Ossiculoplasty is a surgical treatment that aims to reconstruct at least one of the bones (ossicles) of the middle ear.¹ It is recommended that hearing loss has occurred as a result of ossicular damage.¹ In this article, we bring your attention to a condition commonly treated with ossiculoplasty: tympanosclerosis.² Secondly, we provide an overview of ossiculoplasty, including what it entails, its successes and risks. 

Role of the middle ear

The middle ear is a part of the human anatomy that captures and transmits sounds from the external ear to the inner ear, where they are turned into electric signals that the auditory nervous system can interpret.^3,4 The first element to receive these vibrations is the eardrum (also known as the tympanic membrane). For vibrations to travel from the eardrum to the inner ear, they need to cross the middle ear through the ossicular chain –three tiny bones called the malleus, incus and stapes.^3,4 Malfunction of any part of this mechanism results in conductive hearing loss.⁵ 

Overview of Tympanosclerosis

What is tympanosclerosis? 

Tympanosclerosis is an irreversible condition referring to the presence of hardened scar tissue on the eardrum, the middle ear cavity and/or ossicles.⁶ Although the exact circumstances leading to the development of tympanosclerosis are not fully understood, it occurs when the middle ear abnormally recovers from an inflammation.⁶ Indeed, in some cases, the recovery from inflammation creates scar tissue, in other terms, tympanosclerosis.⁶ It is generally accepted that this is most likely to happen for people with a genetic predisposition to the condition and people with a history of chronic ear infections (also known as chronic otitis media).^7,8,9,10 The exact incidence of tympanosclerosis is hard to determine, but it is currently estimated between 3% and 33% for people with a history of chronic ear infections.² In children, tympanosclerosis is most often only seen on the eardrum (in this case, it is called myringosclerosis), whereas the rest of the middle ear is most often affected in adults.^6,11 

Generally, it appears that events causing inflammation of the middle ear are the main causes for tympanosclerosis:⁶

• Ear infections (chronic): repeated inflammation during infection episodes
• Surgery of the ear: surgeries cause trauma to the ear, which the immune system responds to by inflaming the area
• Genetic predisposition: the type of inflammatory mediators produced as a response to inflammation is determined by someone’s genes

What does tympanosclerosis do?

Despite being irreversible, tympanosclerosis does not always cause symptoms. Many people with tympanosclerosis do not know they have it, and it causes no harm. It is usually the case when only the eardrum is affected.^12,13  However, if tympanosclerosis is on any elements of the middle ear, particularly the ossicles, it affects the ability for sound to travel to the inner ear and causes hearing loss. Indeed, the hardened tissue created during the abnormal healing of the ear makes the ossicles stiffer and sometimes fuses, compromising their ability to transmit sound vibrations.¹⁴ This is known as conductive hearing loss, and can be partial or complete. 

The presence of tympanosclerosis is usually suspected if hearing loss starts after repeated ear infections or ear surgery. It is more formally diagnosed by confirming the presence of white plaque on the eardrum and/or middle ear using medical imaging techniques such as otoscopy and CT scanning.^6,14 

Treatment

Tympanosclerosis only requires treatment in the case of hearing loss.⁶ Depending on the case, a specialist will either recommend hearing aids or surgical intervention to remove tympanosclerosis or replace elements of the middle ear, for example, ossiculoplasty.^6,16 

Overview of Ossiculoplasty

What is ossiculoplasty?

Ossiculoplasty is a surgical intervention of the middle ear that aims to reconstruct the malfunctioning elements of the ossicular chain.¹ Damage to the ossicular chain includes a break in the chain (discontinuity) or fixation of the elements. These can be caused by a range of events such as:

• Trauma: injury caused directly by a foreign body into the ear canal or indirectly through a head injury can disrupt the ossicular chain and lead to conductive hearing loss^1,17
• Surgery: The middle ear is a small space, therefore, any accidental movement of the ossicles during ear surgery might disrupt their ability to transmit sounds¹
• Ear pathology: Some conditions, such as cholesteatoma, otosclerosis, chronic suppurative otitis media, and tympanosclerosis, can damage ossicles^1,18

How does ossiculoplasty work?

In practice, ossiculoplasty is usually performed under general anaesthesia and consists of removing the damaged parts of the ossicular chain and replacing them with bone grafts (bone from other parts of the human body) or prosthetics, depending on the cause behind the original damage and how many ossicles are affected.^1,18 The use of autografts (graft of the patient’s tissue) can be too time-consuming for surgery, and homograft (graft of another human individual’s tissue) presents a higher risk of infection.^1,6 Therefore, synthetic (alloplastic prosthetics are most often used.¹ They can be made of metals (titanium and gold), plastics, ceramics or hydroxyapatite.^1,6,19 These materials present different properties which lead to more or less hearing recovery depending on the original damage of the ossicular chain and individual ear anatomy. It is therefore best to choose the prosthesis material on a case-by-case basis.^1,6,18,19

The surgery follows one of two approaches: endoscopic or microscopic.¹⁸ Both techniques offer different benefits and negatives, but the majority of studies have not shown any significant difference in long-term hearing outcomes and complication rates.¹⁸ Therefore, a surgeon will choose one of the approaches depending on particular cases, circumstances and resources.

• Microscopic approach: The surgeon can use both hands to operate, which lowers the risk of burns¹⁸
• Endoscopic approach: closer image of the middle ear, decreased chances of residual disease, and shorter surgery¹⁸

Treating tympanosclerosis with ossiculoplasty

Tympanosclerosis refers to hard and scarred tissues in the middle ear cavity and on the ossicles that form the ossicular chain.⁶ As a result of this condition, the parts of the ossicular chain become stiffer, limiting the transmission of sound vibrations to the middle ear, resulting in conductive hearing loss.^5,6

To recover hearing in tympanosclerosis cases, it is recommended to try using hearing aids.⁶ If unsuccessful, getting ossiculoplasty to remove the disease from the bone surface of the ossicles and/or replacing them with prosthetics can be considered, depending on the severity of the condition and the areas affected.^2,6 

Success of ossiculoplasty in tympanosclerosis 

Ossiculoplasty is considered a successful treatment for tympanosclerosis if the patient recovers hearing long-term and if no or few complications arise post-surgery.²⁰ To achieve this goal, many factors need to be taken into account, such as:

• Severity of tympanosclerosis: the chances of successfully removing tympanosclerosis are higher if the stapes is not fixed to the oval window. If it is, the operation requires mobilising it, increasing the chances of complications²
• Surgical approach: the anatomy of the patient, resources available, the severity of the condition and the areas affected are considered to choose the most appropriate approach (microscopic or endoscopic)¹⁸
• Type of graft (and its material): if a prosthesis is needed, the choice of the material depends on resources and the patient’s anatomy^1,6,19
• Ear environment: More hearing can be recovered after ossiculoplasty if the ear has not been changed by the effects of chronic ear infections²⁰

Risks and complications 

Surgery always represents a risk, even in the best circumstances, particularly in the middle ear, where the area is small and requires high levels of precision. Consequently, the use of surgery as treatment for tympanosclerosis is still highly debated among experts, as some consider that the risks outweigh the positives.^2,15 The main concerns related to ossiculoplasty are:

• Residual or returning hearing loss: In these cases, the ossiculoplasty did not completely restore the ossicular chain, and conductive hearing loss returns either short-term or long-term after surgery²¹ 
• Infection: The incision needed to perform the surgery exposes the surgical site (in this case, the middle ear) to bacteria²²
• Prosthesis dislocation: the prosthesis moves out of its place, causing a return of hearing loss and a need for revision surgery to resolve the issue^21,23
• Sensorineural hearing loss: This could be caused by accidental damage to the inner ear during surgery in the middle ear²
• Facial palsy: This could be caused by accidental damage to the facial nerve during surgery in the middle ear²

Summary

Tympanosclerosis can be found on the eardrum, middle ear cavity and ossicular chain. It consists of the formation of hard scar tissue, which can impact the ability of sound vibrations to travel from the eardrum to the inner ear. In most cases, it is asymptomatic, but for some, it causes conductive hearing loss. If hearing aids fail to help the issue, ossiculoplasty can be considered as treatment for tympanosclerosis.

Ossiculoplasty is a surgery that aims to repair and/or replace malfunctioning parts of the ossicular chain so that sound vibrations can be transmitted and hearing can be recovered. Although it can be an efficient solution in milder cases of tympanosclerosis, risks are involved with this procedure, particularly in more severe cases and/or those of stapes fixation.

The use of ossiculoplasty as treatment for tympanosclerosis can yield great results and long-term hearing recovery. However, it is not always an appropriate solution depending on ear health history, patient’s anatomy, severity of the condition and areas affected.