Intracranial blood flow velocities and CO2 reactivity in diagnosing migraine-related dizziness.

OBJECTIVE: Migraine-related dizziness can present with or without headache, often making diagnosis difficult. Flow velocity and CO 2 reactivity testing using transcranial Doppler (TCD) measurement of intracranial blood flow has been described as abnormal in patients with classic or common migraine. This study sought to determine the utility, if any, of this noninvasive technique in the diagnosis of migraine-related dizziness. STUDY DESIGN AND SETTING: A prospective, controlled study in academic neurotology and neurology practices was conducted. Nine patients with migraine-related dizziness and 10 patients with no history of migraine or dizziness were tested with transcranial Doppler ultrasound in a blinded fashion. RESULTS: No statistically significant differences in intracranial blood flow velocities or in cerebrovascular reactivity to hypocapnia were found between patients and controls. CONCLUSIONS: Assessment of intracranial blood flow velocity and CO 2 reactivity using TCD does not help in the diagnosis of migraine-related dizziness. SIGNIFICANCE: A reliable objective test for the diagnosis of migraine-related dizziness remains elusive, and the diagnosis of this patient group continues to be suboptimal.