Endolymphatic hydrops

The cochlear hydrops, endolymphatic hydrops or Labyrinthhydrops is a disorder of the inner ear. He has long been regarded solely as a pathological mechanism of Meniere's disease. Yet, recent studies show that the cochlear hydrops without the frame of Meniere's disease can occur. The etiology (cause) of the endolymphatic hydrops is still unclear.

History

For the first time the endolymphatic hydrops has been described in human temporal bone preparations Menière's disease in 1938 by Yamakawa in Japan and a few months later by Hallpike and Cairns in England. Both groups found a curvature of the Reissner membrane towards scala vestibuli and makes an obstruction in the stria vascularis, the cochlear aqueduct and the internal auditory canal. Further confirmatory observations were made by Altmann and Fowler, 1943 by Lindsay in 1946, Brunner 1948 and Paparella 1984.

Description

• Perilymph of the scala vestibuli and scala tympani (both are available from the helicotrema in conjunction )
• Endolymph of the scala media
• Organ of Corti
• Tectorial membrane
• Basilar membrane
• Reissner membrane
• When hydrops the Reissner membrane is curved by the pressure of the endolymph in the scala media toward Scala vestibuli.

The cochlea ( cochlear ) of the inner ear contains three courses: Atrial stairs ( scala vestibuli ), auger ( scala media or cochlear duct ) and scala tympani ( scala tympani ). The atrium stairs and the scala tympani are available through the helicotrema (Greek: Screw hole ) at the "top " of the cochlea with each other, the spiral ends at the screw tip. The worm gear is separated from the scala vestibuli by Reissner membrane of the scala tympani by the basilar membrane. In the worm gear, the organ of Corti, which is responsible for the conversion of sound waves into nerve impulses and thus of the actual auditory sensation is. The screw flights are filled with liquids of different composition, scala vestibuli and scala tympani with perilymph of the cochlear duct with endolymph (of endolymph is derived the term endolymphatic hydrops from ).

Under a cochlear hydrops ( hydrops = dropsy, accumulation of fluid ) is defined as an increase of the endolymph in the cochlear duct. It creates a positive pressure in the worm gear. Its diameter is increased by the Reissner membrane is bulging toward the atrium staircase. Primary cause is overproduction of endolymph or too low a flow of endolymph. But what leads to the overproduction or congestion, is largely unclear.

It is believed that an excessive pressure on the Reissner membrane to tear this membrane and can lead to a Menière'scher attack is triggered.

Cause

The cause of endolymphatic hydrops is unknown. Explanations range from a excessive salt content in food intake, autoimmune reaction, allergic reactions to a viral illness. None of these possible causes could be clinically confirmed and thus corroborated. As a psychological cause, stress is often called.

Studies suggest that does not have to be just looking for a cause, but several causes can lead to a Endolymphstau. Possibly. the cochlea responds relatively sensitive to all kinds of loads, which may lead to a disruption of the Zufluss-/Abflusssystems the endolymph and finally results in a endolymphatic hydrops.

Symptoms

These symptoms must not occur. More often, even single phenomenon groups, such as vertigo without hearing loss and tinnitus or hearing loss and tinnitus without vertigo.

• The excess pressure, the patient may perceive as a pressure that is perceived similarly as the pressure in the middle ear by changes in air pressure.
• The overpressure the organ of Corti is affected. The patient takes this mostly true in the form of a low-frequency tinnitus.
• Also, the pressure on the organ of Corti can lead to hearing impairment. The patient hears " as if through cotton wool ." It can generally hear low sounds bad as well.
• Sometimes, the disease also leads to dizziness, which may briefly or longer occur. Must be distinguished dizziness was from a long-lasting severe dizziness, such as occurs during a Meniere's attack.

Other symptoms of physical illness often joined after diagnosis should also psychological symptoms.

• Depression because of the hearing loss and the consequent impaired quality of life.
• Anxiety prior to an exacerbation of the disease and before a possible beginning of a Crohn's Meniere's disease.

Diagnosis

These procedures help to suspect a cochlear hydrops:

• Tuning fork tests: Was Weber test and Rinne test may be close to an inner ear problem.
• With an audiogram by a hearing test on air and bone conduction can be determined whether especially the hearing has decreased in the low frequency range.
• Information of the patient: he Describes a hearing disorder that primarily affects low frequencies and a " listening through cotton wool " and low frequency hum and pressure in the ear, must in addition to other causes such as sudden deafness or conductive hearing loss, a cochlear hydrops should be considered.

Treatment

Most of the dropsy is treated with betahistine. Betahistine attacks, among others, the histamine H1 receptors of the inner ear, where it acts a vasodilator, which leads to a decrease of the excess pressure in the worm gear. In addition, the excitation of nerve cells, the equilibrium nuclei is inhibited, resulting in a positive effect, together with the improved blood circulation in the vertigo symptoms. Should be administered 48 mg per day. There are sometimes problems with the regression of the hydrops, if too low a dose has been prescribed. Even with mild symptoms, a dose of 48 mg is attached, so that the excitation of the blood vessels by the betahistine can take full effect.

Aftermath

Also a back hydrops previous can cause permanent damage to the inner ear. Distinction must be made between objectively and subjective issues.

As the organ of Corti is charged during the dropsy, after a decline hydrops tinnitus can stay. This may come an increased sensitivity to noise. Loud sound waves are bothersome or almost painful. Likewise Hörempfindungsstörungen can remain as reverberation. It may be as well as the subjective feeling, the tone of what is heard acts like " remixed ". These phenomena are partially explained physically as a permanent or temporary impairment of the organ of Corti, but also by psychological processes, such as increased mental alertness to the affected ear.

All these after-effects may lessen over time. First, because recovering the cochlea and, secondly, because the brain is used to the new hearing sensation.

Demarcation to Meniere's disease

Although the classification according to ICD -10 Meniere's disease is classified the same as the endolymphatic hydrops, but must be distinguished probably in the future. This is the result from the conclusions of the current research cause. Recent studies show that a hydrops probably seen not only from a single cause, but rather can occur fluctuations of Endolymphmenge also in healthy people. Therefore, the ear can respond to all kinds of loads with Endolymphstau. Probably the hearing organ evolutionarily developed earlier also reacts more sensitive than the older organ of balance, which can help balance Endolymphschwankungen. But a specific reason might be assumed for Meniere's disease, which leads to a chronic or recurrent hydrops.

The most severe form of a cochlear hydrops is a chronic hydrops or a recurrent hydrops including seizures with symptoms of Meniere's triad. From the appearance of the first symptoms to the development of a full - 's disease Meniere's disease is an average of one year. The practical experience of ear, nose and throat doctors and a study from Japan shows that only about ten percent of diagnosed hydrops cochleae forms a chronic Meniere's disease. Approx. 70 % of patients who do not suffer from Meniere's disease, develop normal hearing again. Only 30 % keep a fluctuating hearing loss, which could be confirmed over ten years, at follow-up. Can be concluded from these statistical considerations, of course, not yet fully own disease.