title: Onyx extravasation during embolization of a brain arteriovenous malformation.
abstract: During Onyx embolization to treat brain arteriovenous malformation (AVM), carefully observing the penetration of Onyx to the nidus is important in order to avoid complications such as hemorrhage, ischemia, and difficulty with microcatheter removal. We encountered a case of Onyx extravasation during embolization of a cerebellar AVM confirmed by surgical resection and pathological analysis. The patient was a 44-year-old man with Spetzler-Martin grade I cerebellar AVM who underwent Onyx embolization prior to resection of the brain AVM. While injecting Onyx into the nidus using the "plug-and-push" technique, Onyx extravasation was observed. Onyx injection was paused and subsequently restarted, thereby allowing continuation of embolization. An oblate Onyx cast that was entirely covered in cerebellar tissue was removed during total resection of the AVM, performed the same day. The surgically removed oblate Onyx cast did not contain brain tissue or vessel wall, and immunohistochemical staining against glial fibrillary acidic protein (GFAP) showed Onyx penetration into GFAP-positive cerebellar tissue. Onyx extravasation was confirmed based on intraoperative findings during resection as well as pathological findings. The patient has been followed for four years postoperatively, and adverse events caused by Onyx extravasation have not been observed. Unexpected cast of Onyx, remote from the vascular architecture of the AVM, may represent an intra-parenchymal extravasation.
authors.affiliation: 1 Department of Neurosurgery, Kobe City Medical Center General Hospital, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Ikeda
authors.affiliation: 1 Department of Neurosurgery, Kobe City Medical Center General Hospital, Japan.
authors.forename: Hirotoshi
authors.initials: H
authors.lastname: Imamura
authors.affiliation: 1 Department of Neurosurgery, Kobe City Medical Center General Hospital, Japan.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Agawa
authors.affiliation: 2 Department of Pathology, Kobe City Medical Center General Hospital, Japan.
authors.forename: Yukihiro
authors.initials: Y
authors.lastname: Imai
authors.affiliation: 1 Department of Neurosurgery, Kobe City Medical Center General Hospital, Japan.
authors.forename: Shoichi
authors.initials: S
authors.lastname: Tani
authors.affiliation: 1 Department of Neurosurgery, Kobe City Medical Center General Hospital, Japan.
authors.forename: Hidemitsu
authors.initials: H
authors.lastname: Adachi
authors.affiliation: 1 Department of Neurosurgery, Kobe City Medical Center General Hospital, Japan.
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Ishikawa
authors.affiliation: 1 Department of Neurosurgery, Kobe City Medical Center General Hospital, Japan.
authors.forename: Yohei
authors.initials: Y
authors.lastname: Mineharu
authors.affiliation: 1 Department of Neurosurgery, Kobe City Medical Center General Hospital, Japan.
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Sakai
mesh_terms: D000328:Adult; D004121:Dimethyl Sulfoxide / Q000627:therapeutic use*; D004621:Embolization, Therapeutic / Q000379:methods*; D005119:Extravasation of Diagnostic and Therapeutic Materials / Q000601:surgery*; D006801:Humans; D002538:Intracranial Arteriovenous Malformations / Q000601:surgery / Q000628:therapy*; D008297:Male; D011145:Polyvinyls / Q000627:therapeutic use*
chemical_list: C450660:Onyx copolymer; D011145:Polyvinyls; D004121:Dimethyl Sulfoxide
keywords: Onyx; arteriovenous malformation; embolization; extravasation