To reach the inner ear and generate an auditory signal, sound waves entering the human ear must be amplified by the vibrations of the eardrum and middle ear bones (ossicles). Otosclerosis is a disease in which the ossicles lose the ability to vibrate, resulting in progressive hearing loss.¹ Despite being more common in adults, otosclerosis can also affect children and adolescents who, according to studies also benefit from corrective surgery (stapedectomy) and hearing aids.²

Introduction

Otosclerosis is a medical condition in which the bones inside the middle ear undergo faulty remodeling preventing them from vibrating to sound. In turn, this affects the way sound waves are propagated to the inner ear and results in progressive hearing loss. In the United States, over 3 Million people are currently diagnosed with otosclerosis. Some risk factors include family history, previous Measles infection and fractures to the ear bones. Unfortunately, there is no definitive cure for otosclerosis, though surgery and hearing implants can reduce hearing loss and improve quality of life.¹

Otosclerosis most frequently affects adults, however, it can also occur in children and adolescents affecting as much as 4-6% of children and adolescents between 5 and 18. Amongst those diagnosed as adults, 15% had childhood-onset hearing loss. In fact, researchers estimate it might be an under-recognised cause of hearing impairment in children and young people.² Because of the anatomical and clinical differences between diagnosing and treating children and adults, understanding otosclerosis in the paediatric population is fundamental to identifying important features and providing the appropriate surgical or non-surgical treatment.

Causes and pathophysiology of otosclerosis

The human ear is organised into three main portions from outer- to innermost: the ear canal, the middle ear and the inner ear. Upon passing through the ear canal, sound reaches an air-filled chamber known as the middle ear where it causes the eardrum to vibrate, amplifying the original wave and eliciting a slight movement of the ossicle bones. These help transmit the amplified air wave to the fluid-filled inner ear where the subsequent movement of fluid activates specialised hair cells which send a signal to the auditory cortex in the brain.

Otosclerosis happens when the middle ear bones lose the ability to vibrate to sound, being unable to generate strong enough waves to move the fluid in the cochlea. It can occur due to fixation or remodelling of any of the ossicle bones, but most frequently it affects the stapes bone which becomes strongly attached to the oval window where it meets the inner ear. The cause of otosclerosis is poorly understood but different factors can increase the risk, such as genetic predisposition, suffering from chronic secretory otitis media, abnormal bone remodelling after a fracture, and being previously affected by certain autoimmune disorders or measles infection.¹³

Presentation and diagnosis of otosclerosis in children and adolescents

In children and adolescents, the most common cause of otosclerosis is the chronic secretory otitis media, a condition relatively frequent in the children where the middle ear mucosa is chronically inflamed with the persistent discharge. It is believed that the destruction mediated by the immune system can affect bone remodeling and the growth factors increasing the risk of otosclerosis.^3,4

Childhood/adolescence-onset sometimes called Juvenile Otosclerosis typically presents with progressive conductive hearing loss, which can affect one or most commonly both ears. Usually, otosclerosis causes greater difficulty in hearing the lower frequency sounds.² Some patients may also experience a form of ringing in the ears known as tinnitus. In young children, hearing loss can also be accompanied by the verbal development delay.^1,3

If otosclerosis is suspected, usually an Ears, Nose and Throat (ENT) doctor will first order an audiogram to assess and quantify hearing loss. Typically otosclerosis patients perform worse with lower-frequency sounds. Comprehensive clinical history, otoscopic examination and middle ear conduction studies can help rule out the other causes such as simple secretory otitis media, congenital stapes fixation, cholesteatoma or connective tissue disorders. ³ Tympanometry and acoustic reflex studies can be used to identify problems with the eardrum or the ossicles.2 Definitive diagnosis is often, however, only possible through high resolution CT scanning to visualise ossicle bone anatomy.⁵ 

How is childhood-onset otosclerosis treated?

The most effective treatment for otosclerosis in children is surgery, particularly a procedure called stapedectomy in which all parts of the bone are removed and replaced with a prosthetic that can adequately vibrate. Studies show over 80% of people with Juvenile Otosclerosis show hearing improvements with surgical treatment. Importantly, however, stapedectomy is not typically performed in children younger than 10 due to anatomical differences as it may carry a greater risk of nerve damage and potential sensorineural hearing loss.^2,6

The patients can also benefit from different types of hearing aids alongside, or sometimes instead of the surgery. Since most people with otosclerosis do not have anything wrong with the inner ear and cochlea, simple vibration amplifiers can greatly improve the hearing which might be enough to manage the condition. It is said otosclerosis tends to get worse over time to the point where a lot of patients require surgery.⁷

Medications are not normally used to treat otosclerosis. There is some evidence that sodium fluoride supplements and a class of medicines known as bisphosphonates can delay the progression of otosclerosis by affecting bone composition. However, their use is not recommended due to the limited efficacy and risk of side effects.^{7, 8} 

FAQ’s

What is otosclerosis?

Otosclerosis is a medical condition that affects the ossicle bones of the middle ear preventing them from vibrating and propagating sound waves to the inner ear. Most commonly, the stapes bone becomes fixated to the oval window.¹ 

Can children and adolescents develop otosclerosis? 

Yes, although otosclerosis is more commonly diagnosed in adults, children and adolescents can also develop the condition, particularly if they have a chronic secretory otitis media or a family history of otosclerosis.³ 

How can otosclerosis affect a child's development?

Hearing loss from otosclerosis can impact speech and language development, academic performance, and social interactions. Early diagnosis and treatment are crucial to mitigate these effects. ⁽³⁾

How is otosclerosis in children treated?

The main treatment for otosclerosis in children and adolescents is corrective surgery to replace the stapes bone with a functional prosthetic.² In mild cases, however, hearing deficiencies can sometimes be corrected with hearing aids and implants.³ In addition, there is some evidence that sodium fluoride supplements might delay disease progression.⁸ 

What should parents do if they suspect their child has otosclerosis?

If parents notice signs of the hearing loss or any related symptoms, they should consult an audiologist or an otolaryngologist (ear, nose, and throat specialist) for a comprehensive evaluation and appropriate testing.

Summary

Otosclerosis is a relatively common cause of hearing loss in adults that results from abnormal fixation of the middle ear bones preventing them from adequately vibrating to the sound waves. In children and adolescents, however, the exact prevalence of otosclerosis is poorly documented, but it is believed it might be higher than previously thought. Certain factors might also increase the risk of Juvenile Otosclerosis such as Chronic suppurative otitis media, previous measles infection, certain autoimmune disorders, or simply genetic predisposition.

Children affected will normally present with progressively worse hearing difficulties, which, in toddlers, might also be accompanied by delays in verbal development. ENTs will typically start by performing an audiogram test to assess the child's hearing and investigate possible causes of any impairment present. Otoscopy, middle ear conduction studies and acoustic reflex tests can all help identify the site of the problem. If there is a strong suspicion of otosclerosis, a CT scan can be ordered to get an image of the ossicle bones.

Surgical correction through stapedectomy is the most effective treatment for otosclerosis in both adults and children, however, it is not recommended in patients younger than 10 due to the possible risk of complications. Instead, hearing aids can be used to ameliorate hearing difficulties.

Understanding the similarities and differences between otosclerosis in children and adults is fundamental to grasp how the condition presents itself and can be managed in younger individuals. As we expand our awareness of Juvenile Otosclerosis, new guidelines and treatment options will arise to tackle the unique challenges faced by paediatric populations.