A preliminary report on the correlation of vestibular Meniére's disease with electrocochleography and glycerol test

The value of vestibular evoked myogenic potential and electrocochleography in unexplained aural fullness

BACKGROUND

Unexplained aural fullness, after excluding external or middle ear diseases and vertigo, is not easily diagnosed.

AIM

The aim of this study is to determine the vestibular evoked myogenic potential (VEMP) and electrocochleography (ECochG) abnormal rates in patients with unexplained aural fullness, and analyzed the relationship between unexplained aural fullness and endolymphatic hydrops (EH).

MATERIAL AND METHODS

The VEMP and EcochG abnormal rates in 54 patients with unexplained aural fullness and 21 healthy volunteers, and the VEMP and EcochG abnormal rates in the four hearing loss groups were compared. The distribution of abnormal of VEMP and EcochG in age, sex or hearing loss groups were investigated.

RESULTS

The VEMP abnormal rate in patients was greater than that in healthy volunteers (p = .000). The abnormal rate of VEMP was greater than the EcochG in patients (p = .003). The VEMP abnormal rate was greater than the EcochG in patient with low-tone or high-tone hearing loss (p = .008).

CONCLUSION AND SIGNIFICANCE

Abnormal of VEMP in a significant proportion of patients with unexplained aural fullness maybe indicative of EH, and EH was more likely to involve the utricle or saccule in patients with low- or high-tone hearing loss.

Preclinical and clinical studies of unrelieved aural fullness following intratympanic gentamicin injection in patients with intractable Ménière's disease

OBJECTIVE

To clarify whether gentamicin affects vestibular dark cells in guinea pigs and relieves patients of aural fullness with intractable Ménière's disease following intratympanic administration.

MATERIALS AND METHODS

Purified gentamicin-Texas Red (GTTR) was injected intratympanically in guinea pigs that were sacrificed at 1, 3, 7, 14 and 28 days. GTTR uptake was examined in hair cells, and transitional cells and dark cells in vestibular end-organs were examined. Specific attention was paid to its distribution in dark cells under confocal microscopy, and the ultrastructure of dark cells using electron microscopy, following intratympanic injection.

RESULTS

Dark cells in the semicircular canals showed weak GTTR uptake at 1, 3, 7, 14 and 28 days after intratympanic injection, with no significant differences at various time points after injection. However, the adjacent transitional cells demonstrated intense GTTR uptake that was retained for at least 28 days. Ultrastructural studies demonstrated negligible characteristics associated with apoptosis or necrosis in these dark cells. The tight junctions between dark cells showed no signs of disruption at 7 or 28 days after injection.

CONCLUSION

Intratympanic gentamicin has little direct impact on vestibular dark cells.

CLINICAL APPLICATION

A modified low-dose titration intratympanic approach was used in 29 patients with intractable vertigo and the clinical outcomes were followed. Aural fullness following intratympanic gentamicin injection was not relieved based on our subjective scales, demonstrated by no statistically significant difference between preinjection (4.16 ± 3.08) and postinjection (3.58 ± 2.93; p > 0.05) aural fullness scores. Vertigo control was achieved in 88% of patients, with hearing deterioration identified in 16% of patients. Intratympanic gentamicin administration might not lead to relief of aural fullness in patients with intractable vertigo, although it can achieve a high vertigo control rate with some cochleotoxicity.

Postural control and glycerol test in Ménière's disease

Ménière's disease is a clinical disorder, characterized by fluctuating hearing loss, recurrent spontaneous episodic vertigo, tinnitus and aural fullness, which may be defined as the idiopathic syndrome of endolymphatic hydrops. The most important test for diagnosis of Ménière's disease is the glycerol test. This is a simple and rapid method and several authors have confirmed its efficiency for identifying endolymphatic hydrops. This test provides information on the cochlear response to the osmotic changes produced by glycerol in the inner ear, whereas modifications in the vestibular labyrinth are usually not evaluated. The aim of this study was to evaluate the effects of glycerol on postural control during attacks of Ménière's disease, and to correlate this data with data on cochlear function. After the glycerol test, an improvement in postural control was recorded in 70% of patients, with all patients reporting a recovery of vertigo. The impairment of postural control during endolymphatic hydrops could be related to a pressure increase in the labyrinth, which interferes with the normal dynamics of the endolymph, and a rapid functional recovery could occur during an osmotic depletion. Dynamic posturography improves the sensitivity of the glycerol test and may therefore be useful in the diagnosis and staging of Ménière's disease.