Spectrum of autonomic dysfunction in orthostatic dizziness.

Objective: To investigate the frequency and detailed spectrum of autonomic dysfunction in patients with orthostatic dizziness (OD).

Methods: Over 20 months, 217 consecutive patients with OD as a presenting symptom of orthostatic intolerance were enrolled. The distribution and severity of autonomic dysfunction were measured by the composite autonomic severity score (CASS), which was derived from a standard autonomic function test including Finapres for recording of the beat-to-beat blood pressure. Sympathetic indexes (SIs) were calculated from the Valsalva maneuver (VM).

Results: Approximately 83% of patients showed at least one abnormal autonomic testing result. We classified OD into 11 groups according to the patterns of autonomic dysfunctions. The most common pattern was generalized autonomic failure of sympathetic adrenergic and parasympathetic cardiovagal functions (n=60). Patients with delayed OH had larger BP increases during late phase II of the VM (p=0.04), showed greater phase IV overshoot (p=0.04), and had a smaller pressure recovery time increase (p=0.02) than patients with classic OH. Each SI showed the strongest correlation with the CASS adrenergic subscores.

Conclusions: OD can present with a board spectrum of autonomic dysfunctions.

Significance: This investigation could be useful in understanding the pattern and mechanism of autonomic dysfunction associated with OD.