Otosclerosis: Gradual Hearing Loss

Beethoven was undoubtedly one of the very great European composers. He composed some of his most famous works when he could only communicate with “conversation books” due to his deafness. His progressive hearing loss began when he was only 26 years old. Today, most researchers believe that its cause was otosclerosis of the inner ear.

What is otosclerosis?

Behind the eardrum, three tiny ossicles sit in the tympanic cavity: Mallet, Anvil and Stirrup. They are movably connected like a chain, dampening sound waves arriving from outside and transmitting them further into the inner ear. The stapes, the smallest bone in the body, is attached to the membrane of the oval window, the connection to the inner ear. In otosclerosis, remodeling processes and increased new bone formation occur in various parts of the middle and inner ear. Hence the name for this disorder derived from the Greek: “oto” for ear, “sclerosis” for hardening. The oval window and stapes are almost always affected, and in some cases, structures of the inner ear such as the cochlea or the organ of equilibrium. The new bone can grow around the attachment site of the stapes and virtually wall it in. As a result, this ossicle increasingly loses its mobility (stapes fixation) and becomes less and less capable of performing its task of transmitting sound. Hearing disorders (conductive hearing loss) are the result. If the inner ear is also affected by the ossifications, this can also lead to ringing in the ears (tinnitus) and – rarely – to dizziness. There are also cases in which only the inner ear is affected (capsular otosclerosis); then there is a pure sensorineural hearing loss, the sound conduction is intact.

Who is affected and what are the causes?

Otosclerosis almost always begins between the ages of 20 and 40. Studies show that women suffer from the disease about twice as often as men, and whites are again particularly susceptible. In almost two-thirds of cases, both ears are affected in the course of the disease. It is still not known exactly how new bone formation occurs. A genetic component has long been suspected. Studies indicate that certain genes are altered at a specific site in otosclerosis patients. However, it still cannot be ruled out that other triggers are present. For example, in many affected women, symptoms worsen during pregnancy or menopause, suggesting hormone involvement. In some patients, antibodies to measles have been found in the inner ear fluid, which is why viruses are also being discussed as a trigger.

What symptoms does otosclerosis cause?

In most affected individuals, hearing loss becomes noticeable after the age of 20, usually initially in one ear, and later often in both ears. This progresses slowly but steadily to complete deafness. Many also suffer from ringing in the ears (tinnitus). If the inner ear is also affected, dizziness may be added. A common symptom is that sufferers hear better in ambient noise – this phenomenon is known as “paracusis willisii”. The cause is presumably that, on the one hand, other people automatically speak louder in such situations and, on the other hand, that the disturbing ear noises then become less noticeable. The affected persons themselves speak rather softly, since the own voice is passed on over the bone, which works.

How is the diagnosis made?

There is a whole range of ear examinations, but ultimately these only give more or less clear indications of otosclerosis or allow other diseases to be ruled out. The physician puts the examination results together like a puzzle. The following examinations are used to diagnose otosclerosis:

  • Medical history interview: In the conversation, the doctor clarifies with you whether there are any possible pre-existing conditions and exactly what your symptoms are.
  • Otoscopy: With a magnifying glass, the doctor examines the eardrum and the auditory canal, for example, to rule out inflammation. In most cases, otosclerosis is not visible during an otoscopy.
  • Tuning fork test (Weber / gutter test): In the context of the tuning fork test, such is struck and placed on different parts of the head or held in front of the ears.In doing so, you tell the doctor if and if so when you can no longer perceive vibrations of the tuning fork.
  • Gellé test: in addition to striking the tuning fork, a rubber ball is placed on the ear canal. This creates an overpressure, which impedes the conduction of air in a normal hearing. The sound of the tuning fork seems softer. In the case of otosclerosis, however, the sound does not change for the affected person.
  • Speech audiogram: with the help of a speech audiogram, speech understanding is measured.

Magnetic resonance therapy and computed tomography, respectively, can provide an accurate picture of the ear and skull region if otosclerosis is suspected.

What therapy is available for otosclerosis?

The most important treatment method for otosclerosis, if the inner ear is not affected or hardly affected, is microsurgical operation. This involves partial removal of the stapes, drilling a hole in its base plate, inserting a stamper-shaped prosthesis (called a piston) made of Teflon, platinum, titanium, or gold, and attaching it to the anvil with a small eyelet. This procedure (stapedotomy/stapedoplasty) restores the mobility of the ossicular chain and thus the transmission of sound to the inner ear. In the past, the entire stapes was often replaced by a prosthesis (stapedectomy). This procedure is rarely used today due to the higher risk. If sensorineural hearing loss is also present, surgery will not help. In such cases (or if surgery is not desired by the affected person), a hearing aid can be fitted. This amplifies sound but does not prevent the progression of the disease.

Procedure of the surgery

The operation lasts at least 30 minutes and is usually performed under local anesthesia – this has the advantage that the doctor can already check the hearing during the procedure. Access is gained from outside the ear canal by cutting open the eardrum and folding it away. This allows access to the tympanic cavity and – after removing the upper stirrup – a hole can be drilled in its “foot” with a needle or laser beam. Improvement usually occurs within two weeks after surgery at the latest.

What do you need to watch out for after surgery?

For the first few days after surgery, the ear canal is stuffed with a sponge or gauze strip soaked in antibiotic ointment. The patient must stay in the clinic for about two to three days, and is usually off sick for two to three weeks. During the first two weeks, no water should get into the ears; therefore, even when showering, a bathing cap, earmuffs or similar should be worn. About four to six weeks pass until complete healing. During this time, the affected person should not yet undertake any air travel or diving, as the pressure fluctuations can damage the ear. Some experts even advise not to do so for three months. In case of a cold, decongestant nasal drops should be taken for the same reason.

Cochlear implant as an alternative

An alternative in the treatment of otosclerosis, especially in cases of sensorineural hearing loss, is the cochlear implant (CI). This is placed behind the pinna under the skin. Through a thin channel, the doctor inserts an electrode into the cochlea, which is connected to the implant. The cochlear implant converts sound waves into electrical impulses, which it transmits to the auditory nerve. After surgery, there may be soreness and light bleeding. Stitches are removed approximately seven days after surgery. It usually takes two to three weeks for the wounds to heal completely. The implant is activated for the first time about four to six weeks after the operation. This requires a hospital stay of several days. During this time, the patient receives instructions on how to use the cochlear implant and the first hearing tests are performed. In the following months, hearing training also takes place with a speech therapist.

Course and prognosis in otosclerosis

The difficulty in treating otosclerosis lies in deciding whether and when to operate. The sooner the surgery is performed, the easier it is to succeed and the higher the success rates (improvement of hearing in more than 90 percent, and in many, disappearance of tinnitus). However, as with any surgery, complications can occur, which of course makes the decision to operate at a time when hearing is not yet too impaired difficult.Thus, hearing deteriorates in affected individuals after surgery in about one percent of cases, and deafness even occurs in 0.5 percent.