Ears Flashcards
which parts of the external ear partially cover opening of ear canal (prevent foreign body entrance)?
Tragus and conchal cartilage
what is the function of ear Hair and isthmus narrowing?
inhibit entry of contaminants.
what are the properties of cerumen (earwax) and their purpose?
It is acidic, which helps to inhibit the growth of bacteria and fungi.
Its hydrophobic properties repel water, preventing the ear canal from becoming too moist, which could otherwise lead to infections.
Additionally, its sticky nature allows it to trap dust, debris, and small particles, preventing them from reaching the eardrum.
which portion of ear canal is bony and which is cartilaginous?
the inner 2/3 is bony while the outer 1/3 is cartilaginous.
what produces furuncle or pustule in otitis externa?
folliculitis of hair follicle
what is the most common bacteria that causes otitis externa?
Pseudomonas aeruginosa and Staphylococcus aureus
However, it can also be caused by fungal infections (eg. Candida Albicans)
what bacterial skin infection of the outer layer can affect the concha and ear canal if it spreads there and what bacteria causes it?
Erysipelas
group A Streptococcus
what is otitis externa?
Otitis externa, commonly known as “swimmer’s ear,” is an inflammation of the ear canal.
what are the clinical symptoms of otitis externa?
Clinical Features: The infection typically presents with:
Erythema: Redness of the skin lining the external ear canal. [redness of eardrum]
Edema: Swelling due to inflammation, which can narrow the ear canal.
Pus and Skin Debris: Discharge is common in otitis externa, which may contain pus and flakes of skin debris from the infected and inflamed skin within the ear canal.
Pain: The ear canal is sensitive and inflammation can lead to significant pain, which can be exacerbated by moving the ear or jaw.
Lymphadenopathy: The infection can cause the regional lymph nodes (often in the neck or near the ear) to become swollen and tender.
[cellulitis-infection of skin]
[otorrhea-discharge from ear]
[pruritus]
what is a furuncle?
A furuncle, commonly known as a boil, is a deep folliculitis, or infection of a hair follicle. It is typically caused by bacterial infection, most commonly by Staphylococcus aureus. When a furuncle occurs in the ear canal, it can almost completely occlude the meatus (the external opening of the ear canal), leading to pain and other symptoms.
which health condition are risk factors for otitis externa more common in?
Risk Factors:
The condition is more common in individuals with a weakened immune system, diabetes, and swimmers due to increased exposure to moisture.
what are the risk factors for otitis externa?
Swimming (Water Exposure):
Excess moisture from activities like swimming can lead to skin maceration (softening and breaking down of the skin) and disrupt the protective skin-cerumen (earwax) barrier.
Microflora Changes:
The ear canal’s normal flora may shift towards predominantly gram-negative bacteria following prolonged moisture exposure, increasing infection risk.
Trauma:
Trauma from excessive ear cleaning or aggressive scratching can strip away the protective cerumen and create abrasions through which bacteria or fungi may infect deeper tissues.
Foreign Bodies:
Items such as cotton swabs or tissue paper can partially disintegrate inside the ear canal, leading to severe skin reactions and possible infection.
Ear Canal Occlusion:
Devices that occlude the ear canal, like hearing aids, earphones, or diving caps, can create a moist environment conducive to infection.
Allergic Contact Dermatitis:
Allergies to materials in earrings or chemicals found in cosmetics or shampoos can cause inflammation of the ear canal.
Dermatologic Conditions:
Skin conditions such as psoriasis and atopic dermatitis can predispose individuals to develop otitis externa.
Radiation Therapy:
It can lead to ischemic changes in the ear canal, altering normal cerumen production and the natural migration of epithelial cells, making the ear more susceptible to infection.
how does otitis externa develop?
Breakdown of Skin-Cerumen Barrier: The skin lining the ear canal has a protective layer of cerumen (earwax), which has antimicrobial properties and forms a barrier against water and pathogens. Disruption of this layer, often due to moisture (as in swimmers), trauma from scratching or cleaning, or skin conditions like eczema, can initiate otitis externa.
Inflammation and Edema: Once the barrier is compromised, bacteria or fungi can invade, leading to inflammation. This results in swelling (edema) and narrowing of the ear canal.
Pruritus and Obstruction: The inflammation is irritating and causes itching (pruritus), which leads individuals to scratch the ear, causing further damage to the skin and exacerbating the condition. The swelling can also lead to partial or complete obstruction of the ear canal, trapping any fluid or debris and creating an environment conducive to infection.
Altered Cerumen: The normal acidic pH and protective properties of cerumen are altered. This, combined with the impaired migration of the epithelial cells that line the ear canal due to inflammation, can lead to an increase in the pH, making the environment more alkaline.
Ideal Environment for Pathogens: The combination of a warm, moist, and alkaline environment in the ear canal provides an ideal breeding ground for pathogens.
what is otomycosis and how does it present clinically?
This is a fungal infection of the ear canal, often caused by Aspergillus or Candida species.
Aspergillus: Typically presents as a fine, dark coating within the ear canal.
Candida: May present as a whitish, sebum-like substance in the ear canal.
how do you differentiate mild, moderate, or severe otitis externa?
Severity Grading:
Mild External Otitis: Characterized by minor discomfort, itching, and minimal swelling of the ear canal.
Moderate External Otitis: Involves more pain and itching, with the ear canal partially blocked by swelling.
Severe External Otitis: Presents with intense pain, complete occlusion of the ear canal, and may be accompanied by redness around the ear (periauricular erythema), swollen lymph nodes (lymphadenopathy), and fever.
what are 2 complications of acute otitis externa?
Periauricular cellulitis and Malignant external otitis
what is an infection of the skin around the ear (auricle), characterized by redness (erythema), swelling (edema), and warmth.
Pain is generally mild, and systemic symptoms, such as fever or malaise, are typically absent.
usually does not spread far beyond the local site of infection?
Periauricular Cellulitis
what is a severe and potentially life-threatening infection that extends from the external ear canal to the base of the skull, particularly affecting the temporal bone and the soft tissues of the temporal region.
The infection is often caused by Pseudomonas aeruginosa, though Methicillin-Resistant Staphylococcus aureus (MRSA) has also been reported.
It is more common among older individuals, diabetics, or those with compromised immune systems?
Malignant External Otitis (Necrotizing Otitis Externa or Skull Base Osteomyelitis)
what is the main bacteria that causes Malignant External Otitis (Necrotizing Otitis Externa or Skull Base Osteomyelitis)?
Pseudomonas aeruginosa
what is a sign of poor prognosis in acute otitis externa complications?
If cranial nerves are involved, resulting in palsies, it’s a poor prognostic sign.
what lab findings are revealed in acute otitis externa complications?
Laboratory findings often reveal a markedly elevated erythrocyte sedimentation rate (ESR), indicating inflammation.
what are some clinical presentations of acute otitis externa complications?
Patients typically present with severe ear pain (otalgia) and discharge from the ear (otorrhea).
A classic sign is granulation tissue at the junction of the bony and cartilaginous parts of the ear canal floor.
There may be edema and erythema around the ear, along with actual skin necrosis within the ear canal.
what is a classic sign of acute otitis externa complications?
A classic sign is granulation tissue at the junction of the bony and cartilaginous parts of the ear canal floor.
what imaging modality is used in acute otitis externa complications?
Imaging with CT (computed tomography) or MRI (magnetic resonance imaging) can provide detailed views of the extent of the infection and any bone involvement.
what is cholesteatoma?
A cholesteatoma is an abnormal, noncancerous skin growth that can develop in the middle section of the ear, behind the eardrum. It is typically caused by repeated infection or a poorly functioning Eustachian tube that does not equalize ear pressure properly and causes the eardrum to retract ( forming a pocket or cyst that fills with old skin cells and other debris. Over time, this cyst can grow and may become infected). Cholesteatoma can also occur as a birth defect (thought to arise from embryonic epithelial remnants in the middle ear), though this is less common.
Over time, a cholesteatoma can expand and erode through the delicate structures within the temporal bone, which houses the middle and inner ear.
This erosive process can lead to the destruction of the ossicles (tiny bones necessary for sound conduction), the inner ear, and can even affect the facial nerve which traverses the middle ear.
These are more common and usually occur as a result of chronic ear infections or eustachian tube dysfunction.
They can also form after a perforation of the tympanic membrane, which may occur due to chronic otitis media, trauma, or previous ear surgeries.
With the perforation, skin cells from the outer layer of the eardrum and external ear canal can migrate into the middle ear and form a cholesteatoma.
how do you confirm an ear infection is fungal in nature?
It doesn’t respond to topical antibiotics
what’s the difference between diffuse otitis externa and localized otitis externa?
Diffuse affects the entire ear canal, more severe pain, more systemic symptoms like fever or malaise, and hearing loss may be more pronounced
localized involve a localized area in ear canal often the hair follicle, presents as furuncle/boil in ear canal while rest of ear canal looks normal.
what also form after a perforation of the tympanic membrane, which may occur due to chronic otitis media, trauma, or previous ear surgeries?
Cholesteatoma
what is the classic sign of cholesteatoma and what causes it?
The classic sign of a cholesteatoma is a painless ear discharge, which is often chronic and foul-smelling. The discharge occurs due to the accumulation and breakdown of skin cells and other debris from the cholesteatoma.
If there is an associated infection, abscess formation, or mastoiditis (infection of the mastoid bone) with cholesteatoma, pain will be present. Why might these conditions be difficult to treat when cholesteatoma is present?
because the cholesteatoma may impede adequate blood supply, making it difficult for antibiotics to reach the infected area effectively.
what kind of hearing loss is typical in cholesteatoma? conductive or sensorineural?
Hearing loss in cases of cholesteatoma is typically conductive, meaning that sound waves are not efficiently conducted through the outer and middle ear to the inner ear.
This can be due to obstruction from the cholesteatoma itself or from the destruction of the ossicles (the small bones in the middle ear that transmit sound vibrations).
what causes conductive hearing loss in cholesteatoma?
This can be due to obstruction from the cholesteatoma itself or from the destruction of the ossicles (the small bones in the middle ear that transmit sound vibrations).
what does vertigo indicate in cholesteatoma?
Vertigo is less common but can be very concerning when it occurs. It indicates that the cholesteatoma has created a fistula, which is an abnormal connection into the labyrinth (inner ear structures responsible for balance). This can lead to balance disturbances and dizziness.
what are some neurologic complications from cholesteatoma?
Neurologic Complications:
Facial Nerve Palsy: The facial nerve runs through the middle ear, and a cholesteatoma can exert pressure on this nerve, leading to paralysis of the facial muscles.
Sigmoid Sinus Thrombosis: A serious complication where the cholesteatoma causes a blood clot in the sigmoid sinus, a major blood vessel within the skull.
Epidural Abscess: An accumulation of pus between the tough outer membrane of the central nervous system (the dura mater) and the skull.
Meningitis: The most serious complication, which is an infection of the membranes covering the brain and spinal cord.
what is the most serious complication of cholesteatoma?
Meningitis: The most serious complication, which is an infection of the membranes covering the brain and spinal cord.
what’s the most important factor in the development of otitis media?
dysfunction of eustachian tube
what is acute otitis media?
Acute otitis media (AOM) is an infection of the middle ear, which is the air-filled space behind the eardrum that contains the tiny vibrating bones of the ear. It’s common in children and often happens after a child has had a cold for a few days.
what normally precedes acute otitis media in a child?
a cold for a few days
which ear infection is most common in children?
acute otitis media
what are the most common bacterial causes of acute otitis media?
It’s typically caused by bacteria, and the most common bacterial pathogens are Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis. Viruses can also contribute to the infection, either alone or as part of a co-infection with bacteria.
what are risk factors associated with Acute otitis media?
Risk Factors for AOM include:
Tobacco Smoke Exposure: Children exposed to tobacco smoke may have increased colonization of S. pneumoniae in their nasopharynx, which can lead to more frequent and severe infections.
Young Age: Children between 6 and 16 months old are at a higher risk due to their still-developing immune system and less functional Eustachian tubes.
Anatomical Variations: Children with Down syndrome or Pierre Robin sequence may have anatomical differences that affect the function of the Eustachian tube, leading to fluid build-up and infection.
Lack of Immunizations: Immunizations help protect against certain pathogens that can cause AOM. A lack of immunizations means the child’s immune system may not be primed to fight off these pathogens.
Lack of Breastfeeding: Breastfeeding provides important antibodies, like IgA, that help protect infants from infections. A lack of breastfeeding can increase the risk of colonization with pathogens.
Daycare Attendance: Children who attend daycare are exposed to more infectious agents due to overcrowding and greater exposure to other children who may be ill.
why is tobacco smoke exposure in children a risk factor for acute otitis media?
Tobacco Smoke Exposure: Children exposed to tobacco smoke may have increased colonization of S. pneumoniae in their nasopharynx, which can lead to more frequent and severe infections.
which bacterial growth does tobacco smoke exposure encourage in children leading to AOM?
Streptococcus Pneumoniae
what is the function of eustachian tube?
The Eustachian tube connects the middle ear to the back of the throat and serves to equalize air pressure and drain fluid from the middle ear.
Fluid can accumulate behind the eardrum, and negative pressure can develop in the middle ear, leading to a conducive environment for bacterial or viral growth.
why is otitis media more common in children than adults?
In children, the Eustachian tube is shorter, narrower, and more horizontally positioned than in adults, which makes it more challenging for the tube to function properly. These anatomical differences contribute to the higher incidence of otitis media in children compared to adults.
what role does the soft palate muscle play related to the eustachian tube and how does this relate to children getting more frequent acute otitis media infections than adults?
The muscles of the soft palate play a role in the opening and closing of the Eustachian tube. In young children, the relative position of the muscle sling that opens the Eustachian tube is not as effective, leading to less frequent and less efficient opening.
what is a characteristic finding in otitis media with effusion (OME), where fluid is present in the middle ear without signs or symptoms of an acute infection?
air-fluid level
what does the appearance of air-fluid level in middle ear look like?
Translucent Above the Line: The upper part of the tympanic membrane appears more clear or translucent when air is above the fluid level in the middle ear. This indicates that there is still some air present in the middle ear space.
Opaque Below the Line: Below this line, the tympanic membrane looks cloudy or opaque due to the presence of fluid, which can vary from serous (clear fluid) to purulent (pus) depending on the nature and severity of the infection or inflammation.
The line that demarcates the separation between the air and fluid is a horizontal line that can be seen during an examination with an otoscope. It is an indication that there is a difference in the density of the middle ear contents — air above and fluid below. You may also see bulging tympanic membrane.
what are some complications of acute otitis media?
Vestibular Dysfunction: When fluid builds up in the middle ear for a prolonged period, it can affect the inner ear where the balance apparatus is located, leading to balance problems or vertigo.
Perforation of the Tympanic Membrane (TM): The pressure from the fluid accumulation in the middle ear can lead to a rupture of the eardrum. This can provide temporary pain relief as the pressure decreases, but also leads to discharge from the ear (otorrhea).
Conductive Hearing Loss: The fluid in the middle ear can interfere with the transmission of sound to the inner ear, leading to a temporary reduction in hearing.
Mastoiditis/Mastoid Abscess: The infection can spread to the mastoid cells, which are air spaces in the bone behind the ear, leading to mastoiditis or the formation of an abscess.
Effect on Cranial Nerve VIII: While mastoiditis can affect the nearby cranial nerve VIII (vestibulocochlear nerve), resulting in hearing problems, sensorineural hearing loss due to AOM is quite rare.
Severe Infection/Spread: In some cases, the infection can spread beyond the middle ear to other parts of the body, which can lead to very serious complications such as meningitis (inflammation of the membranes around the brain and spinal cord), brain abscesses, sepsis (a widespread infection in the bloodstream), high fever, and febrile seizures.
what is one of the causes of otorrhea in acute otitis media?
Perforation of the Tympanic Membrane (TM): The pressure from the fluid accumulation in the middle ear can lead to a rupture of the eardrum. This can provide temporary pain relief as the pressure decreases, but also leads to discharge from the ear (otorrhea).
what is mastoiditis?
Mastoiditis/Mastoid Abscess: The infection from acute otitis media can spread to the mastoid cells, which are air spaces in the bone behind the ear, leading to mastoiditis or the formation of an abscess.
what are some complications of mastoiditis?
Lateral Sinus Thrombosis:
This condition occurs when the infection leads to a clot within the lateral sinus (a large vein within the brain).
Symptoms may include spiking fevers, headache, neck stiffness or pain (meningeal signs), swelling and tenderness over the mastoid bone, discharge from the ear (otorrhea), ear pain (otalgia), and potential issues with cranial nerves IX (glossopharyngeal), X (vagus), and XI (spinal accessory).
Bezold Abscess:
This type of abscess occurs when the infection spreads from the mastoid bone to the surrounding neck muscles, particularly the sternocleidomastoid muscle.
It may present as a painful, swollen area in the neck.
Subperiosteal Abscess:
An abscess that forms beneath the periosteum, the layer covering the mastoid bone.
This can push the outer ear (pinna) forward and outward.
Facial Nerve Palsy (CN VII):
The facial nerve (cranial nerve VII), which passes through the middle ear and mastoid bone, can be affected by the infection or pressure from an abscess, leading to weakness or paralysis of the muscles on one side of the face.
Sensorineural Hearing Loss and Labyrinthitis (CN VIII):
Inflammation or infection that affects the inner ear (labyrinth) can cause vestibular symptoms such as vertigo (labyrinthitis) and sensorineural hearing loss, involving cranial nerve VIII (vestibulocochlear).
Meningitis:
Infection can spread to the meninges, the protective membranes covering the brain and spinal cord, leading to meningitis, a potentially life-threatening condition.
Temporal Lobe Abscess:
An abscess in the temporal lobe of the brain can occur if the infection spreads through the inner ear or via bone erosion.
Epidural/Subdural Abscess:
These abscesses form between the skull and the dura mater, or between the dura mater and the arachnoid mater, respectively. They can exert pressure on the brain and require urgent treatment.
Cerebellar Abscess:
An abscess in the cerebellum, the part of the brain responsible for coordinating movement, can cause problems with balance, coordination, and other cerebellar functions.
what is a type of abscess that occurs when the infection spreads from the mastoid bone to the surrounding neck muscles, particularly the sternocleidomastoid muscle.
It may present as a painful, swollen area in the neck?
Bezold abscess
If the infection spreads further, it can lead to necrotizing fasciitis, which is a severe, rapidly progressing infection that results in the death of the soft tissue.
what type of abscess pushes the outer ear forward and outward?
Subperiosteal Abscess:
An abscess that forms beneath the periosteum, the layer covering the mastoid bone.
This can push the outer ear (pinna) forward and outward.
which cranial nerve passes through the middle ear and mastoid bone and can be affected by mastoiditis what abnormal effect does it cause when affected?
Facial Nerve Palsy (CN VII):
The facial nerve (cranial nerve VII), which passes through the middle ear and mastoid bone, can be affected by the infection or pressure from an abscess, leading to weakness or paralysis of the muscles on one side of the face.
What is the mastoid antrum and where is it located?
The mastoid antrum is an air-filled cavity located in the temporal bone behind the middle ear. It is connected to the middle ear via a short passageway known as the aditus ad antrum.
What is the function of the mastoid antrum?
The mastoid antrum serves as a resonating chamber for sound and also helps to protect the delicate structures of the middle ear. Additionally, it is part of the system of air spaces that helps to equalize air pressure within the middle ear.
What is the tegmen mastoideum and its significance?
The tegmen mastoideum is the superior wall or roof of the mastoid antrum. It extends anteriorly as the tegmen tympani and forms a barrier that protects the brain from infections that may originate in the mastoid antrum.
How do the mastoid antrum and the mastoid air cells relate to each other?
The mastoid antrum intercommunicates peripherally with the mastoid air cells, which are multiple, variably-sized air spaces extending throughout the mastoid process. These air cells provide additional air volume and surface area to assist with the functions of the mastoid antrum.
What imaging technique is used to assess the mastoid antrum and air cells?
A CT (computed tomography) scan is commonly used to assess the mastoid antrum and air cells, as it provides detailed images of the bone structures and can help identify any abnormalities or infections.
