Cerebral Granulomatous Inflammation Secondary to Hydrophilic Polymer Embolization Following Thrombectomy

BACKGROUND Given the recent completion of multiple trials demonstrating the benefit of endovascular mechanical thrombectomy for select patients with proximal large artery occlusive ischemic strokes, there has been a large increase in the performance of these procedures. In the context of increased thrombectomy performance, there have also been increased reports of rare occurrences of granulomatous inflammatory response to the hydrophilic polymer which coat many of these interventional devices. CASE REPORT A 59-year-old female presented with a complete occlusion of her right proximal middle cerebral artery (MCA) and imaging showed a large area of penumbra. Cerebral angiogram and mechanical thrombectomy were successfully performed with reversal of clinical symptoms. Eight months following her stroke, she developed progressive recurrence of left-sided neurological deficits. After extensive workup culminating in tissue sampling, she was found to have developed granulomatous inflammation surrounding microscopic embolization of hydrophilic polymer, which is used to coat many interventional devices such as wires and catheters. The patient responded both clinically and radiographically to anti-inflammatory steroid therapy. CONCLUSIONS Recognizing the significant potential morbidity of a large vessel ischemic stroke and the expanded use of endovascular interventions aimed at staving off this disability, there are emerging and at times indolent complications from the use of hydrophilic polymer coated wires and catheters. This rare and potentially under-recognized complication should be considered in the differential for any patient with new neurological findings following cerebral intervention, especially given the consideration that this appears to a treatable complication.