Perhaps the most controversial subject in neurotology concerns the diagnosis and management of patients with Meniere’s disease. There is uncertainty regarding not only the etiology and pathophysiology, but also the role of medical management, particularly because the precise cause is unknown, the illness has frequent periods of remission, and only anecdotal reports of efficacy exist for most treatments. Furthermore, there is a perception that many of the surgical procedures used to control the disorder may merely be inducing a remission phase or may have no effect at all. Much of the conventional wisdom regarding Meniere’s disease merely reflects the opinion of experienced clinicians, rather than scientific fact. With such a controversial subject, it is easy to extrapolate that certain findings, symptoms, or responses to treatment are indicative of the nature of the problem. The reader should be reminded that neither an apparent response to therapy nor postmortem histopathologic findings represent scientific evidence of the exact pathophysiology of a condition. Plainly stated, Meniere’s disease is a chronic condition characterized by a progressive dysfunction of the inner ear or the cochleovestibular nerve, or both. Beyond this basic description, the precise etiology of the problem remains to be clearly elucidated. As a consequence, to manage Meniere’s syndrome patients successfully, the physician must assume their care for many years, albeit the need for services may vary considerably. This is particularly true in light of the long periods of remission as well as the cyclic nature of this condition in some patients. Therefore, management of these patients should be done with the mindset of a long-term chronic disorder, much like adult-onset diabetes mellitus, chronic pain, or hypertension. Although treatment may modify the clinical course of Meniere’s disease patients somewhat, cures are indeed rare. Patients must be followed and therapy adjusted as clinical circumstances warrant. Also, measuring the effects of therapy can be extremely difficult, and the physician should never assume that the recommended intervention or treatment has actually stopped the progression of this disorder. Rather, the condition may simply have entered a remission phase. Having stated that the exact etiology is unknown, what do we know of Meniere’s disease? Meniere’s disease is a clinical disorder associated with the histopathological finding of endolymphatic hydrops. Most of the hydropic distention found in postmortem specimens is seen in the cochlea and the saccule, although occasionally the utricle and the ampullae are involved. Other histopathologic features include ruptures or fistulae, collapse of membranes, and vestibular fibrosis. Minimal histopatho-logic changes are seen in the sensory epithelia, although the loss of ganglion and neuronal cells, inner and outer hair cells, and strial vascularity has been reported. Recognized causes of Meniere’s syndrome include idiopathic, post-traumatic, postinfectious (i.e., delayed onset after a viral illness), late-stage syphilitic, and Cogan’s syndrome or one of its variants. One theory of Meniere’s disease is that increased endolymphatic pressure causes the symptoms as well as the histopatho-logic features. According to this theory, pressure buildup leads to membrane ruptures, so that potassium-rich endolymph gains access to the sensory and neural structures, causing sudden or fluctuant hearing loss and episodic vertigo. This theory also suggests that pressure buildup develops as a result of altered resorption of fluid by the endolymphatic sac. Abnormalities that lead to this altered resorption include perisaccular and vestibular epithelial fibrosis, altered glycoprotein metabolism, viral infection of the inner ear, and autoimmune-mediated dysfunction of the sac. Bony narrowing of the endolymphatic duct might also contribute to the obstruction and dysfunction of the sac. A number of studies from the Massachusetts Eye and Ear Infirmary refute the pressure theory and suggest that endolymphatic hydrops is an epiphenomenon. These studies propose that Meniere’s disease develops as a result of a problem with altered biochemical gradients within the endolymphatic space. Findings in support of this theory include a number of biochemical alterations found in hydropic inner ears. These alterations include a decrease in endocochlear potential, an increase in intracochlear calcium, alterations in potassium permeability, inhibition of electrogenic transport processes, and increased endolymph fluid protein content. It seems likely that Meniere’s disease can be caused by a number of factors, each resulting in an alteration that leads to similar clinical features. It also seems likely that, at some point, idiopathic endolymphatic hydrops will no longer be an appropriate description of this syndrome. Rather, the specific biochemical or cellular abnormality will be identified and treated by the clinician. In this era of managed care with declining health care revenues, most clinicians are uncertain as to which studies are needed for proper evaluation of patients with suspected Meniere’s disease. The history can be helpful, specifically with regard to fluctuating hearing loss, ear pressure, hearing distortion or hypersensitivity, and severe episodic vertigo accompanied by increased tinnitus or hearing loss. Physical findings that should be elicited include spontaneous or gaze-evoked nystagmus (usually away from the affected ear), fistula test, Dix-Hallpike maneuver, and Romberg and gait tests. The otologic examination, although usually unremarkable, occasionally indicates other causes, such as cholesteatoma or middle ear tumor. A comprehensive audiogram is also essential, with particular attention to the presence of a low-frequency sensorineural hearing loss. Unexpectedly low speech discrimination scores or abnormal acoustic reflexes may be helpful in determining the need for additional testing.
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