Bow hunter’s syndrome presenting with embolism in an older patient treated with C1–2 posterior fixation using intraoperative digital subtraction angiography: illustrative case

BACKGROUND: Bow hunter's syndrome (BHS) is a rare cause of vertebrobasilar insufficiency (VBI) or artery-to-artery embolism resulting from vertebral artery (VA) occlusion during head rotation due to cervical instability. VBI predominates, whereas embolic BHS is rare. OBSERVATIONS: A 77-year-old man presented with recurrent posterior circulation ischemic strokes. A cardiac embolism was initially suspected, and a brief episode of paroxysmal atrial fibrillation (AF) was detected via an insertable cardiac monitor. However, wall irregularity was noted in the left VA at the C1-2 level, together with atlantoaxial subluxation associated with os odontoideum. Dynamic digital subtraction angiography (DSA) with head rotation demonstrated left VA occlusion at C1-2 in the right rotational flexion position, with distal flow maintained via collateral circulation. The patient was diagnosed with a cerebral embolism due to BHS. Given the recurrent strokes, atlantoaxial fixation was performed, and intraoperative DSA confirmed a cervical alignment preserving VA flow. No recurrence occurred during postoperative follow-up. LESSONS: BHS should be considered in the differential diagnosis of infarction confined to the posterior circulation, even in older patients with AF. C1-2 posterior fixation effectively prevents recurrent infarction, and intraoperative DSA is useful for determining a cervical alignment that preserves VA blood flow. https://thejns.org/doi/10.3171/CASE26750.