Characterizing nystagmus using a portable eye movement recorder in patients with Meniere's disease and MRI-confirmed endolymphatic hydrops.

OBJECTIVE

Meniere's disease (MD) causes episodic vertigo and fluctuating hearing loss. During attacks, nystagmus may appear either toward (i.e., irritative) or away from (i.e., paralytic) the affected ear, but it is difficult to observe these patterns in real-time. This study captured nystagmus using a portable eye movement recorder (PEMR) at the onset of attacks and analyzed its characteristics in patients with endolymphatic hydrops (EH) confirmed on contrast-enhanced magnetic resonance imaging (CE-MRI).

METHODS

This study enrolled 54 patients with MD diagnosed using the Japan Society for Equilibrium Research criteria. All patients were provided with a PEMR and instructed to record their eye movements immediately after the onset of a vertigo attack and at designated follow-up time points. Patients were grouped into those with endolymphatic hydrops (EH) (certain MD group, CMD) and without EH (definite MD group, DMD) based on CE-MRI findings. Nystagmus was categorized as either irritative or paralytic based on direction.

RESULTS

Based on CE-MRI, 41 out of 54 patients had EH. In the CMD group, 38 patients had nystagmus, including 33 and 5 with irritative and paralytic nystagmus, respectively. In the DMD group, 10 patients had nystagmus, including 2 and 8 with irritative and paralytic nystagmus, respectively. The distribution of nystagmus types differed significantly between the groups (χ² = 14.69, p = 0.00013). Reversal of nystagmus direction over 24 h tended to be more frequent in the CMD versus DMD group, although the difference was not significant (15 vs. 2 cases, χ² = 1.313, p = 0.251). No significant association was found between the direction or directional change of nystagmus and the localization of EH (vestibular, cochlear, or both) or the laterality of EH (unilateral or bilateral).

CONCLUSION

PEMR enabled the real-time recording and characterization of nystagmus during vertigo attacks. Irritative nystagmus was significantly more common among patients with EH versus those without EH, suggesting that irritative nystagmus reflects active hydropic stimulation of the vestibular apparatus. In contrast, paralytic nystagmus, which was more frequently observed in patients without EH, may indicate relative vestibular hypofunction rather than acute hydropic excitation.