119

Aneurysms of the Middle Cerebral Artery: Giant, Partially Thrombosed

Aneurysms of the Middle Cerebral Artery:
Giant, Partially Thrombosed

Special Patients with giant, partially thrombosed
Considerations aneurysms of the middle cerebral artery
(MCA) present with seizures, ischemia
caused by distal embolization, and mass
effect; hemorrhage is rare. The potential for
distal branch occlusion and the need for
vascular bypass are assessed preopera-
tively. Although intraoperative reanasto-

mosis of vessels is an option, we prefer to
protect the patient with a preoperative
high-flow vein graft from the cervical exter-
nal carotid artery to the distal MCA. Local
hypotension by trapping is achieved by
temporarily occluding the proximal and dis-
tal MCA. Cerebral protection must be ad-
ministered by the anesthesiologist.

120 Aneurysms of the Anterior Circulation

Approach The patient is placed in a supine position
(see Chapter I) with the head maintained at
45 degrees rotation. The craniotomy is
pterional with half-and-half exposure of the
frontal and temporal lobes. A radiolucent
head-fixation device is used when intra-
operative angiography is anticipated.

2.57

segment)

2.58

2.57 Exposure of both the
temporal lobe and the sylvian fissure is
achieved by a modified pterional approach.

2.58 The sylvian fissure is
opened over the dome of the giant aneu-
rysm. Multiple retractors are used to retain
exposure of the sylvian veins, distal arte-
ries, and dome of the lesion. The proximal
M,, is exposed adjacent to the aneurysm
base.

Aneurysms of the Middle Cerebral Artery: Giant, Partially Thrombosed 121

2.59 The aneurysm is punc-
tured to ensure that the exposed dome is
thrombosed.

2.61

122 Aneurysms of the Anterior Circulation

123

Aneurysms of the Middle Cerebral Artery: Giant, Partially Thrombosed

2.60 In the presence of a
large intraluminal hematoma, the dome is
incised widely.

2.61 Retractors retain an
opening in the dome as the surgeon at-
tempts to remove a thrombus with forceps.

2.62

2.62 A thrombus inside a gi-
ant aneurysm is usually organized or cal-
cified and is best removed with an
ultrasonic aspirator. The residual lumen of
the aneurysm is covered with soft red
thrombus, which is not evacuated at this
stage.

124

Aneurysms of the Anterior Circulation

2.63 Cerebral protective
agents and systemic hypertension are in-
duced by the anesthesiologist. The col-
lapsed sac is folded on itself and a
temporary clip is placed on the proximal M,
segment.

2.64 The sac is retracted
proximally and temporary clips are placed
on the M₂ branches.

2.64

Aneurysms of the Middle Cerebral Artery: Giant, Partially Thrombosed 125

2.65 The remaining soft
thrombus is evacuated. The capacious col-
lapsed sac is excised, leaving a generous
cuff of aneurysm wall near the base of the
middle cerebral bifurcation.

2.66 A sufficient amount of
aneurysm wall is preserved to permit clo-
sure of the aneurysm base.

2.66

126

Aneurysms of the Anterior Circulation

2.69

2.67-2.69 Multiple hemostatic
clips (2.67), continuous monofilament su-
ture (2.68), or multiple right-angle aneu-
rysm clips (2.69) can be used to obtain
secure closure. Temporary clips are re-
moved to test the security of closure. Intra-
operative angiography should be completed
in most cases even though Doppler analysis
may indicate that the distal vessels are
patent.

If clips cannot be applied safely be-
cause of firm calcification of the aneurysm
base and branch arteries, then permanent
trapping may be necessary. In this cir-
cumstance, a bypass graft is mandatory.
Another option is reimplantation of the M₂
branches to the M, segment.

Closure Closure is completed as for a pterional cra-
niotomy (see Chapter I).

127

Aneurysms of the Middle Cerebral Artery: With Temporal Lobe Hematoma

Aneurysms of the Middle Cerebral Artery: With
Temporal Lobe Hematoma

Special Aneurysms of the middle cerebral artery
Considerations (MCA) frequently present with a temporal
lobe hematoma that may produce a life-
threatening mass effect. In these situations,
we prefer a direct approach through the

middle temporal gyrus. The hematoma is
entered and aspirated until the aneurysm is
reached. Aneurysm rupture is controlled by
counterpressure and temporary trapping.

128

Aneurysms of the Anterior Circulation

Approach The patient is placed in a supine position
(see Chapter I) with the head maintained at
45 degrees rotation. The craniotomy is
pterional with half-and-half exposure of the
frontal and temporal lobes.

2.71 If the brain is very
tense, then a small opening may be made
over the temporal lobe. After the hema-
toma is partially evacuated by aspiration,
the dura can be opened safely. The arach-
noid overlying the middle temporal gyrus is
coagulated.

2.71

Aneurysms of the Middle Cerebral Artery: With Temporal Lobe Hematoma 129

Hematoma Aneurysm

2.73

2.72 A cortical incision (4
cm) is made in the middle temporal gyrus.
The opening is maintained with two 15-mm
self-retaining retractors.

2.73 The hematoma is aspi-
rated and dissected superiorly and inferi-
orly from its attachment to the temporal
lobe. The aneurysm dome lies al the base of
the clot and is approached at the final stage
of clot removal.

, 130 Aneurysms of the Anterior Circulation

MCA

Frontal
artery

Temporal
artery

2.74 A microretractor is di-
rected toward the proximal margin of the
clot as the dissection approaches the MCA.
Caution is exercised to avoid removing
the clot from the aneurysm dome until the
distal mi segment of the MCA can be
exposed.

131

Aneurysms of the Middle Cerebral Artery: With Temporal Lobe Hematoma

2.76

2.75 Two additional micro-
retractors are placed as further dissection
exposes the distal M, segment. A tempo-
rary clip is placed at this site. To prepare a
site for clip placement, the dissection sepa-
rates the base of the aneurysm from the
temporal and frontal branches of the MCA.
Premature rupture of the aneurysm can be
controlled by counterpressure on the dome
and placement of temporary clips on the
distal M₂ branches.

2.76 A clip is placed across
the aneurysm base.

132 Aneurysms of the Anterior Circulation

Lateral

lenticulostriate

arteries

2.77

2.77 The dome is reflected to
show that the parent vessels and lateral len-
ticulostriate arteries are excluded from the
clip blades and that the aneurysm base is
completely obliterated.

Closure Closure is completed as for a pterional ap-
proach (see Chapter I).

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