Audiology Review Quiz #1

Aural Rehabilitation SLP 440

Eardrum (Tympanic Membrane)

Eardrum (Tympanic Membrane)

Function is to transduce sound pressure into mechanic vibrations

Ossicular Chain

Three smallest bones in our body which are attached to the tympanic membrane.

• Mallus, incus, and stapes

• Function: Transmit sound

Function of the middle Ear

To overcome impedance mismatch (the traveling of air to fluid).

• Overcome with the thumbtack and the crowbar (lever) methods

Inner Ear

Consists of 2 systems (cochlea and the vestibular system)

• Cochlea: organ of hearing

• Vestibular System: organ of balance

Outer Hair Cells (OHC)

• Receive and Detect Sounds

• Amplifiers

• they exhibit motility

• responsible for OAEs

• connected to efferent neurons

Inner Hair Cells (IHC)

• Transmits sounds to the brain

• connected with afferent neurons: carry information from the cochlea to the higher auditory system.

• causes the release of neurotransmitters

OHC Characteristics

3 to 5 rows

12,000 cells

50-150 Sterocilia per cell

IHC Characteristics

1 to 2 rows

3,500 Cells

50-70 Stereocilia per cell

Afferent Neurons

Carry information from the cochlea to the higher auditory system.

Efferent Neurons

Carry information from the higher auditory system (brain) to the cochlea

Functions of the Outer Ear

• Collect Sounds

• Localization

• resonator

• Protection of the middle ear

• Self-mutilation

4 Different Types of output Transducers

1. Standard headphones (supra-aural)

2. Insert Earphones

3. Bone vibrator

4. Speakers in a sound field

Masking

To rule out participation of the non-test ear by using a masking noise (competing sound) in that ear

Sound can cross over based on the output transducer

Insert Earphones = 90dB

Supra-aural Headphones = 50dB

Bone Conductor= 0dB

Tympanogram

Measures the movement of the eardrum

What Type of Tymp is this?

Type A

What Type of Tymp is this?

Type As

What Type of Tymp is this?

Type Ad

What Type of Tymp is this?

Type B

What Type of Tymp is this?

Type C

Type A Tympanogram

• Normal middle ear pressure

• normal eardrum movement

• normal ear canal volume

• Pathologies associated with this Tymp:

  • Otosyphillis

  • Presbycusis

  • Meniere’s Disease

  • Acoustic Neuroma

  • Microtia

  • Anotia

  • Otitis Externa

  • Noise Induced Hearing Loss

  • Ototoxicity

  • Auricular Tag

  • sometimes Tympanosclerosis

Type B Tympanogram

• “Flat”

• No compliance or pressure peak indicated

• Middle Ear Fluid

• can be normal or increase ear canal volume

• Pathologies associated with this Tymp:

  • Perforated Eardrum

  • P.E Tubes

  • impacted Cerumen

  • Atresia

  • Chronic Otitis Media

  • Keratoma/ Cholesteatoma

  • Foreign Body in Ear Canal

  • Temporal Bone Fracture

Type C Tympanogram

• Excessive negative middle-ear pressure

• Normal or reduced compliance

• Pathologies associated with this Tymp:

  • Eustachian Tube Dysfunction (initiation or resolution of middle ear fluid)

Type As Tympanogram

• “Shallow”

• the movement of the eardrum is there, but it is very slow it is hard to move

• normal middle-ear pressure

• reduced compliance

• Pathologies related to this tymp:

  • Otosclerosis

  • Sometimes Tympanosclerosis

  • Fixation of the ossicles

Type Ad Tympanogram

• “Flaccid”

• The eardrum moves too much

• increased compliance

• normal middle ear pressure

• Pathologies associated with Tymp:

  • Ossicular Disarticualtion (the bones detached from one another)

  • Ossicular Discontinuity (born with it)

Distortion Product Otoacoustic Emission (DPOAE)

• Evoked following the presentation of two tones with frequencies that are mathematically determined to create a difference tone (the distortion product) in the cochlea.

• 2 tones need to go in and one need to come back out in order for an OAE to be present

• When you have OAE present then it rules out any pathologies in the middle ear, outer ear or inner ear

Diagnosing Hearing Loss

Severity, configuration and Type of hearing loss

Types of Hearing Loss

1. Conductive Hearing Loss (temporary)

2. Sensorineural Hearing Loss (permanent)

3. Mixed Hearing Loss (both conductive and sensorineural)

4. Non-organic Hearing Loss (Pathological or faking)

Causes for sensorineural hearing Loss

• Exposure to loud sounds

• Consequences of the aging process

• Genetic syndrome

• Neural disorder

• Vascular disorder

• Infections or trauma during fetal development, at birth, in childhood, or as an adult.

true or false

The ability to hear plays a direct role in the ability to perceive and produce speech

True

4 Basic Parameters of Hearing Loss

1. Degree of Hearing Loss – severity of the impairment

2. Configuration – Shape of the hearing loss

3. Type of Hearing Loss – conductive, sensorineural, or mixed

4. Symmetry – comparison of results between ears

Air Conduction Testing

sound travels via air on a sound wave through the three parts of the ear.  Traditional circumaural headphones, insert earphones, or speakers are used to transmit the sound

Bone Conducting Testing

Sound travels via bone, bypassing the outer ear and middle ear by setting the bones of the skull into vibration.  The bone vibrator is placed on the mastoid bone

Conductive Hearing Loss

• Involves the structures in the ear that are responsible for CONDUCTING sound to the cochlea

• Can be caused by an obstruction, abnormality, or disease and is found in the outer or middle ear 

• This loss is typically temporary, but left untreated it can lead to a permanent condition

Sensorineural hearing Loss

• Involves both the cochlear function of sensory reception and the function of the auditory nerve

• Most often the problem is due to damage to the inner or outer hair cells or other structures in the cochlea

• Sometimes, this problem occurs because of problems with auditory nerve fibers, in the auditory nerve, or centrally in the auditory central nervous system extending through the brain stem to the cerebral cortex

• Because of its location, sensorineural hearing loss is usually permanent in nature and most often untreatable medically or surgically

• Can be congenital or acquired, early onset or delayed, unilateral or bilateral

Otitis Externa

• Can cause swelling, pain, and drainage

• Inflammatory consequences can occlude the outer ear causing conductive hearing loss

• Caused by several types of common bacteria

• May be caused by fungus, which we call otomycosis

• Treated with medication to fight infection and swelling

• Can be extremely dangerous for diabetics if it develops into malignant otitis externa

Perforation in the Tympanic Membrane

• Significant because it can create a conductive hearing loss, but also because it leaves the middle ear space open to the elements

• Causes:

  • Spontaneous: secondary to middle ear infection or fluid buildup

  • Direct trauma: from an object (Q-tip, foreign object, or welding slag)

  • Concussive incident: (slap to the head, explosion, or waterskiing)

  • Barotrauma: (change in pressure frequently seen with scuba divers)

Tympanosclerosis

• White plaques seen on the eardrum usually after repeated middle ear infections or after PE tubes

• Plaques are caused by deposits of calcium in the tissue (collagen) of the tympanic membrane, but does not usually cause hearing loss

• Type A or As Tymp

Eustachian Tube Dysfunction

• Inflammatory tissue change in the nasopharynx:

  • Sinusitis, Adenoiditis, Tonsillitis, or growth of a mass

• Treatment includes:

  • Antibiotics or surgical removal of the tonsils and/or adenoids

Eustachian tube dysfunction ALONE creates at most a mild conductive hearing loss, but may lead to further problems in the middle ear space

• Type C Tymp

Otitis Media

General term for an inflammation or infection of the middle ear, which can invade the mastoid cavity

3 main characteristics

• Fluid present in the middle ear

• Fluid may or may not be infected

• might be degenerative changes to the tissues of the middle ear

Otitis Media with Effusion (OME)

• Common version of OM and one of the most common conditions affecting the auditory systems in children

• More than 2 million episodes of OME occur annually medical costs = $4 billion dollars a year

• Otitis Media with effusion is fluid build up without infection

• If untreated/unresolved fluid may thicken and become  “glue ear”

• Conductive hearing loss varies from slight to mild depending on the thickness of the fluid

Acute Otitis Media

• Fluid buildup in the middle ear is infected

• this version of otitis media typically is the result of bacterial infection and may or may not present with the hallmarks of infection: (fever, pain, accumlation of whote blodd cells, etc)

• conductive hearing loss is usually mild but can be moderate in some cases.

Chronic Otitis Media

• Unresolved infection of the middle ear including the mastoid spaces as well as the mucosal lining with non-intact TM and discharge

• Infectious, permanent, progressive, and Erosive/destructive process

• Unchecked erosive infection can lead to damage to the inner ear, Facial nerve and ultimately the brain (you cause damage to the barrier it can be lethal)

Cholesteatoma

• Accumulation of dead, exfoliated skin cells from the external canal and lateral surface of the tympanic membrane also referred to as a keratoma (similar only)

• Can form at any perforation site, but is most often seen on the edge of the tympanic membrane, or the upper area of the tympanic membrane when it is pulled into the middle ear space due to eustachian tube dysfunction.

• Smooth, white, pearl-like growths that can erode the ME ossicles completely and may enlarge and erode into the brain cavity

• Mild conductive hearing loss that is usually treated by surgical removal first and may ultimately result in the use of a hearing ai

Otosclerosis

• Progressive conductive hearing loss that results in fixation of the stapes bone in the oval window

• Type As Tymp

• Happens because vascular and enzymatic activity degrade the old bone and new bone is structurally different – some call it spongy

Otosyphillis (Aquired Syphillis)

• Symptoms of SNHL and dizziness

• type A tymp

• HL is usually progressive and fluctuating, bilateral but asymmetrical.

• Symptoms mimic meniere’s disease and acoustic neuroma, therefore it has been called “the great imitator”

Ototoxicity

• Certain medications and chemical substances cause hearing loss through sensory cell damage and interference with inner ear metabolism

• Will affect the cochlea and sometimes can affect the vestibular system

• Changes can be permanent and severe, or maybe revered once the appropriate medication is used

• 4 classes of drugs in this category

  • Antineoplastic Drugs

  • Aminoglycoside Drugs

  • Loop Diuretics

  • Analgesics and Antimalarials

Neurofibromatosis Type 2

• When bilateral acoustic neuromas are found, the underlying cause is almost always NF2

• Genetically/inherited condition that causes multiple neuromas, typically on sensory nerves in the head and spinal cord

• Treatment is usually surgical reduction of the tumors, and the surgeon’s focus is on preserving facial nerve function and hearing

• Prognosis with regard to hearing is poor with surgical reduction or without, and unfortunately hearing aids are often useless.  Another option might be the Auditory Brainstem Implant (ABI)

• The ABI bypasses the cochlea and auditory nerve entirely and provides direct neural stimulation to the brain stem

Treacher Collins Syndrome

• Inherited

• Abnormalities on the eyelids

• Downward slanting eyelids

• Underdevelopment of the jaw

• Cleft Palate

• Microtia

• Atresia

• Ossicular malformation or fixation

• Conductive Hearing Loss

Waardenberg Syndrome

Pigmentation abnormalities of the skin, hair and eyes

Usher Syndrome

• Rentinitis Pigmentosa

• an inherited condition characterized by impairment of vision and hearing, resulting from the occurrence of retinitis pigmentosa and abnormal auditory neural conduction.

• Type A Tymp if there is sensorineural HL

Eustachian tube Function

To equalize pressure of the middle ear

• Keep the air pressure behind the eardrum the same as the pressure outside