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Chen et al. Contralateral cerebral ischemia after MMD bypass

INTRODUCTION bilateral watershed. Perfusion computed tomography
(CT) showed a reduced cerebral blood flow of the
Moyamoya disease (MMD) is one of the major causes bilateral hemisphere with a mild domain on the left
of stroke in children and adults. It is characterized side [Figure 2].
by progressive stenosis or occlusion of terminal
portion of internal carotid arteries and development Considering the patient had barylalia, a left STA-
of fragile collateral vessels (moyamoya vessels). MCA anastomosis was first performed between
[1]
Revascularization surgery is a recommended the parietal branch of the STA and MCA (M4
therapy in these patients. Although the long-term segment) supplying the frontal and parietal lobe. The
[2]
outcome of direct revascularization through superficial intraoperative blood pressure (BP) remained between
temporal artery (STA)-middle cerebral artery (MCA) 120-140 mmHg. We followed our postoperative protocols
bypass is generally favorable, early postoperative with fluid infusion, a prophylactic anti-epileptic drug,
neurological events are still frequently reported and aspirin, and statins. The patient did not display any
contribute to neurological deterioration. The change neurological deficits after surgery until she appeared
[3]
of perioperative cerebral perfusion is suggested restless and delirious 8 h afterwards. We suspected
to be dynamic, therefore to identify the underlying hyperperfusion syndrome after revascularization,
mechanisms and risk factors might improve the while the perfusion CT was not available at night.
postoperative management, especially in patients with Consequently, the patient was managed with blood
advanced MMD and unstable hemodynamics. In MMD pressure control (systolic blood pressure between
with unilateral STA-MCA bypass, symptomatic cerebral 110-130 mmHg) and intravenous fluid infusion. On the
ischemia in the contralateral hemisphere occurs in 1st day after surgery, she appeared to have barylalia
about 3-14% of patients. [4-7] and retrograde amnesia, thus intravenous edaravone
(60 mg/day) was added. On the 2nd day after surgery,
We herein presented a case of childhood-onset the retrograde amnesia completely resolved, while
bilateral MMD, which developed transient cerebral left limb weakness appeared with muscle strength of
ischemia in the contralateral hemisphere after STA- Grade 3. Postoperative imaging on the 3rd and 6th day
MCA bypass in her young adulthood. Transient after surgery revealed an improved perfusion of left
weakness of the left extremities and acute cerebral hemisphere, but identified a de novo lesion between
infarctions in the contralateral hemisphere were the right temporal and occipital cortex with high
observed from postoperative Day 1 to Day 6. The intensity on T2 weighted image (T2WI) and diffusion
neurological deficit improved after intravenous infusion weighted image (DWI) and decreased cerebral blood
of fluid and free radical scavenger. There were no flow (CBF), which was in the contralateral hemisphere
subsequent neurological events, and the preoperative of STA-MCA anastomosis [Figure 3]. Fluid infusion
neurological deficit significantly improved during the ensuring euvolemia, and edaravone were continued
follow-up period. The mechanism and management with systolic blood pressure between 130-140 mmHg.
of the neurological events in the early postoperative The patient’s left limb weakness was completely
period were further discussed with a literature review. resolved by the 6th day after surgery. She was
discharged 13 days after surgery with the barylalia
CASE REPORT relieved and no other neurological deficits during the
latest follow-up period of 2 months.
A 21-year-old female with 5-year history of paroxysmal
limbs weakness presented to our hospital with a DISCUSSION
reoccurrence of symptoms and slurred speech 15
days ago. There was no family history of MMD. Digital Extracranial-intracranial direct anastomotic bypass
subtraction angiography (DSA) revealed extensive is recognized as a treatment for ischemic MMD
stenosis of the bilateral terminal portions of the internal with favorable long-term outcome. In the acute
[1]
carotid arteries (ICAs) and abundant moyamoya postoperative period of STA-MCA bypass, however,
vessels on both sides, leading to a diagnosis of transient neurological events or stroke can be observed
MMD. The bilateral anterior cerebral artery (ACA) despite the improvement of cerebral perfusion at the
and the right posterior cerebral artery (PCA) were not site of anastomosis. [1,3] Rapid, increased local perfusion
identified. The left PCA was also involved with stenosis and perioperative hemodynamic fluctuations after
and collaterals of vascular network. Collaterals from bypass surgery might increase the risk of abnormal
the posterior circulation formed between right occipital perfusion in the adjacent area or remote regions,
and parietal lobe [Figure 1]. Magnetic resonance especially in patients with advanced stage, bilateral, or
imaging (MRI) showed multiple infarct lesions in the unstable MMD. [8-10]
Neuroimmunology and Neuroinflammation ¦ Volume 4 ¦ March 24, 2017 47