Understanding the Causes of Hearing Loss

foreign [Applause] [Music] ers.com in this video I'm going to be going through hearing loss and you can find written notes on this topic at xerodifinals.com hearing loss or in the ear nose and throat section of the zero to finals surgery book so let's jump straight in there are two main categories of hearing loss conductive hearing loss and sensory neural hearing loss conductive hearing loss relates to a problem with sound traveling from the environment into the inner ear the sensory system may be working correctly but the sound is not reaching the sensory system an example of

how you can create conductive hearing loss is to put earplugs into your ear the sound can't reach the inner ear because the ear plugs are in the way sensory neural hearing loss is caused by a problem with the sensory system or the vestibular cochlear nerve in the inner ear the sound is reaching the inner ear but it can't be sensed properly or transmitted to the brain properly let's talk about some basic ear anatomy there are three sections to the ear and they're the outer ear the middle ear and the inner ear the basic structures from

the outside in are the Pinner which is the external portion of the ear the external auditory canal which is the tube into the ear the tympanic membrane which is the eardrum the eustachian tube which connects the middle ear to the throat to equalize the pressure in the middle ear the malleus incus and stapes are the small bones in the middle ear that connect the tympanic membrane to the structures of the inner ear the semicircular canals are responsible for sensing head movement and this is the vestibular system the cochlea is responsible for converting the sound vibration

into a nerve signal and the vestibular cochlear nerve transmits nerve signals from the semicircular canals and the cochlea to the brain let's talk about the presentation hearing loss may be gradual and Insidious patients may present because other people have noticed that they're not paying attention or they're missing details of conversations sometimes patients can present with concerns about dementia when in fact the issue is hearing loss sudden onset hearing loss which is defined as hearing loss over less than 72 hours requires a thorough assessment to establish the cause there may be Associated symptoms alongside the hearing

loss which can give clues about the potential cause and these symptoms may include tinnitus which is a ringing sound in the ears vertigo which is a sensation that the room is spinning pain which may indicate infection discharge which may indicate an outer or middle ear infection and potentially neurological symptoms it's worth noting patients with hearing loss are more likely to develop dementia and treating the hearing loss for example using a hearing aid May reduce the risk of dementia developing let's talk about Weber's and rini's tests Weber's and rini's tests are used to differentiate between sensory

neural and conductive hearing loss a tuning fork is used to perform both of these tests firstly let's start with Weber's test to perform Weber's test strike the tuning fork to make it vibrate and hum use the palm of your hand or your knee and not the patient place the tuning fork in the center of the patient's forehead and ask the patient if they can hear the sound and which ear the sound is loudest in a normal result on Weber's test is when the patient hears the sound equally in both ears in sensory neural hearing loss

the sound will be louder in the normal ear and quieter in the affected ear the normal ear is better at sensing the sound which is why it's louder in that ear in conductive hearing loss the sound will be louder in the affected ear and quieter in the normal ear this is because the affected Ear Has Turned Up the Volume and becomes more sensitive as the sound has not been reaching that side as well due to the obstructive problem when the tuning Forks vibration is transmitted directly to the cochlea through the bones of the skull during

Weber's test rather than having to travel through the ear canal and the middle ear structures The increased sensitivity in the affected ear makes the sound louder on that side a Tom tip for you the way I remember which way around these tests are is to picture Spider-Man shooting a web meaning Weber's test right in the middle of someone's face which is where you would put the tuning fork in the middle of their forehead next let's talk about rinny's test the perform release test strike the tuning fork to make it vibrate and hum then place the

flat end on the mastoid process which is the Bony lump behind the ear and this tests for bone conduction the sound will be transmitted through the bones straight into the cochlea and the patient will hear a humming noise ask the patient to tell you when they can no longer hear this humming noise when they can no longer hear the noise remove the tuning fork while it's still vibrating and hover it one centimeter from the same ear with the tuning fork hovering next to their ear ask the patient whether they can hear the sound and this

tests their air conduction then repeat the whole process on the other side a normal result on rini's test is when the patient can hear the humming sound with bone conduction then the bone conduction sound stops and the tuning fork is moved next to the ear rather than on the mastoid process and then they can hear the sound again through air conduction it's normal for air conduction to be better or more sensitive than bone conduction and this is referred to as rini's positive an abnormal result meaning rini's negative is when bone conduction is better than air

conduction the sound is not heard after removing the tuning fork from the mastoid process and holding it near the ear canal this suggests a conductive cause for the hearing loss sound is transmitted through the bones of the skull directly to the cochlea during the bone conduction portion of the test meaning that bone conduction is intact and the sensory system of the ear is working okay however the sound is less able to travel through the air the ear canal tympanic membrane and middle ear to reach the cochlear due to a conductive problem let's talk about the

causes of sensory neural hearing loss the causes of adult onset centrineural hearing loss are sudden sensory neural hearing loss which is defined as hearing loss over less than 72 hours presbycusis which is age-related hearing loss noise exposure Meniere's disease labyrinthitis acoustic neuromas neurological conditions for example stroke multiple sclerosis or brain tumors infections such as meningitis and medications there are a large number of medications that can cause sensory neural hearing loss some of the more common ones and ones worth remembering are Loop Diuretics for example fruzamide aminoglycoside antibiotics for example Gentamicin and chemotherapy drugs for example

cisplatin next let's talk about the causes of conductive hearing loss the causes of adult onset conductive hearing loss are earwax blocking the ear canal foreign body in the ear canal infection for example otitis media or otitis externa fluid in the middle ear which is called an effusion eustachian tube dysfunction a perforated tympanic membrane otosclerosis a cholesteatoma exostoses or benign bone growths and tumors if you like this video consider joining the zero to finals patreon account where you get early access to these videos before they appear on YouTube you also get access to my comprehensive course

on how to learn medicine and do well in medical exams digital flash cards for rapidly testing the key facts you need for medical exams early access to the zero to finals podcast episodes and question podcasts which you can use to test your knowledge on the go thanks for watching and I'll see you in the next video