Factors associated with spontaneous nystagmus changes in acute Ménière's disease.

BACKGROUND

Neuro-otological factors that influence changes in spontaneous nystagmus (SN) during vertigo attacks in Ménière's disease (MD) remain unclear.

OBJECTIVE

To identify neuro-otological factors that might influence the initial direction of SN and the directional change of SN.

METHODS

A prospective, observational study of 22 patients with definite MD to evaluate the initial direction and directional change of SN during vertigo attacks, endolymphatic hydrops (EH) volume, and the function of horizontal semicircular canal and hearing levels.

RESULTS

SN consistently began as irritative in 17 of 22 cases, and 9 of 17 cases showed a definite change in direction after onset. SN consistently began as paralytic in 5 of 22 cases, and 3 of 5 cases showed a definite change in direction after onset. Subjects in the irritative initial SN group had less severe degrees of hearing loss, smaller cochlear and vestibular EH volume than the paralytic initial SN group (P = 0.017, < 0.001, and 0.009, respectively). Subjects in the SN direction change group had significantly smaller maximum slow phase velocity, percentage of caloric weakness and canal paresis than the no SN direction change group (P = 0.001, 0.006, and 0.001, respectively). Simple logistic regression analysis showed that smaller EH volume was significantly associated with initial irritative SN (OR = 0.867, 95% CI 0.762-0.988, P = 0.032) and that the degree of canal paresis was negatively associated with the presence of directional change of SN (OR = 0.022, 95% CI 0.002-0.289, P = 0.004).

CONCLUSIONS

The morphology of EH and canal paresis may independently affect the characteristics of SN in patients with MD.