Key-words:
Aneurysm - clipping - intracranial - multiple - subarachnoid hemorrhage
Introduction
Regarding patients with subarachnoid hemorrhage (SAH) with multiple intracranial aneurysms
(MIAs), it is the most important to diagnose the precise rupture site preoperatively
and treat the ruptured aneurysm promptly. If the rupture site is misidentified, more
invasive multiple treatment approaches may be required in the acute phase of SAH possibly
worsening the prognosis. Therefore, treatment design and strategies to reduce brain
invasion are essential. We present an excellent outcome case of SAH with MIAs treated
with our surgical design and strategies, in which we could not determine the precise
rupture site preoperatively, and both pterional approach (PA) and interhemispheric
approach (IHA) were required in the acute phase of SAH.
Case Report
The patient was a 71-year-old female presenting with severe headache and disturbance
in consciousness. She was admitted to our hospital with a systolic blood pressure
of 106 mmHg, Glasgow Coma Scale 12 (E3V3M6), and no focal symptoms. Computed tomography
(CT) scan revealed diffuse SAH, particularly thickened at the right Sylvian fissure
and basal cistern [[Figure 1]]a. We diagnosed as SAH, the World Federation of Neurological Surgeons Grading System
for SAH Grade 4.
Figure 1: (a) Computed tomography imaging obtained after admission showed diffuse subarachnoid
hemorrhage, particularly thickened at the right Sylvian fissure and basal cistern.
(b) Preoperative digital subtraction angiography showed the right middle cerebral
artery aneurysm, anterior communicating artery aneurysm, and right distal anterior
cerebral artery aneurysm (allowed)
The patient was admitted and underwent digital subtraction angiography (DSA). DSA
revealed three aneurysms: right middle cerebral artery (MCA) aneurysm, anterior communicating
artery (AcomA) aneurysm, and right distal anterior cerebral artery (ACA) aneurysm.
Dome size of the MCA aneurysm, AcomA aneurysm, and right distal ACA aneurysm was 3.5,
2, and 4.1 mm. All the aneurysms were irregularly shaped having no bleb. Dome/neck
ratio of the right MCA aneurysm, AcomA aneurysm, and right distal ACA aneurysm was
1.75, 1, and 2.7 [[Figure 1]]b. We diagnosed the right MCA aneurysm as the rupture site according to the uneven
distribution of SAH and performed right PA first.
The patient was positioned 15° semi-Fowler position; the head was rotated at approximately
30° contralaterally, skull vertex in the neutral position and fixed in Mayfield skull
clamp. We opened right frontotemporal skin incision and reflected anteriorly, placed
a burr hole at right Kocher's point, and inserted an external ventricular drain into
the right anterior horn in standard fashion.[[1]] We performed a right frontotemporal craniotomy and dissected to open the Sylvian
fissure widely taking care not to apply strong retraction to the right frontal lobe
in consideration of latter possible IHA. We exposed and clipped the MCA aneurysm which
was apparently an unruptured aneurysm with a round shape and no bleb [[Figure 2]]a.
Figure 2: Intraoperative findings. (a) The middle cerebral artery aneurysm with no rupture
point on the surface was exposed and clipped. (b) The anterior communicating artery
aneurysm with no rupture point on the surface was exposed. (c) The operative view
of the latter interhemispheric approach. The obvious rupture point and fibrin plug
were confirmed on the top of the right distal anterior cerebral artery aneurysm
Subsequently, we continued to approach the AcomA aneurysm through trans-Sylvian approach,
opened the Sylvian fissure completely, and released the anchorage between the frontal
lobe and frontal base. We exposed and clipped the AcomA aneurysm which was located
on fenestrated AcomA and was also apparently an unruptured aneurysm with a round shape
and no bleb [[Figure 2]]b.
As a result, the distal ACA aneurysm was identified as the rupture site and continuously
treated through subsequent IHA. Performing IHA, the operating table was rotated 30°
to affected side laterally and 15° vertically up. We extended the frontotemporal skin
incision to the contralateral side and performed a right frontal parasagittal craniotomy
using the puncture point of the external ventricular drain. We dissected to open the
interhemispheric fissure widely and exposed and clipped the right distal ACA aneurysm
with obvious rupture point and fibrin plug [[Figure 2]]c. Consequently, we could treat the whole aneurysm in the acute phase with minimally
invasive.
[[Figure 3]]a shows DSA on day 7, in which all aneurysms were obliterated and moderate vasospasm
presented. However, the patient was not complicated with apparent neurological deficit,
and the vasospasm improved after the acute phase. [[Figure 3]]b shows the head CT at the time of discharge revealing no visible brain contusion
on the approach route. The patient was discharged home after rehabilitation in a state
of modified rankin scale (mRS) 1 and is returning for a follow-up visit now.
Figure 3: (a) Digital subtraction angiography on day 7. All aneurysms were obliterated, and
there was moderate vasospasm. The vasospasm was improved after the acute phase. (b)
Computed tomography imaging at discharge shows no obvious contusion injury on the
approach route
Discussion
MIAs have an occurrence frequency of 14%–34% and have been known that the risk of
poor outcome increases in the setting of SAH.[[2]],[[3]],[[4]],[[5]] However, there are no rigid guidelines for the methods to diagnose the rupture
site, treating coexisting unruptured aneurysms and approach to treatment.
Preoperative diagnosis of the rupture site
Regarding preoperative diagnosis of the patients with SAH associated with MIAs, the
aneurysmal morphological factors (the largest aneurysm,[[6]],[[7]] dome/neck ratio >1.6,[[8]],[[9]] presence of bleb, and irregular shape)[[10]] are known as the predictors of the rupture site. In addition, the previous studies
reported that the rupture site could be estimated in 45%–59% of cases by uneven distribution
of SAH or the location of intracerebral hemorrhage on CT.[[7]],[[11]] However, there are several cases, in which these predictors are not reliable, and
the precise rupture site cannot be estimated preoperatively.[[11]],[[12]]
In our case, the distribution of SAH on CT suggested the right MCA aneurysm as the
rupture site; however, the size and dome/neck ratio were largest in the right distal
ACA aneurysm. In addition, it was expected that the rupture rate of a small aneurysm
in MIAs was not negligible and that locations with the highest probability of rupture
in MIAs were the AcomA.[[6]],[[7]],[[13]] Therefore, in our case, it was difficult to estimate the precise rupture site preoperatively,
and the treatment design and strategies taking into consideration, the possibility
of miscegenation the rupture site was essential.
Treatment strategies
Ruptured aneurysms used to be treated with surgical clipping, but recently, surgical
clipping procedures remained stable while the number of aneurysms treated by means
of endovascular procedure doubled.[[14]] Although the safety of endovascular one-stage coiling for ruptured aneurysm has
been reported,[[15]],[[16]] endovascular treatment for AcomA aneurysm, distal ACA, and MCA aneurysms still
remains challenge because of the distal location, incorporated branching, and wide
neck shape. Furthermore, it was reported that intraprocedural complications during
endovascular coiling of ruptured aneurysm more often occur in patients with these
aneurysm locations.[[17]],[[18]],[[19]],[[20]]
In our case, there were three aneurysms considered unsuitable for endovascular coiling.
Furthermore, in endovascular coiling, we had to treat all the aneurysms to reliably
treat the precise rupture site because it was impossible to identify the ruptured
aneurysms with the fibrin plug at the rupture point under direct vision. In surgical
clipping, on the other hand, we were able to judge whether to treat other unruptured
aneurysms simultaneously in consideration of the damage to the brain at the time of
treating the rupture site. For these reasons, we performed surgical clipping for this
case.
Surgical design
Several studies have reported that the unruptured aneurysms in MIAs have a higher
risk of rupture than that of ordinary unruptured aneurysms.[[21]],[[22]],[[23]] Other studies also reported that one-stage clipping of MIAs within 72 h after SAH
can be performed without increasing the risk of cerebral vasospasm and symptomatic
vasospasms.[[24]] In addition, when treating the other unruptured aneurysms in the chronic phase,
the likelihood of infection or skin disorder associated with reoperation and the operational
difficulties due to arachnoid thickening after SAH may occur.[[25]] Therefore, if other unruptured aneurysms in MIAs are able to be observed in one
stage, they are desirable to be treated simultaneously with the rupture site. Indeed,
multiple unilateral supratentorial aneurysms are commonly treated in one stage through
frontotemporal craniotomy,[[26]] and on the other hand, multiple bilateral intracranial aneurysms may be treated
in one stage if anatomically feasible but usually treated in two stages.[[27]],[[28]] However, the presence of distal ACA aneurysm coexisting with unilateral MCA or
internal carotid artery (ICA) aneurysm complicates the treatment strategies because
both PA and IHA require separate procedures that the skin incision and the fields
of craniotomies interfere with each other.
The previous literature showed that 47% of multiple aneurysms are on opposite sides
and 29% have one in the midline and one on the side.[[29]] Other reports showed that distal ACA aneurysm coexisted with other aneurysms 35%
of the time compared with other aneurysm locations.[[30]] In our institution, 48 patients of SAH with MIAs were identified between January
2005 and March 2016, and only 3 (6%) patients had distal ACA aneurysms coexisting
with MCA or ICA aneurysms. Thus, the distal ACA aneurysm coexisting with unilateral
MCA or ICA aneurysm is uncommon, and few studies have focused on the concrete surgical
method. Although the methods with large bone flap or two separated bone flaps through
a single skin incision have been reported,[[26]],[[31]] we present below our surgical design modifying the previously reported methods.
First, the patient is positioned 30° semi-Fowler position, the head is rotated at
approximately 30° contralaterally, skull vertex in neutral position, and fixed in
Mayfield skull clamp. When performing IHA, the operating table is rotated 30° to affected
side laterally and 15° vertically up to accommodate to approach the distal ACA aneurysm.
Regarding the skin incision and craniotomies, we make a coronal skin incision spreading
PA side widely to be possible to accommodate the frontotemporal craniotomy and ipsilateral
frontal parasagittal craniotomy, and separate the field of the two craniotomies [[Figure 4]]a. We can accommodate to contralateral PA or basal IHA by symmetrically extending
the skin incision to the contralateral side. Considering surgical stress on the frontal
lobe by two approaches, we design the craniotomy of the temporal region to not expose
the frontal lobe to the extent possible. We can maintain the strength and blood flow
of the cranial bone by setting two bone flaps and prevent the postoperative infection.
In addition, the remaining bone in a bridge shape is responsible for anchoring dura
preventing acute epidural hematoma after the surgery and is used as a hand placement
for improving the stability of the surgical operation [[Figure 4]]b.
Figure 4: The skin incision and craniotomies. (a) The skin incision spreading pterional approach
side widely is extended contralaterally for interhemispheric approach. (b) Skull X-ray
after the surgery shows the craniotomy separated into two bone pieces
Distal ACA aneurysms are able to be observed from either the right or left side of
falx but are usually treated from the ipsilateral side of the aneurysm existing. However,
in cases of MIAs, where distal ACA aneurysm coexists with MCA or ICA aneurysm, we
should treat the distal ACA aneurysm from the ipsilateral side of coexisting MCA or
ICA aneurysm to protect the contralateral frontal lobe by the falx preventing the
surgical stress on the bilateral frontal lobe. Furthermore, AcomA aneurysm is able
to be observed by either PA or IHA, but in cases of MIAs, where AcomA aneurysm coexists
with unilateral MCA or ICA aneurysm, the AcomA aneurysm is desirable to be treated
simultaneously with the other aneurysms by PA to avoid the surgical stress on the
bilateral frontal lobe. However, if it is difficult to treat the AcomA aneurysm by
PA due to the large size or upward direction, AcomA aneurysm may be treated by IHA
or additional endovascular coiling of necessity.
Conclusion
We experienced a case of SAH with MIAs. We could treat all the aneurysms in one-stage
operation and obtain a good outcome using the described surgical design and strategies.
Surgical clipping with ipsilateral frontotemporal and frontal parasagittal craniotomies
through a single skin incision is a useful procedure for the cases of MIAs, in which
distal ACA aneurysm coexists with other aneurysms on the side.
Declaration of patient consent
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