Flow diverter therapy for immunosuppressant-resistant vertebral artery fusiform aneurysm due to eosinophilic granulomatosis with polyangiitis: illustrative case

Abstract

BACKGROUND Eosinophilic granulomatosis with polyangiitis (EGPA) is a systemic small-vessel vasculitis characterized by the presence of asthma and eosinophilia. Because cerebral aneurysm formation induced by EGPA is a rare occurrence, there is no established treatment strategy for this condition. OBSERVATIONS A 67-year-old female who was diagnosed with idiopathic eosinophilia 3 months ago developed de novo fusiform aneurysms in the left vertebral, left internal carotid, and bilateral superficial temporal arteries, as noted during a regular follow-up examination of a convexity meningioma. Pathological examination of the resected superficial temporal artery revealed eosinophilic granulomas, which led to the diagnosis of EGPA, as well as EGPA-induced aneurysm formation. As the partially thrombosed vertebral artery fusiform aneurysm enlarged, the compression of the medulla oblongata occurred despite intensive immunosuppressive therapy for 1 year. The patient underwent flow diversion therapy administered using the pipeline embolization device, resulting in complete disappearance of the aneurysm. LESSONS Considering that the entire circumference of the aneurysmal wall is affected by necrotizing vasculitis, flow diverter therapy would be a reasonable and efficient approach for the treatment of EGPA-related aneurysms in cases in which the patient is nonresponsive to immunosuppressants.