POSTERIOR CIRCULATION STROKE PRESENTING AS A BOW HUNTER’S SYNDROME:WHEN A DYNAMIC APPROACH IS NEEDED

Background and Aims: Posterior circulation stroke cause detection represents a diagnostic challenge in emergency. Vertebral artery (VA) dissection is a frequent cause in young patients. Methods: We describe two cases of posterior circulation stroke, both related to VA dissection, in which ultrasound evaluation with dynamic study, was fundamental for diagnosis. Results: Case 1: 38 yrs old man admitted at the ER for acute onset of severe neck pain, headache, objective vertigo, nausea. Cerebral MRI showed left cerebellum ischemic lesion. Ultrasound revealed right V2 vertebral artery dissection with intramural hematoma and distal poststenotic flow, that was less identifiable with angioTC. Case 2: 44 yrs old man admitted at the ER for neck pain, vertigo and left limb paresthesias after head rotation while parking the car in reverse gear. Cerebral MRI showed a left cerebellum ischemic lesion. Both MR and CT angiographies failed to identify vertebral artery dissection. At ultrasound, flow stop in the left VA, only during right neck rotation, was detected while performing transcranial imaging through subnucal approach. Angio-CTwith right head rotation confirmed the vertebral artery occlusion at C1-C2 level, without disc herniation or osteophytes. This findings support a Rotational Vertebral Artery Occlusion syndrome with ischemic stroke (Bow Hunter’s stroke), probably due to left VA dissection at V3. Conclusions: Accurate ultrasound evaluation of posterior circulation, eventually with dynamic manouvers, have to be considered in the diagnostic work-up of posterior circulation strokes. Bow Hunter’s syndrome is a rare cause of vertebrobasilar insufficiency and could be underdiagnosed in clinical practice.