of
our experience, we have to carefully check for coil migration, even some weeks after completing treatment with no
negative occurrences.
Our patient had two associated pathological conditions,
vasospasm and tortuous cervical ICA. In particular, the
tortuous cervical ICA hindered balloon remodeling and
fine control of the microcatheter. As a result, the coil packing ratio did not reach adequate values. Such multiple factors might still make endovascular treatment complex.
Catheterization to treat peripheral severe tortuous arteries
is difficult. Treatment must be planned on the assumption
of difficulty in using a balloon in the acute phase, and the
possibility of clipping. To employ catheterization to complete treatment without a balloon, we should use a triple
coaxial system, such as the Cerulean catheter (Medikit), or
the head position should be rotated beforehand to release
coiling of the cervical ICA.
The coil placed in the aneurysm was displaced and
embolization became incomplete, so we performed
craniotomy and clipping to prevent re-rupture. Coil embolectomy, vessel repair, and clipping of the aneurysm are
necessary for surgical treatment after such distal coil
migration. Coil embolectomy and neck clipping is the optimum treatment strategy. However, removal of intravascular coils is not always possible due to adhesion to the arterial wall. Symptomatic arterial stenosis has been caused
by a coil which migrated into the peripheral artery during
an operation.6) Therefore, surgical management that considers even revascularization procedures such as superficial temporal artery-MCA bypass is necessary. Coil
manipulation should be carefully performed because the

dynamics of coils inserted into the human body are
difficult to predict.9,10)
The present patient with SAH was treated with coil embolization in the spasm phase, but part of a protruding coil
migrated distally in the chronic phase. Although endovascular treatment is useful for SAH in the spasm phase, application may be difficult in some cases and should be
carefully performed. If a protruding coil is detected at the
finish of endovascular treatment, we should consider additional endovascular treatment in the chronic stage. Surgical treatment of a migrating coil may be difficult due to
adhesion to the vascular wall.

References
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Brisman JL, Roonprapunt C, Song JK, Niimi Y, Setton A,
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Address reprint requests to: Hajime Wada, MD, Department of
Neurosurgery, Asahikawa Medical University, 2–1, 1–1,
Midorigaoka–Higashi, Asahikawa, Hokkaido 078–8510,
Japan.
e-mail: hjwada＠asahikawa-med.ac.jp

Neurol Med Chir (Tokyo) 52, June, 2012