Background and Purpose Endovascular thrombectomy is an increasingly used treatment for arterial occlusion in acute stroke. Various devices (including most extensively the Mechanical Embolus Removal in Cerebral Ischemia/MERCI Retriever device) have been utilized for this. Methods We review the neuropathologic findings in 5 patients (age range 59–87 years) who died acutely or as late as 38 days after procedures using the Merci (4 patients) and Penumbra (1 patient) devices were carried out to remove thrombo-emboli from the middle cerebral artery (MCA). Partial recanalization was achieved by thrombectomy in all 5 patients. Results All patients showed extensive cerebral infarcts, 3/5 with clinical hemorrhagic transformations of the infarct or frank intraparenchymal hemorrhage after thrombectomy— in one case this was judged to be at least partly on the basis of concomitant hypertensive microvascular disease. With one exception basal arteries examined in detail by immunohistochemistry, showed prominent, though usually non-occlusive (and generally non-ulcerated) atheromata, often with significant luminal stenosis. One patient showed a subintimal dissection with resultant occlusion of the MCA. Conclusions In this highly selected group of patients, the vascular pathologic abnormalities affecting basal arteries were variable, but complicated atherosclerosis was a common finding. Extensive irreversible brain necrosis prior to therapeutic procedures may have contributed to deaths.

FK506 binding protein (FKBP)-51 and FKBP52 act as molecular chaperones to control glucocorticoid receptor (GR) sensitivity. Dysregulation of proteins involved in GR-mediated signaling can lead to maladaptive stress response and aging-related cognitive decline. As HIV infection is related to chronic stress, we hypothesized that altered cortical expression of these proteins was associated with HIV-associated neurocognitive disorders (HAND). We used quantitative immunohistochemistry to assess expression levels of these proteins in the mid-frontal gyrus of 55 HIV-infected subjects free of cerebral opportunistic diseases compared to 20 age-matched non-HIV controls. The immunoreactivity normalized to the neuroanatomic area measured (IRn) for FKBP51 was increased in HIV subjects both in the cortex and subcortical white matter (p<0.0001, U test), while no significant alterations were observed for GR or FKBP52. Notably, the cortical FKBP51 IRn was higher in HAND subjects than in cognitively normal HIV subjects (p=0.02, U test). There was also a trend for increasing cortical FKBP51 IRn with the increasing severity of HAND (p=0.08, Kruskal-Wallis test). No significant changes in FKBP51 IRn were found with respect to hepatitis C virus infection, lifetime methamphetamine use, or antiretroviral treatment in HIV subjects. In conclusion, the increased cortical expression of FKBP51 (an inhibitor for GR activity) might represent negative feedback in an attempt to reduce GR sensitivity in the setting of chronic stress-induced elevation of GR-mediated signaling inherent in HIV infection. The further increased FKBP51 expression might lead to maladaptive stress response and HAND.

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Background and purposeEffectiveness of currently used mechanical thrombectomy devices has been evaluated using animal models mainly based upon the angiographical data analysis. However very little has been described about the histologic changes observed in the arteries treated with mechanical thrombectomy devices. The purpose of this study is to evaluate acute arterial histologic changes induced by mechanical thrombectomy using a dedicated swine stroke model.Materials and MethodsA total of eight Superficial Cervical Arteries in four swine were occluded with experimental thrombus and treated using the Merci Clot Retrieval System®. Each treated artery was harvested immediately after the procedure and histologic analysis of each arterial sample was performed. Four untreated Superficial Cervical Arteries were used as controls.ResultsA total of 24 attempts at clot retrieval were made. The average number of retrieval attempts per artery was three. Circumferential intimal denudation and separation of smooth muscle layers in the tunica media were seen in all samples. The intimal denudation was seen regardless of the number of retrieval attempts. A minor sub-intimal dissection was seen in one artery. Arterial perforation with sub-adventitial hematoma was seen in two arteries and these findings were associated with microwire/microcatheter navigation rather than the use of the clot retrieval device.ConclusionMinor histologic changes including intimal denudation and separation of smooth muscle layers in tunica media were seen in every artery treated by mechanical thrombectomy. Two arteries that showed major histologic change (sub-adventitial hematoma) were both associated with microwire/catheter navigation rather than the use of the clot retrieval device. It is possible that major arterial injury (eg vessel perforation) during the mechanical thrombectomy is more likely to be associated with microcatheter/microwire navigation rather than clot retrieval itself. This animal model may be useful in the preclinical safety evaluation of the mechanical thrombectomy devices.Competing interestsI Yuki: None. I Kan: None. A Golshan: None. H Vinters: None. R Kim: None. N Yin: None. G Duckwiler: Concentric Medical. F Vinuela: None. Y Murayama: None. F Vinuela: None.Abstract E-038 Figure 1