Vertebrobasilar insufficiency presenting as isolated positional vertigo or dizziness: a double-blind retrospective cohort study.

OBJECTIVES/HYPOTHESIS: Vertebral artery (VA) stenosis caused mainly by atherosclerosis accounts for up to 20% of posterior circulation strokes. Isolated positional vertigo or dizziness can be the initial presentation symptom. The objective is to compare the presence of isolated positional vertigo or dizziness in patients with evaluation of VA morphology, thrombotic stroke risk factors, and evolution of symptoms with time.

STUDY DESIGN: Double-blind retrospective cohort study.

METHODS: Magnetic resonance angiography reports describing the VAs of 258 patients were reviewed, and 133 were questioned and their hospital charts reviewed for positional vertigo or dizziness. Neurotologic examination was performed on 75 patients. Vestibular testing using electronystagmography was performed on 46 patients. The prevalence of thrombotic stroke factors was evaluated in all patients. Groups were compared using chi-square statistical analysis.

RESULTS: A total of 72 patients with normal VAs (group A) were compared with a group of 61 patients with stenotic or hypoplastic VAs (group B). When stratifying patients for stroke risk factors, 85.7% of group B patients complaining of isolated positional vertigo on the questionnaire with at least three stroke risk factors had a vertebral artery abnormality (P = .026). A hypothesized mechanism is transient ischemic attack of the semicircular canals or vestibular nucleus during rotation and extension of the neck, which compresses a contralateral stenotic VA in patients with bilateral VA abnormalities.

CONCLUSIONS: In patients complaining of isolated positional vertigo or dizziness of unexplained etiology and having at least three thrombotic stroke risk factors, we recommend a vertebrobasilar radiological evaluation for timely treatment accordingly to the results.