Objective: Mechanical thrombectomy (MT) is an effective treatment for patients suffering from acute ischemic stroke secondary to large vessel occlusion. However, recanalization failure rates of interventions were about 20% in literature studies. We report our experience of unsuccessful MT with a focus on technical reasons. Methods: From December 2010 to June 2021, six hundred eight patients with acute ischemic stroke due to large artery occlusion received MT using a stent retriever with or without an aspiration catheter in our institution. We divided the reasons for failure into six categories. We analyzed the reasons for failure by dividing our experience time into 3 periods. Results: A total of 608 cases of thrombectomy for large vessel occlusion were identified in the study period. The successful recanalization rate was 90.4%. In most of the cases (20/57, 35%), the thrombus persisted despite several passes, and the second most common cause was termination of the procedure even after partial recanalization (10/57, 18%). Similar proportions of in-stent occlusion, distal embolization, and termination due to vessel rupture were observed. On analysis of three periods, the successful recanalization rate improved over time. Conclusions MT fails due to various reasons, and intracranial artery stenosis is the main cause of MT failure. With the development of rescue techniques, the failure rate has gradually decreased. Further development of new devices and techniques could improve the recanalization rates.

After craniotomy, bone flap fixation can be performed using wires, sutures, microplates, and Craniofix®. Well-margined and fixed bone flaps are important not only for postoperative brain protection but also for esthetics. Herein, we report a case of cranioplasty due to bone flap dislocation by Craniofix® clamp loosening after craniotomy with acute subdural hemorrhage removal. Iatrogenic outward force during epidural drain removal adjacent to Craniofix®, insertion of the clamp around the circumference of the bone flap, increased intracranial pressure due to brain swelling and fluid collection, and external shock during postoperative patient management are thought to be the causes of bone flap dislocation. To our knowledge, this is the second reported case of craniotomy with a Craniofix® clamp release.