Keywords
proximal A1 segment - aneurysm - microsurgical clipping - endovascular therapy - anterior
cerebral artery - surgery
Introduction
Proximal (A1) segment anterior cerebral artery (ACA) aneurysms are rare and represent
less than 1% of all intracranial aneurysms.[1]
[2]
[3]
[4]
[5] The high risk of intraoperative perforator injury, encountering an anomalous anatomy,
and the presence of a small or a sessile aneurysm, make both surgical and endovascular
management challenging. The frequent rupture and re-rupture of these aneurysms, the
development of a parenchymal hematoma, and the difficulty in visualizing an aneurysm
of this segment on angiography further complicate the treatment process. There are
only a few case series and reports of A1 segment aneurysms.[1] We reviewed the literature to develop a consensus on their clinical presentation,
anomalous anatomy, surgical nuances, endovascular management, and outcome.
Surgical Anatomy and Anomalies of Proximal ACA
Surgical Anatomy and Anomalies of Proximal ACA
The most accepted classification of ACA divides it into five segments, A1 to A5. The
A1 segment, also known as the proximal segment, the precommunicating segment, or the
horizontal segment, lies in the segment of ACA between the points of internal carotid
artery (ICA) bifurcation and the origin of anterior communicating artery (AComA).
Rest of the segments of ACA are the following: From the AComA to the genu is termed
as the A2, the infracallosal or the vertical segment; the part of ACA running along
the genu to the body of corpus callosum is called the A3 or the precallosal segment;
from the distal point of the A3 segment to the coronal suture is termed the A4 (supracallosal)
segment; and the distal part of the ACA from the coronal suture is termed as the A5
(posterocallosal) segment. This classification is at variance with the common misconception
that the bifurcation of ACA should be considered as the dividing point between A4
and A5 segments. The bifurcation of ACA occurs mostly at the A3 segment when the main
vessel trunk divides into the pericallosal and callosomarginal arteries.[1]
[6]
[7]
The proximal ACA, after its origin from the ICA lateral to the optic chiasm, travels
medially and anteriorly over the optic nerve (in 30% cases) or the optic chiasma (in
70% cases).[6] The length of the A1 segment is variable, ranging from 7.2 to 18 mm (average 12.7 mm).[8] Multiple perforating branches arise from the A1 segment, more from its proximal
part, gradually reducing in number distally. Most of these perforators arise from
the posterosuperior surface and they rarely take origin from the inferior surface.[9] They may range from 2 to 15 (average 8) in number and their size varies from 1.5
to 3 mm. Their mean diameter is 2.3 mm.[6]
[9] They supply the chiasma, anterior third ventricle, and anterior hypothalamus. Their
injury during proximal ACA aneurysm dissection, clipping, or their occlusion on coiling
can lead to behavioral and cognitive impairment, including alteration in sensorium,
without the development of any motor deficits. Another important branch that arises
from the A1 segment in around 14% of the cases is the recurrent artery of Heubner.[8] It is usually encountered at the A1 segment of ACA on retracting the frontal lobe.
It runs along with the proximal ACA retrogradely from its origin to end in the anterior
perforated substance. It supplies the anterior part of the caudate nucleus, the anterior
third of putamen, the anterior part of globus pallidus externus, the inferior portion
of the anterior limb of the internal capsule, and the uncinate fasciculus. When injured,
it may lead to contralateral hemiparesis with dominant faciobrachial weakness. Thus,
the perforators and the recurrent artery of Heubner are the important branches of
proximal ACA that need to be meticulously preserved during either surgical or endovascular
intervention.
An anomalous anatomy of the proximal and distal ACA is frequently encountered with
proximal ACA aneurysms.[10]
[11]
[12]
[13]
[14]
[15] Misidentification of vessels, leading to an injury to them, or resulting in an incorrect
placement of the clips may occur. Hence, a preoperative knowledge of the anomalous
anatomy, aided by angiographic findings may prevent intraoperative surprises and misadventures.
The anomalies of proximal ACA are associated with nonregression of the ventral or
the dorsal ophthalmic artery (VOA and DOA). The VOA arises from the ACA, and DOA from
the cavernous ICA. They fuse to form the primitive ophthalmic artery, which later
becomes the definitive ophthalmic artery. Failure of regression of DOA leads to the
anomalous origin of ACA from the cavernous ICA. This anomaly poses a risk of aneurysm
development. A1 segment fenestration is the most common anomaly noted with these aneurysms.[10] It may result from incomplete fusion, partial duplication, or persistence of a remnant
plexiform anastomosis between the primitive olfactory artery and the ACA.[13]
[16]
[17]
[18]
The anatomical status of AComA and distal ACA may also vary and is equally important
in deciding the surgical strategy. The presence of AComA allows the possibility of
trapping the aneurysm as a collateral flow through the contralateral proximal ACA
is provided. The proximal ACA segment may be single, multiple, or fenestrated. The
variants of distal ACA have been classified by Baptista et al,[19] as azygous or unpaired (involving a common trunk in the A2 segment; type I), bihemispheric
(which gives branches to both hemispheres; type II), and accessory (there is an additional
vessel arising from AComA accompanied by two hypoplastic ACA in the A2 segment; type
III) ACA.
Etiopathogenesis of Proximal ACA Aneurysms, and Their Classification
Etiopathogenesis of Proximal ACA Aneurysms, and Their Classification
The A1 segment aneurysms are rare, with only a few case series reported on their surgical
and endovascular management ([Fig. 1] and [Table 1]).[10]
[20]
[21] Turbulent blood flow at the wide fenestration of proximal ACA or at the point of
origin of the medial lenticulostriate arteries causes hemodynamic stress. This may
be the underlying etiopathogenesis. It is backed by the finding that most A1 segment
aneurysms are in their proximal part as compared to distal. It also explains why these
aneurysms are blister-like and tend to rupture early.[22]
[23] These aneurysms are commonly associated with bilateral, co-occurrence of other intracranial
aneurysms.[2]
[10]
[24]
[25]
[26]
[27] Giant proximal ACA aneurysms are rare.
Fig. 1 Plain computed tomography (CT) scan showing diffuse subarachnoid hemorrhage along
with intraventricular bleed. Ventriculomegaly is also present. The three-dimensional
reconstruction CT angiography showed a 5-mm saccular aneurysm arising from the mid
portion of A1 segment anterior cerebral artery (ACA). It is seen arising from the
posterosuperior surface of ACA and is directed superiorly.
Table 1
Reported series of A1 segment aneurysms treated with microsurgical clipping with number
of cases ≥ 10
Series
|
Number of cases
|
Incidence
|
Age
|
Male gender
|
SAH
|
IVH
|
ICH
|
Right side
|
H
HG
|
Location
|
Direction
|
Multiple
|
Anomaly
|
Size, mm
|
Mortality
|
Morbidity
|
|
|
|
|
%
|
|
|
|
|
|
P
|
M
|
D
|
A
|
PS
|
PI
|
|
|
O
|
R
|
U
|
|
|
Yasargil 1984[27]
|
14
|
1.4
|
46
|
100
|
14
|
–
|
1
|
4
|
–
|
2
|
6
|
6
|
|
|
|
3
|
1
|
|
|
|
1
|
GR 12, MD 12
|
Wakabayashi et al 1985[19]
|
10
|
2.1
|
48
|
33
|
8
|
–
|
|
9
|
–
|
7
|
2
|
1
|
|
|
|
4
|
2
|
3.6
|
|
|
1
|
GR 7
|
Suzuki et al 1992[10]
|
38
|
0.88
|
51
|
61
|
30
|
–
|
5
|
18
|
–
|
|
|
|
|
|
|
17
|
24
|
|
|
|
3
|
GR 34, MD 1
|
Hino et al 2002[25]
|
11
|
3.4
|
60
|
45
|
7
|
–
|
2
|
5
|
–
|
11
|
0
|
0
|
|
|
|
8
|
1
|
5.4
|
|
|
0
|
GR 10, MD 1
|
Dashti et al 2007[2]
|
23
|
0.8
|
–
|
–
|
12
|
–
|
3
|
14
|
–
|
|
|
|
|
|
|
16
|
–
|
4(1–15)
|
|
|
0
|
|
Lee et al 2010[26]
|
20
|
0.59
|
52.15 (39–69)
|
20
|
18
|
–
|
1
|
10
|
–
|
9
|
11
|
|
|
|
4
|
3
|
6.9
|
|
|
1
|
GR 15, MD 2, SD2
|
Bhaisora et al 2014[1]
|
14
|
0.98
|
38.02 (5–68)
|
57
|
13
|
8
|
2
|
7
|
<3 = 8
iv = 5
|
6
|
1
|
7
|
2
|
5
|
7
|
2
|
6
|
(3–15)
|
|
|
3
|
GR 6, MD 3, SD 2
|
Abbreviations: GR, good response; HHG, Hunt and Hess scale; ICH, intracerebral hemorrhage;
IVH, intraventricular hemorrhage; MD, major disability; SAH, subarachnoid hemorrhage;
SD, sudden death.
Note: Location: P, proximal; M, middle; D, distal. Direction: A, anterior; PS, posterosuperior;
PI, posteroinferior. Size: O, overall; R, ruptured; U, unruptured.
The proximal A1 aneurysms were earlier classified by Wakabayashi et al and Yasargil.[20]
[28] Later Bhaisora et al classified these aneurysms based on the site of origin as proximal
(near ICA bifurcation), distal (near AComA), and intermediate (between proximal and
distal ends). They were further classified as anterior, posterosuperior, and posteroinferior
based on the origin of neck of the aneurysm in relation to the circumference of the
A1 segment. The classification is based upon the anatomical relationship of the aneurysm
to its location, allowing for an adequate preoperative planning while anticipating
the surgical difficulty. The proximal A1 segment aneurysms are the most common varieties
followed by the middle and distal segment aneurysms.[10]
[21]
[29]
[30] Most of them originate and project posteriorly.[29]
[31] Concerning the morphology, saccular aneurysms are the most common aneurysms encountered,
and most proximal A1 segment aneurysms are of this variety. Fusiform and dissecting
aneurysms are more commonly seen in the middle A1 segment.[32]
[33] Blister aneurysms are also commonly seen in the A1 segment of ACA. Ding et al suggested
a similar classification system but they identified only the proximal (type I) and
distal (type II) types based on the location of aneurysm longitudinally along the
A1 segment of ACA. These were further subclassified based on the direction of fundus
of the aneurysm. They included the fusiform or dissecting aneurysms as a separate
subtype (termed the type III aneurysms). Most studies confirmed that the most common
direction of the aneurysm in the proximal A1 segment is posterior, inferior in the
middle segment, and superior in the case of distal A1 segment of ACA.[1]
[11]
[30] A classification system encompassing the aneurysmal relationship to the perforators
in the vicinity, the status of distal flow/collateral circulation to distal ACA, the
aneurysm morphology, and the associated anomalous anatomy would be a more comprehensive
one in deciding the surgical strategy for proximal ACA aneurysms.
Clinical Presentation of Proximal ACA Aneurysms
Clinical Presentation of Proximal ACA Aneurysms
Proximal ACA aneurysms frequently present following their rupture or are diagnosed
as co-aneurysms with another ruptured aneurysm. Most studies concluded that the risk
of rupture is higher in these aneurysms as compared to aneurysms at other sites. They
are relatively smaller as compared to aneurysms at other sites.[11]
[20]
[27]
[31] A1 segment aneurysms often rupture when they are relatively smaller in size compared
to other aneurysms.[30] The mean size of ruptured A1 segment aneurysms varied from 3.2 to 7 mm in the available
literature.[3]
[27]
[29]
[34] Kim et al reported no significant relationship between the location of an aneurysm
on the A1 segment and the risk of rupture; however, a higher rate of rupture in the
distal A1 segment aneurysms was noted. The association with gender and side was variable
in different studies. However, most studies reported A1 segment aneurysms to be more
common in males and on the right side.[2]
[3]
[10]
[20]
[25]
[27]
[34]
[35]
[36]
[37]
[38]
[39]
[40]
Following the rupture of the aneurysm, most patients presented in a poor Hunt and
Hess grade (grade 3–5).[1]
[26]
[27]
[34] Patients with distal as compared to proximal A1 segment aneurysms had relatively
poorer grades. Occurrence of intraventricular bleed and acute hydrocephalus is common
following their rupture.[2]
[10] Ruptured aneurysms, especially the posterosuperiorly directed ones, commonly may
present with intracerebral hematoma involving the frontal gyrus in 16 to 29% cases.[1]
[2]
[3] A1 segment aneurysms have been reported in all age groups, but most of the series
reported them in the mean age group ranging from 50 to 60 years.[1]
[2]
[3]
[34] The proximal A1 aneurysms occur in a relatively younger age group. Also, relatively
younger patients were reported to present with a ruptured proximal A1 aneurysm.[11]
Radiological Features
The A1 segment aneurysms are frequently missed on angiography (computed tomographic
angiography and digital subtraction angiography [DSA]) due to their small size, associated
hematoma, overlapping A1 segments and perforators, associated multiple aneurysms at
other sites, parent vessel vasospasm, and their being near the skull base. They are
frequently misdiagnosed as ICA bifurcation aneurysms or as AComA aneurysms due to
the close anatomical situation between these sites and a similar pattern of subarachnoid
hemorrhage (SAH).[11]
[41] In some cases, especially in the case of posterosuperiorly directed aneurysms, where
the fundus is embedded in the orbitofrontal cortex, there may be only parenchymal
hematoma with no SAH following aneurysmal rupture.[1]
The various characteristics of the aneurysm as described in the classification of
proximal ACA aneurysms should be evaluated on preoperative radiology. In addition
to these points, the size of the fundus and its neck, presence of intracerebral hematoma
and the associated mass effect, the Fisher grade of SAH (if SAH is present), and presence
of hydrocephalus must be assessed ([Table 1]).
Giant aneurysms of proximal ACA are rare.[42]
[43]
[44]
[45]
[46] When present, a cross-flow study across the AComA may be essential in the cases
where clipping and reconstruction of the aneurysm are not possible, and these kind
of aneurysms may require trapping. Multiple aneurysms have been reported in 10 to
70% of the cases.[2]
[10]
[20]
[21]
[25]
[26]
[30]
Management of Proximal ACA Aneurysms
Management of Proximal ACA Aneurysms
Given the high risk of rupture of a small sized A1 segment aneurysm, obliteration
of the aneurysmal sac is always recommended even when these kind of aneurysms are
diagnosed incidentally.[2]
[3]
[11]
[27]
[30] This is against the recommendation for management of aneurysms at other locations,
where definitive treatment is often deferred until the size of the aneurysm is more
than 5 mm.[27]
[44]
[45]
[46]
Both microsurgical clipping and endovascular management of proximal ACA aneurysm are
viable options. Most authors recommend microsurgical clipping due to the unfavorable
anatomy present for the successful carrying out of endovascular management, like a
small sessile aneurysm with a fragile wall present in the proximal ACA aneurysms.
A variable vessel anatomy, multiple perforator origin, and A1 segment hypoplasia or
aplasia may further tilt the balance in favor of surgical management.[2]
[37]
[47]
[48] These same characteristics make microsurgical clipping a challenging task as well.
A formal comparison between the clinical outcome and cost-effectiveness between the
two treatments options is still lacking.
Microsurgical Clipping
The microsurgical clipping of proximal ACA aneurysms requires an ipsilateral standard
pterional craniotomy. The patient's head is kept in a neutral position with slight
(10–20 degrees) rotation to the opposite side. Jang et al reported a greater turning
of the head in proximal A1 segment aneurysms, as often a posterior direction of the
fundus is encountered.[11] Minimally invasive techniques like the supraorbital keyhole approach or a modified
pterional approach with a limited craniotomy may also be employed.[2] However, the variable anatomy that is often associated with these aneurysms is a
specific deterrent in the utilization of these minimally invasive approaches.
Splitting of the proximal Sylvian fissure and opening of the optico-carotid cistern
are the initial steps in all cases. Care is taken to avoid any retraction of the frontal
lobe. Deep and wide splitting of the Sylvian fissure helps to avoid undue frontal
lobe retraction.[1]
[34] Following cerebrospinal fluid release from the cisterns, adequate space is available
to continue further dissection. The ICA or the middle cerebral artery is traced to
the A1 segment of ACA. The aneurysm neck is then defined. In selected cases, the frontal
horn of the lateral ventricle can be tapped through the modified Paine's point to
relax the brain. Resection of the gyrus rectus, which is helpful in facilitating exposure
in case of AComA aneurysms, is contraindicated in proximal ACA aneurysms, as the gyrus
will be encountered distal to the aneurysm while approaching from the pterional route.
As perforators are encountered more often in the proximal than in the distal part
of the A1 segment, and are arising and are being directed posterosuperiorly, aneurysms
in this region need a careful dissection and clipping to avoid their injury.[49] They are most difficult to clip among all other types of A1 segment aneurysms, especially
when sessile.[1] The posterosuperiorly directed aneurysms may be embedded in the frontal lobe, preventing
a frontal lobe retraction during the exposure to avoid an early rupture of the aneurysm.[1]
[3] Distal and anteriorly directed aneurysms are easier to clip and can be approached
with a wide Sylvian fissure splitting. The identification of the course of recurrent
artery of Heubner is of particular importance in the case of the distal A1 segment
aneurysms.[3] Thus, an adequate preoperative planning concerning the relationship between aneurysms
and the perforators in the proximity is the key step for an A1 segment aneurysm management.
The inferiorly directed aneurysms are rare. When present, they may adhere to the optic
chiasma or the optic nerve.[3] The fundus of these aneurysms may often overlap the parent artery and their neck
may have to be dissected meticulously from the trunk of the parent artery.[34]
A proximal temporary clip over the A1 segment may be hazardous due to a possible perforator
injury, especially in cases where there is no collateral flow through the AComA. Similarly,
distal temporary clips may aggravate the vasospasm in the A2 segment of ACA. Thus,
temporary proximal as was as distal clip application may be attempted only in dire
needs where there is premature rupture of the aneurysm, and is often not carried out
routinely.
Surgical clipping gets difficult in the case of proximal A1 segment aneurysm due to
the posterior direction of their fundus in most cases, in association with perforator
origin at the neck, and the neck of the aneurysm being overlapped by the A1 main trunk.[11]
[27]
[30] Maiti et al suggested the use of the smallest possible clips to avoid clip rotation
and subsequent tortuosity of the parent vessel.[3]
[34] Reinforced wrapping, use of fenestrated clips, and reconstruction using tandem clipping
are the possible options for sessile or fusiform aneurysms.
Jang et al highlighted the important role of the endoscope, especially the 30- or
60-degree ones, in visualizing the perforators and in the detection of their kinking,
in otherwise blind spots.[11] Intraoperative indocyanine green and micro-Doppler are other important intraoperative
adjuncts that may aid in the successful clipping of these aneurysms, as they are helpful
in avoiding the inclusion of perforators, the main trunk of the blood vessel or other
anomalous vessels within the clips.
The reported surgical outcome in various series of proximal ACA aneurysms has been
comparable to the outcome of aneurysms at other sites. Good recovery has been reported
in 75% (n = 15), moderate disability in 10% (n = 2), and death in 5% (n = 1) of the patients in a surgically treated series of proximal ACA aneurysms by
Lee et al. The outcome correlates with the preoperative neurological status or the
preoperative Hunt and Hess grade.[1]
Endovascular Treatment
With successive improvements in the endovascular techniques, more and more complex
aneurysms have been managed with a good outcome. Multiple series, though with small
sample sizes, have reported successful endovascular management. They have also frequently
described the associated technical difficulties.[2]
[10]
[20]
[21]
[31]
[34]
[50]
[51]
[52]
Due to the common encountered proximal location and the posterior direction of A1
segment aneurysms, the tip of the microcatheter needs to be curved and conformed on
a case-to-case basis. Different shapes like the “S shape,” “Z-shape,” or “straight”
tip of microcatheters have been reported.[29]
[53] Successful utilization of stent-assisted coiling, balloon-assisted coiling, and
flow-diverters have been reported in recent series.[29] Perforator infarction remains a significant complication and a definitive evidence
of their safety needs further investigation.[54]
[55]
A major drawback with endovascular management of proximal ACA aneurysms is their incomplete
occlusion [Tables 2] and [3]. Kim et al reported that incomplete occlusion of the aneurysm is more common in
proximal A1 segment aneurysms (22.2%) as compared to the middle and distal sites (10%).
Zhang et al reported complete occlusion in 80% of their cases at follow-up evaluation.[29] Most perforating arteries may not be visible on DSA.[31]
[34] This may lead to their inadvertent occlusion and the subsequent development area
of an infarcted are at the corresponding site. Procedure-related complications following
endovascular management of these aneurysms have been reported in 15.8% of the patients
by Liu et al.[56]
Table 2
Reported series of A1 segment aneurysms treated with endovascular therapy with N ≥ 10
Series
|
No cases
|
Incidence
|
Age
|
Male gender
|
SAH
|
IVH
|
ICH
|
Right side
|
H
&H
|
Location
|
Direction
|
Multiple
|
Anomaly
|
Size, mm
|
Mortality
|
Morbidity
|
|
|
|
|
%
|
|
|
|
|
|
P
|
M
|
D
|
A
|
PS
|
PI
|
|
|
O
|
R
|
U
|
|
|
Chang et al 2011[46]
|
12
|
1.64
|
51
|
25
|
3
|
–
|
–
|
6
|
G0: 9
G2: 3
|
9
|
3
|
1
|
2
|
2
|
9
|
8
|
–
|
4.4
|
4.5
|
4.3
|
1
|
GR 12
|
Xiaochuan et al 2013[50]
|
15
|
–
|
53.9
|
13.3
|
0
|
–
|
–
|
–
|
G 0: 15
|
|
|
|
|
15
|
|
|
–
|
5.12
|
|
|
|
GOS 5: 15
|
Ko et al 2013[54]
|
11
|
–
|
55.6
|
36.3
|
5
|
–
|
–
|
8
|
< 3: 9,
> 4: 2
|
5
|
4
|
2
|
1
|
4
|
6
|
4
|
–
|
|
|
|
|
mRS 0: 10 mRS 2: 1
|
Cho et al 2014[30]
|
48
|
–
|
57.8
|
45.8
|
7
|
–
|
–
|
|
< 3: 46, > 4: 2
|
39
|
6
|
5
|
|
|
|
33
|
|
3.9
|
|
|
|
GOS 3: 1
GOS 4: 1
GOS 5: 46
|
Liu et al 2016[55]
|
38
|
1.7
|
53.8
|
12
|
20
|
–
|
–
|
21
|
< 3: 19
4: 1
|
22
|
7
|
9
|
4
|
1
|
33
|
10
|
12
|
|
3.6
|
6.1
|
1
|
mRS 0: 34
1 = 3
|
Zhang et al 2017 [28]
|
30
|
|
50.6
|
59.4
|
19
|
2
|
2
|
|
1–2: 15
3–4:
4
|
|
|
|
|
|
|
9
|
|
3.2
|
|
|
|
mRS 0–1 = 22 3 = 1
5 = 1
|
Li et al 2020[51]
|
15
|
1.25
|
50.9
|
20
|
15
|
|
|
8
|
< 3: 11
> 4: 4
|
|
|
|
|
|
|
8
|
|
|
|
|
2
|
mRS0: 6
1 = 5
4 = 1
5 = 1
|
Abbreviations: GOS: Glasgow Outcome Scale; GR, good response; H&H, Hunt and Hess scale;
ICH, intracerebral hemorrhage; IVH, intraventricular hemorrhage; mRS, modified Rankin
scale; SAH, subarachnoid hemorrhage.
Note: Location: P, proximal; M, middle; D, distal. Direction: A, anterior; PS, posterosuperior;
PI, posteroinferior. Size: O, overall; R, ruptured; U, unruptured.
Table 3
Reported series of A1 segment aneurysms treated with microsurgical clipping and endovascular
therapy with N ≥ 10
Series
|
No cases
|
Incidence
|
Age
|
Male gender
|
SAH
|
IVH
|
ICH
|
Right side
|
HHG
|
Location
|
Direction
|
Multiple
|
Anomaly
|
Size, mm
|
Mortality
|
Morbidity
|
|
|
|
|
%
|
|
|
|
|
|
P
|
M
|
D
|
A
|
PS
|
PI
|
|
|
O
|
R
|
U
|
|
|
Park et al 2013[33]
|
15
|
1.8
|
56.1
|
40
|
7
|
|
|
10
|
< 3: 6
4: 1
|
14
|
|
1
|
1
|
3
|
7
|
6
|
2
|
3.26
|
|
|
1
|
GR Sx 8
Endo 3
SD Sx 1
|
Maiti et al 2016[3]
|
17
|
1.71
|
52.5
|
37.5
|
8
|
|
2
|
6
|
< 3: 6
4: 2
|
8
|
4
|
5
|
4
|
11
|
2
|
8
|
5
|
5.46
|
4.38
|
6.23
|
1
|
GR Sx 4 Endo 6
|
Ding et al 2017[34]
|
42
|
1.76
|
54
|
53.6
|
34
|
|
|
23
|
1–2: 25, 3–4: 13
|
26
|
0
|
9
|
|
16
|
19
|
7
|
7
|
< 5: 27
> 5:
15
|
|
|
3
|
GR 33
MD 4
|
Yilmaz et al 2014[35]
|
15
|
2.1
|
|
33
|
|
4
|
3
|
7
|
|
13
|
|
2
|
|
|
|
5
|
5
|
|
|
|
0
|
GR 15
|
Kim and Lim 2019[29]
|
32
|
1.89
|
31–83
|
53
|
18
|
|
|
19
|
G0: 13
1–3: 12
G4–5: 6
|
16
|
7
|
7
|
2
|
6
|
22
|
13
|
13
|
4.1
|
|
|
2
|
SD 1
|
Abbreviations: Endo, endovascular; GR, good response; HHG, Hunt and Hess scale; ICH,
intracerebral hemorrhage; IVH, intraventricular hemorrhage; MD, major disability;
SAH, subarachnoid hemorrhage; SD, sudden death; Sx, surgery.
Note: Location: P, proximal; M, middle; D, distal. Direction: A, anterior; PS, posterosuperior;
PI, posteroinferior. Size: O, overall; R, ruptured; U, unruptured.
Conclusion
Proximal ACA aneurysms are rare and are anatomically unique. They have a distinct
clinical presentation and are also special in terms of the decision making required
for their management. It is recommended to aggressively obliterate the proximal ACA
aneurysms even when they are small. Both microsurgical clipping and endovascular therapy
have reported good outcomes, with progressive improvement in the management with endovascular
therapy. These aneurysms pose technical challenges during their management due to
their unique location, their fundi being surrounded by perforators, and the unique
morphology of the parent vessel.