Rotational vertebral artery occlusion secondary to completely extraosseous vertebral artery.

Rotational vertebral artery (VA) occlusion is a possible cause of reduced blood flow through the posterior circulation of the brain due to compression of the VA on head turning when blood flow from the contralateral VA is compromised. When compression occurs in the V2 segment of the VA, it is usually due to compression from the longus colli muscle or cervical osteophytes. We present a unique case of a patient with a completely extraosseous course of the V2 segment of her dominant right VA that resulted in symptomatic rotational VA occlusion.