A rare case of Bow Hunter’s syndrome: intermittent vision loss as a result of cervical uncovertebral arthrosis

Background Bow Hunter’s Syndrome (BHS) is caused by vertebrobasilar insufficiency due to mechanical occlusion during head rotation. This case of BHS highlights a rare presentation of intermittent left-sided occlusion of the vertebral artery caused by cervical degenerative disease in a patient with a with an anomaly of the posterior circulation of the circle of Willis. The article depicts how neurological examination and imaging modalities could help clinicians in their diagnostic approach in the context of an unusual presentation of BHS. We present this case to outline the clinical process that led from first presentation to diagnosis, and treatment of the patients’ disease. Case presentation The sixty-year-old patient initially presented with headaches, and ultimately reported progressive transient symptoms right-sided homonymous hemianopia, vertigo and tinnitus upon left-sided rotation of the head. Digital subtraction angiography (DSA) revealed mechanical occlusion of the left vertebral artery as a result of uncovertebral arthrosis at the C4-C5 level when rotating the head to the left. The right vertebral artery was hypoplastic with a PICA ending and ipsilateral fetal PCOM. Surgical decompression of C4-C5 with anterior discectomy and fusion was performed. Conclusions We emphasize that computed tomography angiography (CTA) could reveal underlying vascular anatomical variations predisposing to the symptomology of BHS. DSA is necessary to make the definitive diagnosis of BHS because of its dynamic nature. Removal of spondylotic spurring and decompression of the vertebral artery completely resolved the patients’ signs and symptoms.