Orbital inflammatory syndrome after mechanical thrombectomy of acute carotid occlusion

Introduction: Orbital ischemic syndrome (OIS) is a rare disorder that presents with acute loss of visual acuity, chemosis, proptosis, ptosis and ophtalmoparesis. We present a case with acute onset of orbital inflammation following mechanical thrombectomy that mimicked an OIS, except for the absence of vision loss. Case report: A 65-year-old woman presented to our emergency department after an episode of transient dysarthria and left-sided hemiparesis and paresthesia that lasted about forty minutes. Head computed tomography showed no signs of intracranial bleeding or acute ischemia. CT angiogram showed occlusion of the right ICA terminus. Mechanical thrombectomy was then performed and the clot was removed with combined technique. Eight hours later, she developed orbital pain, ptosis, chemosis and complete ophthalmoplegia of the right eye. She had no diplopia, visual acuity and funduscopic examination were normal and there was no audible bruit in the orbit. Brain MRI performed showed hyperintensity of orbital fat along with hyperintensity and enlargement of all the extraocular There were no signs of orbital infarction and the optic nerve was structurally normal. Time of flight magnetic resonance angiography revealed reduced calibre of the distal portion of ICA, with associated contrast enhancement on vessel wall imaging. She was started on intravenous dexamethasone with full recovery two days later. Discussion: We present the case of an orbital inflammatory syndrome after mechanical thrombectomy. The mechanical stress exerted by endovascular devices has been associated with endothelial damage that correlates with vessel wall thickening and contrast enhancement in high resolution MRI studies. The temporal correlation with mechanical thrombectomy, the absence of vision loss or orbital infarction and the good clinical response to steroids support the hypothesis of an internal carotid artery wall inflammation due to endovascular manipulation of the stent retriever to be responsible for this acute orbital syndrome. This case highlights the need for close postprocedural monitoring after MT and the consideration of orbital inflammation secondary to endovascular devices in the differential diagnosis of an acute orbital syndrome. Further studies are needed to understand the long-term consequences of arterial wall lesions associated with these devices.