Sensorineural hearing loss results when tiny hair cells inside the inner ear (cochlea) are not fully formed or are damaged, resulting in hearing loss. It may also occur when the auditory nerve does not function properly, though this is less common.
Conductive Hearing Loss
This type of hearing loss involves the outer and/or middle ear. A conductive loss prevents sound from moving effectively through the outer and/or middle ear to the inner ear.
Causes of conductive hearing loss in children are:
Atresia - closure of the ear canal
Microtia - malformation of outer ear
Malformations of the middle ear
Middle ear infections, otitis media or fluid in the middle ear
Obstruction of the ear canal by wax or foreign objects
Mixed Hearing Loss
A mixed hearing loss occurs in both the outer/middle ear and in the inner ear. It is a combination of a conductive hearing loss and sensorineural hearing loss.
Auditory Neuropathy Spectrum Disorder
Auditory neuropathy is an uncommon disorder where there is an abnormality in the transmission of sound from the inner ear to the brain. Individuals with this disorder may have a normally functioning cochlea.
Risk Factors of Hearing Loss
The following are common risk factors for hearing loss:
Caregiver concern regarding hearing, speech, language or developmental delay
Family history of permanent childhood hearing loss
Neonatal intensive care (NICU) for more than five days
In utero infections, such as CMV, herpes, rubella, syphilis, and toxoplasmosis
Craniofacial anomalies, including those that involve the pinna, ear canal, ear tags, ear pits and temporal bone anomalies
Syndromes associated with hearing loss or progressive or late-onset hearing loss, such as neurofibromatosis, osteopetrosis and Usher syndrome; other frequently identified syndromes include Waardenburg, Alport, Pendred and Jervell and Lange-Nielson
Neurodegenerative disorders, such as Hunter syndrome, or sensory motor neuropathies, such as Friedreich ataxia and Charcot-Marie-Tooth syndrome
Culture-positive postnatal infections associated with sensorineural hearing loss, including confirmed bacterial and viral (especially herpes viruses and varicella) meningitis