Does acute dysfunction of the saccular afferents affect the subjective visual horizontal in patients with vestibular neurolabyrinthitis?

Conclusions: The results of a series of studies including the present study suggest that acute dysfunction of the utricular afferents accompanied by acute dysfunction of the saccular afferents might require more time for the compensation of the otolith-ocular system than acute utricular dysfunction that was not accompanied by acute saccular dysfunction. Perhaps the inputs from the saccule also have some contribution to the subjective visual horizontal (SVH).

Objective: To clarify if acute dysfunction of the saccular afferents affects the SVH.

Patients and methods: Twenty-six patients with vestibular neurolabyrinthitis (20 men and 6 women, 23-67 years of age) were enrolled in this study. They had undergone measurement of SVH at the early stage (within 1 month after the attack) and 3 months after the attack. For the measurement of SVH, we used a device that has a red bar of light-emitting diodes with a head fixing frame. They also underwent vestibular evoked myogenic potentials (VEMPs) testing. For the recording of VEMPs, 95 dBnHL clicks were presented.

Results: Patients with vestibular neurolabyrinthitis showed deviation of SVH toward the affected side-down at the early stage after the attack, irrespective of VEMP results. However, 3 months after the attack SVH was significantly more deviated toward the affected side-down in patients who showed absent VEMPs than those with VEMPs present (p<0.01 Mann-Whitney U test).