Three-Hertz postural oscillation in patients with brain stem or cerebellar lesions.

Postural instability was quantitatively studied in patients with lesions in the 1) pontine tegmentum, 2) deep cerebellar nuclei, or 3) cerebellar hemisphere. As compared to controls, patients with each lesion demonstrated a characteristic 3 Hertz (Hz) body oscillation. Cross-correlation functions revealed a strong correlation between the body sway and activities in the lower leg muscles. Based on these findings, we conclude that the 3 Hz body oscillation may be the result of any disturbance in the loop of long-latency reflexes mediated by the cerebellum.