Treatment of acute exacerbations

Acute attacks of MD are characterized by acute rotational vertigo, transient fluctuations in hearing, tinnitus, and, in many, aural fullness. Typically patients feel unwell and in some instances experience dramatic diaphoresis. Initial management focuses on excluding other conditions that can present with some of the same symptoms, including vestibular neuronitis, migraine, cerebral vascular events, and rarely other central conditions, including multiple sclerosis and tumors. The diagnosis of MD may become more apparent with time as the fluctuating and episodic nature of the symptoms becomes more obvious. The acute management of a patient with known MD is mainly symptomatic. Although hospitalization is rarely required, intravenous fluids may be required in the emergency department. Vestibular suppressants can be used for symptomatic control, although they can delay patients’ recovery by suppressing the adaptive response if used over a longer interval. More recently, corticosteroids have been advocated in this setting to help with the vertigo and hearing loss. However, the use of steroids in this context is unproved.

Low-salt diet and lifestyle modification

Classic treatment paradigms of MD often begin with salt restriction and lifestyle modification. Endolymphatic hydrops has long been proposed as being related to the pathogenesis of MD. Classically, it has been believed that a high-salt diet can influence the osmotic gradients in the inner ear, resulting in endolymphatic hydrops. Some patients (although not all) report that a salt binge seems to precipitate an acute episode of MD. On the other hand, the exact relationship between endolymphatic hydrops and MD remains controversial. Furthermore, some investigators have challenged the simple notion that salt restriction affects the fluid dynamics of the ear in ways that would significantly influence the degree of hydrops present. Levels of recommended salt restriction vary but figures often quoted range from 2 g per 24 hours down to 1 g per 24 hours. This level of salt restriction can be limiting on patients’ lifestyles and quality of life. Patients are instructed to avoid adding salt to food, pay close attention to food labeling, and avoid processed foods. The input of a dietician is often helpful. Effective compliance is difficult to maintain in the long-term for most patients. Given these side effects, no strong evidence exists to support the role of salt restriction alone in reducing the frequency or severity of symptoms from MD.

Low-salt diet and lifestyle modification

Classic treatment paradigms of MD often begin with salt restriction and lifestyle modification. Endolymphatic hydrops has long been proposed as being related to the pathogenesis of MD. Classically, it has been believed that a high-salt diet can influence the osmotic gradients in the inner ear, resulting in endolymphatic hydrops. Some patients (although not all) report that a salt binge seems to precipitate an acute episode of MD. On the other hand, the exact relationship between endolymphatic hydrops and MD remains controversial. Furthermore, some investigators have challenged the simple notion that salt restriction affects the fluid dynamics of the ear in ways that would significantly influence the degree of hydrops present. Levels of recommended salt restriction vary but figures often quoted range from 2 g per 24 hours down to 1 g per 24 hours. This level of salt restriction can be limiting on patients’ lifestyles and quality of life. Patients are instructed to avoid adding salt to food, pay close attention to food labeling, and avoid processed foods. The input of a dietician is often helpful. Effective compliance is difficult to maintain in the long-term for most patients. Given these side effects, no strong evidence exists to support the role of salt restriction alone in reducing the frequency or severity of symptoms from MD.

Diuretics

Diuresis has been proposed as a treatment of MD since at least the 1930s. Theoretically, diuresis reduces the amount of endolymphatic hydrops by reducing the extracellular fluids in the body. There are many different diuretics and almost all of them have been proposed as a potential treatment of MD. Hydrochlorothiazide is perhaps the most widely advocated, although furosemide and spirinolactone have their supporters. Despite their widespread use, no clear scientific evidence exists to support their efficacy. A recent Cochrane review found “there is no good evidence for or against the use of diuretics in MD.”

Betahistine

Cochlear vascular insufficiency as a result of autonomic dysfunction has been proposed as a cause of MD. As a result, betahistine has been proposed as a treatment because of its theoretic vasodilatory effects on the blood supply to the inner ear. The exact mechanism of action of betahistine in this setting is not known. Pharmacologic testing in animals has shown that the blood circulation in the striae vascularis of the inner ear improves, probably by means of a relaxation of the precapillary sphincters of the microcirculation of the inner ear. In further animal pharmacologic studies, betahistine was found to have weak H ₁ -receptor agonistic and considerable H ₃ -antagonistic properties in the central nervous system and autonomic nervous system. The clinical efficacy of betahistine has been the subject of several trials. Individually, many of these trials found betahistine to be effective in reducing the frequency or severity of vertiginous episodes and to some extent helping with tinnitus. No evidence exists to show betahistine helps with symptoms of hearing loss. A recent Cochrane review examining the role of betahistine reported that although individual trials provided positive results, a large randomized controlled trial is required to clarify its clinical efficacy.

Corticosteroids

The potential autoimmune cause of MD, and the recent use of transtympanic steroids to treat sudden sensorineural hearing loss, have stimulated interest in the use of steroids for the treatment of MD. In addition to a possible immune-modulating effect, recent studies have suggested that steroid perfusion can influence sodium and fluid dynamics in the inner ear because of their mineralocorticoid properties. Potential advantages of steroid use include the low risk of complications and the potential beneficial effect on hearing (when compared with the risk of hearing loss with gentamicin therapy). This effect may be particularly advantageous for those patients with bilateral MD. Early studies investigating the role of steroids in MD showed promising results, although these studies lacked adequate control groups. Silverstein and colleagues were the first to perform a randomized double-blind trial in which injection of transtympanic steroid was compared with placebo injection of saline. Although the trial was limited by small numbers, no difference was found between the 2 groups with regards to vertigo control, hearing loss, or tinnitus levels. However, more recently, Garduno-Anaya and colleagues performed a similar study and found a beneficial effect in the group treated with steroids. Boleas-Aguirre and colleagues have reported the results of a large retrospective series (129 patients) treated with transtympanic steroids for MD. Results were not reported according to the 1995 American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) guidelines but rather by using the Kaplan-Meier method. Using these reporting criteria, 91% of patients were classified as achieving acceptable vertigo control. The use of steroids in MD remains an area in which more research is required.

Miscellaneous medical treatments

Various other medications have been proposed as being useful for the management of MD. Isosorbide, adenosine triphosphate, γ-globulin, urea, glycerol, lithium, and anticholinergics have all been proposed as beneficial therapies. Clear evidence is lacking for the efficacy of these treatments.

Hormonal manipulation has been reported as a potential treatment of MD. Andrews and colleagues reported a series of 6 female patients who suffered exacerbations of their MD in relation to their menstrual cycle. These investigators proposed that fluctuations in fluid retention in association with hormonal changes in the body may be an underlying cause. Subsequently Price and colleagues reported on a patient with MD related to the menstrual cycle whose symptoms were alleviated when she was started on leuprolide acetate, a drug that blocks normal sex-hormone production.

Innovar is an anesthetic agent comprised of droperidol and fentanyl. Although not widely used for this purpose, Innovar has a strong suppressive effect on the vestibular system. Gates reported his experience using Innovar to treat 12 patients with intractable vertigo despite maximal medical therapy as an alternative to second-line surgical interventions. Innovar resulted in long-term control of vertigo in 58% of patients in this study, and the author outlined his practice of offering treatment with Innovar to all patients in his practice as an alternative to traditional surgical intervention. Gates reported several potential advantages compared with endolymphatic sac surgery, including lower cost, reduced risk to hearing, and faster patient recovery following treatment.

Hyperbaric oxygen therapy has also been proposed as a treatment of patients with MD. The efficacy of this therapy is unproved.

Education, stress reduction, hearing aids, and tinnitus training

In addition to the pharmacologic treatments mentioned earlier, other measures can have a significant clinical benefit for the patient with MD. Education is an important part of the treatment of MD. MD is a chronic condition and can be debilitating for patients. In an effort to reduce the effect of this disease on their quality of life, it is important that patients understand the likely clinical course of their condition and required treatment paradigms. Appropriate information can help alleviate the frustration and depression many patients experience because of feelings of helplessness or the misunderstanding of treatment options. Yardley and Kirby examined the role of vestibular rehabilitation and psychological therapies such as relaxation techniques and cognitive behavioral therapy in 360 patients with MD. These investigators found a significant improvement in patients’ outcomes following this therapy. Hearing aids can be used to treat the hearing loss associated with MD. Potential problems related to fluctuating hearing can be overcome if patients are capable of self-programming their own aids. Tinnitus therapy can help patients to cope better with this often-distressing symptom.

Meniett device

The Meniett device (Medtronic, Jacksonville, FL, USA) is a minimally invasive, nondestructive therapy that is a new addition to the treatment paradigm for MD. The rationale for its use is based on the observation that pressure changes applied to the inner ear result in beneficial changes in the symptoms of patients with MD. Patients require a standard ventilation tube to be placed before use. The Meniett device applies pulses of pressure to the inner ear via the ventilation tube. A treatment cycle takes 5 minutes and is repeated 3 times a day. Several studies investigating the efficacy of this treatment have reported promising results. No significant complications have been reported with its use. Gates and colleagues reported that 67% of patients using the device in their trial reported either a complete or significant long-term improvement in their vertigo. Similarly, Mattox and Reichert used the Meniett device as an alternative to second-line therapy when first-line medical therapy had failed. A total of 63% of patients required no further intervention (ie, second-line treatments) despite being followed for 3 years. In addition, those patients who failed to gain a benefit from the device did so early in therapy, thereby avoiding the potential frustration of a prolonged trial, only to find limited success. Dornhoffer and King followed 12 patients using the Meniett device for an average duration of 4 years. Of these patients, 25% showed no benefit from the device, whereas 75% reported a reduction in the frequency and severity of their vertigo. Rajan and colleagues analyzed 18 patients using the device and reported that 12 patients achieved a significant improvement in their vertigo and 5 patients showed improved hearing results. All 6 patients who did not respond to the Meniett device had been previously treated with gentamicin or surgery. These investigators propose that the efficacy of the Meniett device may be impaired by these previous treatments. Thomsen and colleagues performed a randomized double-blind placebo-controlled study of the effect of the Meniett device. Patients were randomized into 2 groups. The first group used the Meniett device for 2 months. The placebo group was given a fake device that was indistinguishable from the true Meniett device. Forty patients entered the study. The study showed a reduction of the frequency of vertiginous attacks in those with the real device versus those with the placebo. However, this result was not statistically significant. Patient perception of the severity of the vertigo and the functionality level of the active group improved when compared with the placebo group, with results that were statistically significant. With respect to patient perception of hearing, tinnitus, and aural pressure, there was no significant difference between the groups. Although many of these studies reported positive findings, the numbers of patients in these studies is small and the efficacy of the Meniett device remains unclear.