ARTICLE IN PRESS

Case Studies

Revascularization for Aplastic or Twiglike Middle Cerebral
Artery: A Case Report
Yuki Matsunaga, MD, Tsuyoshi Izumo, MD, PhD, Yoichi Morofuji, MD, PhD,
Nobutaka Horie, MD, PhD, Kentaro Hayashi, MD, PhD, and
Takayuki Matsuo, MD, PhD

An aplastic or twiglike middle cerebral artery (Ap/T-MCA) is a congenital anomaly
related to interference of normal embryonic development of the middle cerebral
artery (MCA). This condition may cause ischemic and hemorrhagic strokes as a
result of hypoperfusion, vulnerable collateral circulation, and associated aneurysms. We reported a case of Ap/T-MCA with transient ischemic attack, which
was successfully treated with revascularization. A 19-year-old woman with a history
of transient left upper limb hemiparesis, dysesthesia, and headache visited our
hospital. Digital subtraction angiography showed an occlusion in the M1 segment
of the MCA and abnormal vascular networks distal to the occlusion site. The patient
underwent direct and indirect revascularizations, including superficial temporal
artery-to-MCA bypass and encephalomyosynangiosis. She was discharged home
without any neurological deficit. Magnetic resonance angiography at 12 months
after revascularization showed regression of blood flow signals at the twigs network.
In spite of congenital anomaly, revascularization for an Ap/T-MCA may be useful
to reduce collateral stress in microvascular networks and to prevent future stroke
in selected patients. Key Words: Aplasia—middle cerebral artery—moyamoya
disease—revascularization—twig.
© 2017 National Stroke Association. Published by Elsevier Inc. All rights reserved.

Case Report
A 19-year-old woman was referred to our hospital on
suspicion of unilateral moyamoya disease. She suffered
from transient left upper limb hemiparesis, dysesthesia,
and headache for 8 years. Physical examination on adFrom the Department of Neurosurgery, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan.
Received August 23, 2017; revision received October 31, 2017;
accepted December 3, 2017.
Address correspondence to Yuki Matsunaga, MD, Department of
Neurosurgery, Nagasaki University Graduate School of Biomedical
Sciences, 1-7-1 Sakamoto, Nagasaki 852-8501, Japan. E-mail:
y.matsunaga923@gmail.com.
1052-3057/$ - see front matter
© 2017 National Stroke Association. Published by Elsevier Inc. All
rights reserved.
https://doi.org/10.1016/j.jstrokecerebrovasdis.2017.12.004

mission showed no neurological deficit, and there was
no brain parenchyma change suggesting old cerebral infarction on magnetic resonance imaging. Digital subtraction
angiography revealed occlusion from the right internal
carotid artery (ICA) terminal portion to the middle cerebral artery (MCA) proximal portion, a poorly developed
main arterial trunk of the M1, and twiglike vascular networks on this site (Fig 1, A-D). These findings suggested
an aplastic or twiglike middle cerebral artery (Ap/TMCA) rather than unilateral moyamoya disease. Cerebral
blood flow examination demonstrated a significant decrease in regional cerebrovascular reserve capacity at the
right anterior cerebral artery-MCA watershed area (Fig 1,
E). The patient underwent superficial temporal artery to
MCA bypass and encephalomyosynangiosis. She was
discharged home without any neurological deficit on postoperative day 12. Magnetic resonance angiography at 12

Journal of Stroke and Cerebrovascular Diseases, Vol. ■■, No. ■■ (■■), 2017: pp ■■–■■

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Y. MATSUNAGA ET AL.

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months after revascularization showed regression of blood
flow signals at the twigs network (Fig 1, F-G).

Discussion
An Ap/T-MCA does not have a normal M1 segment,
with multiple plexiform arterial networks found along
the normal route of the M1 segment, related to interference in normal embryonic MCA development.1 Recent
studies revealed that Ap/T-MCA is confined to the unilateral M1 segment, with the M2 segment maintaining
a nearly normal vessel caliber, and no adjacent major cranial
arteries had stenosis or occlusions.1,2 Reported cases of
Ap/T-MCA that had single-photon emission computed
tomography exhibited ipsilateral hypoperfusion areas, suggesting that Ap/T-MCA increases the risk of developing
ischemic stroke.3 Additionally, the fetal arterial networks, which appear to persist in these cases, are usually
thinner and the muscular layer is less developed. These
fragile vessels are at higher risk of bleeding at sites of
weak collateral circulation or aneurysm with increasing
pressure.2
For moyamoya disease characterized by progressive occlusion of the bilateral ICAs, recent studies have shown
that bypass surgery reduces the risk of future ischemic
and hemorrhagic strokes.4,5 However, it has been suggested that Ap/T-MCA is a congenital anomaly, with no
progressive occlusion or collateral circulation. Thus, it was
unclear whether revascularization in Ap/T-MCA was useful
for recurrent stroke. In the present case, postoperative
magnetic resonance angiography showed a decrease of
blood flow in the abnormal vascular networks. These findings indicate that revascularization for Ap/T-MCA may
improve misery perfusion, as well as hemodynamic stress
in abnormal vascular networks.
In conclusion, we experienced a case of Ap/T-MCA
with transient ischemic attack, which was successfully
treated with revascularization. Revascularization for Ap/
T-MCA may reduce collateral stress in microvascular
networks and may prevent risk of future stroke.

References
Figure 1. Digital subtraction angiography images. (A) The right internal carotid artery angiography in AP view. The proximal M1 segment is
not visualized, whereas the distal M1 is supplied by plexiform vascular networks of small arteries (“twiglike vessels”). (B-D) The left internal carotid
artery angiography in lateral view (B), vertebral angiography in AP view
(C), and right external carotid artery angiography in AP view (D). No adjacent major artery exhibited stenosis or occlusions, and there was no evidence
of transdural anastomosis. Preoperative N-isopropyl-p-123I-iodoamphetamine
single-photon emission computed tomography images. (E) These revealed a
significant decrease in regional cerebrovascular reserve capacity at the right
anterior cerebral artery-middle cerebral artery watershed area. Magnetic resonance angiography images. (F, f) Preoperative image. (G, g) Postoperative
image at 12 months after revascularization showing a decrease of blood flow
signals at the twigs network. Abbreviations: AP, anterior-posterior; CVR,
cerebral vascular reserve; DIAMOX, cerebral blood flow after acetazolamide loading; REST, cerebral blood flow in the resting state.

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