What is the Current and Potential Future Role of Imaging in the Investigation of Patients with Suspected Meniere's Disease?

Abstract

Meniere's disease (MD) represents a diagnostic challenge. It's symptoms of episodic vertigo, hearing loss, tinnitus, and a sense of aural fullness share overlap with multiple other conditions. It remains a diagnosis of exclusion, with imaging only used to rule out other pathologies, notably acoustic neuroma. Technological advance has brought increased resolution to the inner ear. In the future it is likely that MD will become a radiological diagnosis.Keywords: Hydrops; Imaging; Dizziness; Vertigo Meniere's DiseaseCurrently, the primary role of imaging in the investigation of suspected MD is to exclude other pathology. MD can present with asymmetrical hearing loss. In such circumstances it is usual to perform an MRI to exclude an acoustic neuroma or other forms of cerebellopontine angle tumour. The guidance on precisely when a patient requires an MRI to investigate asymmetrical SNHL is less clear. A comparison of eight screening protocols found that the best compromise between sensitivity and specificity was achieved by a criterion requiring either a 20 dB asymmetry at two neighbouring frequencies, or 15 dB asymmetry at two frequencies between 2 and 8 kHz [1]. Similarly, in the vertiginous patient an MRI can be used to exclude, space occupying lesions such as endolymphatic sac tumours, cholesteatoma fistulas, and brain metastasis [2].In the acute setting, the symptoms of a Meniere's attack can be mimicked by an anterior inferior cerebellar artery (AICA) stroke, which shares the symptoms of vertigo, tinnitus, deafness. The other symptoms of hemiplegia, and facial weakness offer greater distinction. However, all patients presenting with such a first episode of such symptoms should have a Computed Tomography (CT) scan to exclude a central cause [3]. The symptoms of AICA occlusion, display the lack of collateral vessels to the inner ear and its high metabolic rate, an anatomical fact which may have a bearing on the pathophysiology of MD.The future importance of imaging in the investigation of the suspected MD patient will depend on the other diagnostic modalities with which it is competing. Therefore it is necessary to comparatively discuss their diagnostic accuracy.A pure tone audiogram (PTA) is a basic step in the Meniere's diagnosis. MD classically produces a fluctuating low frequency hearing loss that becomes permanent as the disease progresses. However, it can cause many other patterns of hearing loss, which may mimic differentials such as otosclerosis, or noise induced losses [4]. Electronystagmography(ENG), is another routine investigation as MD causes a reduced vestibular response in the ear affected. However, it has limited sensitivity as recent work shows only a 50% positive rate in confirmed MD cases [5].Electrocochleography (ECoG) provides electrophysiological verification. An elevated summating potential/ nerve action potential of greater than 35% is a sign of MD. However, whilst a useful part of the diagnostic battery, specificity and sensitivity remains low particularly when performed in betwee...