Flow diversion of a middle cerebral artery pseudoaneurysm secondary to a gunshot wound: A case report.

Pseudoaneurysms are rare but devastating complications of penetrating head traumas. They require rapid surgical or endovascular intervention due to their high risk of rupture; however, complex presentations may limit treatment options. Our objective is to report a case of severe vasospasm, flow diversion, and in-stent stenosis complicating the treatment of a middle cerebral artery pseudoaneurysm following a gunshot wound. A 33-year-old woman presented with multiple calvarial and bullet fragments within the right frontotemporal lobes and a large right frontotemporal intraparenchymal hemorrhage with significant cerebral edema. She underwent an emergent right hemicraniectomy for decompression, removal of bullet fragments, and evacuation of hemorrhage. Once stable enough for diagnostic cerebral angiography, she was found to have an M1 pseudoaneurysm with severe vasospasm that precluded endovascular treatment until the vasospasm resolved. The pseudoaneurysm was treated with flow diversion and in-stent stenosis was found at 4-month follow-up angiography that resolved by 8 months post-embolization. We report the successful flow diversion of an middle cerebral artery (MCA) pseudoaneurysm complicated by severe vasospasm and later in-stent stenosis. The presence of asymptomatic stenosis is believed to be reversible intimal hyperplasia and a normal aspect of endothelial healing. We suggest careful observation and dual-antiplatelet therapy as a justified approach.