BACKGROUND AND IMPORTANCE Posterior inferior cerebellar artery (PICA) aneurysms are uncommon, and PICA pseudoaneurysms are even rarer. Endovascular treatment options exist for such lesions but usually require arterial sacrifice. This case report describes the successful treatment of a PICA pseudoaneurysm by trapping and end-to-end PICA reanastomosis. CLINICAL PRESENTATION A 70-yr-old woman with a history of multiple microvascular decompressions for hemifacial spasm presented with new-onset

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... l droop caused by an enlarging, unruptured left PICA pseudoaneurysm. It was treated with trapping and end-to-end PICA reanastomosis, which is the first reported case of this technique for a PICA pseudoaneurysm. The bypass was patent, the pseudoaneurysm occluded, and the patient recovered well from her surgery. CONCLUSION Pseudoaneurysm formation and growth after microvascular decompression is unusual. Albeit a deep and challenging bypass, trapping and an end-to-end PICA reanastomosis excluded the pseudoaneurysm, prevented further growth and/or rupture, and alleviated the patient's compressive symptoms.