OBJECTIVECerebral arteriovenous malformations (AVMs) are vascular lesions that are amenable to various treatment modalities including stereotactic radiosurgery, fractionated radiotherapy, endovascular embolization, microsurgical obliteration or combined modality treatment. A potential complication of endovascular therapy with embolization material is microcatheter entrapment. We report on a patient for whom surgery was combined with endovascular embolization to obliterate an AVM and retrieve an entrapped endovascular microcatheter.PARTICIPANTA 52-year-old woman suffered a left parietal hemorrhage from an AVM. She underwent staged endovascular embolization of the lesion using Onyx material. During the second stage of the embolization, the microcatheter (Marathon Flow Directed Microcatheter; eV3 Neurovascular, Inc., Irvine, CA, USA) was retained in the Onyx plug. It was decided to section the microcatheter at the groin and proceed with microsurgical obliteration of the AVM, with removal of the entrapped microcatheter remnant.INTERVENTIONThe AVM was dissected circumferentially allowing the meticulous obliteration of the feeding vessels. A single remaining feeding vessel originating from the distal anterior cerebral artery was identified and suspected to contain the entrapped microcatheter. The location was confirmed using stereotactic guidance (BrainLab, Munich, Germany) and the vessel was then sectioned allowing complete removal of the AVM. The microcatheter (102 cm) was then extracted cranially using gentle traction.CONCLUSIONThis demonstrates the first incidence of microcatheter removal after procedural entrapment in Onyx embolization material.