39.1: Introduction to the Ears
By the end of this section, you should be able to:
- 39.1.1 Describe the structures and functions of the ears.
- 39.1.2 Identify common types of ear disorders.
Ear Structure and Function
The ear is connected to the central nervous system through inputs from the vestibulocochlear nerve —the eighth cranial nerve—which transmits sound from the inner ear to the auditory cortex in the temporal lobe of the brain. The vestibulocochlear nerve splits into the vestibular and cochlear nerves. The vestibular nerve controls motion and position; the cochlear nerve transmits signals from the cochlea to the temporal lobe in the brain so that sound can be heard. Sensorineural hearing loss (SNHL) is the most common type of hearing loss and accounts for the majority of all hearing loss. SNHL refers to any cause of hearing loss due to a pathology of the cochlea, auditory nerve, or central nervous system (Tanna et al., 2023).
The external ear, the middle ear, and the inner ear comprise the ear, as shown in Figure 39.2. The external ear—also called the outer ear, pinna, or auricle—structures include the ear lobe and cartilage. The external ear also consists of the external auditory canal , whose function is to transmit sound waves to the eardrum (also called the tympanic membrane). The external auditory canal gathers sound from outside the body and transmits it to the middle ear. This canal accumulates ear wax that typically self-cleans through daily chewing, grinding, and yawning motions (Sevy et al., 2023).
The tympanic membrane is the window from the outer ear into the middle ear. The middle ear consists of the tympanic membrane, tympanic cavity , and ossicles , which include three small bones: the malleus , incus , and stapes . The purpose of the middle ear is to transmit sound from the tympanic membrane to the inner ear. The tympanic cavity surrounds the three ossicles. The malleus, incus, and stapes transmit oscillatory vibrations from one small bone to another; the delicate stapes sends sound to the inner ear in a highly coordinated relay system. The tympanic membrane can rupture from infection, barotrauma, or the use of cotton swabs.
The Eustachian tube connects the middle ear to the back of the nose. It has three major functions:
- To protect the middle ear from infection
- To equalize air pressure on both sides of the eardrum for normal vibration
- To drain secretions from the middle ear
The inner ear is well protected within the temporal bone of the skull. The inner ear consists of the cochlea, the semicircular canals, and the vestibular and cochlear nerves. The cochlea translates sound waves into electrical impulses through mechanical stimulation of tiny hair cells that the brain can then interpret to recognize sounds. The semicircular canals sense head rotations to allow proprioception—the body’s ability to sense movement, action, and location—and balance. These canals contain fluid known as lymph and must be clear of debris such as small crystals called otoliths (Casale et al., 2023; Wang et al., 2020).
The inner ear is part of the central nervous system (CNS). Therefore, clients’ complaints about hearing can also be a sign of a more serious CNS disease process. The nurse should listen carefully to the client’s description of hearing issues and communicate concerns with the provider. Muffled hearing can represent a range of concerns from ear wax buildup to multiple sclerosis or neurosyphilis (Ramchandani et al., 2020). The nurse must also be aware of the ears’ structure and function, both within the parameters of normal function and when the client sustains a serious head injury or barotrauma.
Link to Learning
This 4-minute client education video describes the three parts of the ear: the external ear, the middle ear, and the inner ear.
Ear Disorders
This section describes common ear disorders for which pharmacological drops or solutions are prescribed. Selected common ear conditions for which systemic medications are prescribed will be reviewed as well.
Eustachian Tube Dysfunction and Post-Viral Syndrome
Barotrauma can result in a ruptured eardrum due to Eustachian tube dysfunction, which occurs when the air pressure in the middle ear does not equalize with ambient pressure. This can occur with sudden pressure changes, such as when flying or scuba diving. A ruptured eardrum can heal spontaneously or may require surgical intervention (Cleveland Clinic, 2022a). The Eustachian tube can become blocked during and after an upper respiratory infection as well. After an upper respiratory infection, the Eustachian tube may remain swollen, causing pain, muffled sound, or a feeling of fullness in the ear.
Tinnitus
Tinnitus is an ear disorder characterized by ringing or other annoying sounds in the ear. Tinnitus can be age-related, exacerbated by loud noises, or a result of circulation issues. Some medications can cause tinnitus, and hearing may not always fully return after stopping the medication. Medications associated with tinnitus include nonsteroidal anti-inflammatory drugs (NSAIDs), some antibiotics, anticancer medications, and antidepressants (Kim et al., 2021). The mechanism of these intrusive sounds is related to damaged hairs in the cochlea. Although there is no cure for tinnitus, there are treatments—including sound generators and stress management—that can help clients better cope with distracting sounds (Cleveland Clinic, 2022b; National Institute on Deafness and Other Communication Disorders, n.d.).
Ménière’s Disease
Ménière’s disease occurs when there is excess fluid in the inner ear. The cause is largely unknown. Ménière’s disease can have a hereditary component, or it can be triggered by viral or bacterial pathogens. This condition is characterized by hearing loss, vertigo, increased sweating, nausea, and vomiting. The nurse must implement fall precautions when caring for a client with Ménière’s disease because vertigo can predispose them to falls, including falls with injuries. There is no cure for Ménière’s disease, and though it does not affect life expectancy, it interferes with the client’s quality of life. Corticosteroids and antihistamines are offered as potential treatments and have varying effects (Webster et al., 2023).
Otitis Externa
Otitis externa (also known as swimmer’s ear) is an inflammation and/or infection of the external ear canal characterized by itchiness, pain, and a red ear canal. Otitis externa occurs in swimmers as well as older adults and those with poorly controlled diabetes. It can be exacerbated by using hearing aids, ear buds, and stethoscopes. The nurse should report client complaints of itchy, painful ear(s) to the provider because an untreated infection can spread to the bones and deep tissues of the ear canal and lead to skull osteomyelitis (Bruschini et al., 2019).
Otitis Media
Otitis media is an inflammation or infection of the middle ear. It typically occurs when the client has a cold, upper respiratory infection, or secondhand smoke exposure. Children are more likely to develop otitis media because of their horizontal Eustachian tube architecture, which increases the likelihood of fluid being trapped, causing an infection. Bottle feeding has been identified as a contributing factor to otitis media. Infants that breastfeed have fewer otitis media infections due to the oligosaccharides that are in breast milk, which function as prebiotics. These substances help infants develop their immune system to fight off infection. In addition, the breastfeeding infant utilizes a sucking motion, resulting in a negative pressure vacuum, thereby reducing pooling of breast milk (Bowatte et al., 2015). Though the incidence of otitis media in adults is less, adults can also develop otitis media. Eustachian tube edema can narrow the diameter of the tube, allowing fluid to back up to the middle ear.
There are three major types of otitis media: acute otitis media, otitis media with effusion, and chronic otitis media with effusion (Johns Hopkins Medicine, n.d.). Acute otitis media is characterized by ear discomfort, in addition to systemic symptoms including fever and pain. Acute otitis media is frequently treated with systemic antibiotics, otic antibiotics, or a combination of both.
Otitis media with effusion occurs when some fluid remains after an infection has cleared and presents as fullness in the ear. Often decongestants or nasal steroids are prescribed to treat these symptoms. Antibiotics are not appropriate at this stage when no infection persists. The condition may become long-term and return although no infection is present.
Acute otitis media in adults can cause significant complications; therefore, adults are treated with antibiotic therapy (Limb et al., 2023). In general, antibiotic therapy is used more judiciously in children to avoid antibiotic resistance and side effects.
Benign Paroxysmal Positional Vertigo
Benign paroxysmal positional vertigo (BPPV) is a condition of the inner ear where otoliths—crystals of calcium carbonate—migrate into the inner ear fluid and cause a false sense of spinning. Otolith displacement occurs in older adults and those with a history of a blow to the head. BPPV is characterized by dizziness and a spinning sensation and may result in nausea and vomiting. Long after a head trauma, these symptoms can be triggered by a changing head position or keeping the head in one position for an extended period. Episodes can last for a few minutes and are disconcerting to the client, who is at risk of falling.
Special Considerations
Candida auris
Nurses must be aware of an emerging deadly fungal infection of the ear known as Candida auris . This fungal infection was first found in a Japanese person’s ear canal in 2009. Since then, there have been more than 3,000 systemic cases in the United States and more than 7,000 cases where the fungus has been found but has not yet caused infection (Centers for Disease Control and Prevention, 2023a, 2023b). C. auris must be reported to the Centers for Disease Control and Prevention (CDC) for tracking. Cases in the United States have occurred in health care settings largely among immunocompromised clients. Current treatment includes a drug class, echinocandins , that act on the Candida species. Echinocandins include anidulafungin ( Eraxis ), caspofungin ( Cancidas ), and micafungin ( Mycamine ).
(Source: Cândido et al., 2020)
Communicating with a Client with Hearing Impairment
There are different causes of hearing loss—including congenital hearing loss, aging, prolonged exposure to noise, and trauma—that are outside of the scope of this chapter. However, when treating clients with otic medications, the client’s hearing may be impaired by these medications or by the underlying ear condition the nurse is treating. The following guidelines can assist the nurse when working with these clients (UCSF Health, n.d.):
- Face the client with the hearing impairment directly when communicating.
- Refrain from talking while in another room or area away from the client.
- Do not shout; rather, speak slowly, clearly, and distinctly.
- Pause between concepts to ensure you are understood before continuing.
- If the hearing-impaired client does not seem to understand a word or phrase, rephrase the message.
- Avoid interrupting the client.
- Provide the client with written information such as a schedule and directions and ask them to repeat the specifics.