Deafness (Hearing Loss): Definition, Types, Risk Factors, Diagnosis And Treatment

Deafness (Hearing Loss): Definition, Types, Risk Factors, Diagnosis And Treatments.

What is Deafness?

Deafness can be defined as a total hearing loss to a patient, while hearing loss is used for partial reduction in hearing capacity.

What are the types (classification) of deafness?

Deafness can also be classified based on which portions of the hearing system (auditory system) are affected. When the nervous system is affected, it is referred to as sensorineural deafness. When the portions of the ear that are responsible for transmitting the sound to the nerves are affected, it is referred to as conductive deafness.

Conductive deafness: is a type of deafness that affects and caused a lesion on the external and middle of the ear.

Conditions that affect the ear canal, eardrum (tympanic membrane), and middle ear lead to conductive deafness. Examples of conductive deafness include:

ear wax blocking the ear canal

otitis media 

otosclerosis.

Features of conductive deafness.

Site of the lesion: External and middle ear.

Audiometry: Bone conduction better than air conduction.

Hearing loss: Not more than 60dB.

Speech: Speak in a low voice.

Speech discrimination: Good.

Weber test: Lateralise to the worse ear.

Rinne test: Bone conduction better than air conduction.

Sensorineural deafness: this type of deafness causes a lesion on the middle ear via cranial nerve and central connection.

Conditions affecting the cochlea, eighth cranial nerve, spinal cord, or brain cause sensorineural deafness. Examples include:

Meniere's disease,

noise-induced hearing loss (such as prolonged or excessive exposure to loud music or machinery),

hearing loss of aging (presbycusis),

nerve injury from syphilis,

hearing loss of unknown cause (idiopathic hearing loss)

nerve tumors 

drug toxicity (such as aspirin and aminoglycosides).

Features of sensorineural deafness.

Site of lesion: inner ear via cranial nerve and central connections.

Audiometry: Air conduction better than bone conduction.

Hearing loss: May be more than 60dB.

Speech: Speak loudly.

Speech discrimination: Poor.

Weber test: Lateralise to the better ear.

Rinne test: Air conduction better than bone conduction.

Mixed deafness: it comprised the conductive and sensorineural deafness that is, there are both conductive and sensorineural problems.

What are forms of deafness?

Deafness or hearing loss, can be present at birth (congenital), or become evident later in life (acquired). The distinction between acquired and congenital deafness specifies only the time that the deafness appears. It does not specify whether the cause of the deafness is genetic (inherited).

Acquired deafness may or may not be genetic. For example, it may be a manifestation of a delayed-onset form of genetic deafness. Alternatively, acquired deafness may be due to damage to the ear due to noise or from other conditions.

Congenital deafness may or may not be genetic. In non-genetic causes, congenital deafness may be due to a condition or infection to which the mother was exposed during pregnancy, such as the rubella virus. Alternatively, congenital hearing loss may be associated with certain other characteristic findings. For example, a white forelock may be a sign of a genetic disease called Waardenburg syndrome that includes congenital deafness in the spectrum of disease. Overall, more than half of congenital hearing loss is inherited. 

What are the risk factors of deafness?

The risk factors that may trigger on a person to have deafness or hearing loss are:

Heredity

Mother's exposure to rubella virus during pregnancy

Impacted wax

Ototoxic drugs (drugs that are toxic to ear)

Infections that cause inflammation of the ear

High exposure to loud music or machinery

Injury to the nerve of the ear

Genetic disorder. Etc

What are the symptoms of deafness?

The patient may complain of hearing loss or reduction in frequency of hearing which may be on one ear or both the ears.

There may be associated ear symptoms like ear discharge (Otorrhea), tinnitus (noise in the ear), ear pain (otalgia) and vertigo (feeling of rotatory movement).

People who are experiencing hearing loss may refrain from taking part in conversations, may turn the volume up high on the radio or TV, and may frequently ask others to repeat what they have said.

How to diagnose deafness?

It is important to check the ear for any congenital lesions of the external ear, the external auditory canal for impacted wax, foreign body, discharge or debris, pain and infections.

Investigations to be carry out.

The following tests can be carry out to diagnose deafness:

Test of hearing: audiometry, watch test, tuning fork test and voice test

VDRL (Venereal Diseases Research Laboratory).

Blood Pressure estimation

Cholesterol levels

Blood sugar test

Skull x-ray for internal auditory meatus

What is the treatment for deafness or hearing loss?

The treatment of hearing loss depends on its cause.

1. Conductive deafness

The majority of patients with conductive deafness can helped. When the cause is treated, the patient gets better. For example:

Ear wax can be removed

Ear infection like otitis media can be treated with medications

Hearing aid is advised for those patients who could not benefit from surgery.

2. Sensorineural deafness

Those with long standing sensorineural hearing loss may be difficult to treat. However, recent onset sensorineural hearing loss may benefit from:

Specific diseases like syphilis, diabetes, it should be treated.

Medications that are toxic to the ear can be avoided.

Hearing aid may help to augment the hearing.

Multivitamins are often advised. Vitamin B1, B6, B12, also A, C, E as antiarterosclerotic.

Tranquilizers may be given to alleviate the effect of the upset due to deafness and tinnitus in some patients.

During conversation with deaf people, one should speak to the deaf person slowly and loudly.

Auditory training and lip reading may be of help to the patient.

Sources:

Community Health Unpublished Lecture Note.

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