Cerebral autoregulation in patients with orthostatic hypotension.

The present study was conducted to determine the relationship between autonomic nervous function and cerebral autoregulation in 17 patients with vertigo or dizziness. Autonomic nervous function was examined by measuring systolic blood pressure response and dynamic electrocardiogram R-peak to R-peak response upon standing up. Regional cerebral autoregulation was examined by comparing cerebral blood flow in both supine and standing positions with single photon emission computed tomography. Moreover, the relationship of each of these three measures to postural provocation of symptoms was studied. The findings indicated that autonomic nervous dysfunction does not influence cerebral autoregulation, but autonomic nervous dysfunction was related to postural provocation of symptoms. This might indicate that impaired autoregulation in the brain stem or the peripheral vestibule, which could not be detected by the single photon emission computed tomography, played a role in inducing vertigo or dizziness in patients with orthostatic hypotension.