Spinal cord infarction resulting from perforator occlusion and ischemia after Pipeline Embolization Devices (PEDs) deployment in the posterior circulation is a feared complication. However, only 2 case reports described such occurrences, one involving the posterior spinal artery after basilar artery aneurysm embolization and the other involving the anterior spinal artery (ASA) after embolization PICA dissecting aneurysm. We present the first reported case of ASA syndrome after embolization of the V4 segment of the vertebral artery (VA), with a unique unilateral presentation.

Case Description: A 72-year-old right-handed woman with a prior stroke without residual deficits underwent elective pipeline stent placement for an incidental, unruptured right V4 segment VA aneurysm originating at the origin of the right PICA. She was premedicated with aspirin and ticagrelor for one week preoperatively. The initial procedure was uneventful, and the Pipeline Shield® was deployed across the aneurysm neck.

Several hours postoperatively, she developed acute right-sided weakness (4/5 upper limb, 3/5 lower limb). CT head and CT-angiogram were normal. She was returned to the angiography suite, where distal stent foreshortening was noted. A second stent was placed successfully, with immediate symptom resolution.

Later the same day, she experienced recurrent right-sided weakness. Neurological examination revealed persistent hemiparesis without cranial nerve involvement. Repeat imaging showed no acute bleeding and complete patency of the devices deployed. Despite continued dual antiplatelet therapy and blood pressure augmentation, her deficits persisted. Subsequent MRI demonstrated a right anterolateral spinal cord infarct, consistent with perforator-related ischemia.

To our knowledge, this case is the first reported ASA syndrome after flow diversion of a V4 segment VA aneurysm. While spinal cord infarction is rare, it can present with either unilateral or bilateral symptoms, and physicians should remain vigilant for it as a possible complication of posterior circulation flow diversion.