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Chen et al. Contralateral cerebral ischemia after MMD bypass

combination of CBF analysis and neuroimaging within Postoperative agitating delirium would increase the
2 days after surgery might be reasonable [Table 1]. [13,15] cerebral oxygen consumption, which might increase the
risk of cerebral ischemia during the early postoperative
Although the positron emission tomography (PET) period of MMD. We did not find any evidence
and single-photon emission computed tomography opposing sedation in patients with MMD. However,
(SPECT) are the most extensively used quantitative most sedative agents have a potential side effect of
methods for cerebral hemodynamics assessment, hypotension. Although these agents might be used
the use of radionuclides and the high cost of the during anesthesia, intraoperative hypotension was
examination limit the serial perioperative PET or common and did not independently increase the risk of
SPECT scans. Therefore, the alternative noninvasive postoperative ischemic complications. [7,30] In contrast,
methods without contrast agent, such as blood- postoperative hypotension was a significant risk factor
[7]
oxygen-level dependent functional MRI (BOLD-fMRI) for postoperative ischemic events. Therefore, further
or arterial spin labeling MRI (ASL-MRI), might be of studies might be conducted to discuss the sedation in
great clinical importance. Previous studies suggested MMD patients with postoperative, agitating delirium.
that the delayed and reduced magnitude of the BOLD Postoperative transient neurological events were
response might indicate the severity of compromised reported to occur in 40-60% of revascularization
hemodynamics in patients with cerebral ischemic surgery for MMD, and 4-14% of patients exhibited
[10]
diseases. [18,19] A most recent report observed BOLD postoperative cerebral infarction. [10,31] This report
responses to specific stimulation in patients with is congruent with previous observations that early
MMD before and after revascularization, and found postoperative neurological deficits usually resolve
a predicator for postoperative outcomes, suggesting within 7 days, while irreversible cerebral infarction may
the feasibility of using BOLD-fMRI for individualized persist in some patients with or without neurological
assessment of cerebral hemodynamic impairment and deficits. The incidence of transient neurological
[12]
hemodynamic improvement after revascularization events varies among different reports, and it seems
in patients with MMD. ASL is another promising that studies from Asian countries showed a higher rate
[20]
technology for cerebral hemodynamics assessment of postoperative stroke than those from America. [31,32]
in perioperative management of MMD. Several The association between perioperative neurological
[21]
studies have demonstrated the advantage and events and permanent neurological deficits should be
accuracy of ASL in cerebral blood flow evaluation. [22,23] further examined in future studies.
Recent advances in multiple-parameter ASL (multiple
inversion time-pulse or post labeling delay) might Authors’ contributions
allow for more precise assessment of cerebral The definition of intellectual content: X.L. Chen, L. Ma
hemodynamics. [24-26] Future studies in neuroimaging Literature review: X.L. Chen, L. Ma
will provide better radiological tools for evaluation of Manuscript preparation and editing: X.L. Chen, L. Ma,
cerebral blood perfusion. J.L. Lu
Data acquisition: Y. Chen, J.L. Lu
Free radical scavenger and anti-inflammatory Concept contribution: X. Ye, R. Wang, Y.L. Zhao
medicine might also be helpful in reducing the risk Definition of intellectual content: X. Ye, R. Wang, Y.L.
of perioperative neurological events. A recent Zhao
[15]
case-control study suggested MMD patients using Manuscript review: X. Ye, R. Wang, Y.L. Zhao
edaravone (a free radical scavenger) had a decreased Acknowledgments
frequency of transient neurological event after direct The authors would like to thank members of the Joint
revascularization surgery. We added ederavone in Cerebrovascular Surgery Study Project of Peking
[27]
this case as recommended in some protocols, and University International Hospital and Beijing Tiantan
the neurological function markedly improved without Hospital, and Dr. Sun Yuming of the Department
disability, despite a cerebral infarction. Minocycline, of Neurosurgery at Sanbo Brain Hospital, Capital
a matrix metalloproteinase-9 inhibitor, might also Medical University.
ameliorate the reperfusion injury at the site of
anasotmosis and the remote area after blood pressure Financial support and sponsorship
reduction and has been used in patients with MMD This project was supported by the Ministry of Science
to prevent both hyperperfusion and cerebral infarction and Technology of China, National Key Technology
at the remote area. [9,28,29] Further studies might be Research and Development Program (2015BAI12B04,
feasible to unravel the therapeutic effect of these 2013BAI09B03); Beijing Institute for Brain Disorders
medicines in larger populations. grant (BIBD-PXM2013_014226_07_000084); and
Neuroimmunology and Neuroinflammation ¦ Volume 4 ¦ March 24, 2017 51