01.05 Hearing Loss

Okay guys, so today we’re going to review the different types of hearing loss. By the end of this lesson, you’ll have a better understanding of the different types of hearing loss, their causes, diagnostic testing, and the nursing considerations when caring for these patients.

Ok guys, so hearing loss is when the hearing acuity is decreased. This can be caused by alterations in the external, middle, or inner ear. So sound is transmitted by air conduction and bone conduction - basically how the person receives sound. Usually air conduction of sound is more sensitive than bone conduction. So if a person’s hearing acuity is decreased, this is characterized as conductive, sensorineural, or mixed hearing loss.

Ok so let’s start with conductive hearing loss. So with conductive hearing loss, this is a physical obstruction of sound wave transmission. So the sound waves are blocked from contact with inner ear nerve fibers because of external or middle ear disorders or abnormalities. Let’s talk about some of the causes of this type of hearing loss. So like we said before, it is caused by an obstruction of sound waves. So really any object such as cerumen or other foreign bodies can cause this and cause inflammation or obstruction in the external or middle ear. It can also be caused by eardrum changes like bulging, retractions, or perforations. These may indicate damage to middle ear structures, which can lead to conductive hearing loss. Infection in the external or middle ear could also contribute to this type of hearing loss as well. Finally, abnormal tissue growth such as tumors, scar tissue, or overgrowth of soft bony tissue on the ossicles, also known as otosclerosis can all lead to conductive hearing loss. The good thing with this type of hearing loss is that the disorders that cause the hearing loss can usually be corrected with minimal or no permanent damage - remove the obstruction and the hearing improves. So let’s give this picture some cerumen right here and ok now the patient is having conductive hearing loss because of a blockage. By getting rid of the blockage, the patient’s hearing improves.

Alright guys, so sensorineural hearing loss is a defect in the cochlea itself, or a defect of the eighth cranial nerve, which is the auditory nerve. It is also caused by damage to cochlear hair cells. So, unlike conductive hearing loss, sensorineural hearing loss is a problem in the inner ear. Some of the causes of this type of hearing loss include prolonged exposure to loud noise, which directly damages the delicate hair cells of the inner ear. Presbycusis, which is the most common type of this kind of hearing loss and it’s basically just the natural aging process of the auditory system. Ototoxic medications can also cause this type of hearing loss by damaging the inner ear structures. Unfortunately, this is often permanent damage to the inner ear, so the focus is to prevent further damage to the ear or implement interventions to improve hearing.

Mixed or combination hearing loss is literally a combination of conductive and sensorineural hearing loss occurring at the same time. These patients can have pretty profound hearing loss just due to the nature of both of the types of hearing loss. So with the combination of the two types of hearing loss, these patients will have a problem in the inner ear as well as the middle or external ear. A cause of this could be an elderly patient who has sensorineural hearing loss at baseline, who develops a new ear infection or has cerumen impaction. So both types of hearing loss are occuring at the same time.

Let’s compare assessment findings in conductive vs sensorineural hearing loss. In conductive hearing loss, you will see an actual obstruction in the ear upon otoscopic examination. The tympanic membrane could also be abnormal - so it could be bulging or perforated. These patients could also have a softer tone of voice or may speak softly. They also usually hear better in a noisy environment. We’ll go over the difference between the Rinne test and Weber test in the next slide, but with conductive hearing loss patients will have greater air conduction than bone conduction with the Rinne test. With the Weber test, they will have lateralization to the affected ear. With sensorineural hearing loss, the external canal and tympanic membrane will appear normal upon examination. These patients can complain of tinnitus or dizziness. They will often have a louder tone of voice. Unlike conductive hearing loss, they will have poor hearing in a loud environment. These patients will present the opposite of conductive loss in the Rinne and Weber tests. So air conduction will be less than bone conduction, and there will be lateralization to the unaffected ear.

To help diagnose the type of hearing loss there are a few diagnostic tests that are utilized. One method of diagnosis is the use of a tuning fork. So with a tuning fork the Weber and Rinne test can be performed. The tuning fork helps us test the patient’s hearing acuity. With the Weber test, the vibrating tuning fork is placed on the middle of the patient’s head and then asking the patient to indicate which ear is louder. With normal hearing, it should be equal in both ears. The Rinne test compares hearing by air conduction with hearing by bone conduction. The vibrating tuning fork atem is placed on the patient’s mastoid process for bone conduction. The patient is asked when the sound is no longer heard. When it is no longer heard, the tuning fork is brought in front of the pinna to test air conduction and the patient again is asked when the sound is no longer heard. Sound is normally heard 2-3 times longer by air conduction than by bone conduction. With an otoscopic exam, the external ear canal, eardrum and structures of the inner ear are examined for any abnormalities. Imaging such as a CT scan or MRI can be used to help determine non-auditory problems. Audiometry can help show whether hearing loss is only conductive, or if it also has a sensorineural component.

So with management, let’s look at nonsurgical and surgical management options. So with nonsurgical management, we are looking at early detection of hearing problems in the first place. Patient’s can utilize different assistive devices such as hearing aids or portable amplifiers. Hearing aids are helpful with conductive hearing loss and are less helpful for sensorineural hearing loss, as they can make hearing worse by amplifying background noise. Cochlear implants can also be used and are helpful in patients with sensorineural hearing loss. One surgical procedure that is helpful for conductive hearing loss is a tympanoplasty, which reconstructs the middle ear to help improve hearing loss.

One of the important education topics we want to cover with patients includes prevention. So this would include things like hearing protection during loud events and minimizing exposure to loud music. We also want to educate that objects should not be inserted into the ear canal for cleaning. We also should educate about hearing aid application and care if applicable. Finally, we want to help maximize the patient’s communication. So we can educate about the proper use of assistive devices and other methods of communication as applicable like sign language, lip reading, and closed captioning on the TV.

Two nursing concepts relating to patients with hearing loss include alterations in sensory perception and functional ability. With changes in hearing this not only alters their sense of hearing but it also impacts their functional ability with day to day tasks.

Ok guys let’s quickly go over the key points on today’s lesson. So the differences between the types of hearing loss - conductive is a blockage of sound waves and occurs in the external or middle ear, and sensorineural is a problem with the inner ear in the cochlea or eighth cranial nerve such as damage to the hair cells of the cochlea. Mixed is a combination of the two. There will be different assessment findings for each type such as tinnitus for sensorineural and a visual obstruction for conductive hearing loss. A tuning fork is a helpful diagnostic tool and helps us conduct the Rinne and Weber tests which help us differentiate between conductive and sensorineural hearing loss. I also want you to remember the management, so the use of assistive devices and a tympanoplasty procedure if indicated. Finally we want to educate patients about prevention, device use, and different interventions to help maximize communication.

Okay guys, that’s all on our lesson about hearing loss. Make sure you check out all the resources attached to this lesson. Now, go out and be your best self today. And, as always, Happy Nursing!