[Low frequency rotational responses in bilateral caloric weakness patients].
Comparative analysis of low frequency (0.01-0.64Hz) sinusoidal harmonic acceleration (SHA) responses of 50 patients with bilateral caloric weakness (summed slowphase velocities SSVs < or = 20 degrees/s) revealed that SHA stimuli reflected not only the existence of bilateral caloric weakness but also the impairment degree. The phase values of the patients with SSVs < or = 10 degrees/s were greater than that of the patients with SSVs > 10 degrees/s and the normals, and the gain values of the patients with SSVs < or = 10 degrees/s were smaller than those with SSVs > 10 degrees/s and the normals. The patients with SSVs < or = 10 degrees/s showed more severe impairments than those with SSVs > 10 degrees/s. However, even in the frequencies having higher impairment identifying rate, such as 0.01 and 0.02 Hz, about 30 percent of the patients with SSVs < or = 10 degrees/s revealed rotational responses that were within normal limits. These findings indicated that even marked bilateral caloric reduction is in sufficient to diagnose vestibular loss.
Yin
S
S
Jinzhou Medical College.
Sun
L
L
Li
D
D
D002150:Caloric Tests / Q000379:methods*; D004584:Electronystagmography; D006801:Humans; D014717:Vertigo / Q000503:physiopathology*; D014722:Vestibule, Labyrinth / Q000503:physiopathology*