Medical treatment of Menière's disease: a review of literature

Therapeutic Response of Meniere's Disease Utilizing Sorbus domestica

Introduction Meniere's disease (MD) is a chronic condition characterized by episodic attacks of vertigo, fluctuating hearing loss, and tinnitus. MD can impart a significant socioeconomic impact with associated progressive hearing loss. First-line therapies consist of diuretics and antihistamines, with second-line therapies including intratympanic steroids and pulse therapy. Third-line treatments include endolymphatic sac surgery (ELSS) followed by intratympanic gentamicin injection and/or vestibular neurectomy. The gemmotherapy Sorbus domestica's inherent properties to regulate venous circulation and lymphatic drainage have been utilized in the European literature for the treatment of MD and the patients in this study. Methods Patients presenting for rehabilitation at Pulaski Health and Rehabilitation Facility with a history of vertigo were examined and, through history and specific exam, to define MD. This resulted in six patients whose symptoms and exam were consistent with MD and interfered with their therapeutic progression. These patients were offered and accepted treatment with Sorbus domestica for their MD. Results All patients responded with either resolution or significant improvement in their symptoms and hearing loss. Treatment also resulted in an improved and probably shortened rehabilitative course. All patients had no adverse reactions and were supplied with resources for continual treatment upon discharge. Conclusion Sorbus domestica is a safe and viable treatment option for MD. It has been useful, especially in treatment-resistant diseases, without side effects and can be utilized in initial cases with improvement or resolution of hearing loss.

Systemic pharmacological interventions for Ménière's disease

BACKGROUND

Ménière's disease is a condition that causes recurrent episodes of vertigo, associated with hearing loss and tinnitus. A number of pharmacological interventions have been used in the management of this condition, including betahistine, diuretics, antiviral medications and corticosteroids. The underlying cause of Ménière's disease is unknown, as is the way in which these treatments may work. The efficacy of these different interventions at preventing vertigo attacks, and their associated symptoms, is currently unclear.

OBJECTIVES

To evaluate the benefits and harms of systemic pharmacological interventions versus placebo or no treatment in people with Ménière's disease.

SEARCH METHODS

The Cochrane ENT Information Specialist searched the Cochrane ENT Register; Central Register of Controlled Trials (CENTRAL); Ovid MEDLINE; Ovid Embase; Web of Science; ClinicalTrials.gov; ICTRP and additional sources for published and unpublished trials. The date of the search was 14 September 2022.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) and quasi-RCTs in adults with definite or probable Ménière's disease comparing betahistine, diuretics, antihistamines, antivirals or systemic corticosteroids with either placebo or no treatment. We excluded studies with follow-up of less than three months, or with a cross-over design (unless data from the first phase of the study could be identified).  DATA COLLECTION AND ANALYSIS: We used standard Cochrane methods. Our primary outcomes were: 1) improvement in vertigo (assessed as a dichotomous outcome - improved or not improved), 2) change in vertigo (assessed as a continuous outcome, with a score on a numerical scale) and 3) serious adverse events. Our secondary outcomes were: 4) disease-specific health-related quality of life, 5) change in hearing, 6) change in tinnitus and 7) other adverse effects. We considered outcomes reported at three time points: 3 to < 6 months, 6 to ≤ 12 months and > 12 months. We used GRADE to assess the certainty of evidence for each outcome.  MAIN RESULTS: We included 10 studies with a total of 848 participants. The studies evaluated the following interventions: betahistine, diuretics, antivirals and corticosteroids. We did not identify any evidence on antihistamines.  Betahistine Seven RCTs (548 participants) addressed this comparison. However, we were unable to conduct any meta-analyses for our primary outcomes as not all outcomes were considered by every study, and studies that did report the same outcome used different time points for follow-up, or assessed the outcome using different methods. Therefore, we were unable to draw meaningful conclusions from the numerical results. Some data were available for each of our primary outcomes, but the evidence was low- or very low-certainty throughout. One study reported on the outcome 'improvement in vertigo' at 6 to ≤ 12 months, and another study reported this outcome at > 12 months. Four studies reported on the change in vertigo, but again all used different methods of assessment (vertigo frequency, or a global score of vertigo severity) or different time points. A single study reported on serious adverse events.  Diuretics Two RCTs addressed this comparison. One considered the use of isosorbide (220 participants), and the other used a combination of amiloride hydrochloride and hydrochlorothiazide (80 participants). Again, we were unable to conduct any meta-analyses for our primary outcomes, as only one study reported on the outcome 'improvement in vertigo' (at 6 to ≤ 12 months), one study reported on change in vertigo (at 3 to < 6 months) and neither study assessed serious adverse events. Therefore, we were unable to draw meaningful conclusions from the numerical results. The evidence was all very low-certainty.  Other pharmacological interventions We also identified one study that assessed antivirals (24 participants), and one study that assessed corticosteroids (16 participants). The evidence for these interventions was all very low-certainty. Again, serious adverse events were not considered by either study.

AUTHORS' CONCLUSIONS

The evidence for systemic pharmacological interventions for Ménière's disease is very uncertain. There are few RCTs that compare these interventions to placebo or no treatment, and the evidence that is currently available from these studies is of low or very low certainty. This means that we have very low confidence that the effects reported are accurate estimates of the true effect of these interventions. Consensus on the appropriate outcomes to measure in studies of Ménière's disease is needed (i.e. a core outcome set) in order to guide future studies in this area and enable meta-analyses of the results. This must include appropriate consideration of the potential harms of treatment, as well as the benefits.

Low Dose Betahistine in Combination With Selegiline Increases Cochlear Blood Flow in Guinea Pigs

OBJECTIVE

Betahistine is frequently used in the pharmacotherapy for Menière's Disease (MD). Little is known about its mode of action and prescribed dosages vary. While betahistine had an increasing effect on cochlear microcirculation in earlier studies, low dose betahistine of 0.01 mg/kg bw or less was not able to effect this. Selegiline inhibits monoaminooxidase B and therefore potentially the breakdown of betahistine. The goal of this study was to examine whether the addition of selegiline to low dose betahistine leads to increased cochlear blood flow.

METHODS

Twelve Dunkin-Hartley guinea pigs were anesthetized, the cochlea was exposed and a window opened to the stria vascularis. Blood plasma was visualized by injecting fluoresceinisothiocyanate-dextrane and vessel diameter and erythrocyte velocity were evaluated over 20 minutes. One group received low dose betahistine (0.01 mg/kg bw) and selegiline (1 mg/kg bw) i.v. while the other group received only selegiline (1 mg/kg bw) and saline (0.9% NaCl) as placebo i.v.

RESULTS

Cochlear microcirculation increased significantly (P < .001) in guinea pigs treated with low dose betahistine combined with selegiline by up to 58.3 ± 38.7% above baseline over a period of up to 11 minutes. In one guinea pig, the increase was 104.6%. Treatment with Selegiline alone did not affect microcirculation significantly.

CONCLUSIONS

Low dose betahistine increased cochlear microcirculation significantly when combined with selegiline. This should be investigated in further studies regarding dose-effect relation in comparison to betahistine alone. Side effects, in particular regarding circulation, should be considered carefully in view of the clinical applicability of a combination therapy in patients with MD.

Association between Meniere's disease and air pollution in South Korea

Meniere's disease is thought to be a disorder of the inner ear function, affected by genetic and environmental factors. Several recent studies have shown that air pollution could affect middle and inner ear diseases. The purpose of this study was to investigate the relationship between the Meniere's disease occurrence and air pollution status in Korea. This study used a time-stratified case-crossover design. Hospital visit data by Meniere's disease were collected from the Korea National Health Insurance Service-National Sample Cohort (NHIS-NSC) database. Daily air pollution data for sulfur dioxide (SO2), nitrogen dioxide (NO2), carbon monoxide (CO), ozone (O3), and particulate matter (PM10: ≤ 10 μm in diameter, and PM2.5: ≤ 2.5 μm in diameter) were collected from the National Ambient air quality Monitoring Information System (NAMIS) database. We used two-stage analysis to assess the association between degree of air pollution and the occurrence of Meniere's disease. In the first stage, region-specific analysis was conducted to estimate the odds ratios (ORs) of Meniere's disease risk associated with each air pollutant exposure by using conditional logistic regression for matched case-control sets in 16 regions. In the second stage, region-specific ORs from the first stage were combined and the pooled effect estimates were derived through fixed and random effect meta-analysis. Subgroup analysis was conducted for age, sex, seasonality, and urbanization of residence. In total, 29,646 (32.1% males and 67.9% females) Meniere's disease cases were identified from Korea NHIS-NSC database between 2008 and 2015. Overall, SO2, NO2, CO, and PM10 showed significant correlation with Meniere's disease risk at immediate lags, and weaker correlation at delayed lags, whereas O3 showed slightly negative correlation at the immediate lag (lag0) and PM2.5 did not show strong correlation (SO2: 1.04 [95% confidence interval: 1.01, 1.06]; NO2: 1.08 [1.06, 1.11]; CO: 1.04 [1.02, 1.06]; O3: 0.96 [0.93, 0.99]: statistically significant ORs at lag0 are listed). These positive and negative associations between Meniere's disease and each air pollutant were generally stronger in the age of 40-64, female, summer (June-August) season, and urban subgroups. Our results showed that hospital visits for Meniere's disease were associated with the measured concentrations of ambient air pollutants SO2, NO2, CO, and PM10. Further studies are required to confirm these associations and find their mechanisms.

Tenotomy of the middle ear muscles : An unknown surgical approach in Meniere's disease

Tenotomy of the tendon of the stapedius and tensor tympani muscles is a relatively unknown therapeutic procedure in Menière's disease. Widespread approaches include medicinal treatment with betahistine or diuretics as well as interventional procedures, such as intratympanic gentamicin or glucocorticoid injection, vestibular neurectomy, labyrinthectomy or endolymphatic sac surgery. The exact pathomechanism of this approach is not fully known. It is assumed that by cutting the tendons of both middle ear muscles in cases of endolymphatic hydrops the stapes is not additionally actively pushed against the oval window but can deviate laterally and thereby does not augment the inner ear pressure even further. Studies have shown that this method does not only improve vestibular symptoms but also, in contrast to most other strategies, increases the hearing level. The formation of scar tissue and the resulting reduction of ossicular chain mobility, especially due to postoperative infections, may limit the success of tenotomy and should be considered as a possible factor in cases of limited postoperative vertigo control.

Inner ear symptoms and disease: pathophysiological understanding and therapeutic options

In recent years, huge advances have taken place in understanding of inner ear pathophysiology causing sensorineural hearing loss, tinnitus, and vertigo. Advances in understanding comprise biochemical and physiological research of stimulus perception and conduction, inner ear homeostasis, and hereditary diseases with underlying genetics. This review describes and tabulates the various causes of inner ear disease and defines inner ear and non-inner ear causes of hearing loss, tinnitus, and vertigo. The aim of this review was to comprehensively breakdown this field of otorhinolaryngology for specialists and non-specialists and to discuss current therapeutic options in distinct diseases and promising research for future therapies, especially pharmaceutic, genetic, or stem cell therapy.

Betahistine exerts a dose-dependent effect on cochlear stria vascularis blood flow in guinea pigs in vivo

OBJECTIVE

Betahistine is a histamine H(1)-receptor agonist and H(3)-receptor antagonist that is administered to treat Menière's disease. Despite widespread use, its pharmacological mode of action has not been entirely elucidated. This study investigated the effect of betahistine on guinea pigs at dosages corresponding to clinically used doses for cochlear microcirculation.

METHODS

Thirty healthy Dunkin-Hartley guinea pigs were randomly assigned to five groups to receive betahistine dihydrochloride in a dose of 1,000 mg/kg b. w. (milligram per kilogram body weight), 0.100 mg/kg b. w., 0.010 mg/kg b. w., 0.001 mg/kg b. w. in NaCl 0.9% or NaCl 0.9% alone as placebo. Cochlear blood flow and mean arterial pressure were continuously monitored by intravital fluorescence microscopy and invasive blood pressure measurements 3 minutes before and 15 minutes after administration of betahistine.

RESULTS

When betahistine was administered in a dose of 1.000 mg/kg b. w. cochlear blood flow was increased to a peak value of 1.340 arbitrary units (SD: 0.246; range: 0.933-1.546 arb. units) compared to baseline (p<0.05; Two Way Repeated Measures ANOVA/Bonferroni t-test). The lowest dosage of 0.001 mg/kg b. w. betahistine or NaCl 0.9% had the same effect as placebo. Nonlinear regression revealed that there was a sigmoid correlation between increase in blood flow and dosages.

CONCLUSIONS

Betahistine has a dose-dependent effect on the increase of blood flow in cochlear capillaries. The effects of the dosage range of betahistine on cochlear microcirculation corresponded well to clinically used single dosages to treat Menière's disease. Our data suggest that the improved effects of higher doses of betahistine in the treatment of Menière's disease might be due to a corresponding increase of cochlear blood flow.

Current treatment of vestibular, ocular motor disorders and nystagmus

Vertigo and dizziness are among the most common complaints with a lifetime prevalence of about 30%. The various forms of vestibular disorders can be treated with pharmacological therapy, physical therapy, psychotherapeutic measures or, rarely, surgery. In this review, the current pharmacological treatment options for peripheral and central vestibular, cerebellar and ocular motor disorders will be described. They are as follows for peripheral vestibular disorders. In vestibular neuritis recovery of the peripheral vestibular function can be improved by treatment with oral corticosteroids. In Menière's disease a recent study showed long-term high-dose treatment with betahistine has a significant effect on the frequency of the attacks. The use of aminopyridines introduced a new therapeutic principle in the treatment of downbeat and upbeat nystagmus and episodic ataxia type 2 (EA 2). These potassium channel blockers presumably increase the activity and excitability of cerebellar Purkinje cells, thereby augmenting the inhibitory influence of these cells on vestibular and cerebellar nuclei. A few studies showed that baclofen improves periodic alternating nystagmus, and gabapentin and memantine, pendular nystagmus. However, many other eye movement disorders such as ocular flutter opsoclonus, central positioning, or see-saw nystagmus are still difficult to treat. Although progress has been made in the treatment of vestibular neuritis, downbeat and upbeat nystagmus, as well as EA 2, state-of-the-art trials must still be performed on many vestibular and ocular motor disorders, namely Menière's disease, bilateral vestibular failure, vestibular paroxysmia, vestibular migraine, and many forms of central eye movement disorders.

Pharmacotherapy of vestibular and ocular motor disorders, including nystagmus

We review current pharmacological treatments for peripheral and central vestibular disorders, and ocular motor disorders that impair vision, especially pathological nystagmus. The prerequisites for successful pharmacotherapy of vertigo, dizziness, and abnormal eye movements are the “4 D’s”: correct diagnosis, correct drug, appropriate dosage, and sufficient duration. There are seven groups of drugs (the “7 A’s”) that can be used: antiemetics; anti-inflammatory, anti-Ménière’s, and anti-migrainous medications; anti-depressants, anti-convulsants, and aminopyridines. A recovery from acute vestibular neuritis can be promoted by treatment with oral corticosteroids. Betahistine may reduce the frequency of attacks of Ménière’s disease. The aminopyridines constitute a novel treatment approach for downbeat and upbeat nystagmus, as well as episodic ataxia type 2 (EA 2); these drugs may restore normal “pacemaker” activity to the Purkinje cells that govern vestibular and cerebellar nuclei. A limited number of trials indicate that baclofen improves periodic alternating nystagmus, and that gabapentin and memantine improve acquired pendular and infantile (congenital) nystagmus. Preliminary reports suggest suppression of square-wave saccadic intrusions by memantine, and ocular flutter by beta-blockers. Thus, although progress has been made in the treatment of vestibular neuritis, some forms of pathological nystagmus, and EA 2, controlled, masked trials are still needed to evaluate treatments for many vestibular and ocular motor disorders, including betahistine for Ménière’s disease, oxcarbazepine for vestibular paroxysmia, or metoprolol for vestibular migraine.

Which medication do I need to manage dizzy patients?

Vertigo and dizziness are not independent disease entities, but instead symptoms of various diseases. Accordingly, a variety of treatment approaches are required. Here we review the most relevant drugs for managing dizziness, vertigo, and nystagmus syndromes. It is important to differentiate symptomatic treatment of nausea and vomiting with, for example, dimenhydrinate and benzodiazepines, and prophylactic treatment of motion sickness with scopolamine from a causal therapy of the underlying disorders. Examples of such causal therapy include aminopyridines for downbeat nystagmus and episodic ataxia type 2; carbamazepine for vestibular paroxysmia, paroxsymal dysarthria and ataxia in multiple sclerosis, and superior oblique myokymia; betahistine, dexamethasone, and gentamicin for Menière's disease; gabapentin and memantine for different forms of acquired and congenital nystagmus; corticosteroids for acute vestibular neuritis and Cogan's syndrome; metoprolol and topiramate for vestibular migraine; and selective serotonin reuptake inhibitors such as paroxetine for phobic postural vertigo. The clinical entities are briefly described, the various medications are discussed in alphabetical order, and dosage, major side effects, contraindications, and alternative medications of each drug are displayed in boxes for easy reference.

Medical treatment of vestibular disorders

BACKGROUND

The lifelong prevalence of rotatory vertigo is 30%. Despite this high figure, patients with vertigo generally receive either inappropriate or inadequate treatment. However, the majority of vestibular disorders have a benign cause, take a favorable natural course, and respond positively to therapy.

OBJECTIVE

This review puts special emphasis on the medical rather than the physical, operative, or psychotherapeutic treatments available.

METHODS

A selected review of recent reports and studies on the medical treatment of peripheral and central vestibular disorders.

RESULTS/CONCLUSIONS

In vestibular neuritis, recovery of the peripheral vestibular function can be improved by oral corticosteroids; in Menière's disease, there is first evidence that high-dose, long-term administration of betahistine reduces attack frequency; carbamazepine or oxcarbamazepine is the treatment of first choice in vestibular paroxysmia, a disorder mainly caused by neurovascular cross-compression; the potassium channel blocker aminopyridine provides a new therapeutic principle for treatment of downbeat nystagmus, upbeat nystagmus, and episodic ataxia type 2.

Pharmacological advances in the treatment of neuro-otological and eye movement disorders

PURPOSE OF REVIEW

First, to describe the current pharmacological treatment options for peripheral and central vestibular, cerebellar, and ocular motor disorders. Second, to identify vestibular and ocular motor disorders in which treatment trials are warranted.

RECENT FINDINGS

Peripheral vestibular disorders: In vestibular neuritis recovery of the peripheral vestibular function can be improved by treatment with oral corticosteroids. In Ménière's disease treatment strategies range from low-salt diet, diuretics, and betahistine, to intratympanic injection of corticosteroids or gentamicin. Unfortunately most of the trials on Ménière's disease do not have an up-to-date design. In bilateral vestibulopathy steroids do not seem to improve vestibular function.Central vestibular, cerebellar, and ocular motor disorders: The use of aminopyridines introduced a new therapeutic principle in the treatment of downbeat and upbeat nystagmus and episodic ataxia type 2 (EA2). These potassium channel blockers presumably increase the activity and excitability of cerebellar Purkinje cells, thereby augmenting the inhibitory influence of these cells on vestibular and cerebellar nuclei. A few studies showed that baclofen improves periodic alternating nystagmus, and gabapentin and memantine, pendular nystagmus. Many other eye movement disorders, however, such as ocular flutter, opsoclonus, central positioning, or see-saw nystagmus are still difficult to treat.

SUMMARY

Although progress has been made in the treatment of vestibular neuritis, downbeat and upbeat nystagmus, as well as EA2, state-of-the-art trials must still be performed on many vestibular and ocular motor disorders, namely Ménière's disease, bilateral vestibulopathy, vestibular paroxysmia, vestibular migraine, and many forms of central eye movement disorders.

Meniett therapy: rescue treatment in severe drug-resistant Ménière's disease?

CONCLUSION

Our data indicate that Meniett therapy is unlikely to be helpful in the long-term treatment of patients with severe, drug-resistant Ménière's disease (MD) in whom injection of intratympanic gentamicin (ITG) or another destructive procedure would otherwise be performed.

OBJECTIVE

To investigate the value of Meniett therapy in patients with drug-resistant MD referred for injection of ITG.

MATERIAL AND METHODS

Twelve patients referred for ITG treatment were followed during a 2-month period of Meniett therapy. Symptoms, functional level and hearing status were evaluated using a standardized staging system. Disease-specific quality-of-life measures were obtained before and after Meniett therapy. At the end of the study period, patients were followed for a mean of 37 months, thus providing long-term outcome data.

RESULTS

In two patients, Meniett treatment was interrupted after 1 month because of persistent severe vertigo. In the remaining 10 subjects, we found a significant decrease in the median number of vertigo spells from 10.0/month (25th-75th percentile 4.0-19.0) prior to treatment to 3.0/month (25th-75th percentile 1.5-4.5) after treatment (p = 0.02). There was, however, no improvement in hearing status, tinnitus, functional level or self-perceived dizziness handicap. Long-term (>1 year) follow-up data revealed that only 2 subjects preferred to continue Meniett therapy and that ablative surgery had to be performed in 6/12 study patients.

Reduction in sick leave and costs to society of patients with Meniere's disease after treatment of temporomandibular and cervical spine disorders: a controlled six-year cost-benefit study

This study compares the frequency of sick leave between the three-year period after and the three-year period before coordinated treatment of temporomandibular and cervical spine disorders in 24 patients (ten males and 14 females) diagnosed with Meniere's disease. The frequency of sick leave for the patients was also compared with the frequency of sick leave in a control group from the population. A cost-benefit analysis was made regarding the costs to society of sick leave related to the treatment costs of the patients. In a previous study the same patients were treated for their severe signs and symptoms of temporomandibular and cervical spine disorders, and they reported a substantial reduction in their vertigo, non-whirling dizziness, tinnitus, feeling of fullness in the ear, pain in the face and jaws, pain in the neck and shoulders, and headache. The number of days of sick leave and the year the patient began to receive disability pension due to the symptoms of Meniere's disease were obtained from the National Health Insurance Service in Sweden. Two of the patients received disability pension benefits due to Meniere's disease 17 years prior to their normal retirement pension. A third patient received disability pension for another reason and two were receiving a retirement pension. Data on the remaining 19 patients showed a considerable reduction in number of days of sick leave during the three-year period after coordinated treatment (270 days) compared with the three-year period before the treatment (1,536 days). The control subjects used a total of 14 days sick leave for the same symptoms during the same six-year period. Vertigo (nine days) was the dominant cause followed by pain in the neck and shoulders, and headache. The reduction in sick leave for the 19 nonretired patients and the treatment costs for the 24 patients can be used for a simple cost-benefit calculation for the subgroup of nonretired patients. During the first three years after treatment the reduction in sick leave was on average 66.6 days for each of the 19 nonretired patients. Within the limits of this study, it can be concluded that the costs to society for sick leave and disability pension due to Meniere's disease are substantial. A coordinated treatment of temporomandibular and cervical spine disorders appears to substantially reduce these costs.

Symptom relief after treatment of temporomandibular and cervical spine disorders in patients with Meniere's disease: a three-year follow-up

This study describes the coordinated treatment of temporomandibular disorders (TMD) and cervical spine disorders in patients diagnosed with Meniere's disease. The aim was to follow up treatment outcomes for three years with regular follow-up examinations every six months. Of the 31 patients with Meniere's disease who participated in a controlled comparative study on the signs and symptoms of TMD, 24 participated in a subsequent controlled comparative study on the signs and symptoms of cervical spine disorders (CSD). These 24 Meniere's disease patients (ten males and 14 females) agreed to participate in this longitudinal study. At each follow-up, their symptoms were evaluated using self-administered questionnaires and visual analog scales (VAS). The results of the coordinated treatment showed simultaneous decreases in the intensities of vertigo, nonwhirling dizziness, tinnitus, feeling of fullness in the ear, pain in the face and jaws, pain in the neck and shoulders, and headache that were both longitudinal and highly significant. Significant longitudinal reductions in the frequencies of vertigo, nonwhirling dizziness, and headache were also reported by the patients as well as a complete disappearance of pain located in the vertex area. A significant relief of TMD symptoms and a decrease in nervousness was also achieved. The results showed that a coordinated treatment of TMD and CSD in patients with Meniere's disease is an effective therapy for symptoms of this disease. The results also suggested that Meniere's disease has a clear association with TMD and CSD and that these three ailments appeared to be caused by the same stress, nervousness, and muscular tension.

Meniere's disease: overview, epidemiology, and natural history

Meniere's disease is a disease of the inner ear characterized by a triad of symptoms: vestibular symptoms, auditory symptoms, and pressure. The pathologic correlate of Meniere's disease is endolymphatic hydrops and the etiopathogenesis involves a deficiency in the absorption of endolymph. The pathophysiology of the symptoms is still disputed: membranous ruptures, pressure and mechanical displacement of the end organs, or obstruction followed by an abrupt clearance of the endolymphatic duct. The course of the disease may be progressive or nonprogressive and, in addition to the typical presentation of Meniere's disease, two variations of the disorder have been identified: cochlear Meniere's disease, and vestibular Meniere's disease. It can be further broken into two subsets: Meniere's syndrome, with a known and well-established cause, and Meniere's disease, in which the cause seems to be idiopathic. It is likely that there are racial (genetic) as well as environmental factors that influence differences in incidence among countries and among various sections of countries. The disease is much more common in adults, with an average age of onset in the fourth decade, the symptoms beginning usually between ages 20 and 60 years. Meniere's disease is (grossly) equally common in each sex, and right and left ears are affected with fairly equal frequency. The diagnosis of Meniere's disease is by exclusion, and a careful history is the most important guide to a correct diagnosis. Its medical treatment is largely empiric. Surgery can be considered when, even after medical therapy, the disease progresses and the symptoms become intractable. Surgery may be either conservative or destructive. Bilaterality must be considered when deciding the best surgical option for a patient with Meniere's disease. It is the authors' opinion that endolymphatic sac surgery is an extension of conservative treatment.

[Variability of N in Meniere's disease]

Intratympanic treatment of incapacitating vertigo in Menière's disease has become a first option treatment for most otolaryngologists nowadays. Reporting their results following adequate minimum follow-up and under the same criteria is as important as to clearly state the indications that have been settled, through adequate handicap psychometric tests. Furthermore, when results are reported, knowing the total number of patients (N) with a diagnosis of Menière's disease is essential to evaluate such results in those treated patients, bearing in mind that most Menière's patients do well with medical treatment as well.

The physiology of brain histamine

Histamine-releasing neurons are located exclusively in the TM of the hypothalamus, from where they project to practically all brain regions, with ventral areas (hypothalamus, basal forebrain, amygdala) receiving a particularly strong innervation. The intrinsic electrophysiological properties of TM neurons (slow spontaneous firing, broad action potentials, deep after hyperpolarisations, etc.) are extremely similar to other aminergic neurons. Their firing rate varies across the sleep-wake cycle, being highest during waking and lowest during rapid-eye movement sleep. In contrast to other aminergic neurons somatodendritic autoreceptors (H3) do not activate an inwardly rectifying potassium channel but instead control firing by inhibiting voltage-dependent calcium channels. Histamine release is enhanced under extreme conditions such as dehydration or hypoglycemia or by a variety of stressors. Histamine activates four types of receptors. H1 receptors are mainly postsynaptically located and are coupled positively to phospholipase C. High densities are found especially in the hypothalamus and other limbic regions. Activation of these receptors causes large depolarisations via blockade of a leak potassium conductance, activation of a non-specific cation channel or activation of a sodium-calcium exchanger. H2 receptors are also mainly postsynaptically located and are coupled positively to adenylyl cyclase. High densities are found in hippocampus, amygdala and basal ganglia. Activation of these receptors also leads to mainly excitatory effects through blockade of calcium-dependent potassium channels and modulation of the hyperpolarisation-activated cation channel. H3 receptors are exclusively presynaptically located and are negatively coupled to adenylyl cyclase. High densities are found in the basal ganglia. These receptors mediated presynaptic inhibition of histamine release and the release of other neurotransmitters, most likely via inhibition of presynaptic calcium channels. Finally, histamine modulates the glutamate NMDA receptor via an action at the polyamine binding site. The central histamine system is involved in many central nervous system functions: arousal; anxiety; activation of the sympathetic nervous system; the stress-related release of hormones from the pituitary and of central aminergic neurotransmitters; antinociception; water retention and suppression of eating. A role for the neuronal histamine system as a danger response system is proposed.

Vertigo

Vertigo is a subtype of dizziness, which results from an imbalance within the vestibular system. This seminar focuses on three common presentations of vertigo: prolonged spontaneous vertigo, recurrent attacks of vertigo, and positional vertigo. The patient's history is usually the key to differentiation of peripheral and central causes of vertigo. The most common cause of vertigo, benign paroxysmal positional vertigo, can be cured with a simple positional manoeuvre. Other common causes of vertigo include vestibular neuritis, Ménière's syndrome, migraine, and vertebrobasilar insufficiency. Treatment should be directed at the underlying cause whenever possible, but antivertiginous and antiemetic drugs can suppress symptoms when a specific cause cannot be found. These drugs are generally not indicated for long-term daily use, however, since they may interfere with the normal compensation process.