The limited value of the glycerol test in Menière's disease

Contrast-Enhanced MRI Combined With the Glycerol Test Reveals the Heterogeneous Dynamics of Endolymphatic Hydrops in Patients With Menière's Disease

BACKGROUND

The sensitivity of endolymphatic hydrops (EH) to the glycerol test varies in patients with Menière's disease (MD).

PURPOSE

To explore the features of EH and its glycerol-induced dynamics in MD.

STUDY TYPE

Case-control study.

POPULATION

Twenty patients with MD (24 affected ears) were included.

FIELD STRENGTH/SEQUENCE

3.0T 3D-FLAIR (fluid-attenuated inversion recovery) MRI and late gadolinium enhancement.

ASSESSMENT

Intratympanic gadolinium-enhanced MRI was performed in the MD-affected ears before and after the glycerol test. The borders of the endolymphatic and total lymphatic space were contoured on the axial MRI slices to evaluate the volume of hydrops in both the cochlear and vestibular regions.

STATISTICAL TESTS

Paired and unpaired t-tests, the Mann-Whitney U-test, linear discriminant analysis, Pearson's correlation, and linear regression.

RESULTS

After glycerol ingestion, vestibular EH decreased in all patients, whereas cochlear EH significantly decreased only in patients with positive glycerol test results (all P < 0.01). At baseline, cochlear EH in the positive result group was greater than in the negative result group (P = 0.007). Unexpectedly, in the positive result group a drastic glycerol-induced dehydrating effect was observed in patients whose pretest cochlear EH ratio was >16% (P = 0.011). Moreover, the dehydrating role of glycerol was positively correlated with the baseline cochlear hydrops level (r = 0.7691, P < 0.001).

DATA CONCLUSION

MRI provides evidence that glycerol administration improves the hearing threshold via dehydrating the EH. In the cochlear region, the baseline level of cochlear EH is a closely related factor for the validity of the glycerol test, whereas EH is consistently dehydrated in the vestibular component.

LEVEL OF EVIDENCE

2 TECHNICAL EFFICACY STAGE: 3 J. Magn. Reson. Imaging 2020;52:1066-1073.

Is dehydration test using isosorbide useful in Meniere's disease?

CONCLUSION

The dehydration test using isosorbide is well tolerated when used to detect endolymphatic hydrops and may also be used to improve the sensitivity of ECoG performed on patients with MD, especially in poor hearing at low-frequency.

OBJECTIVE

This prospective study was to explore the diagnostic utility of a dehydration test, administering oral isosorbide, which has been used to treat Meniere's disease (MD).

METHOD

Electrocochleography (ECoG) and the dehydration test with isosorbide were performed on 32 patients diagnosed with definite diagnosed MD. Isosorbide (120 mL) was orally administered after baseline audiometric testing, and the testing was repeated 3 h later. The dehydration test was considered positive when improvements in hearing thresholds of 10 dB or more were evident at two or more frequencies, or the speech discrimination score increased by 12% or more. An abnormal ECoG finding was defined as an SP/AP (summating potential/action potential) ratio ≥0.4.

RESULTS

The dehydration test using isosorbide was positive in 10 of 32 patients (31.3%). The test was not associated with development of any serious side-effect. Abnormal ECoG findings were noted in 14 of 32 patients (43.8%). When endolymphatic hydrops was defined as an abnormal ECoG or a positive dehydration test, the condition was detected in 21 of 32 patients (65.6%). The positive result in dehydration test was significantly higher in patients with above moderate hearing loss at low-frequency.

Dynamics of pure tone audiometry and DPOAE changes induced by glycerol in Meniere's disease

The purpose of this study is to follow up the dynamics of pure tone threshold and DPOAE amplitude changes induced by glycerol with reference to its activity in the inner ear. Selection was made among 38 patients with Meniere’s disease for those having positive glycerol test. Pure-tone audiometry and DP-gram were performed in four series: as an initial examination before glycerol intake, 1, 2 and 3 h after. Audiometric changes formed distinct biphasal pattern at all frequencies between 250 and 4,000 Hz. The most dynamic pure tone threshold decrease occurred during the first hour. Between the first and second hour after glycerol ingestion there was a phase of no significant hearing changes. Further pure tone threshold decrease went on within the third hour reaching its top. Observing DPOAE changes, the highest DP amplitude growth occurred after the second and the third hour at DP-gram frequencies 2, 3 and 4 kHz. The fastest DP-amplitude increase was registered as well during the first hour after glycerol ingestion. In 11 persons with both audiometry and DPOAE positive glycerol test, parallel dynamics in the course of the glycerol test was observed. Biphasal glycerol test dynamics suggests the possibility of two mechanisms of glycerol activity in the inner ear.

Audiovestibular testing in patients with Meniere's disease

In this article, the present state of the art with respect to audiovestibular testing for Meniere's disease (MD) is reviewed. There is no gold standard for MD diagnosis, and the classic dictum is that even the "best" tests yield positive results in only two-thirds of patients with MD. Still, we advocate the use and further investigation of advanced audiovestibular testing in patients with MD in an attempt to answer the questions that confront any clinician who cares for patients with audiovestibular symptoms.

Oral versus i.v. administration of the glycerol test: side-effects and usefulness

OBJECTIVE

To compare two methods of performing the glycerol test.

MATERIAL AND METHODS

Glycerol was given orally and intravenously to 12 patients suspected of having Ménière's disease.

RESULTS

Glycerol given orally at a dose of 0.51 g/kg produced a change of > 10 mOsm/kg in all 12 patients while glycerol given intravenously at a dose of 0.30 g/kg produced the same change in osmolality in only 1/12 patients. The results of the tests were similar in 10 cases using the Klockhoff criteria and in 8 cases using the Snyder criteria. Positive test results after oral compared to i.v. administration occurred in four and two cases, respectively using the Klockhoff criteria and in six and eight cases, respectively using the Snyder criteria. The amount of discomfort was consistently higher, with one exception, when glycerol was given orally rather than intravenously.

CONCLUSION

The glycerol test using the Snyder criteria probably yields most additional diagnostic information when the patient fulfils the clinical criteria of possible or probable Ménière's disease.

Diagnosis of Meniere's disease: routine and extended tests

Meniere's disease can compromise the quality of life of some patients in a manner so seriously that it can cause social segregation, even from family. Hearing loss, tinnitus, aural pressure, and disturbances in equilibrium added to an emotional instability frequently present in these patients may take them to a progressive state of solitude and depression, marking their lives by personal tragedy and making life a living hell. The clinical picture of Meniere's disease fluctuates, however. Individually, subsidiary examinations become impotent in diagnosing Meniere's disease. To be called Meniere's disease, the cause must be unknown; otherwise it would constitute Meniere's syndrome. Taking all of this into consideration, one would call this an unusual situation, or at least confusing. The lack of an etiologic diagnosis in medicine always creates anxiety for doctors and patients. What is considered to be either a routine or an extended test may change from service to service. The physician does not need to order all tests. What the physician needs is a protocol he or she trusts. Test results can vary, even depending on the moment when they are performed. More important than the number of tests ordered is the strategy by which the tests should be put together at that certain moment. The authors believe that one should have his or her own protocol for diagnosis, always beginning with a detailed history taking being guided by them most of the time. It is the authors' understanding that patients with Meniere's disease should be followed closely by their ear, nose, and throat doctor in episodes of vertigo or fluctuation of their hearing, tinnitus, or aural pressure. Should the patient be experiencing a stable period, a clinical visit along with an audiovestibular workup should be performed at least once a year. By monitoring the course of the disease, clinicians would be able to detect early changes in symptoms and/or test results, giving them the possibility to intervene clinically as early as possible in acute episodes of vestibulocochlear disorganization, protecting the inner ear, and minimizing sequelae from spells of hydrops. The authors believe that only the association of clinical sense and as many subsidiary tests as are useful will lead to a desirable level of certainty in the diagnosis of Meniere's disease, and will allow clinicians to presume bilateral involvement, monitor the development of the disease, intervene in its natural course, and idealize appropriate treatment.

Clinical application of transiently evoked otoacoustic emissions after glycerol administration for diagnosis of sensorineural hearing loss

Pure-tone audiometry and transiently evoked otoacoustic emission (TEOAE) measurements were made before and after glycerol administration in the ears of sensorineural hearing loss with three different clinical entities, i.e. Meniere's disease, cochlear Meniere's disease and unilateral sensorineural hearing loss of unknown cause without hearing fluctuation (SNHLWF). TEOAE was evoked after glycerol administration in several ears of Meniere's disease and cochlear Meniere's disease, in which it was not evoked before glycerol administration. Especially in patients with cochlear Meniere's disease, TEOAE was altered without an accompanying significant change in mean hearing level. The change in TEOAE after glycerol administration indicates that the active motile property of outer hair cells may be affected by endolymphatic hydrops.