Syncope Induced by Dynamic Head and Shoulder Motion in the Setting of Left Subclavian Stenosis.

Introduction: Dynamic vertebral artery insufficiency is a rare vascular phenomenon characterized by insufficient flow of the posterior cerebral circulation induced by dynamic motion of the head. Prior case reports have been limited to vertebral artery occlusion by cervical osteophytes or other structural impingements.

Case report: In this case report, we discuss the unusual case of a 61-year-old female with a history of vertigo, diplopia, nystagmus, and left subclavian stenosis admitted to the hospital for syncope elicited by a left head turn and left shoulder raise. Transcranial Doppler (TCD) ultrasound and angiography showed evidence of dynamic vertebrobasilar insufficiency elicited by a left-head turn. Percutaneous stenting of the left subclavian artery led to the resumption of normal vessel flow as assessed by TCD and the resolution of the patient's symptoms.

Conclusions: This case highlights an unusual cause of dynamic vertebrobasilar insufficiency induced by head turn and/or left shoulder raise due to subclavian stenosis, diagnosed by TCD and angiography, and successfully treated with subclavian artery stenting.