Abstract 042: Bow‐hunter's syndrome as an under‐recognized cause of recurrent strokes.

Introduction Rotational occlusion of the vertebral artery, known as Bow Hunter's Syndrome, is a rare but recognized cause of transient neurological symptoms due to dynamic vascular compression during head rotation. While typically associated with positional vertigo or dizziness, it can occasionally lead to vertebrobasilar ischemia and infarction. We present 2 unique cases of recurrent posterior circulation strokes due to compression of the same vertebral artery segment, highlighting the diagnostic importance of dynamic vascular imaging. Case Description: Case 1 A female in her 50s with ADHD, chronic migraines, and cervical spine pathology (status post C3‐T2 posterior fusion and C4‐C7 anterior discectomy) presented with sudden‐onset headache, blurry vision, and dizziness. CTA showed occlusion of the right vertebral artery at C3‐C4 with distal reconstitution, initially interpreted as chronic. MRI revealed bilateral cerebellar infarcts, right > left. RCVS was considered given Vyvanse use, but DSA showed no vasospasm, and the artery had spontaneously recanalized. Further workup revealed a PFO and positive JAK2 mutation. She underwent PFO closure and was discharged on aspirin. Six months later, she re‐presented with left facial droop, left‐sided weakness, and right gaze preference. She received TNK and was admitted. MRI showed multifocal infarcts in the right > left cerebellum, right thalamus, and midbrain. MRA showed recanalization of the right vertebral artery with features suggestive of intramural hematoma consistent with dissection. Repeat DSA with head maneuvers demonstrated dynamic, flow‐limiting stenosis of the right V3 segment, worsened with leftward and upward head positioning. Imaging identified a chronic odontoid fracture with posterior displacement. Neurosurgery deferred intervention, opting for follow‐up after healing of the dissection. The patient was managed conservatively with dual antiplatelet therapy, neck bracing, and avoidance of provocative neck movements. Case 2 A female in her 70s with hyperlipidemia, hypothyroidism, and diabetes mellitus established care in 2023. She reported episodic dizziness since a presumed TIA in 2021. In 2022, she had an acute left cerebellar and occipital infarct, plus chronic infarcts in the left PICA territory and anterior circulation. Imaging revealed a hypoplastic left vertebral artery with compression at the V2 segment. A loop recorder remained unremarkable. In July 2024, she developed new subacute bilateral occipital infarcts. CTA showed persistent occlusion of the left V3 segment. Given recurrent strokes without cardioembolic source, antiplatelet therapy was switched to anticoagulation. Follow‐up CTA after two months showed spontaneous recanalization, raising concern for intermittent compression. DSA with head positioning revealed positional occlusion of the left vertebral artery at C3 transverse foramen when the head was neutral or turned left, and reconstitution with the head turned right. She underwent C2‐C5 laminectomy and posterior cervical fusion. Discussion In patients with recurrent posterior strokes and spontaneous vertebral artery recanalization, dissection should be suspected. DSA with provocative maneuvers is critical to identify dynamic compression and delineate the injury mechanism. No consensus on optimal management. Both DAPT and anticoagulation are used, often guided by protocols, patient‐specific factors, and recurrence risk. These cases underscore the importance of recognizing cervical pathology as a precipitant of dynamic vascular injury.