145

Aneurysms of the AC A: Anterior Communicating Artery (Interhemispheric Approach)

Aneurysms of the Anterior Cerebral Artery:
Anterior Communicating Artery
(Interhemispheric Approach)

Special The anterior communicating artery (ACoA)
Considerations complex is the most common origin for an-
eurysms of the anterior cerebral artery
(ACA). Preoperative angiograms in multi-
ple views are reviewed to assess collateral
circulation, configuration, and orientation
of the aneurysm. We prefer the inter-
hemispheric precallosal approach (see
Chapter I) for (1) ruptured ACoA aneu-

rysms pointing directly anterior that may
adhere to the optic chiasm, (2) ACoA aneu-
rysms unsuccessfully clipped by a pterional
approach, and (3) multiple aneurysms of
the ACoA and pericallosal artery. Aside
from these considerations, the pterional ap-
proach (see Chapter I) is used for aneu-
rysms of the A, and ACoA segment.

146

Aneurysms of the Anterior Circulation

2.98

Approach A frontal parasagittal craniotomy is made
as for a standard interhemispheric precal-
losal approach (see Chapter I). The patient
is placed in the supine position with the
head extended in 0 degrees rotation and the
thorax raised 15 degrees. Preoperative
placement of a lumbar spinal catheter or
ventricular catheter for intraoperative aspi-
ration of cerebrospinal fluid will facilitate
brain relaxation and retraction.

2.98 A dural flap is reflected
over the sagittal sinus. If possible, cortical
bridging veins are dissected free from the
arachnoid and preserved. Two 15-mm self-
retaining retractor blades are applied to the
falx and medial frontal lobe. Arachnoid ad-
hesions overlying the cingulate gyrus are
coagulated and sectioned.

Aneurysms of the AC A: Anterior Communicating Artery (Interhemispheric Approach) 147

2.99

2.99 The cingulate gyrus is
retracted to allow visualization of the origin
of the callosomarginal artery. The cal-
losomarginal branch defines the transition
from anterior cerebral to pericallosal artery
and distinguishes the ACA from the fron-
topolar artery, which follows a course
above the cingulate gyrus.

2.100 The retractors are
moved anteriorly to follow the course of the
ACA around the genu of the corpus cal-
losum. The adhesions between the cingu-
late gyri are coagulated and sectioned to
expand the exposure.

f —

2.100

148 Aneurysms of the Anterior Circulation

2.101

2.101 Sagittal view of the
movement of the retractors around the
genu of the corpus callosum: from anterior
to the genu (position 1), to inferior to the
genu (position 2), and to expose the aneu-
rysm (position 3). Figures 2.100 and 2.101
show the importance of keeping the ACA in
view and tracing it to the source of the
aneurysm at the ACoA region.

Aneurysms of the ACA: Anterior Communicating Artery (Interhemispheric Approach) 149

2.102 Two 15-mm retractors
retract both inferior frontal gyri (position
3). Two additional 3-mm retractors supple-
ment the exposure of the aneurysm base
and the ACoA. Adhesions between the
frontal lobes are coagulated and sectioned.
At this point, removal of parenchyma! and
interhemispheric clot will provide addition-
al exposure of the aneurysm.

2.102

150 Aneurysms of the Anterior Circulation

2.103

2.104

2.105

2.103 Systemic hypotension is
induced to reduce intra-aneurysmal pres-
sure. The microretractors are repositioned
to expose the base of the aneurysm, ACoA,
and posteriorly coursing hypothalamic per-
forators. The dome of the aneurysm should
remain protected beneath the inferior fron-
tal gyrus.

2.104, 2.105 The ACoA and an-
eurysm base are sharply dissected from the
left (2.104) and right (2.105) A, segments to
prepare a path for clip placement, thus ob-
taining proximal control. This exposure
creates a deep and narrow corridor.

152

Aneurysms of the Anterior Circulation

2.108

Recurrent "
artery of /
Heubner

2.108, 2.109 The collapsed an-
eurysm sac is manipulated to ascertain the
integrity of both A, and A₂ segments, the
ACoA, recurrent arteries of Heubner, and
hypothalamic perforators.

Closure Because this operation is performed through
the forehead, good cosmetic closure is im-
portant. A detailed description of the clo-
sure is given in Chapter I (Interhemi spheric
Approach: Precallosal).

2.109

Aneurysms of the ACA: Anterior Communicating Artery (Interhemispheric Approach) 151

2.106

2.106 A clip is guided into
place across the aneurysm base. Because
the application of temporary clips is diffi-
cult in this exposure, premature rupture
should be controlled by direct suction at the
rupture site.

I

2.107

2.107 The aneurysm is punc-
tured with a 22-gauge needle. The clip is
closed as blood is aspirated from the
aneurysm.

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