Hemorrhagic Acquired Pial Arteriovenous Fistula Occurring after Mechanical Thrombectomy: A Case Report

Objective: We report a patient in whom thrombectomy for occlusion of the middle cerebral artery was performed, and a pial arteriovenous fistula (AVF) developed in the relevant vascular area. Case Presentation: The patient was a 72-year-old male. In 2011, thrombectomy with a Penumbra system for right M1 occlusion causing right cerebral infarction was performed. Recanalization was achieved (modified thrombolysis in cerebral infarction [TICI] 2b) although occlusion of the M2 anterior trunk remained. After 1 week, MRA confirmed complete recanalization. The course was favorable, and he was discharged. After 5 years, convulsion occurred, and he was brought to our hospital by ambulance. MRI showed subcortical hemorrhage of the right precentral gyrus. DSA confirmed an arteriovenous (AV) shunt between the right central artery and vein of Trolard, which had not been present. There was no nidus, leading to a diagnosis of a pial AVF. Under craniotomy, the shunt point was disconnected. Conclusion: Intraoperative findings suggested the involvement of cortical vein thrombosis after thrombectomy in the etiology.