Surg Neurol
1992;38:347-52

347

Giant Aneurysm of the Distal Anterior Cerebral Artery: Associated
with an Anterior Communicating Artery Aneurysm and a Dural
Arteriovenous Fistula
Mark Preul, M.D., Donatella Tampieri, M.D., and Richard Leblanc, M.Sc., M.D., FRCSC
Divisions of Neurosurgery and Neuroradiology, Montreal Neurological Institute and Hospital, McGill University, Montreal,
Quebec, Canada

Preul M, Tampieri D, Leblanc R. Giant aneurysm of the distal
anterior cerebral artery: associated with an anterior communicating
artery aneurysm and a dural arteriovenous fistula. Surg Neurol
1992;38:347-52.

We describe an unusual case of a giant pericallosal artery
aneurysm, producing psychomotor depression from mass
effect, associated with a smaller aneurysm of the anterior
communicating artery, a dural arteriovenous fistula, and
a meningioma. Magnetic resonance imaging (MRI) and
cerebral angiography demonstrated the giant aneurysm
and the meningioma. Cerebral angiography provided a
detailed appreciation of the cerebral circulation, including both aneurysms, the dural arteriovenous fistula, and
the potential collateral supply to the involved anterior
cerebral distribution. T h e anterior communicating artery
aneurysm was successfully clipped as was the distal anterior cerebral branch supplying the giant aneurysm before
its resection, T h e patient made a full recovery but with
persisting, slight dysphasia. We conclude that computed
tomography, cerebral angiography, and MRI are of specific value in the assessment of giant aneurysms, but only
angiography can provide detailed characterization of the
aneurysm and demonstrate other possible cerebrovascular
pathology such as multiple aneurysms and arteriovenous
fistulas.
KEYWORDS: Anterior cerebral artery; Cerebral aneurysm; Cerebral angiography; Giant aneurysm; Magnetic resonance imaging; Pericallosal artery

Five to thirteen percent o f intracerebral aneurysms are
greater than 2.5 cm in diameter (giant aneurysms)
[2,3,5,9,10,12,25,27,29]. W h e n arising f r o m the anterior cerebral artery, they usually originate from the anterior communicating complex [13,15,17]. Giant aneu-

Address reprint requests to: Richard Leblanc, M.D., FRCSC, Department of Neurology and Neurosurgery, Montreal Neurological Institute and Hospital, 3801 University St., Montreal, PQ, Canada H3A
2B4.
Received January 22, 1992; accepted March 25, 1992.

© 1992 by Elsevier Science Publishing Co., Inc.

rysms of the distal anterior cerebral artery are rare: we
k n o w of only nine previous reports [5,7,14,16,18,
20,22,26]. N o report has d o c u m e n t e d the association of
a smaller saccular aneurysm with a giant distal anterior
cerebral artery aneurysm, nor has a case been described
with an associated dural arteriovenous fistula.
Magnetic resonance imaging (MRI) has been suggested to be superior to angiography in characterizing
giant anterior cerebral artery aneurysms [ 14]. H o w e v e r ,
in our case angiography d e m o n s t r a t e d a second aneurysm and a dural arteriovenous fistula not seen on MRI,
and demonstrated extensive collateral supply across the
anterior border zone f r o m the middle cerebral to the
anterior cerebral territory not discernable on the MR
images. Angiography therefore played a crucial role in
the diagnosis and treatment o f this patient.

Case Report
A 72-year-old man was admitted to hospital because of a
10-day history o f mental deterioration and inappropriate
behavior. H e was alert but oriented only to person. H e
did not initiate conversation and answered questions
with difficulty with sparse, simple words or phrases. H e
was disinterested in his e n v i r o n m e n t and could only
concentrate on one activity at a time. Wunduscopic examination was not possible because of cataracts. H e had a
mild left central facial palsy. Strength and sensation were
normal, but he was bradykinetic. H e was hypertonic in
both lower limbs, m o r e so on the right. H e was diffusely
hyperreflexic and had clonus o f the right patella and a
right extensor plantar response. Frontal signs, including
visual fixation, and palmomental, grasp, snout, and glabellar tap reflexes were present.
A noninfused c o m p u t e d t o m o g r a p h y (CT) scan
showed a well demarcated 7 x 5-cm mixed density mass
with peripheral calcification, centered in the anterior
interhemispheric fissure, extending m o r e into the left
frontal lobe than the right, and displacing the genu of
the corpus callosum posteriorly (Figure 1 A). Contrast0090-3019/92/$5.00

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infused CT revealed a small meningioma of the left frontal convexity (Figure 1 B). MRI (Figure 2) showed the
large, frontal, mixed signal intensity mass to originate
from the region of the distal left anterior cerebral artery.
The periphery was hyperintense. The center was hypointense, corresponding to slow blood flow, as was the
anterior rim, corresponding to the area of calcification.
The small, parasagittal meningioma was also identified.
Left internal carotid angiography (Figure 3) demonstrated partial filling of the giant aneurysm from the
origin of the left pericallosal artery and opacification
of both anterior cerebral arteries. The giant aneurysm
displaced both orbito-frontal arteries inferiorly. The
right anterior cerebral artery was displaced anteriorly
and laterally in a round-shift fashion, and the left anterior
cerebral artery was displaced posteriorly. Extensive collaterals from the left middle cerebral artery supplied the
territory of the distal left anterior cerebral artery across
the watershed region. A second, small, bilobed aneurysm was discovered at the level of the anterior communicating artery. Left external and common carotid artery
(Figure 4) injections demonstrated hypertrophy of the
middle meningeal artery, and a small area of prolonged
capillary blush in the upper frontal convexity consistent
with a meningioma. There was also a dural arteriovenous
fistula next to the superior sagittal sinus at the upper
parietal convexity supplied by the posterior branch of
the middle meningeal artery and drained away from the
superior sagittal sinus by a superficial cortical vein.

Operation and Hospital Course

Figure 1. Noninfused C T scan (A) demonstrating the giant aneurysm.
The relative hypodense areas within the aneurysm represent thrombosis. The
anterior rim zs hyperdense representing calcification in the wall of the
aneurysm. The lateral ventricles and genu of the corpus callosum are displaced
posteriorly. Areas of hypodensity in the frontal lobes anterior and lateral to
the aneurysm are consistent with edema and, especially on the left, with
necrotic changes caused by long-standing compression. Contrast-infused C T
scan (B) shows a small area of enhancement, without associated mass effect,
in the left frontal convexity adjacent to the left side of the falx cerebri
consistent with a meningioma.

The anterior cerebral artery and anterior communicating
artery complex were exposed through a left pterional
craniotomy, and the anterior communicating artery aneurysm was clipped. The large, firm, and noncompliant
partially thrombosed giant aneurysm filled the undersurface of the orbito-frontal region. The left pericallosal
artery was clipped, and the wall of the giant aneurysm
was incised, revealing liquified hematoma, calcification,
organized thrombus, and neovascularization of the aneurysm wall. The giant aneurysm was evacuated of as much
thrombus as allowed through this approach, and the procedure was concluded. The patient awoke from anesthesia without new neurologic deficits; the effects of clipping of the pericallosal artery were mitigated by the
extensive collateral supply from the left middle cerebral
artery. The remainder of the giant aneurysm was excised,
except for the inferior most portion of its wall overlying
the hypothalamus, through an interhemispheric approach 14 days later. Pathologic examination confirmed
the diagnosis of an aneurysm with partial thrombus and
calcification.
The patient did not undergo further surgery to re-

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349

Figure 2. MRI T l-weighted (TR 550, TE 30) sagittal (A) and T2-weighted (TR 2100, TE 60) axial (B) scans. The thrombosed portion of the aneurysm
appears hyperintense, and the residual sac is iso- to hypointense. In the T2-weighted image, a portion of the thrombus appears hypointense because of
hemosiderin content. The anterior wall of the aneurysm is calcified as demonstrated by the hypointense signal in both TI- and T2-weighted images. The
small, parasagittal meningioma is isointense on the Tl-weighted image.

Figure 3. Left internal carotid angiogram demonstrating filling of both anterior cerebral arteries, the mass effect of the extensively thrombosed giant
pericallosal aneurysm, and slow filling of the distal left anterior cerebral artery. The residual lumen of the pericallosal artery aneurysm is indicated by the
arrow. A small anterior communicating artery aneurysm is also seen (arrowhead).

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of a slight, persisting expressive dysphasia. Postoperative
CT showed small hypodensities in the left frontal and
left precentral gyrus compatible with sequelae of mass
effect.
Discussion

Clinical Presentation and Treatment

i i!i ~?i

Figure 4. Left external carotid (A) and common carotid (B) angiograms
show the anterior branch (white arrowhead) of the hypertrophied middle meningeal artery supplying the small meningioma, noted as a persistent blush
(white arrow). The small dural arteriovenousfistula (asterisk)adjacent to the
superior sagittal sinus at the parietal convexity is fed by the posterior branch
(white double arrowheads) of the middle meningeal artery and drained away
from the superior sagittal sinus by an earlyfilling corticalvein (white double
arrqws). The giant aneurysm is also demonstrated (black arrow).

move the meningioma or dural arteriovenous fistula because of his advanced age and because both lesions were
small, asymptomatic, and (in the case of the meningioma)
not associated with mass effect. The patient gradually
made a complete neurologic recovery with the exception

Nine cases of giant distal anterior cerebral artery aneurysms have previously been reported (Table 1) [5,7,14,16,
18,20,22,26]. The aneurysms originated from the pericaUosal or callosomarginal artery in six cases [5,14,
18,20,22,26] and from the division of an azygos anterior
cerebral artery into two pericallosal arteries in three
others [7,16]. Our case, the tenth, is unique in that the
giant pericallosal aneurysm was associated with a smaller
aneurysm and a dural arteriovenous fistula. Ours is only
the third report to address the usefulness of MRI in
assessing giant distal anterior cerebral artery aneurysms.
The incidence of all giant aneurysms is low
(5%-13%), and female patients predominate [20].
However, seven of nine patients (one report did not
include gender or age) with giant aneurysms of the distal
anterior cerebral artery were male, and were older (mean
59 -+ 10.2 years, median 59, range 41-72) than the
females (mean 24.5 - 6.4 years, median 24.5, range
20-29).
The clinical presentation of distal anterior cerebral
artery giant aneurysms is variable. The onset of symptomatology is usually rapid. Nine of 10 patients were
admitted to hospital and diagnosed with a frontal giant
aneurysm within 10 days of the initial symptoms. One
female patient, however, had symptoms for 6 weeks
before diagnosis and underwent a burrhole biopsy procedure for diagnosis of a suspected frontal tumor [ 18].
Distal anterior cerebral artery giant aneurysms may
produce mass effect [7,18,22], hemorrhage [5,20,26],
or ischemia [7,14] from compression of adjacent arteries
or embolization of platelets or thrombus [4,8,28]. One
patient presented with bacterial meningitis and was
found to have an infected giant aneurysm of the azygos
anterior cerebral artery [ 16]. Our patient had relatively
rapid onset of dementia with features of akinetic mutism,
most likely from expansion of the giant aneurysm producing bifrontal compression [4,22,24]. There was no
evidence of subarachnoid hemorrhage on CT or at
surgery.
Seven of the nine previously reported giant aneurysms were operated [5,7,16,18,20,22,26]. Techniques
of operation included clipping of the aneurysmal neck
with evacuation of thrombus [5,7,20], resection of the
aneurysmal sac with or without clipping of feeding vessel(s) [16,18,22], and resection of the sac with end-toend anastomosis of the anterior cerebral artery [26]. In

Pericallosal Artery Giant Aneurysm

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1992;38:347-52

351

Table 1. Giant Distal Anterior CerebralArtery Aneurysms
Characteristics

Number (n = 10)

Patients

Males
Females

Age (y)

Mean

Range

59 + 10.2
24.5 + 6.4

41-72
20-29

7
2

Clinical presentation (symptomatology)
Mass lesion (headache, seizure, dementia, personality changes,

anosmia, incontinence, incoordination)
Subarachnoid hemorrhage
Transient ischemic attack (hemiparesis, ataxia, vertigo, vision loss)
Mycotic aneurysm (bacterial meningitis)
Origin
Pericallosal artery
Azygos anterior cerebral artery

Operation
Neck clipped, sac resected
Neck clipped, thrombus evacuated (sac not resected)
Sac resected, end-to-end anatomosis
Unoperated

Outcome

Operated patients
Cured
Coma
Died

Unoperated patients
Symptom free

our case the anterior communicating artery aneurysm
and left pericallosal artery were clipped by the same
approach. It was necessary to clip the pericallosal artery
supplying the giant aneurysm, because no neck was discernible, and the aneurysm filled briskly so that arterial
supply had to be interrupted before resection. A bypass
was not necessary because of extensive collateral flow
from the left middle cerebral artery across the anterior
border zone. T h e aneurysm was resected subsequently
through an interhemispheric approach.
Pathologic examination of all the operated aneurysms
revealed that they were partially thrombosed and
calcified.

Radiological Investigation
Giant aneurysms of the distal anterior cerebral circulation may mimic a frontal or callosal tumor on CT, appearing as a partially calcified mass with little or no contrast
enhancing features; or they may suggest an intracerebral
hematoma if thrombosis or hemorrhage within the aneurysmal sac is relatively recent [1,6,11,12,14,18,19,

21,23]. MRI is more specific than CT in diagnosing giant
anterior cerebral artery aneurysms and better demonstrates their relationship to the surrounding brain. Cerebral angiography is essential in characterizing the fine
details of these aneurysms and o f the remainder o f the
cerebral circulation. Only angiography demonstrated an
unsuspected smaller aneurysm of the anterior communicating artery complex and the dural arteriovenous fistula
in our case. Angiography also demonstrated the arterial
filling of the giant aneurysm, the slow filling of the left
anterior cerebral artery, and the extensive compensatory
collateral supply from the left middle cerebral artery
across the anterior border zone that was crucial in the
eventual clipping of the distal anterior cerebral artery
and uneventful resection of the giant aneurysm.

Conclusions
We conclude that giant distal anterior cerebral artery
aneurysms can be successfully treated; that angiography,
CT, and MRI have specific values; and that all may be
required to adequately define the aneurysm, its relation-

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ship to cerebral tissue, and possible associated pathology. The role of MR angiography in the assessment of
giant aneurysms remains to be elucidated.

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