Conductive and Sensorineural Hearing Loss

Hearing loss can be broadly classified into two categories: conductive hearing loss and sensorineural hearing loss. Each type has distinct causes, mechanisms, and associated diseases.

Conductive Hearing Loss

Definition: Conductive hearing loss occurs when there is a problem with the outer or middle ear that prevents sound from being conducted to the inner ear.

Causes:

1. Earwax Blockage: Excessive earwax can block the ear canal.

2. Otitis Media: Middle ear infection causing fluid accumulation.

3. Otosclerosis: Abnormal bone growth in the middle ear, affecting the stapes bone.

4. Tympanic Membrane Perforation: A hole or tear in the eardrum.

5. Eustachian Tube Dysfunction: The tube fails to open properly, causing pressure issues.

Examples of Diseases:

. Chronic Otitis Media: Persistent ear infections can lead to a buildup of fluid or pus in the middle ear, reducing hearing.

. Otosclerosis: This hereditary condition causes abnormal bone growth around the stapes bone, leading to progressive hearing loss.

Diagnosis:

. Otoscopy: Visual examination of the ear canal and eardrum.

. Tympanometry: Test to evaluate the function of the middle ear.

. Audiometry: Hearing tests to assess the degree of hearing loss.

Management:

i. Medical Treatment: Antibiotics for infections, earwax removal.

ii. Surgical Intervention: Procedures such as tympanoplasty (eardrum repair) or stapedectomy (removal of the stapes bone in otosclerosis).

Sensorineural Hearing Loss

Sensorineural hearing loss occurs due to damage to the inner ear (cochlea) or the auditory nerve pathways to the brain.

Causes:

. Age-Related Hearing Loss (Presbycusis): Degeneration of inner ear structures due to aging.

. Noise-Induced Hearing Loss: Damage caused by exposure to loud sounds.

. Ototoxic Medications: Drugs that can damage the inner ear, such as certain antibiotics and chemotherapy agents.

. Genetic Disorders: Inherited conditions affecting the inner ear.

. Meniere’s Disease: A disorder causing episodes of vertigo, tinnitus, and hearing loss.

Examples of Diseases:

. Presbycusis: Gradual hearing loss in both ears due to aging.

. Meniere’s Disease: Characterized by episodes of vertigo, tinnitus, and fluctuating hearing loss.

. Acoustic Neuroma: A benign tumor on the auditory nerve causing hearing loss, tinnitus, and balance problems.

Diagnosis:

. Pure Tone Audiometry: Measures hearing sensitivity.

. Speech Audiometry: Assesses ability to hear and understand speech.

. Otoacoustic Emissions (OAE): Tests cochlear function.

. Auditory Brainstem Response (ABR): Evaluates the auditory nerve and brain pathways.

Management:

i. Hearing Aids: Amplify sound for better hearing.

ii. Cochlear Implants: Electronic devices that directly stimulate the auditory nerve.

iii. Medications: For underlying conditions such as Meniere’s disease.

iv. Surgical Options: Removal of tumors or other corrective surgeries.