Meniere’s disease is associated with an increase in the amount of fluid (endolymph) in the inner ear. The complex of symptoms was described for the first time in 1861 by the French physician Prosper Ménière and was later called Ménière’s disease.
Inner ear anatomy. The inner ear is located inside the canals and cavities of the temporal bone called the bony labyrinth. Inside the bone labyrinth, there is a membranous labyrinth repeating its contours and dimensions.
The space between the membranous and bony labyrinth is filled with perilymph fluid, similar in composition to cerebrospinal fluid. The space inside the membranous labyrinth is filled with endolymph, and its walls completely isolate it.
There are three different structure and function parts of the inner ear vestibule, cochlea, and semicircular canals. The snail is the organ of sound perception. It is in it that the sensitive hair cells are located, which give rise to the auditory nerve. The vestibule and semicircular canals are the organs of balance.
What is the reason for the appearance of symptoms of Meniere’s disease? The appearance of symptoms is associated with an increase in the amount of endolymph. The endolymph, increasing in volume, stretches the walls of the membranous labyrinth. This condition is called endolymphatic hydrops or dropsy of the labyrinth. Since the membranous labyrinth has many sensitive receptor zones in all three sections, their irritation leads to the appearance of symptoms of the disease.
Meniere’s disease is currently not fully understood, so there are several theories where excess endolymph comes from:
- the penetration of fluid from the blood plasma through the vascular wall of the capillaries
- penetration of liquid from the perilymph through the wall of the membranous labyrinth
- violation of the mechanism of production and absorption (absorption) of endolymph
- accumulation of ions and substances with high molecular weight in the endolymph, which leads to an increase in osmotic pressure
- insufficient volume of perilymph.
The reasons for the development of Meniere’s disease
The pathophysiology of Meniere’s disease is not well understood, and at present, no theory would fully explain its origin. But clinically, factors can be identified that contribute to the development of the disease or provoke its attacks. These factors include:
- viral infections
- autoimmune processes
- psycho-emotional stress
- allergic reactions
- endocrine diseases.
Meniere’s disease is characterized by the appearance of seizures with the following symptoms:
- noise in ears
- hearing loss.
In the absence of one of the symptoms, careful differential diagnosis is needed since dizziness, tinnitus, and hearing loss occur in many other diseases. In most cases, tinnitus and hearing loss is unilateral; that is, the pathological process occurs only in one ear.
The dizziness is quite intense and manifests itself in the rotation of the body or surrounding objects; this type of dizziness is called systemic. Nausea and vomiting are common at the time of an attack. Non-systemic dizziness (staggering when walking, darkening in the eyes, flickering before the eyes) is not common for the typical picture of Meniere’s disease and can only be in its final stage.
Also, there may be a feeling of fullness, fullness, congestion in the affected ear at the time of an attack.
There can be many attacks from once a few months to daily, which determines the severity of the disease.
Clinically distinguish the stages of the disease:
- Stage 1 (initial). Dizziness attacks occur suddenly or after stress. There may be precursors before an attack, such as congestion in a sore ear. Noise appears in the ear during an attack, hearing decreases; after the attack, hearing is restored to normal within a few days. Outside of the seizures, they feel good; there is no tinnitus.
- Stage 2 (pronounced clinical manifestations). Dizziness attacks become more frequent and worse, accompanied by nausea and vomiting. Tinnitus is also present outside of seizures. Hearing is also steadily declining. There may be constant pressing headaches, a feeling of stuffiness, and distention in the sore ear.
- Stage 3 (final). At this stage, the examination does not reveal the typical signs of dropsy of the labyrinth. There is an irreversible death of the receptor cells of both the auditory and the vestibular parts of the inner ear. Therefore, the dizziness attacks weaken- they become rarer and less pronounced. There is an unsystematic nature of unsteadiness of gait, swaying when walking. Hearing on the sore ear is significantly and persistently reduced.
Diagnostics Meniere’s disease
Routine examination of the outer ear and tympanic membrane does not reveal any changes. To establish a diagnosis of Meniere’s disease, a comprehensive examination of the inner ear is necessary. Tests with tuning forks, a study of hearing thresholds by taking an audiogram, vestibular tests, an X-ray examination of the temporal bones, CT and MRI of the head, ultrasound dopplerography of the head’s main vessels, and neck are carried out. Consultations of a neurologist, otoneurologist, otosurgeon, ophthalmologist, therapist, endocrinologist are required.
At the initial stage of the disease outside the attack, all indicators can be within normal limits, and the clinical symptoms resemble those in other diseases. It is necessary to identify and confirm the dropsy of the labyrinth to establish an accurate diagnosis. Currently, there are two reliable methods for diagnosing the hydrops of the labyrinth: electrocochleography and dehydration tests.
- Dehydration test technique. Initially, a hearing test is performed with an audiogram. Then the patient drinks a solution of glycerol with lemon juice. The amount of glycerol is calculated based on the patient’s body weight. Then again, remove the audiogram after 1, 2, 3, 24, and 48 hours after taking the solution. The test is considered positive if, after 2-3 hours, hearing improves by 5 dB over the entire frequency range or by 10 dB at three studied frequencies and speech intelligibility improves by at least 12% of the original. The test is considered negative if, after 2-3 hours, hearing decreases and speech intelligibility deteriorates. Other options are considered questionable.
- Electrocochleography technique. Electrocochleography is a recording of the electrical activity of the cochlea and the auditory nerve after a sound stimulus. A sound such as clicks is fed into the ear understudy at a predetermined interval. The device’s sensor amplifies the amplitude of the electrical signal arising in the cochlea’s hair cells, resulting in a graph resembling an ECG. The dropsy of the labyrinth has certain symptoms in this graph.
What other diseases can resemble Meniere’s disease? Tinnitus, dizziness, and hearing loss are not exclusive symptoms of Meniere’s disease; therefore, it is precisely a comprehensive examination of the patient using the above methods that are necessary to exclude other pathologies with similar manifestations: acute cerebrovascular accident, vertebrobasilar insufficiency, benign paroxysmal positional dizziness, brain tumors, skull trauma, labyrinth fistula, inflammation of the vestibular nerve, multiple sclerosis, purulent complications of acute or chronic otitis media, psychogenic dizziness.