PT - JOURNAL ARTICLE AU - Yager, P AU - Lin, L AU - Fraser, J AU - Alhajeri, A TI - E-042 Cerebral hyperperfusion syndrome following endovascular cerebral aneurysm stent-coiling: case reports and diagnostic challenges AID - 10.1136/neurintsurg-2019-SNIS.117 DP - 2019 Jul 01 TA - Journal of NeuroInterventional Surgery PG - A68--A69 VI - 11 IP - Suppl 1 4099 - http://jnis.bmj.com/content/11/Suppl_1/A68.3.short 4100 - http://jnis.bmj.com/content/11/Suppl_1/A68.3.full SO - J NeuroIntervent Surg2019 Jul 01; 11 AB - Introduction Cerebral hyperperfusion syndrome (CHS) has been reported sparsely after aneurysm clipping and is likely underreported after endovascular treatments. We report two cases of CHS following endovascular embolization and discuss diagnostic and differential challenges.Cases Patient 1 is a 64yo woman who underwent elective stent-assisted-coiling of an unruptured 11×10 mm right MCA trifurcation aneurysm without intraoperative complication. Immediate and delayed post-treatment angiography showed patent vasculature with no extravasation of contrast. Initial post-procedure neurological exam was normal; 4 hours later, she developed left hemiplegia. CT showed a large right intraparenchymal parietal hematoma with local cerebral edema distal to aneurysm treatment (figure A). Follow up diagnostic angiography showed no extravasation from the MCA and no change in the treated aneurysm. Transcranial doppler showed proportional increase in right MCA and right ICA flow velocity, concerning for hyperperfusion. During decompressive craniotomy, multiple small arterial intraparenchymal bleeders were encountered.Patient 2 is a 70yo man who underwent two stage stent assisted coiling of an unruptured ACOM aneurysm. Post-stenting but pre aneurysm coiling showed uniform contrast distribution (figure B), whereas post aneurysm coiling showed persistent contrast blush in the temporal and parietal regions (figure C, yellow arrows). This correlated with cortical edema found on CT twenty-four hours post-procedure. Cortical edema resolved the following day with conservative blood pressure management.Abstract E-042 Figure 1 Discussion CHS following endovascular stent-coiling of aneurysms is not described in literature. Differential diagnosis considerations for these cases include vasospasm, which is far more prevalent, and contrast induced encephalopathy (CIE), which is rare. In both cases, increased arterial flow to the territory of the parent vessel was demonstrated. This is in contrast to vasospasm, where reduced flow results in ischemic infarct. CIE has also been reported to have decreased perfusion in studies which utilize flow imaging and is generally associated with posterior circulation angiography and symptoms. In contrast, our cases demonstrated increased flow, so we strongly favor CHS as the diagnosis. However, the incidence and mechanism of CHS, as well as CVS and CIE, in endovascular treatments requires more in-depth evaluation.Disclosures P. Yager: None. L. Lin: None. J. Fraser: 2; C; Stream Biomedical, Medtronic. 4; C; Fawkes Biotechnology. A. Alhajeri: None.