Sensorineural Hearing Loss In One Ear

Introduction

Sensorineural hearing loss in one ear, also known as unilateral hearing loss (UHL), is a condition that affects the inner ear or the auditory nerve, resulting in an abnormality in the neural pathway that carries information between the inner ear and the auditory cortex, which is responsible for processing sounds in the brain. Research published in the International Journal of Audiology suggests that approximately 1 in 10 adults aged 50 years and older have some degree of UHL.¹ In developed countries, the estimated incidence of sensorineural hearing impairment (>40 dB HL) at birth is 1.86 per 1000 newborns, with 30-40% being unilateral. ² Given the prevalence of this condition, it is crucial for both patients and healthcare providers to understand its causes and available treatment options.

Causes of sensorineural hearing loss in one ear

Several factors can cause sensorineural hearing loss in one ear. One of the most common causes is ageing. The inner ear undergoes changes as we age, and this can lead to sensorineural hearing loss in one ear. 

Exposure to loud noises is another leading cause of sensorineural hearing loss in one ear. Prolonged exposure to loud noises, such as those encountered in a noisy workplace or from listening to music at high volumes, can damage the inner ear and lead to hearing loss.

Head trauma is another factor that can cause sensorineural hearing loss in one ear. A study published in the Journal of the American Academy of Audiology found that traumatic brain injury (TBI) is a significant cause of unilateral hearing loss in veterans. The study also noted that TBI-related hearing loss is often overlooked and undertreated. ²

Infections, such as meningitis or viral infections like cytomegalovirus, can also cause sensorineural hearing loss in one ear. 

Genetics can also play a role in sensorineural hearing loss in one ear. Certain genetic mutations can cause abnormalities in the inner ear or the nerve pathways that transmit sound signals. 

Ototoxic drugs: Certain drugs, such as some antibiotics and chemotherapy drugs, can be toxic to the inner ear and cause hearing loss. Some examples of ototoxic drugs include aminoglycoside antibiotics (such as gentamicin and streptomycin), chemotherapy drugs (such as cisplatin and carboplatin), and some loop diuretics (such as furosemide). These drugs can cause irreversible damage to the hair cells in the inner ear, leading to permanent hearing loss.

Meniere's disease: This is a disorder of the inner ear that can cause vertigo, tinnitus (ringing in the ears), and sensorineural hearing loss.

Acoustic neuroma: This is a non-cancerous tumour that can develop on the nerve that connects the inner ear to the brain. It can cause sensorineural hearing loss, as well as other symptoms.

Symptoms of sensorineural hearing loss in one ear 

Symptoms of sensorineural hearing loss in one ear can vary depending on the severity and underlying cause of the condition. However, some common symptoms of this type of hearing loss include:

Difficulty hearing in noisy environments: Patients with sensorineural hearing loss in one ear often have difficulty hearing in noisy environments, such as in crowded restaurants or in busy offices. This is because the affected ear is less able to filter out background noise, making it harder to focus on the sounds that the patient wants to hear.

Tinnitus: Tinnitus is a common symptom of sensorineural hearing loss in one ear. Patients with tinnitus hear ringing, buzzing, or other sounds in the affected ear, even when there is no external source of sound present.

Difficulty locating the source of sound: Patients with sensorineural hearing loss in one ear may have difficulty locating the source of sound. This is because sound localisation requires input from both ears, and if one ear is not functioning properly, it can be challenging to determine where sounds are coming from.

Muffled or distorted hearing: Patients with sensorineural hearing loss in one ear may experience muffled or distorted hearing in the affected ear. This can make it difficult to understand speech or other sounds clearly.

Diagnosis of sensorineural hearing loss in one ear

The diagnosis of sensorineural hearing loss in one ear is typically made through a hearing test or audiogram. This test measures the patient's ability to hear sounds at different frequencies and volumes by having them listen to sounds through headphones. During the test, the healthcare provider presents a range of tones and words to the patient and asks them to respond when they hear them. The audiogram provides a graph that shows the softest sounds the patient can hear at each frequency tested, and this graph helps the healthcare provider determine the type and severity of the hearing loss.^4,5

In some cases, imaging tests such as an MRI or CT scan may be ordered to identify the underlying cause of the hearing loss. These tests use noninvasive techniques to create detailed images of the inner ear and surrounding structures. Imaging tests are particularly useful when the hearing loss is sudden or accompanied by other symptoms, such as vertigo, tinnitus, or facial weakness, which may suggest a more serious underlying condition.

Imaging tests can also help identify specific causes of sensorineural hearing loss, such as tumours, malformations, or damage to the auditory nerve. For example, an MRI can detect a vestibular schwannoma, a type of benign tumour that can cause hearing loss and other symptoms. Additionally, a CT scan may be used to diagnose otosclerosis, a condition where the middle ear bones become fixed and cause hearing loss.

Treatment of sensorineural hearing loss in one ear

Treatment for sensorineural hearing loss in one ear depends on the underlying cause and severity of the condition. Some common treatment options include:^4,5

Hearing aids: Hearing aids can be used to amplify sound and improve hearing in patients with mild to moderate sensorineural hearing loss in one ear. These devices are custom-fit to the patient's ear and programmed to meet their specific hearing needs.

Cochlear implants: For patients with severe sensorineural hearing loss in one ear who do not benefit from hearing aids, cochlear implants may be an option. Cochlear implants are electronic devices that are surgically implanted in the inner ear and can directly stimulate the auditory nerve to provide a sense of sound to patients who are deaf or severely hearing impaired.

Bone-anchored hearing aids: Another option for patients with sensorineural hearing loss in one ear is bone-anchored hearing aids. These devices work by transmitting sound vibrations through the skull bone to the inner ear, bypassing the damaged part of the ear.

Antiviral medications or antibiotics: In cases where sensorineural hearing loss is caused by an infection, such as meningitis or mumps, antiviral medications or antibiotics may be prescribed to reduce inflammation and swelling in the inner ear and improve hearing.

Assistive listening devices: These devices, such as FM systems and captioning devices, can help improve speech understanding in noisy environments.

Speech therapy: Speech therapy can be helpful in improving communication skills and enhancing speech understanding.

Prevention of sensorineural hearing loss in one ear

Sensorineural hearing loss in one ear can often be prevented by taking certain precautions. Here are some steps that individuals can take to prevent this condition:

Avoid exposure to loud noises: Loud noises can cause damage to the inner ear and lead to hearing loss. It is essential to limit exposure to loud noises and wear earplugs or earmuffs when in noisy environments, such as concerts or construction sites.

Regular hearing check-ups: Regular hearing check-ups can help identify hearing loss early and allow for prompt intervention. It is recommended that adults have their hearing checked at least once every ten years until age 50 and then every three years thereafter.

Avoiding ototoxic medications: Some medications, such as certain antibiotics and chemotherapy drugs, can cause hearing loss. It is important to discuss any concerns with a healthcare provider before starting any new medication.

Protecting ears during water activities: Water in the ear canal can cause infection, leading to temporary or permanent hearing loss. Wearing earplugs or a swim cap can help prevent water from entering the ear canal during water activities.

By taking these preventative measures, individuals can help reduce the risk of developing sensorineural hearing loss in one ear and preserve their hearing for years to come.

Summary

Sensorineural hearing loss in one ear is a common condition that can have a significant impact on a patient's quality of life. Diagnosis typically involves a hearing test, and treatment options include hearing aids, cochlear implants, and bone-anchored hearing aids. Prevention strategies include protecting ears from loud noises and regular hearing check-ups. If you or someone you know is experiencing hearing loss in one ear, it is important to seek medical advice and explore available treatment options.