Rotational vertebral artery syndrome (Bow Hunter syndrome) initially misdiagnosed as benign paroxysmal positional vertigo: a case report

Rotational vertebral artery syndrome (RVAS), or Bow Hunter syndrome, is an uncommon cause of vertebrobasilar insufficiency mimicking benign paroxysmal positional vertigo (BPPV). We describe a 66-year-old woman with recurrent vertigo that consistently occurred during leftward head rotation. Despite previous BPPV treatment, symptoms persisted. Videonystagmography during the supine head-roll test revealed an atypical multiphasic positional nystagmus, characterized by an initial down-beating followed by prolonged right-beating nystagmus. Positional computed tomography angiography demonstrated severe focal narrowing of the right vertebral artery at the C1-C2 level during leftward rotation, combined with a hypoplastic left V4 segment. Diagnosed with RVAS, she was first treated conservatively by avoiding provocative head rotation, with surgical stabilization considered due to persistent symptoms. This case underscores that RVAS must be included in the differential diagnosis of positional vertigo, particularly when symptoms are specifically rotation-induced or nystagmus patterns are atypical. Vascular imaging in the provocative head position is essential for an accurate diagnosis.