Definition

The ear has three main parts: the outer ear, middle ear, and inner ear. Sound vibrations travel from the outer ear through the middle ear, passing through the inner ear, and are then transmitted to the brain. The brain interprets these sound vibrations, allowing the listener to understand the sounds.

Obstruction or damage to the outer or middle ear can hinder sound transmission to the inner ear and brain, causing hearing impairments or conductive hearing loss.

Common causes of conductive hearing loss include blockages in the ear canal, which can be caused by earwax buildup, for example, or damage to the outer or middle ear structure. Conductive hearing loss can make it difficult to hear soft sounds. Depending on the cause, it can be temporary or permanent.

Causes

 Conductive hearing loss occurs when sound waves fail to reach the inner ear due to complications of hearing impairments in the outer ear or middle ear.

External ear conditions that can lead to conductive hearing loss include:

• Presence of small objects or insects lodged in the ear canal, whether in the outer part or middle part of the ear
• Accumulation of earwax in the ear canal
• Abnormal bone growth obstructing the ear canal
• Infections in the ear canal
• Fluid buildup
• Structural abnormalities
• Narrowing of the ear canal

Middle ear complications that may cause conductive hearing loss encompass:

• Middle ear infections and fluid buildup
• Damage to the tympanic membrane (eardrum)
• Perforation of the eardrum
• Eardrum collapse due to pressure
• Thickening of the eardrum
• Excessive growth of skin cells within the middle ear
• Damage to the auditory ossicles
• Congenital conditions like otosclerosis leading to bone deformities and obstructions in the ear

Risk factor

Several factors may increase the risk of developing conductive hearing loss:

• Frequent ear infections
• Habitual ear cleaning with cotton buds or other small objects that may damage the eardrum
• Swimming
• Prolonged exposure to moist ears
• Exposure to bacteria-laden water in the ears

Symptoms

Individuals with conductive hearing loss typically struggle to hear low-volume or soft sounds, often requiring them to increase the volume on personal devices such as phones, televisions, or speakers.

Additional symptoms of conductive hearing loss may include experience such as:

• Sudden hearing loss
• Progressive worsening of hearing
• Ear pain (in one or both ears)
• Dizziness
• The unpleasant odor coming from the ears
• Ear discharge

Diagnosis

Anamnesis

The doctor will ask you about your medical history and symptoms regarding your hearing loss.

Physical examination

A physical examination is conducted to identify any abnormalities in the ear, such as obstructions in the external ear canal due to infection, tumors, bone abnormalities, or perforations in the eardrum.

Diagnostic tests

Your doctor can recommend various tests to ascertain the type and cause of hearing loss. Audiometry is typically the initial test used to help in diagnosing conductive hearing loss. Audiometric results help determine whether the hearing loss is conductive, sensorineural, or mixed, as well as find the severity of the condition. During this test, you will listen to sounds through the provided headphones and be asked about the sounds you hear.

In addition to audiometry, other diagnostic tests for conductive hearing loss include:

• CT scan, MRI scan, or other imaging tests. These tests can provide detailed images of the ear's structure and help identify the cause of the conductive hearing loss.
• Tympanometry. This test measures middle ear pressure and detects eardrum movement, which is crucial for sound transmission. Normally, an eardrum vibrates when soundwaves pass through it, and the soundwaves are transmitted to the inner ear. An immobile eardrum can impede sound transmission.
• Acoustic reflex test. This assesses the ear muscle's response to sound.
• Static acoustic measures. This test helps detect perforations in the eardrum.

Another diagnostic test that can be recommended by your doctor, often used for infants, is the otoacoustic emission test. This test evaluates any blockage and damage to the ears while checking the brainstem's response to sound.

The Weber and Rinne tests can employ a tuning fork for screening purposes.

Management

Treatment for conductive hearing loss varies based on the cause. Some conditions may resolve spontaneously, others require medical intervention, and some causes are permanent. Treatment options include:

• Removal of earwax or foreign objects obstructing the ear canal.
• Antibiotics for ear infections caused by bacteria.
• Surgery to repair and remove excessive growth of skin cells in the ear.

Hearing aids may be necessary for permanent causes, such as ear canal narrowing. Some hearing aids can be surgically implanted.

Complications

• Conducive hearing loss can lead to delays in speech and language development in children, potentially impacting their progress in school if not diagnosed and treated promptly. 
• Conductive deafness caused by the excessive growth of skin cells in the middle ear (cholesteatoma) can significantly damage surrounding ear structures. 
• Furthermore, untreated conductive deafness in some cases, may result in permanent hearing loss.

Prevention

To prevent ear infections, regularly visit your doctor and follow the prescribed treatment regimen until it is complete. 

• Avoid using cotton buds or other small objects to clean your ears, as these can damage the eardrum. 
• Keep your ears dry to prevent them from becoming excessively moist.

When to see a doctor?

Please seek medical attention immediately if you experience symptoms of sudden hearing loss, progressively worsening hearing loss, or severe ear pain.

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