Delayed presentation and rupture of an intracranial pseudoaneurysm following penetrating trauma: illustrative case.

backgroundPseudoaneurysms are rare vascular lesions that can form following injury to an artery. Damage to the artery can result in a hematoma surrounded by a layer of coagulation products. Intracranial pseudoaneurysms are particularly uncommon, comprising less than 1% of all aneurysms, and are often associated with traumatic brain injuries. OBSERVATIONS: A 37-year-old male presented with two stab wounds, one to the right cheek, extending intracranially. Initial imaging revealed extensive intracranial hemorrhage and a possible right posterior cerebral artery (PCA) pseudoaneurysm. The patient underwent surgical decompression. Notably, the pseudoaneurysm was not seen on postoperative imaging. He remained neurologically stable until postoperative day 19, when he acutely declined and was found to have a new hemorrhage associated with the right PCA pseudoaneurysm. Despite successful coil embolization of the pseudoaneurysm, his condition deteriorated due to worsening vasospasm and ischemia. His family decided to pursue comfort care and compassionate extubation. LESSONS: This case emphasizes the importance of early detection and close monitoring of traumatic intracranial pseudoaneurysms. Since rupture can occur days to weeks following the inciting event, it must be considered in the differential diagnosis when an acute neurological change occurs in patients who have sustained a penetrating traumatic brain injury. https://thejns.org/doi/10.3171/CASE24745.