Definitions

otosclerosis : "abnormal growth of bone around the stapes at the oval window, leading to fixation of the stapes or depositing of toxins into the cochlea in one or both ears"

otitis externa: Bacterial or fungal infection that causes an acute reaction to the skin lining of the external ear.

ototoxicity: Exposure to drugs or substances that systematically poison the auditory system in particular the hair cells in both ears

glomus tumor: benign, slow-growing, highly vascularized tumor/mass in the middle ear arising from neural tissues either from the jugular bulb or other nerves around the promontory of the affected ear."

ossicular chain discontinuity: Head injuries involving impact to the temporal bone such as car accident can cause this

presbycusis: Decline of hearing associated with aging due to damage of the hair cells, stria vascularis, and/or neural pathways, typically in both ears"

Herpes Zoster Oticus: variation of herpes responsible for chickenpox/shingles originates in ganglion of the facial nerve

chronic disorder: A/An __________ persists over time

tympanosclerosis: identified on otoscopy and indicates prior history of perforation

Cholesteatoma: Retraction pocket or congenital condition of the tympanic membrane in the affected ear that creates a benign cyst that grows due to dead skin which is shed and is trapped in the pocket and can invade and erode the middle ear

otitis media: "Poor eustachian tube function, causing an accumulation of fluid in the middle ear that may become infected with bacteria, typically during an upper respiratory infection."

Meniere's Disease: abnormal buildup of endolymph in the inner ear

hyperacusis: "Related terms include misophonia, phonophobia, decreased sound tolerance "

vestibular schwannoma: "Idiopathic/spontaneous benign tumor arising from the vestibular branch of the 8th cranial nerve, leading to an impingement or compression on the cochlear branch of the 8th cranial nerve in the affected ear."

Cytomegalovirus: "belongs to the herpes virus family, and although not easily spread from person to person, infection can occur following contact with saliva, blood, urine, breast milk, cervical secretions, or semen "
noise induced hearing loss: Cell death that causes oxidative stress, metabolic exhaustion, ischemia and ionic imbalance in the inner ear fluids. Disease process is accelerated via exposure to chemicals

Atresia: Congenital, developmental abnormality causing the absence of the external auditory canal in one or both ears

canal stenosis: can arise as congenital or caused by acquired conditions such as chronic otitis externa
exostoses: Repeated exposures to cycles of warm and cold water resulting in bony growths in the external auditory canal

acute disorder:A/An _______ comes on suddently in its initial phase and lasts a reletively short time

General Principles of Audiological Diagnosis

• A wide range of pathologies is encountered in audiological practice.

• Any disorder impacting hearing that necessitates medical intervention requires immediate referral to a medical professional, such as an Ear, Nose, and Throat ($ENT$) specialist or a Primary Care Physician ($PCP$).

• If a pathology is identified as something other than simple Sensorineural Hearing Loss ($SNHL$), patients must be instructed to follow up with their $ENT$ or $PCP$.

Outer Ear Disorders and Pathologies

• Outer ear pathologies can lead to Conductive Hearing Loss ($CHL$). The severity of the $CHL$ typically correlates with the severity of the physical obstruction or malformation, though some pathologies may not impact hearing at all.

• Most outer ear disorders are diagnosed via otoscopy, but testing the function of the inner ear and central auditory system is essential to confirm the viability of the system beyond the outer and middle ear.

Congenital Malformations of the Outer Ear

• Preauricular Pits and Tags:

  • These are malformations caused by incomplete hillock fusion during pregnancy.

  • Pits: Divots located near the tragus with a sinus tract running under the skin near the ear's cartilage. They can lead to cysts, infections, or abscesses but do not inherently affect hearing.

  • Tags: Stalks of cartilage located in front of the tragus. These are often associated with genetic conditions such as $Goldenhar$ syndrome, which may involve hearing loss.

• Microtia and Anotia:

  • These occur during the first trimester of pregnancy.

  • Microtia: Underdevelopment of the pinna.

  • Anotia: Complete absence of the pinna.

  • These occur in approximately $1$ in $10,000$ to $20,000$ births. Unilateral cases are $7$ times more common than bilateral, with higher incidence in males. $10\%$ of cases are associated with syndromes like $Treacher\,Collins$, $Goldenhar$, or hemifacial microsomia.

• Atresia:

  • Underdevelopment or absence of the ear canal.

  • $\sim 90\%$ of cases involve $CHL$, and up to $\sim 15\%$ may also have $SNHL$.

  • $Jahrsdoerfer$ Grading Scale: Assigns points to describe the completeness of structures. $2$ points are given for the presence of the stapes bone, and $1$ point each for an open oval window, round window, middle ear space, and facial nerve.

Cerumen and Obstructions

• Cerumen (Ear Wax): A mixture of sebaceous material, apocrine secretions from ceruminous glands, desquamated epithelium, and hair. Glands increase secretion in response to adrenalin and pain via alpha-adrenergic receptors.

• Variations: Color ranges from golden yellow to black; consistency ranges from soft/oily to dry ("rice bran" wax common in Asian populations).

• Clinical Classifications:

  • Non-occluding/Minimal: Wax around the edges of the canal.

  • Occluded: Significant amount of cerumen present.

  • Impacted: Completely blocking the canal, causing a sensation of fullness, pressure, reduced hearing ($CHL$), pain, or dizziness.

• Management: Removal is necessary if cerumen causes pain, hearing loss, or prevents assessment. Options include cerumenolytic agents, irrigation, or manual removal by an Audiologist ($AuD$) or physician.

• Foreign Bodies: Items such as sand, beads, insects, or hearing aid components (domes, wax guards) can cause pain, discharge, or dizziness. Insects inside the ear may cause nausea.

Keratosis Obturans

• A condition identified by $Wreden$ in $1874$ where the self-cleansing mechanism of the ear canal (keratin maturation and lateral migration) is nonfunctional.

• Characterized by the accumulation of keratin deep in the bony canal, which exerts pressure and causes bone remodeling (widening of the canal).

• Typically occurs in the first two decades of life and is often associated with bronchiectasis or chronic sinusitis.

• Presents with $CHL$, pain, and rarely otorrhea. Treatment requires repeated debridement.

Otitis Externa (Outer Ear Infection)

• Acute Diffuse Otitis Externa (Swimmer’s Ear): Most commonly caused by $Pseudomonas\,aeruginosa$. Symptoms include severe pain, tenderness, itching, and thin serous discharge. The absence of cerumen is characteristic.

• Acute Circumscribed Otitis Externa (Furuncle): A localized infection/abscess at the base of a hair follicle, occurring only in the outer cartilaginous portion of the canal. Usually caused by $Staphylococcus\,aureus$.

• Chronic Otitis Externa: A long-term, souvent painless inflammation characterized by itching and skin thickening (hypertrophic). Can lead to stenosis or complete occlusion.

• Otomycosis: Fungal infection of the $EAC$, most commonly $Aspergillus$ (white, fluffy material with black conidiophores) or $Candida$ (requires agar culture for diagnosis). Primary symptom is itching.

Bony Growths (Exostoses and Osteomas)

• Exostoses (Surfer’s Ear): Multiple, benign bony growths in the deep auditory canal, usually resulting from repeated cold water or wind exposure causing reactive hyperemia and subperiosteal bone deposition.

• Osteomas: Benign bone tumors not caused by external environmental reactions.

• Testing: Otoscopy is primary. If fully occluding, it results in $CHL$, absent $OAEs$, and delayed $ABR$ wave latencies with normal interwave latencies.

Outer Ear Carcinoma

• Squamous Cell Carcinoma: Second most common, more aggressive than basal cell, but less deadly.

• Basal Cell Carcinoma ($BCC$): Most common skin cancer, often presents as a nodular lesion with a central depression or ulcer. Linked to sun exposure.

• Melatnoma: Most deadly and aggressive.

• $ABCDE$ Rule for Identification: $Asymmetry$, $Border$ irregularity, $Color$ variation, $Diameter$ (> 6\,mm), and $Evolving$ (changing spot).

Middle Ear Disorders and Anatomy

• The middle ear ($ME$) is an air-filled space lined with mucous membrane that performs impedance matching to transfer sound energy from air to the fluid-filled cochlea.

Normal Tympanic Membrane (TM) Landmarks

• Pars Tensa: The lower $4/5ths$ of the $TM$, containing a strong fibrous layer.

• Pars Flaccida: The upper $1/5th$, with a sparse fibrous layer.

• Umbo: The distal part of the handle of the malleus at the apex of the cone of light.

• Vascular Strip: Tiny vessels running along the handle of the malleus.

• Chorda Tympani: A branch of the facial nerve ($7th$ cranial nerve) providing taste to the anterior $2/3rds$ of the tongue, visible through a translucent $TM$.

Otitis Media (OM)

• Dynamics: Typically starts with Eustachian Tube ($ET$) dysfunction, leading to negative pressure ($Type\,C$ tympanogram) and eventual fluid secretion ($Type\,B$ tympanogram).

• Classification by Duration:

  • Acute: Resolves within $3$ weeks.

  • Subacute: $3$ weeks to $3$ months.

  • Chronic: Lasts > 3 months.

• Classification by Effusion:

  • Serous: Watery, clear, non-infectious.

  • Mucoid: Thick, cloudy, contains white blood cells.

  • Purulent: White/yellow/green, involves bacterial infection.

• Treatment: Bacterial infections require oral antibiotics (not drops). Recurrent cases may require Pressure Equalization ($PE$) tubes or adenoid removal.

• Complications: $Mastoiditis$, where infection spreads to the mastoid air cells, potentially eroding the temporal bone.

Tympanic Membrane Perforation

• Caused by trauma ($Q-tips$, bobby pins), pressure (scuba diving), or high-intensity sound.

• Diagnosis: $Type\,B$ tympanogram with large Ear Canal Volume ($ECV$).

• Treatment: Small holes may heal naturally; large holes require a tympanoplasty (surgical graft using temporalis fascia).

Other Middle Ear Pathologies

• Tympanosclerosis: Scarring/calcification of the $TM$, often following trauma or chronic $OM$. Results in a $Type\,A_s$ (stiff) tympanogram.

• Cholesteatoma: A pocket of skin cells/debris that increases in size and erodes ossicles and the $TM$. Can be congenital or acquired. Requires mandatory surgical removal.

• Otosclerosis: Spongy bone growth on the stapes footplate, causing stiffness. Characterized by $Carhart's\,Notch$ (a dip in $BC$ thresholds at $2,000\,Hz$) and the "$Schwartze\,sign$" (reddish glow on the promontory). Twice as common in women.

• Ossicular Disarticulation: Interruption of the ossicular chain (usually between incus and stapes) following head trauma. Results in a $Type\,A_D$ (loose/hypermobile) tympanogram.

• Glomus Tumor: A rare, highly vascular tumor arising from glomus bodies usually in the jugular vein. Symptoms include pulsatile tinnitus and a jagged $Type\,A$ tympanogram reflecting the pulse.

Inner Ear and Retrocochlear Disorders

Infections and Hearing Loss

• Bacterial Meningitis: Infection of the meninges. $1$ in $10$ children recovery with permanent $SNHL$. A major risk is cochlear ossification (bone filling the cochlea), making immediate cochlear implant evaluation critical.

• Cytomegalovirus ($CMV$): The leading environmental cause of childhood hearing loss. $90\%$ of babies are asymptomatic at birth but can develop late-onset or progressive $SNHL$.

Presbycusis

• Age-related hearing loss, typically clinically significant by the $60s$.

• Characterized by progressive, symmetric, high-frequency $SNHL$.

• Patients often experience a plateau in speech clarity ($WRS$) regardless of volume increase.

Noise-Induced Hearing Loss (NIHL)

• Temporary Threshold Shift ($TTS$): Ringing and hearing change that recovers within hours.

• Permanent Threshold Shift ($PTS$): Persistent damage to hair cells from repeated exposure or single high-intensity events.

• Pathophysiology: Oxidative stress and metabolic exhaustion lead to hair cell death.

• $NIOSH$ Exposure Limits: $85\,dB$ is safe for $8$ hours. For every $3\,dB$ increase, the safe duration halves ($88\,dB$ for $4$ hours, $91\,dB$ for $2$ hours, etc.).

• Characteristic: A "noise notch" on the audiogram appearing around $4,000\,Hz$.

Ototoxicity

• Damage to the inner ear from chemical substances (chemotherapy agents, heavy metals, or high-dose aspirin).

• Aspirin effects are often reversible; anti-neoplastics are usually permanent.

• Monitoring involves ultra-high frequency testing (up to $20,000\,Hz$) for early detection.

Meniere’s Disease

• Caused by excessive production or under-absorption of endolymph in the scala media.

• Symptom Constellation: Episodes of vertigo, nausea, aural fullness, roaring tinnitus, and fluctuating low-frequency $SNHL$.

• Management includes a low-sodium diet, diuretics, and vestibular suppressants.

Retrocochlear Tumors

• Vestibular Schwannoma: Most common retrocochlear tumor, growing from $Schwann$ cells of the vestibular nerve.

• Signs: Unilateral asymmetric high-frequency $SNHL$, unilateral tinnitus, aural fullness, and poor word recognition ($WRS$) with "rollover."

• MRI: The gold standard for diagnosis ($100\%$ sensitivity and specificity).

Auditory Neuropathy Spectrum Disorder (ANSD)

• A condition where neurons function but do not fire synchronously.

• Diagnosis: Presence of $OAEs$ (normal outer hair cells) but absent or abnormal $ABR$ results.

• Protocol: In neurodiagnostic $ABR$, the waveform inverts or "flips" when the stimulus polarity (condensation vs. rarefaction) is changed.

Central Auditory Processing Disorder (CAPD)

• Difficulty making sense of auditory information despite normal hearing thresholds (often described as "dyslexia for hearing").

• Symptoms include trouble listening in background noise, following multi-step directions, and poor academic performance. Requires a specialized test battery involving binaural integration and temporal processing.

Psychological and Behavioral Considerations

Tinnitus and Hyperacusis

• Tinnitus: Perception of sound without an external source.

• Hyperacusis: Abnormal intolerance to everyday sounds.

• Management involves counseling and Sound Therapy to minimize the emotional reaction. Avoidance of sound (wearing earplugs constantly) is not recommended as it can increase sensitivity.

Exaggerated or False Hearing Loss (Malingering)

• Occurs when a patient purposely (for compensation) or subconsciously (conversion disorder) misrepresents their hearing.

• Red Flags: Poor agreement between $SRT$ and $PTA$, exaggerated listening behaviors (straining/squinting), or related-word responses (e.g., repeating "house" for "home").

• Testing Tactics: Use objective measures ($OAEs$, $ABR$), the $Stenger$ Test, or an ascending method for behavioral thresholds. Always maintain professionalism and avoid terms like "faking" or "lying."