Vertebrobasilar Artery Anomaly Presenting With Transient Bow Hunter's Syndrome

Vertebrobasilar artery anomaly can present with transient Bow Hunter's syndrome. A 37-year-old woman presented with a 1-year history of frequent fainting, dizziness and palpitations when turning her head to the right. Her physical examination showed no abnormalities except that the right Dix-Hallpike test, supine to head-lateral test and squat to stand test transiently induced subjective symptoms but not nystagmus. Time-of-flight magnetic resonance angiography revealed the following central vascular anomalies: (1) vertebrobasilar artery anomaly; (2) hypoplasia of the bilateral posterior communicating arteries; (3) hypoplasia of the posterior inferior cerebellar arteries; and (4) stenosis of the bilateral intracranial vertebral arteries. Diffusion weighted magnetic resonance imaging showed hyperintensity of the left-side midbrain and left-side vermis. One month after antiplatelet therapy with aspirin and recommended changes in head positioning, transient Bow Hunter's syndrome subsided. She had no repeat of symptoms over the following 1 year.