Expert Note Case 1.

Suddenly Dizzy

This patient had a brainstem TIA most likely produced by a cardiac embolus that initially lodged in one vertebral artery and then broke up.  The TIA lasted approximately an hour before the deficits began to clear. Like many patients with brainstem ischemia, he experienced problems related to malfunction of the vestibular system. Vertigo can have many causes, but the combination of vertigo and dysarthria suggests brainstem or cerebellar involvement.

Question

Why does atrial fibrillation increase the risk of TIA or stroke?

Answer

Ineffective contraction of the atrial muscle increases the likelihood that thrombus will form in the atrium. This is a potential source of emboli, which can travel to the brain producing a TIA, like this patient had, or a stroke.