Surgical Neurolog

Aneurysm

Clipping and superficial temporal artery–M2 bypass for unruptured

anterior communicating artery aneurysm associated with atherosclerotic

internal carotid artery occlusion: report of 2 cases

Tomohiro Inoue, MD, Kazuo Tsutsumi, MD4, Shinobu Adachi, MD, Shota Tanaka, MD,

Kuniaki Saito, MD, Naoto Kunii, MDDepartment of Neurosurgery, Showa general hospital, 2-450 Tenjinn-cho Kodaira-shi, Tokyo, 187-8510, Japan

Received 6 January 2006; accepted 4 October 2006

www.surgicalneurology-online.com

Abstract Background: The management of the unruptured AcomA aneurysm associated with atherosclerotic

0090-3019/$ – see fro

doi:10.1016/j.surneu.2

Abbreviations: Ac

spinal fluid; ICA, int

MEP, motor-evoked

MRI, magnetic resona

SEP, somatosensory-e

computed tomograph

intelligence quotient;

4 Corresponding

E-mail address: k

occlusion of the unilateral internal carotid artery (ICA) raises several strategic dilemmas.

Methods: Two such patients with unruptured aneurysm on the AcomA, which supply cross-flow

toward the hemisphere with ICA occlusion, are presented.

Results: Both patients were treated with STA-M2 bypass followed by clipping of the unruptured

AcomA aneurysm in 1 stage through the transsylvian route. Both patients were doing well without

neurological deficit nor cognitive impairment at 1 year follow-up.

Conclusions: In the surgical treatment of unruptured AcomA aneurysm with atherosclerotic ICA

occlusion, preceding bypass would be ideal in case of intraoperative rupture as well as to reduce

perioperative ischemia if the bypass procedure itself could be performed with minimal risk. Enough

and atraumatic exposure of the sylvian fissure contributed to reduce brain retraction during the

clipping of AcomA aneurysm and, in addition, to ease the STA-M2 bypass.

D 2007 Elsevier Inc. All rights reserved.

Keywords: Cerebral revascularization; Cerebral aneurysm; Ischemic cerebrovascular disease

1. Introduction

The management of unruptured intracranial aneurysms

remains controversial. Especially when the patient is

harboring unruptured aneurysm and major trunk occlusion

simultaneously, the surgical risk would be higher and

strategic dilemmas would appear. We recently encountered

2 patients who harbored unruptured aneurysm with rela-

tively small size, however, on the AcomA that supplies

cross-flow toward the hemisphere with atherosclerotic ICA

nt matter D 2007 Elsevier Inc. All rights reserved.

006.10.031

omA, anterior communicating artery; CSF, cerebro-

ernal cerebral artery; MCA, middle cerebral artery;

potential; MRA, magnetic resonance angiography;

nce imaging; PIQ, performance intelligence quotient;

voked potential; SPECT, single photon emission

y; STA, superficial temporal artery; VIQ, verbal

WAIS-R, Wechsler Adult Intelligence Scale Revised.

author. Tel.: +81 424 61 0052; fax: +81 424 64 7912.

.tsutsumi-md@nifty.com (K. Tsutsumi).

occlusion. Both patients underwent successful surgical

repair with clipping in conjunction with STA-M2 bypass.

The details of the management are presented and discussed.

2. Case report

2.1. Case 1

A 59-year-old man presented to another hospital with the

complaint of recent and frequent dizziness. His medical

history included hypertension and hyperlipidemia. Magnetic

resonance imagings were performed, which revealed unrup-

tured AcomA aneurysm, left carotid ICA occlusion, and

multiple lacunar infarctions. He was referred to our

department for possible surgical intervention. Neurological

examination did not show any focal deficit, although WAIS-

R score was dull normal level showing VIQ 96, PIQ 57, and

full scale IQ 78. Cerebral angiography showed atheroscle-

rotic left internal carotid artery occlusion as well as

y 68 (2007) 226–232

Fig. 1. Left panel: preoperative right carotid angiogram (right oblique view) shows AcomA aneurysm and robust cross-flow toward left MCA area. Right panel:

left cervical carotid angiogram (lateral view) shows occlusion of left internal carotid artery.

T. Inoue et al. / Surgical Neurology 68 (2007) 226–232 227

unruptured AcomA aneurysm, which was approximately

7 mm. Left cerebral hemisphere was supplied by the right-

to-left robust cross-flow through AcomA, which was

harboring aneurysm (Fig. 1). Single photon emission

computed tomography with acetazolamide infusion showed

slightly decreased vascular reserve of the left MCA area

compared to right. After thorough discussion, open surgical

repair of the aneurysm in conjunction with STA-M2 bypass

was chosen. A left pterional craniotomy was performed with

the preservation of STA. Under the microscope, distal

sylvian fissure was widely opened with preservation of the

superficial sylvian vein. Then, STA-M2 anastomosis was

Fig. 2. Intraoperative photographs of case 1. Upper left: during STA-M2 bypass; u

after completion of bypass with widely opened sylvian fissure; lower right: after op

ipsilateral rectal gyrus, the AcomA aneurysm is exposed.

performed with 14 stitches. The occlusion time was

25 minutes. After confirming good bypass flow with

microvascular Doppler, we approached the AcomA aneu-

rysm through the transsylvian route. Because the AcomA

complex was open toward the contralateral side (ipsilateral

A2 was placed anteriorly compared with contralateral A2),

we opened the interhemispheric fissure with a microscissor

and retracted the ipsilateral rectal gyrus gently, which

well visualized the aneurysm. With great attention to

preserve AcomA supplying the cross-flow, clipping of

the aneurysm was performed (Fig. 2). Postoperative angio-

grams demonstrated complete clipping of the aneurysm

pper right: after completion of bypass; lower left: bloodless operative field

ening interhemispheric fissure through left transsylvian route. By retracting

Fig. 3. Left panel: postoperative right carotid angiogram (right oblique view) shows complete clipping of the aneurysm as well as preserved cross-flow through

AcomA. Right panel: left carotid angiogram (lateral view) showing patent STA-M2 bypass.

T. Inoue et al. / Surgical Neurology 68 (2007) 226–232228

and preservation of cross-flow in addition to patent STA-M2

bypass (Fig. 3). The patient was discharged without deficit.

At 6 months follow-up postoperatively, his WAIS-R score

was improved (VIQ 97, PIQ 72, full scale IQ 86) compared

preoperatively, in addition to diminished asymmetry of the

vascular reserve in SPECT with acetazolamide. At 2 years

follow-up, he is spending an independent life without stroke

episodes, and the MRI showed neither contusion nor

atrophy of the ipsilateral frontal lobe as well as still patent

bypass (Fig. 4).

Fig. 4. Upper right: preoperative and postoperative (6 months) SPECT with acetaz

side is corrected after operation. Lower left: postoperative T2-weighted MRI (2 y

postoperative MRA (2 years) shows still patent left STA-M2 bypass, although th

2.2. Case 2

A 75-year-old woman presented to another hospital

complaining of a feeling of heaviness in head. Magnetic

resonance imagings were performed, which revealed unrup-

tured AcomA aneurysm, right ICA occlusion, and multiple

lacunar infarction. Her medical history was significant for

hypertension, which was medically controlled. She was

referred to our department for possible surgical intervention.

On neurological examination, she was fully independent and

showed no focal deficit. She refused WAIS-R examination.

olamide challenge shows that slightly decreased vascular reserve on the left

ears) shows no evidence of left frontal contusion nor atrophy. Lower right:

e clip artifact is deteriorating the quality of the image.

Fig. 5. Left panel: preoperative left carotid angiogram (left oblique view) shows AcomA aneurysm and robust cross-flow toward right MCA area. Right panel:

right cervical carotid angiogram (lateral view) shows occlusion of right internal carotid artery.

T. Inoue et al. / Surgical Neurology 68 (2007) 226–232 229

Cerebral angiography showed atherosclerotic right ICA

occlusion as well as AcomA aneurysm that was approxi-

mately 5 mm. Right cerebral hemisphere was supplied by the

left-to-right robust cross-flow through AcomA, which was

harboring aneurysm (Fig. 5). Single photon emission

computed tomography with acetazolamide infusion showed

slightly decreased vascular reserve of the right MCA area

compared to the left. After thorough discussion, open surgical

repair of the aneurysm in conjunction with STA-M2 bypass

was chosen. A right pterional craniotomywas performed, and

the details of the surgical procedure were almost the same as

Fig. 6. Intraoperative photographs of case 2. Upper left: during STA-M2 bypass. U

the aid of a retractor. Small continuous suction tube is located at the base. The tip

after opening interhemispheric fissure through transsylvian route. Only the nec

posteriorly. Lower right: final clipping view through the space posterior to ipsila

that illustrated in case 1. In this case, the AcomA complex

was open toward the contralateral side even more compared

with case 1 (ipsilateral A2 completely hid the aneurysm even

after opening up the interhemispheric fissure and retracting

the ipsilateral rectal gyrus). With great care not to injure the

ipsilateral Heubner artery, we opened the space posterior to

ipsilateral A2 and mobilized it anteriorly, which finally well

visualized the aneurysm. The clipping was completed with

the preservation of AcomA (Fig. 6). Postoperative angio-

grams demonstrated complete clipping of the aneurysm and

the preservation of cross-flow in addition to patent STA-M2

pper right: sylvian fissure is kept open by a prop (rolled Bensheet) without

of the suction tube is located deeper than the anastomosis site. Lower left:

k of the aneurysm is slightly visible even after retracting ipsilateral A2

teral A2.

Fig. 7. Left panel: postoperative left carotid angiogram (left oblique view) shows complete clipping of aneurysm as well as preserved cross-flow through

AcomA. Right panel: right carotid angiogram (lateral view) showing patent STA-M2 bypass.

T. Inoue et al. / Surgical Neurology 68 (2007) 226–232230

bypass (Fig. 7). She was discharged without deficit. At 1 year

follow-up, she is spending a fully independent life without

stroke episodes, and the asymmetry of the vascular reserve in

SPECT with acetazolamide has diminished. Magnetic reso-

nance imaging showed neither contusion nor atrophy of

ipsilateral frontal lobe as well as still patent bypass (Fig. 8).

3. Discussion

The management of unruptured intracranial aneurysm

remains controversial, especially since the recent report of

the International Study on Unruptured Intracranial Aneu-

rysm, which suggested a more benign natural history of the

Fig. 8. Upper right: preoperative and postoperative (1 year) SPECT with acetazol

side is corrected after the operation. Lower left: postoperative T2-weighted MRI (1

postoperative MRA (1 year) shows still patent right STA-M2 bypass, although th

small unruptured aneurysm than what was previously

thought [9]. However, most neurosurgeons do not have

the same impression on the basis of daily clinical practice

[7,11] and would estimate the risk of the aneurysm rupture

higher depending not only on size but also on shape, growth

rate, or hemodynamics of the aneurysm. Although it is

unclear if the unruptured AcomA aneurysm in association

with unilateral ICA occlusion tend to rupture more

compared with the usual AcomA aneurysm, several

ruptured de novo aneurysms of AcomA as the consequence

of previous therapeutic ICA occlusion have been reported

[1,2,3,6,10]. Considering robust cross-flow through AcomA

toward the hemisphere with ICA occlusion, we estimated

amide challenge shows that slightly decreased vascular reserve on the right

year) shows no evidence of right frontal contusion nor atrophy. Lower right:

e clip artifact is deteriorating the quality of the image.

T. Inoue et al. / Surgical Neurology 68 (2007) 226–232 231

that the risk of rupture of the present 2 cases would be high

and decided on surgical intervention.

Surgical treatment of the unruptured aneurysm with

ischemic cerebrovascular disease could be related to

increased risk of postoperative morbidity and mortality due

to general atherosclerotic changes as well as special fragility

of the ischemic brain [8]. In addition, in the cases of AcomA

aneurysm on the robust cross-flow, the ischemic damage of

the hemisphere with ICA occlusion could be devastating in

case of intraoperative rupture necessitating temporary occlu-

sion of A1 or perioperative transient spasm of A1 andAcomA

related to surgical manipulation. For the purpose of insur-

ance, and in the presence of slightly decreased vascular

reserve, the preceding bypass could increase the perioper-

ative general ischemic tolerance against the negative factors

such as retraction during clipping, CSF aspiration, and

hemodynamic instability related to anesthesia effect if the

bypass procedure itself is smoothly performed with accept-

able occlusion time. Therefore, we conducted a preceding

STA-M2 bypass. The reason why we chose M2 as the

recipient is because we expected immediate more robust flow

through the bypass compared with choosing a cortical branch

with smaller caliber as the recipient. The high flow bypass

using radial artery graft, in the presence of multiple lacunar

infarction as well as decreased vascular reserve, was thought

to be not ideal just for the insurance of the inadvertent

temporary occlusion of AcomA or A1, considering the risk of

hyperperfusion as well as the complex nature of this

technique itself. If the preoperative hemodynamic compro-

mise is more severe with decreased cerebral blood flow at rest

as well as severely impaired vascular reserve, 2-staged

operation (bypass surgery in first stage and after improve-

ment of hemodynamic compromise, clipping surgery in

second stage) could be the choice.

From the technical standpoint to reduce perioperative

ischemic complications as well as to prevent cognitive

impairment related to surgery, we used several ideas in the

present cases. First, we continued antiplatelet medication

throughout the perioperative period to reduce general

ischemic risk. Great care was taken to maintain a bloodless

microscopic operative field compared with the usual crani-

otomy by rigid hemostasis, especially of the temporalis

muscle andmiddle meningeal artery, as well as by augmented

peripheral tacking suture of the dura to bone margin. Second,

we paid attention in keeping the blood pressure relatively

high intraoperatively to avoid hemodynamic ischemia

especially before the institution of the bypass. Although we

did not use intraoperative monitoring in the present 2 cases,

such as SEP or MEP, it would help to decide how high the

blood pressure should be controlled. Third, we made every

effort to ease the STA-M2 bypass. During STA-M2 bypass,

rolled Bensheet was inserted between the frontal lobe and the

temporal lobe as a dpropT to keep the sylvian fissure open

enough (Fig. 6) without the aid of a retractor, which is some-

what disturbing during a bypass procedure [5]. Continuous

suction of the CSF with a small soft tube located deeper than

the anastomosis site during recipient occlusion also contrib-

uted to a smooth anastomosis by preventing the overflow of

CSF to the anastomosis site [5]. Fourth, sharp and enough

dissection of the sylvian fissure and interhemispheric fissure

with a microscissor enabled visualization of AcomA aneu-

rysm with minimal and atraumatic retraction. In the present

2 cases, the need for STA-M2 bypass obliged us to approach

the AcomA aneurysm from the side wherein the ipsilateral

A2 is anteriorly located and hindering the visualization of

aneurysm. Opening up the intehemispheric fissure and

careful retraction of the ipsilateral rectal gyrus well compen-

sated the previously mentioned disadvantage [4]. Although

final view and retraction during the clipping procedure are

somewhat frontobasal rather than pure transsylvian, wide

dissection of the sylvian fissure alsomade the retraction of the

ipsilateral frontal lobe and rectal gyrus gentle, which might

have contributed to prevent cognitive impairment by surgical

manipulation. However, if the anatomical condition of the

AcomA aneurysm is not suitable for the approach from the

occlusion side completely, a 2-staged operation using

contralateral or interhemispheric approach should be consid-

ered after bypass surgery.

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