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Electrophysiological monitoring might be useful when intraoperative anatomical findings of the hemodynamic structure are inadequate. Moreover, in our case, intraoperative changes in motor evoked potentials indicated the risk to occlude one of posterior SAs, although it is said that posterior circulation of spinal cord has ischemic tolerance.

Introduction: Intraplaque hemorrhage (IPH) has been reported to be a characteristic feature of a vulnerable plaque, indicated by an area of high signal intensity on carotid MRI. It has been reported that symptomatic low-grade stenosis with IPH is strongly associated with ischemic events, but there are limited data regarding the dynamics of the carotid plaque signal. The aim of this study was to assess the time-dependent change of carotid plaque in the symptomatic patient with low-grade stenosis. Methods: Thirty-eight symptomatic patients with carotid low-grade stenosis (0.31 between time points was considered significant. We then investigated changes in rSI and subsequent ipsilateral ischemic events. Result: Of the 38 patients, there were strong-positive and positive plaque at baseline in 22 and 12 patients, respectively. During a mean follow-up period of 42.5 months, 26 positive plaques (74%) at baseline kept an rSI of >1.25, and all of 4 negative plaques at baseline changed positive. Strong-positive plaques at baseline showed a lower tendency to be negative than positive plaque (p=0.08). Twenty-one of the 38 patients (55%) experienced a total of 26 recurrent ischemic events. In patients who experienced recurrent ischemic events, 19 plaques (73%) were strong-positive and 5 plaques (19%) were positive. Compared to the most recent carotid MRI, rSI at the event was stable in 18 patients (69%) and increased in 8 patients (31%). Conclusions: Most symptomatic plaque with low-grade stenosis retained its hyperintensity after ischemic events and had a high rate of subsequent ipsilateral ischemic events. A sustaining high signal intensity might be associated with an increased risk of subsequent ischemic events. Follow-up observation by carotid MRI has the potential to increase the accuracy of stroke risk stratification in the management of carotid low-grade stenosis.

Objectives: Dissecting aneurysms (DAs) truly localized at the posterior inferior cerebellar artery (PICA) are rare. In addition, bilateral dissecting aneurysms of PICA have never been reported in the literature to our knowledge. We report a case of bilateral DAs of the PICA presented with subarachnoid hemorrhage. Case presentation: A 41-year-old male was referred to the emergency care center of our institute due to sudden onset of posterior cervical pain and dizziness. He was neurologically intact with clear consciousness. CT showed subarachnoid hemorrhage (Fisher Grade 3), and cerebral angiography revealed DAs at anterior medullary segment to lateral medullary segment of bilateral posterior inferior cerebellar artery. He underwent parent artery occlusion (PAO) for the right lesion which showed increase in size during conservative treatment. In spite of negative result of preoperative balloon test occlusion of the right vertebral artery at the origin of the right PICA, he suffered acute infarction in the right cerebellum and medulla after PAO with temporary partial right Wallenberg syndrome and the right limb ataxia. The left lesion showed spontaneous decrease in size at 6 months follow-up angiography. Conclusions: An extremely rare case of bilateral DAs of the PICA is presented. Endovascular treatment for this lesion is feasible though more prudent preoperative evaluation is required.