Subarachnoid hemorrhage due to
middle cerebral artery dissection misdiagnosed as a saccular aneurysm -
case report
Jong-Myong Lee, M.D
Department of Neurosurgery
Jeonbuk National University Hospital and Medical School,
Jeon-Ju, Korea
Corresponding author
Name: Jong-Myong Lee, M.D.
Zip code: 560-182
Address: Department of Neurosurgery,
Jeonbuk National University Hospital & Medical School,
San 2-20, Keumamdong, Dukjin-Gu, Jeon-Ju, Republic of Korea
Tel: +82-63-250-1870
FAX: +82-63-277-3273
E-mail: nsjmlee@gmail.com
Running title: SAH due to middle cerebral artery dissection
Abstract
Introduction: We report a case of subarachnoid hemorrhage due to a
dissecting middle cerebral artery that was misdiagnosed as a saccular
aneurysm.
Presentation of case: A 74-years old female patient presented with
headache and neck pain for four days. Brain magnetic resonance imaging
revealed subarachnoid hemorrhage in both Sylvian fissures. A ruptured
left middle cerebral artery bifurcation saccular aneurysm and an
unruptured basilar tip aneurysm were diagnosed.
Discussion: The patient was treated surgically using a transsylvian
approach. However, no saccular aneurysm was found during surgery, and
the diagnosis was corrected to middle cerebral artery dissection. We
treated the dissected segment of the MCA and performed clip
reinforcement.
Conclusion: We describe MCA dissection misdiagnosed as a saccular
aneurysm without neurologic deficit despite total occlusion of the
dissected segment of MCA. If dissection is suspected, MRI and
angiography should be performed for diagnosis.
Keywords
Middle cerebral artery, Subarachnoid hemorrhage, Dissection
Abbreviations used in this paper.
SAH: Subarachnoid Hemorrhage
MCA: middle cerebral artery
MCAB: middle cerebral artery bifurcation
MRI: Magnetic Resonance Image
CTA: Computed Tomographic Angiography
ACA: anterior cerebral artery
TCD: transcranial Doppler
DSA: digital subtraction angiography
Introduction
Dissection of the intracranial artery is a relatively rare cause of
stroke and subarachnoid hemorrhage (SAH).1 It has been
reported more frequently in recent years. Intracranial dissection is
recognized as a cause of stroke and subarachnoid hemorrhage because of
the developed diagnostic tools and the recognition of dissecting
aneurysms.2-4 Middle cerebral artery (MCA) dissections
are classically rare and severe, presenting mostly as large MCA
infarcts, SAH, or intracerebral hemorrhage.1,2,5-10
We present a case of MCA dissection with subarachnoid hemorrhage without
an initial neurological deficit despite total occlusion of the dissected
segment, which was misdiagnosed as a saccular aneurysm.
Consent for publication
Written informed consent was obtained from the patient for publication
of this case report and accompanying images. This case report was
conducted in accordance with the Declaration of Helsinki.
Case presentation
A 74-old female presented with severe headache and neck pain for four
days. Initial brain MRI showed subarachnoid hemorrhage in both Sylvian
fissures and no newly developed infarction. The Glasgow Coma Scale score
was 15/15 and the SAH grade was II according to the Hunt and Hess
grading system. The other neurological symptoms were unremarkable. The
brain CT and CTA showed ruptured left middle cerebral artery bifurcation
(MCAB) saccular aneurysm and unruptured basilar tip saccular aneurysm
(Figure 1). Other investigations were normal, including electrolyte
level, blood cell count, prothrombin and coagulation tests, and
cholesterol levels.
The patient underwent surgery via a transsylvian approach. The
intraoperative findings differed from our initial disgnosis: they showed
no MCAB saccular aneurysm, MCA dissection, or severe atherosclerotic
changes in the involved segment (Figure 2). Intraoperative transcranial
Doppler (TCD) revealed that the dissected segment of the MCA had no
blood flow. The small distal branch of the dissected segment had scanty
blood flow. The dissected segment was wrapped, and clip reinforcement
was performed (Figure 2). The postoperative neurologic symptom was
transient right-leg weakness (Figure 3). However, the patient has fully
recovered. Postoperative follow-up digital subtraction angiography (DSA)
revealed no changes in the dissected MCA segment (Figure 4).
Discussion
We report a case of subarachnoid hemorrhage due to dissection of the MCA
that was misdiagnosed as a saccular aneurysm. Intracranial artery
dissection has become an important cause of
stokes.8,10-14 Patients with dissected aneurysms may
present with subarachnoid hemorrhage, cerebral infarction, or
both.2,5,8,10-18
Dissections of the carotid and vertebral arteries usually arise from
intimal tears.1 The intramural hematoma is located
within the layers of the tunica media, but it may be eccentric, either
toward the intima or adventitia.7 A Subintimal
dissection tends to result in stenosis of the arterial lumen, whereas
subadventitial dissection may cause aneurysmal artery
dilatation.19
The supraclinoid segment of the ICA is the most common intracranial site
for aneurysms with occasional extension into the MCA and/or
ACA.20
The diagnosis of intracranial dissecting aneurysms is difficult, even
with angiography and brain MRI. The angiographic characteristics of
dissecting aneurysms include the pearl and string sign, narrowing,
fusiform, dilatation, and occlusion, however, these are not
specific.4,7,11 The pathognomonic sign for dissecting
aneurysms may be double-lumen sign, but this is infrequently
found.21-23 The optimal surgical procedure has not yet
been established, however, surgical methods such as trapping with or
without bypass surgery, ligation, or wrapping for ruptured MCA
dissecting aneurysms have been reported.24,25
The incidence of symptomatic dissection aneurysms is thought to be much
lower in the carotid system, than in the vertebrobasilar system,
particularly, in the MCA.1
After dissection, a variety of lesions can develop including
pseudoaneurysms, variable narrowing of the lumen, and occlusion of the
vessel.7 Therefore, follow-up angiography is important
for the correct diagnosis when a dissecting aneurysm is suspected.
Hemorrhage from a dissecting aneurysm may be unrecognized or
misdiagnosed as an unexplained SAH because of the difficulty in the
angiographic diagnosis.4,25,26 If angiography reveals
luminal narrowing, vascular occlusion, or a non-saccular aneurysm in a
patient with SAH, dissecting aneurysm of the carotid system should be
considered as a likely cause of hemorrhage and
infarction.2,4,25,26
In our case, MCA dissection was misdiagnosed as saccular aneurysm.
Despite complete obstruction of the superior branch of the MCA, the
patient showed no neurological deficits. Initial brain magnetic
resonance image (MRI) revealed no newly developed acute cerebral
infarction, and postoperative brain CT showed the same findings. There
were two reasons for this finding. First, abrupt occlusion synchronized
with progressive severe atherosclerotic occlusive disease. Second, the
patient had the capacity to sustain collateral blood flow above the
infarction threshold. Therefore, despite total occlusion of the
dissected segment, the patient presented with only severe headache
without neurological symptoms in the preoperative period.
Postoperatively, she had experienced transient right-leg weakness
without acute infarctions. The patient was discharged without
neurological deficits.
Conclusion
We experienced MCA dissection with no neurological deficit despite total
occlusion of the MCA branch, which was misdiagnosed as a saccular
aneurysm.
Although we misdiagnosed saccular aneurysmal rupture, several options
have been suggested for treating ruptured
MCA dissection.
If dissection is suspected, MRI and angiography should be performed for
diagnosis.