Variability in the perilymphatic diffusion of gadolinium does not predict the outcome of intratympanic gentamicin in patients with Ménière's disease

Clinical Practice Guideline: Ménière's Disease

OBJECTIVE

Ménière's disease (MD) is a clinical condition defined by spontaneous vertigo attacks (each lasting 20 minutes to 12 hours) with documented low- to midfrequency sensorineural hearing loss in the affected ear before, during, or after one of the episodes of vertigo. It also presents with fluctuating aural symptoms (hearing loss, tinnitus, or ear fullness) in the affected ear. The underlying etiology of MD is not completely clear, yet it has been associated with inner ear fluid (endolymph) volume increases, culminating in episodic ear symptoms (vertigo, fluctuating hearing loss, tinnitus, and aural fullness). Physical examination findings are often unremarkable, and audiometric testing may or may not show low- to midfrequency sensorineural hearing loss. Conventional imaging, if performed, is also typically normal. The goals of MD treatment are to prevent or reduce vertigo severity and frequency; relieve or prevent hearing loss, tinnitus, and aural fullness; and improve quality of life. Treatment approaches to MD are many and typically include modifications of lifestyle factors (eg, diet) and medical, surgical, or a combination of therapies.

PURPOSE

The primary purpose of this clinical practice guideline is to improve the quality of the diagnostic workup and treatment outcomes of MD. To achieve this purpose, the goals of this guideline are to use the best available published scientific and/or clinical evidence to enhance diagnostic accuracy and appropriate therapeutic interventions (medical and surgical) while reducing unindicated diagnostic testing and/or imaging.

The Technical and Clinical Features of 3D-FLAIR in Neuroimaging

In clinical MR neuroimaging, 3D fluid-attenuated inversion recovery (3D-FLAIR) with a variable-flip-angle turbo spin echo sequence is becoming popular. There are more than 100 reports regarding 3D-FLAIR in the PubMed database. In this article, the technical and clinical features of 3D-FLAIR for neuroimaging are reviewed and summarized. 3D-FLAIR allows thinner slices with multi-planar reformation capability, a higher flow sensitivity, high sensitivity to subtle T1 changes in fluid, images without cerebrospinal fluid (CSF) inflow artifacts, and a 3D dataset compatible with computer-aided analysis. In addition, 3D-FLAIR can be obtained within a clinically reasonable scan time. It is important for radiologists to be familiar with the features of 3D-FLAIR and to provide useful information for patients.

Reappraisal of the glycerol test in patients with suspected Menière's disease

BACKGROUND

Recent advances in magnetic resonance imaging make it possible to visualize the presumed pathophysiologic correlate of Menière's disease: endolymphatic hydrops. As traditional diagnostic tests can provide only indirect evidence, they are hardly competitive in this respect and need to be rethought. This is done here for the glycerol test.

METHODS

The data of a previous retrospective analysis of the glycerol test in patients with suspected Menière's disease are reinterpreted using a simple model. The mean threshold reduction (MTR) in the frequency range from 125 to 1500 Hz (calculated from audiograms obtained immediately before and four hours after the glycerol intake) is used as the test statistic. The proposed model explains the frequency distribution of the observed MTR by the convolution of a Gaussian probability density function (representing measurement errors) with a template representing the frequency distribution of the true MTR. The latter is defined in terms of two adjustable parameters. After fitting the model to the data, the performance of the test is evaluated using receiver operating characteristic (ROC) analysis.

RESULTS

The cumulative frequency distribution of the observed MTR can be explained almost perfectly by the model. According to the ROC analysis performed, the capability of the currently used audiometric procedure to detect a glycerol-induced threshold reduction corresponds to a diagnostic test of rather high accuracy (area under the ROC curve greater than 0.9). Simulations show that methodological improvements could further enhance the performance.

CONCLUSIONS

Owing to their ability to reveal functional aspects without an obvious morphological correlate, traditional test for Menière's disease could be decisive for defining the stage of the disease. A distinctive feature of the glycerol test is that it is capable of determining, with high accuracy, whether the pathophysiologic condition of the inner ear is partially reversible. Prospectively, this could help to estimate the chances of specific therapies.

Visualization of endolymphatic hydrops with MR imaging in patients with Ménière's disease and related pathologies: current status of its methods and clinical significance

Ménière's disease is an inner ear disorder characterized by vertigo attacks, fluctuating low-frequency hearing loss, ear fullness, and tinnitus. Endolymphatic hydrops has long been thought to be the pathological basis for Ménière's disease. Some patients have inner ear symptoms that do not match the diagnostic guidelines for Ménière's disease, and these are also thought to be related to endolymphatic hydrops. The diagnosis of endolymphatic hydrops is usually made based on clinical symptoms with some assistance from otological functional tests. Recently, the objective diagnosis of endolymphatic hydrops by MR imaging has become possible and many research results have been reported regarding the imaging methods, evaluation methods, the correlation between imaging results and functional otological tests and the correlation between imaging findings and clinical symptoms. In this article we summarize the development of current imaging methods, evaluation techniques and clinical reports based on a review of the literature. We also attempt to characterize the current significance and future directions of MR imaging of endolymphatic hydrops.

Magnetic resonance imaging of the inner ear after both intratympanic and intravenous gadolinium injections

CONCLUSION

Using magnetic resonance imaging (MRI), endolymphatic hydrops could be visualized on both sides after intratympanic (IT) injection of gadolinium contrast agents (Gd) in one symptomatic ear and subsequent intravenous (IV) Gd injection. The MRI revealed a difference of intracochlear Gd distribution between the IT injection side and the contralateral IV side.

OBJECTIVES

Although the IT method allows greater enhancement of the perilymph, many patients feel reluctance in receiving the IT injection in asymptomatic ears. We attempted to evaluate endolymphatic space size on both sides without the IT injection in asymptomatic ears.

METHODS

In 10 patients with Meniere's disease, MRI was performed 24 h after the IT Gd injection in one symptomatic ear and 4 h after the IV Gd injection. The signal intensity of Gd in the basal and apical turns of the cochlea was evaluated.

RESULTS

The signal intensity in the scala tympani of the basal turn of the cochlea was 1.70 ± 0.60 on the IT + IV side and 0.42 ± 0.10 on the contralateral (IV) side. Gd was distributed uniformly in the scala tympani in the cochlea on the IV side, whereas it was strongly localized in the basal turn on the IT + IV side.

Developments in delivery of medications for inner ear disease

INTRODUCTION

Hearing loss, tinnitus and balance disturbance represent common diseases that have tremendous impact on quality of life. Despite the high incidence of inner ear disease in the general population, there are currently no dedicated pharmacologic interventions available to treat these problems.

AREAS COVERED

This review will focus on how treatment of inner ear disease is moving toward local delivery at the end organ level. The authors will discuss current practice, ongoing clinical trials and potential areas of development such as hair cell regeneration and neurotrophin therapy.

EXPERT OPINION

The inner ear is accessible through the middle ear via the oval and round windows allowing diffusion of drugs into the perilymph. With a better understanding of the physiology of the inner ear and the underlying molecular causes of inner ear disease there is great potential for the development of novel therapeutics that can be locally administered. At present, there is a rapid development of drugs to target diverse inner ear diseases that cause sensorineural hearing loss and balance dysfunction.