You might be on this page because you have been told that your hearing loss is sensorineural in nature. This is not an everyday word so let’s break it down to understand what it means for you. The first part of the word refers to the sensory organ associated with hearing, the cochlea. The second part of the word refers to the nerve that passes auditory and vestibular information from the cochlear and balance structures to the middle portion of the brainstem called the pons. It is the eighth cranial nerve and is known as the vestibulocochlear nerve.
It follows that if you have a sensorineural hearing loss, the root cause of the hearing loss will be to do with these structures of the inner ear and beyond. [i]
Common Causes
Presbycusis (age-related):
There are fine hair cells inside the cochlea called kinocilium which is part of the pathway of conversion of sound waves to auditory information. The kinocilium degenerates with time; the rate of degeneration being different for every individual and generally unpredictable. The outer hair cells are the first affected and these are the cells that are associated with the higher frequencies. Because of this, presbycusis generally presents as a sloping high-frequency hearing loss with people noticing a lack of clarity of speech and difficulty in more complex listening environments first. As this type of hearing loss occurs over time, it can often go unnoticed for many years. [ii]
Noise exposure:
Wear and tear of the kinocilium can be accelerated by exposure to loud noise over a prolonged period, this is known as noise-induced hearing loss. If you work in a noisy environment there are measures that can be taken to minimise the risk of noise-induced hearing loss. Taking breaks from the noise and wearing hearing protection are helpful steps you can take.
Acoustic or physical trauma:
A significant head injury can cause damage to the inner ear structures, affecting the hearing pathway. Exposure to an extremely sudden loud noise like an explosion can also cause trauma in a similar way.
Tumours:
Abnormal growths situated in the middle ear structures can cause sensorineural hearing loss. An acoustic neuroma is a non-cancerous growth that develops on your vestibular or cochlear organ, causing sensorineural hearing loss. A cholesteatoma is also a benign skin growth that grows behind the eardrum and can cause a conductive and/or sensorineural hearing loss depending on its exact position within the ear structures.
Ototoxic medication:
Some medications can cause damage to the inner ear and therefore sensorineural hearing loss. These include certain antibiotics, chemotherapy drugs and antimalarial drugs as well as very high doses of aspirin.
Congenital:
Most cases of hearing loss present at birth will be sensorineural in nature and approximately half of these will occur on a genetic basis. Many of these children will be healthy, but some cases of congenital sensorineural hearing loss will occur alongside and as a symptom of a syndrome.[iii] Infections that the mother has contracted during pregnancy, e.g. rubella, cytomegalovirus and toxoplasmosis.
Treatment of sensorineural hearing loss
Managing the difficulties associated with hearing loss with hearing aids is the typical treatment pathway for people with sensorineural hearing loss. There is not yet a “cure” or medication that can be taken to reverse this type of hearing loss. It is rare for hearing loss to be treated with surgical intervention, but some severe/profound sensorineural losses can be helped with medical implants like a cochlear or brain stem implant.
References
[i] http://toosogie-medical-images.blogspot.com/2010/12/cranial-nerves-vi-ix.html
[ii] https://www.cdc.gov/nceh/hearing_loss/how_does_loud_noise_cause_hearing_loss.html
[iii] https://www.luriechildrens.org/en/specialties-conditions/hearing-loss/sensorineural-hearing-loss/
