Surgical Neurology International
James I. Ausman, MD, PhD
University of California, Los
Angeles, CA, USA
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Intraoperative dynamic assessment of the posterior
communicating artery and its branches by indocyanine green
Bora Gürer, Veysel Antar, Ulas Cikla, Andrew Bauer, Mustafa K. Baskaya
Departments of Neurological Surgery, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin 53792, USA
E‑mail: Bora Gürer ‑ email@example.com; Veysel Antar ‑ firstname.lastname@example.org; Ulas Cikla ‑ email@example.com; Andrew Bauer ‑ a.bauer@neurosur‑
gery.wisc.edu; *Mustafa K. Baskaya ‑ firstname.lastname@example.org
Received: 12 June 13 Accepted: 28 August 13 Published: 25 September 13
Background: True hemodynamic assessment of the posterior communicating
artery (PComA) by preoperative angiography in terms of its perforators and
configuration (adult vs. fetal vs. transitional) can be challenging in the surgical
treatment of aneurysms involving the PComA, posterior cerebral artery, and basilar
artery. Indocyanine green videoangiography (ICG‑VA) is a widely accepted new
technique in the surgical treatment of intracranial aneurysms to assess the patency
of the parent artery, branches, and residual flow within the aneurysm after clipping.
Case Description: Here we report two cases in which ICG‑VA was utilized to
assess either the direction of flow in the PComA or preservation of the PComA
perforators with temporary clip application before dividing the PComA.
Conclusions: Our experience is that ICG‑VA can be used to assess the main trunk,
and perforating branches of the PComA providing real‑time, dynamic intraoperative
information of the surgical field. Therefore we suggest that ICG‑VA may increase
the safety of surgical treatment of aneurysm involving PComA.
Key Words: Aneurysm, basilar artery, indocyanine green videoangiography,
perforating arteries, posterior communicating artery
The main goal of aneurysm surgery is the obliteration
of the aneurysm with preservation of flow in the
parent artery, its branches,
This can be achieved by applying the principles of
microsurgical techniques and utilizing intraoperative
adjuncts such as microdoppler
intraoperative angiography (IA), and indocyanine green
videoangiography (ICG‑VA). Since its introduction
into cerebrovascular surgery, many studies have been
published regarding the reliability of ICG‑VA in assessing
residual aneurysm and preservation of the flow within
the parent and branch arteries.[5,12,17]
During surgical clipping of the basilar bifurcation or P1
segment of posterior cerebral artery (PCA) aneurysms,
if the basilar bifurcation is quite high in relation to
the dorsum sella or the posterior communicating
artery (PComA) is tethering the PCA, dividing the PComA
might allow surgeon to access the aneurysm safely, provided
that PComA is not a fetal type. Once the decision is made
to divide the PComA, extreme care must be exercised to
This article may be cited as:
Gürer B, Antar V, Cikla U, Bauer A, Baskaya MK. Intraoperative dynamic assessment of the posterior communicating artery and its branches by indocyanine green videoangiogra‑
phy. Surg Neurol Int 2013;4:122.
Available FREE in open access from: http://www.surgicalneurologyint.com/text.asp?2013/4/1/122/118936
Copyright: © 2013. Gürer B. This is an open‑access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution,
and reproduction in any medium, provided the original author and source are credited.
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avoid injury to the anterior thalamoperforating arteries
arising from the PComA.[8,13]
Clipping of the PComA aneurysms has a reputation of
being easy due to the fact that the aneurysm neck and
the PComA origin can be included in the clip blades
if the PComA is not of the fetal type. However, there
are rare cases in which the assessment of dynamics,
configuration, and flow direction of the PComA cannot
be assessed by preoperative radiologic studies.
Here we report two cases in which ICG‑VA was utilized
to assess the preservation of the PComA perforators with
temporary clip application before dividing the PComA to
allow wider access to the basilar and posterior cerebral
A 42‑year‑old female presented with Hunt and
Hess grade IV subarachnoid hemorrhage (SAH),
which improved to grade III after placement of a
ventriculostomy. Computed tomography (CT) and
CT angiography revealed a diffuse SAH and ruptured
basilar tip aneurysm [Figure 1a]. Digital subtraction
angiography (DSA) confirmed the diagnosis of a basilar
bifurcation aneurysm with a wide neck and shallow
dome [Figure 1b]. Due to its unfavorable neck/dome ratio,
endovascular obliteration of this aneurysm was thought
to be high risk. The basilar bifurcation was noted to be
quite high in relation to the dorsum sella [Figure 1c].
A right cranio‑orbital approach was used for the clipping
of the aneurysm in this patient. After wide opening of
the Sylvian fissure and arachnoid cisterns, the PComA,
and the P1 and P2 segments of the PCA were isolated.
Due to the high riding basilar bifurcation, dissection
of the basilar bifurcation was restricted by the PComA,
which was tethering the PCA. Because the PComA was
not a fetal type, the decision was made to divide the
PComA. However, before dividing it in its perforator‑free
segment, we performed ICG‑VA with a temporary clip
on the perforator‑free segment, and demonstrated that
both perforators were filling from both the PCA and
the internal carotid artery (ICA). The PComA was
divided between the proximal and distal perforators.
Another ICG‑VA was performed and this showed that
the perforators were still filling. The aneurysm was
then clipped (see video, Supplemental Video 1, which
demonstrates the surgery, 3 min 18 s, and 71.8 MB).
Postoperatively the patient’s clinical status improved
and she was extubated on the 7th postoperative day with
intact speech and was able to follow verbal commands.
A postoperative angiogram showed the total obliteration
of the aneurysm [Figure 1d]. Two days after the
removal of the external ventricular drainage, the patient
suffered a rapid decline because of right intraventricular
hemorrhage. Emergency evacuation of the hematoma was
performed. She eventually made a good recovery and was
discharged to a rehabilitation center. On postoperative
3rd month follow‑up she was neurologically intact.
A 47‑year‑old female presented with headache. CT
angiography and a four‑vessel angiogram revealed
a PComA–PCA junction aneurysm on the right
hemisphere and P1 segment aneurysm on the left
side [Figure 2a and b]. The patient elected to undergo
coil embolization of both
the right‑sided P1–PComA junction aneurysm was
successfully coiled the left‑sided P1 aneurysm was not
Figure 1: (a) Computed tomography revealing diffuse subarachnoid
hemorrhage. (b) 3D‑reconstruction of digital subtraction revealing a
broad base small aneurysm of the basilar tip. (c) Digital subtraction
angiography revealing quite high basilar tip in relation to the dorsum
sella. (d) Postoperative digital subtraction angiography revealing
the total obliteration of the aneurysm
Figure 2: Preoperative computed tomography‑angiography
(a) and digital subtraction angiography (b) revealing right posterior
communicating artery‑posterior cerebral artery and left P1
segment aneurysms. Postoperative intravenous‑digital subtraction
angiography (c, d) revealing the total obliteration of the aneurysm
with presentation of the P1 perforating branch
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amenable to safe coiling due to its broad neck involving
the P1 posterior thalamoperforating artery. Therefore,
the patient underwent a cranio‑orbital approach for the
clipping of the left P1 aneurysm. After wide splitting
of the arachnoid cisterns, the ICA, PComA, PCA and
basilar bifurcation were all exposed. The aneurysm was
originating from the P1 segment of the PCA in relation
to the P1 perforating artery. The tethered PComA was
obstructing the view of the aneurysm neck and origin of
the P1 perforator. Preclipping ICG‑VA was performed to
lay out the vasculature. Although few clip options were
exercised, it was felt that without dividing the PComA,
safe clipping would not be possible. As such, a temporary
clip was placed along the distal P1 vessel and then
ICG‑VA performed to ensure that there was flow through
the PComA perforators. After this was confirmed, the
distal portion of the PComA was divided. The aneurysm
was then dissected free and good clip purchase was
provided. Postclipping ICG‑VA revealed no flow through
the aneurysm dome and persistent flow in the P1
perforator and rest of the P1 (see video, Supplemental
Video 2, which demonstrates the surgery, 3 min 18 s, and
97.5 MB). The patient refused to undergo postoperative
arterial DSA, so intravenous‑DSA was performed and
revealed the total obliteration of the aneurysm [Figure 2c
and d]. The postoperative course was uneventful and the
patient was discharged home in stable and neurologically
The ICG‑VA has been widely used in cerebrovascular
surgery and the reliability of ICG‑VA has been previously
demonstrated in aneurysm, arteriovenous malformation,
and dural arteriovenous fistula surgeries.[1,6,10,12] ICG‑VA
provides real‑time, dynamic,
intraoperative images to assess the blood flow in the
Many authors reported that PComA can be safely divided
or occluded when needed in aneurysm surgery,[2,7,9,18]
although the safety of this procedure is highly dependent
upon preservation of the perforating arteries originating
from the PComA.[7,13] Regli et al. reported that dividing
the PComA during clipping of a basilar bifurcation
aneurysm resulted in neurological deficits caused by
tuberothalamic infarct, despite protecting the perforating
arteries. The authors concluded that the combination
of the division of the PComA and cerebrovascular risk
factors of the patient were probably responsible for the
postoperative infarct. Sugita et al. reported one case
in a series of 32 aneurysms of the basilar artery in whom
the PComA was divided at the junction of P1 segment.
Postoperatively, the patient deteriorated progressively due
to severe vasospasm, and it was assumed that circulatory
disturbance would have been better if the PComA had
been preserved. Inao et al. presented four cases of
basilar bifurcation aneurysms where the PComA was
divided. One of these four patients had suffered from
an anterior thalamic infarct, which was thought to be
due to the injury of thalamoperforating arteries from
the PComA. In his series of 50 cases, Yaşargil reported
that the PComA was divided in 11 cases to allow better
access to the basilar tip aneurysms; in these 11 cases,
no morbidity related to the dividing the PComA was
observed. Lawton also indicated that a small PComA
that tethers P1 or compromises the view can be safely
divided, providing that its anterior thalamoperforating
branches can be preserved. However, when present
as the fetal type PComA or if permanent clipping
is expected to compromise antegrade flow in the P1
segment, the PComA cannot be sacrificed.
All of these previous reports were presented before the
ICG‑VA era, and the vascular integrity had been assessed
visually. In this present report, we suggest that ICG‑VA
provides safe and real‑time assessment of the flow and the
perforating arteries. In this technique, the first ICG‑VA is
performed to assess the normal anatomy of the PComA
and perforators. Temporary clip is then applied for
mimicking the division of the PComA. Under temporary
clipping a second ICG‑VA is performed to prove the
patency of the PComA perforators and the direction of
the flow. If the PComA is divided, another ICG‑VA is
performed to verify the final situation after division.
Anatomical studies showed that most of the PComA
perforating arteries seldom arise from the posterior half
of the vessel.[4,11,14] Also, the largest perforating branch
of the PComA, the premamillary artery, rarely emerges
from the posterior third of the PComA. In contrast,
the normal direction of flow through the PComA is
thought to be from the ICA. Thus, dividing a PComA
near to the PCA would be safer than dividing it near the
ICA.[3,7] Although the normal flow through the PComA is
thought to be from ICA, the exact opposite may occur,
as in our second case, and this can be easily assessed
intraoperatively by ICG‑VA.
The basilar artery aneurysm surgery is still a challenging
procedure for neurosurgeons because these aneurysms are
closely related to perforating arteries of the PCA. During
an approach to the basilar tip, the PCA may be tethered
by the PComA and cannot be mobilized. Also, the
PComA may interfere with visibility and manipulation
around the aneurysm neck.[3,9,18] In such situations, the
surgeon may be obliged to divide the PComA. In our
first case, we decided to divide the PComA because of
tethering, and the patency and filling of these perforators
were confirmed by ICG‑VA. After we were certain that all
perforators were preserved, the PComA was then divided.
To assess vessel patency, numerous intraoperative
techniques have been developed, such as intraoperative
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DSA, microvascular Doppler ultrasonography, and
ICG‑VA. Of these, IA is the most sensitive and the gold
standard. However, IA is expensive, technically complex
and invasive, involves ionizing radiation, and carries the
risk of causing neurological deficit. Microscope‑based
ICG‑VA is simple and provides real‑time information
about the perforating vessels. The studies that compare
ICG‑VA to IA suggest that the concordance rate between
these two methods is 90–100%.[5,12,17] Despite ICG‑VA
being widely used in cerebrovascular surgery, to our
knowledge, this is the first report where ICG‑VA is used
to assess either the direction of flow in the PComA or
preservation of the PComA perforators to evaluate if
PComA can be safely divided or not.
In this study, we report our experience utilizing ICG‑VA
in assessing the main trunk and perforating branches of
the PComA providing real‑time, dynamic intraoperative
information about the surgical field. Therefore, we believe
that ICG‑VA may increase the safety of the clipping
procedure in the treatment of PComA, PCA, and basilar
The Authors thank Gregory C. Kujoth, PhD, for technical
assistance in video editing.
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