A non-invasive, objective test of endolymphatic hydrops

Lack of Diagnostic Value of High-Pass Noise Masking of Auditory Brainstem Responses in Ménière's Disease

INTRODUCTION

Different electrophysiologic tests were developed to ascertain or detect endolymphatic hydrops (ELH). Recently, Cochlear Hydrops Analysis Masking Procedure (CHAMP), a new auditory brainstem response (ABR) technique, proved to be able to separate normal controls from definite Ménière's disease (MD) with 100% sensitivity and 100% specificity.

OBJECTIVE

To evaluate the applicability and diagnostic value of CHAMP in a series of MD and non-MD patients with otovestibular complaints.

STUDY DESIGN

An observational retrospective study.

SETTING

Tertiary referral centre.

PATIENTS

Forty-five patients, of which 28 patients had MD.

INTERVENTIONS

Cochlear Hydrops Analysis Masking Procedure test was conducted, and audiometric data and clinical information were collected. All responses were blindly evaluated and divided into three categories: (1) test suggestive for cochlear/ELH, (2) test within normal ranges, and (3) test not interpretable.

MAIN OUTCOME MEASURES

Sensitivity and specificity, evaluation of diagnostic value.

RESULTS

Forty-nine percent of the tests were found to be not interpretable. Of the remaining responses, 13 tests were suggestive for ELH, and 16 tests were within normal ranges. This yields a sensitivity of 31% and a specificity of 28%. There was no significant difference between the mean latency difference (mean [SD]) for Wave V of the MD group (0.43 ms [0.37]) and the non-MD group (0.65 ms [0.44]). Using logistic regression analysis, we found that CHAMP test did not contribute to the ability to discriminate between hydropic and nonhydropic ears.

CONCLUSION

In contrast to studies assessing CHAMP performance in Ménière patients and normal controls, the present study revealed this new test offers no discriminative value in differentiating Ménière's from non-MD subjects with otovestibular symptoms.

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.

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.

Endolymphatic Hydrops in Asymptomatic Ears in Unilateral M??ni??re???s Disease

OBJECTIVES/HYPOTHESIS

The aim of our study was the objective assessment of endolymphatic hydrops in asymptomatic ears in unilateral Ménière's disease with a noninvasive electrophysiological test and investigation of significant clinical signs. The null hypothesis was that there would be no signs of endolymphatic hydrops in the asymptomatic ear.

STUDY DESIGN

Prospective study using the traveling wave velocity test for endolymphatic hydrops.

METHODS

The traveling wave velocity test was used in conjunction with standard audiological tests to investigate both ears of 181 Ménière's patients attending the Medical Research Council Institute of Hearing Research in Southampton, United Kingdom. The test uses derived auditory brainstem responses to estimate the velocity of the cochlear traveling wave that is altered in endolymphatic hydrops. Ménière's disease was assessed using Arenberg's five staging criteria. Significant correlations were evaluated using standard statistical methods.

RESULTS

Of 100 patients with clinically unilateral Ménière's disease, 27% showed evidence of endolymphatic hydrops in their asymptomatic ear. There was a significant correlation between signs of hydrops and the mean air-conduction threshold at 500 Hz.

CONCLUSIONS

We recommend that a full assessment of incipient disease in the asymptomatic ear in unilateral Ménière's disease should be undertaken before offering any treatment options to patients. Any suspicion of early disease in the asymptomatic ear in unilateral Ménière's disease should lead to full electrophysiological assessment to assess the evidence of endolymphatic hydrops in that ear.

Otological evaluation of newborns who failed otoacoustic emission screening

Early identification of congenital hearing loss and early rehabilitation is extremely important. Otoacoustic emissions (OAE) are an efficient tool for hearing screening. Previous studies using click evoked otoacoustic emissions (CEOAEs) for newborn hearing screening resulted in approximately 70% pass rate, reflecting intact hearing. The aim of our study was to perform a detailed otological evaluation of newborns who failed OAE screening, using otoscopy, tympanometry and ABR. CEOAEs were recorded from 257 newborns prior to their release from the hospital. Those babies who did not pass the CEOAE were examined by DPOAE, otoscopy, tympanometry and ABR, if needed. 73% of all the newborns had CEOAE in both ears. 20% had CEOAE in only one ear. When the test was administered again three days postpartum, the CEOAE pass rate increased; 98% passed in at least one ear. Most of the newborns (84%) who failed had an obstruction of the external ear canal (collapsed ear canal or debris). There was a good correlation between the otoscopy and the tympanometry. Based on the above results, a newborn hearing screening protocol was introduced.

Meniere's Syndrome

The primary goals of treatment in Meniere's syndrome are to control attacks of vertigo and, if possible, to arrest the progression of hearing loss. Initial treatment consists of rigid dietary sodium restriction, possibly with the addition of a thiazide diuretic. If disabling attacks of vertigo persist despite sodium restriction, surgical intervention should be considered. Endolymphatic shunting is an option for patients who desire a less invasive surgical remedy, but recurrence of vertigo occurs in about 40% of cases. Vestibular nerve ablative surgery is the definitive surgical treatment for patients with intractable attacks of vertigo who still have useful hearing on the affected side. Labyrinthectomy is a surgical option when there is no serviceable hearing in the damaged ear. Intra-aural gentamicin instillation is an option in carefully selected cases.

Medical Management of Meniere's Disease

The management of Meniere's disease often creates a formidable clinical challenge. Drugs may be helpful in treating the acute attacks of vertigo, and in more long-term management. These remedies are largely symptomatic and there are few properly controlled studies of their efficacy. A critical overview of the scientific and clinical basis for these various pharmacological agents is discussed.

The pharmacological treatment of Menière's disease

The management of Menière's disease often provides a formidable clinical challenge largely because its precise aetiology is unknown. There is no known 'cure' once the condition is established, but drugs may be helpful in treating both the acute attacks of vertigo, and in more long-term management, particularly in the earlier fluctuant stage. These remedies are largely symptomatic and there are few if any properly controlled studies of their efficacy. Suppressant drugs may act centrally at neurotransmitter sites, or peripherally on the labyrinth. Conventional diuretics and osmotically acting agents have been given to reduce the endolymph fluid volume. Histamine analogues directly reduce inner ear fluid pressure mainly by increasing the cochlear blood flow, and are probably the treatment of choice. Otovestibulotoxic drugs given systemically to cause chemical labyrinthine ablation are frequently effective in abolishing attacks of vertigo but often resulted in disabling oscillopsia and ataxia. There is now evidence that local administration by intratympanic injection may well be more efficacious resulting in selective partial end organ ablation. To date innovative immune modifying regimes have not proved helpful.

Difficulties experienced in implementing the ABR travelling wave velocity (Delta V) technique with two commercially available systems

The ABR Delta V technique involves measuring the difference in latency of the wave V click-evoked ABR in the presence of ipsilateral high-pass noise filtered at 1.42 kHz and at 5.68 kHz. It has been reported that a small latency difference between the two conditions is suggestive of Ménière's disease. The aim of this study was to establish normative data for two commercially available systems. The latency differences obtained in the present study are considerably smaller than those previously reported in the literature. Other problems, including difficulty in identifying wave V in the masked conditions, prevent us from currently using this test technique. There are a number of technical problems which may account for some of the problems experienced when implementing the Delta V technique with commercial equipment and there is at least the possibility that the problems may be overcome in the future.

External- and middle-ear factors affecting evoked otoacoustic emissions in neonates

Babies without any of the known risk factors for hearing impairment were taken from normal maternity wards and tested daily for 3 days post-partum. Tympanometric and evoked otoacoustic emission data were obtained from 121 babies. Middle-ear pressure and middle-ear compliance values were obtained with a Grason Stadler Middle-Ear Analyser (GSI-33) using a 1000-Hz probe tone. All babies had their evoked emissions measured on the Programmable Otoacoustic Emissions Measurement System (POEMS) equipment. The middle-ear compliance, the proportion of normally shaped tympanograms, the middle-ear pressure and the proportion passing EOAE testing all improved over the 3 days. However, the statistically significant factors affecting the pass rate appeared to be only the middle-ear pressure (for a small number of babies) and the degree of obstruction of the external ear canal. Whilst both these factors play a part in determining emission pass/fail rates they do not fully account for the observed changes in pass rate. There are developmental and other mechanisms which must contribute to the increase in pass rate as the baby matures.