What is Mixed Hearing Loss? : Conductive vs Sensorineural Hearing Loss
Many people worry about hearing loss, and many have already experienced it without knowing the specific type they have.
Hearing loss varies in symptoms, diagnosis, causes, and most importantly, the crucial methods of treatment based on its type.
Mixed hearing loss encompasses characteristics of both conductive and sensorineural hearing loss, making it essential to understand the traits of these two types to cope effectively.
This article provides insights into the types of hearing loss, differences between conductive and sensorineural hearing loss, the causes, diagnosis, and coping strategies for mixed hearing loss.
Hearing loss Type
There are several types of hearing loss, each categorized based on the affected part of the auditory system.
The main types of hearing loss are:
Conductive Hearing Loss:
- This type of hearing loss occurs when there are problems in the outer or middle ear, hindering the transmission of sound waves to the inner ear.
- Common causes include ear infections, earwax blockage, or issues with the ear canal, eardrum, or middle ear bones (ossicles).
- Conductive hearing loss can often be medically or surgically treated.
Sensorineural Hearing Loss:
- Sensorineural hearing loss results from damage to the inner ear (cochlea) or the auditory nerve pathways in the brain.
- It is usually permanent and can be caused by aging, exposure to loud noises, genetics, head trauma, certain medications, or diseases affecting the inner ear (such as Meniere's disease).
- Sensorineural hearing loss is typically managed with hearing aids or cochlear implants.
Mixed Hearing Loss:
- Mixed hearing loss is a combination of conductive and sensorineural hearing loss, meaning there are problems in both the outer/middle ear and the inner ear or auditory nerve.
- Treatment options depend on the specific causes contributing to the mixed hearing loss.
Central Hearing Loss:
- Central hearing loss occurs due to problems in the central auditory nervous system (brain and central neural pathways).
- This type of hearing loss can affect the brain's ability to process sounds, even if the ears are functioning normally.
Auditory Neuropathy Spectrum Disorder (ANSD):
- ANSD is a hearing disorder where sound enters the inner ear normally, but the transmission of signals from the inner ear to the brain (auditory nerve) is impaired.
- This results in difficulty understanding speech, especially in noisy environments.
Conductive vs Sensorineural Hearing Loss : Symptoms, Diagnosis, Cause, Treatment
Among the various types of hearing loss, the most common ones are likely conductive hearing loss and sensorineural hearing loss. While briefly introduced above, this paragraph will specify their differences based on symptoms, diagnosis, causes, and treatment methods.
Conductive Hearing Loss:
Conductive Hearing Loss Symptoms:
Sounds may seem faint or muffled.
Difficulty in hearing soft sounds.
Ear pain or discomfort.
Tinnitus (ringing in the ears) is less common but can occur.
- Conductive Hearing Loss Diagnosis:
Physical Examination: A healthcare professional examines the ears to look for blockages, earwax, or abnormalities.
Tympanometry: Measures the movement of the eardrum in response to air pressure changes, helping identify problems in the middle ear.
Pure-Tone Audiometry: Determines the extent and nature of hearing loss by testing the ability to hear sounds at various frequencies.
Earwax Blockage: Accumulation of earwax in the ear canal.
- Conductive Hearing Loss Causes:
Otitis Media: Middle ear infection causing fluid buildup.
Otosclerosis: Abnormal bone growth in the middle ear.
Perforated Eardrum: A hole or tear in the eardrum.
Medical Management: Addressing the underlying cause (e.g., removing earwax, treating infections).
- Conductive Hearing Loss Treatment:
Hearing Aids: Amplify sounds to compensate for the hearing loss.
Surgery: In cases like otosclerosis, surgery might be performed to restore hearing.
- Sensorineural Hearing Loss:
Difficulty understanding speech, especially in noisy environments.
- Sensorineural hearing loss Symptoms:
Inability to hear faint sounds.
Tinnitus is common and can be severe.
Sounds may seem distorted or unclear.
Pure-Tone Audiometry: Measures hearing sensitivity across various frequencies.
- Sensorineural hearing loss Diagnosis:
Speech Audiometry: Assesses the ability to hear and repeat spoken words.
MRI/CT Scan: Helps identify structural issues in the inner ear or auditory nerve.
Aging (Presbycusis): Natural aging process affecting inner ear hair cells.
- Sensorineural hearing loss Causes:
Noise Exposure: Prolonged exposure to loud noises damages hair cells.
Genetics: Inherited factors can contribute.
Illnesses or Medications: Certain diseases or drugs can cause sensorineural hearing loss.
Hearing Aids: Amplify sounds for improved hearing.
- Sensorineural hearing loss Treatment:
Cochlear Implants: Surgical devices that provide a sense of sound for individuals with severe or profound hearing loss.
Speech Therapy: Helps improve speech recognition skills.
Management of Underlying Causes: Addressing contributing factors where possible (e.g., managing diabetes or changing medications).
Mixed Hearing Loss Symptoms
- Conductive Hearing Loss Symptoms:
Feeling of Blocked Sound: Hearing feels obstructed, as if something is blocking the ear canal.
Ear Pain or Fluid Discharge: Pain, swelling, or fluid drainage from the ear can occur.
Sounds Muffled or 'Dead': Sounds are significantly muted and difficult to hear.
Temporary Hearing Loss: Hearing loss can sometimes be temporary and might be improved by using earplugs or covering the ear with a hand.
- Sensorineural Hearing Loss Symptoms:
Difficulty Understanding Speech: Speech may sound less clear, and distinguishing certain sounds can be challenging.
High-Frequency Hearing Loss: Difficulty hearing high-frequency sounds (e.g., consonants).
Tinnitus: Ringing or buzzing in the ears might be present.
Balance Issues: Inner ear problems can lead to balance disturbances.
Sounds Amplified or Distorted: Some sounds may be overly loud or distorted.
- Mixed Hearing Loss Symptoms:
Mixed hearing loss combines symptoms from both conductive and sensorineural hearing loss.
Consequently, sensations of blocked sound, difficulty understanding speech, and other symptoms from both categories can occur simultaneously.
The specific symptoms experienced can vary based on the degree and underlying cause of the hearing loss, emphasizing the importance of professional evaluation and diagnosis.
Mixed Hearing Loss Types : Unilateral hearing loss, Biliateral hearing loss
The prevalence of mixed hearing loss, whether unilateral or bilateral, depends on various factors including the underlying causes and individual health conditions.
However, in the case of Sensorineural Hearing Loss, often, it is bilateral hearing loss because the sensitivity of the auditory nerve diminishes with age. You can check the comparison of unilateral hearing loss and bilateral hearing loss due to Sensorineural Hearing Loss below.
And conductive hearing loss often occurs when there is a physical blockage or damage in the ear canal, disrupting the passage of sound, which is why it's more common to occur in one ear.
Unilateral Sensorineural Hearing Loss (USNHL):
Unilateral sensorineural hearing loss affects only one ear.
Causes can include sudden sensorineural hearing loss, viral infections (such as mumps or measles), head trauma, or Meniere's disease.
The prevalence of unilateral sensorineural hearing loss is generally lower than bilateral sensorineural hearing loss.
Bilateral Sensorineural Hearing Loss (BSNHL):
Bilateral sensorineural hearing loss affects both ears.
Causes can include aging (presbycusis), genetic factors, noise exposure, ototoxic medications, and certain medical conditions.
Bilateral sensorineural hearing loss is more common, especially among the elderly population.
Mixed Hearing Loss Diagnosis
Mixed hearing loss is a type of hearing impairment that encompasses symptoms of both conductive hearing loss and sensorineural hearing loss.
A diagnosis of mixed hearing loss is made when the symptoms align with both the diagnostic criteria for conductive hearing loss and sensorineural hearing loss mentioned below.
Conductive Hearing Loss diagnosis:
Hearing Tests: Conductive hearing loss is assessed through audiometry tests, which measure sensitivity to sounds. In conductive hearing loss, there may be reduced hearing at low frequencies.
Tympanometry: This test measures the movement of the eardrum to assess its condition and identify middle ear problems.
Reflex Testing: Reflex tests measure the reflexes of the middle ear muscles, helping confirm conductive hearing loss.
Sensorineural Hearing Loss diagnosis:
Hearing Tests: Sensorineural hearing loss is evaluated through audiometry as well. Sensorineural hearing loss typically affects high frequencies.
Speech Discrimination Testing: This test measures the ability to understand speech accurately, providing insights into the degree of sensorineural hearing loss.
Cross-Checking Tests: Additional tests such as detailed audiometry, magnetic resonance imaging (MRI), or auditory brainstem response (ABR) tests may be conducted to pinpoint the cause of sensorineural hearing loss. These tests cross-check various aspects to arrive at a precise diagnosis, depending on the suspected cause and symptoms presented by the patient.
Mixed Hearing Loss Causes
- Ear Disorders or Abnormalities: Direct problems within the ear, such as the presence of foreign objects, tumors, or damage due to conditions like otitis media or foreign bodies, can lead to conductive hearing loss.
- Aging (Presbycusis): Age-related changes can cause a decrease in the function of auditory cells and nerves, leading to sensorineural hearing loss.
- Noise Exposure: Prolonged exposure to high-intensity noise can damage the structures in the inner ear, resulting in sensorineural hearing loss.
- Genetic Factors: In some cases, genetic factors can contribute to hearing loss, leading to a mixed hearing impairment.
- External Trauma: External injuries or impacts to the ear can result in a combination of conductive and sensorineural hearing loss.
- Otitis Media: Inflammation in the middle ear, known as otitis media, can cause conductive hearing loss.
Mixed Hearing Loss Treatment
In fact, for conductive hearing loss, there is a higher possibility of recovery if appropriate treatment is sought at the right time compared to sensorineural hearing loss.
When it comes to hearing loss, it's challenging to fully revert to the original state with sensorineural hearing loss.
Therefore, in cases of mixed hearing loss where these two types are combined, focusing on treating the symptoms related to conductive hearing loss, which is treatable, and using assistive devices in daily life to alleviate hearing-related discomfort, is a practical approach rather than attempting to treat sensorineural hearing loss, offering a feasible solution for individuals with mixed hearing hearing loss.
- Medical Interventions:
- For conductive hearing loss caused by issues like earwax blockage or tumors, surgical procedures might be necessary to remove or treat these problems. Ear conditions such as ear infections can be treated with appropriate medications.
- Hearing Aids:
- Depending on the severity and type of hearing loss, hearing aids can be worn to amplify sounds and improve hearing. Hearing aids can be effective for both conductive and sensorineural components of mixed hearing loss.
- Cochlear Implants:
- In cases of severe sensorineural hearing loss, cochlear implants, small electronic devices planted in the inner ear, can be surgically placed to help transmit sounds.
- Combination of Hearing Aids and Surgery:
- When mixed hearing loss includes a conductive hearing loss component, surgical correction of the conductive issue followed by the use of hearing aids to assist with the remaining sensorineural hearing loss can be a viable option.
- Speech and Hearing Rehabilitation:
- Language therapy and auditory training can enhance communication skills, while managing the psychological stress associated with hearing loss.