EENT · PANCE / PANRE

Sensorineural and Conductive Hearing Loss

Hearing loss categorized by site of pathology: conductive (outer/middle ear) vs sensorineural (cochlea/CN VIII/central).

Also known as: hearing loss, SNHL, conductive hearing loss, presbycusis, sudden sensorineural hearing loss, SSNHL

Overview

Hearing loss is a reduction in auditory acuity. Conductive hearing loss (CHL) results from impaired sound transmission through the external or middle ear. Sensorineural hearing loss (SNHL) results from damage to the cochlea, cochlear nerve, or central auditory pathways. Mixed loss has both components.

Epidemiology

Affects ~15% of US adults; prevalence rises with age — ~50% of adults ≥75 have disabling hearing loss. Presbycusis is the most common form of adult SNHL. Sudden SNHL incidence ~5-27/100,000/year.

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Risk factors

Age (presbycusis — high-frequency SNHL)
Chronic noise exposure (occupational, recreational firearms, music)
Ototoxic medications: aminoglycosides (gentamicin, tobramycin), platinum chemotherapy (cisplatin), loop diuretics (high-dose furosemide), salicylates, vancomycin, macrolides
Family history (otosclerosis, hereditary SNHL)
Head trauma, barotrauma
Recurrent otitis media → conductive loss
Congenital infections (CMV, rubella, syphilis), neonatal hypoxia, hyperbilirubinemia
Cardiovascular disease, diabetes, smoking

Pathophysiology

Sound is conducted from pinna → EAC → TM → ossicles → oval window (mechanical) → cochlea → hair cells → CN VIII → brainstem → cortex (neural). CHL: cerumen, effusion, TM perforation, ossicular fixation (otosclerosis) or discontinuity. SNHL: cochlear hair cell loss (presbycusis, noise-induced), endolymphatic hydrops (Meniere), retrocochlear (vestibular schwannoma), or central lesions.

Clinical presentation

Symptoms

Difficulty understanding speech, especially in noisy settings
Asking others to repeat; increasing TV/radio volume
Tinnitus (often associated with SNHL)
Vertigo or imbalance (suggests inner ear or CN VIII)
Ear fullness or aural pressure (effusion, Meniere)
Otalgia, otorrhea (otitis media, externa, cholesteatoma)

Signs / physical exam

Otoscopy: cerumen, effusion, perforation, retraction pocket, mass
Weber test: tuning fork on midline forehead. CHL lateralizes to AFFECTED ear. SNHL lateralizes to UNAFFECTED ear.
Rinne test: tuning fork on mastoid, then at ear canal. Normal/SNHL: AC > BC (positive Rinne). CHL: BC > AC (negative Rinne).
Whisper test, finger rub for bedside screening
Speech recognition disproportionately poor for the degree of pure-tone loss suggests retrocochlear (CN VIII) pathology

Classic findings

CHL: negative Rinne (BC > AC), Weber lateralizes to affected ear. SNHL: positive Rinne, Weber lateralizes to unaffected ear.

Differential diagnosis

Cerumen impaction — Conductive loss, ear fullness, exam shows occluding wax; treat with ceruminolytic, irrigation, or curettage
Otosclerosis — Progressive conductive loss in young adult, family history, Schwartze sign (pink TM), low-frequency loss; surgical stapedectomy or hearing aid
Presbycusis — Gradual bilateral high-frequency SNHL in older adult, difficulty understanding speech in noise; hearing aids
Noise-induced hearing loss — Bilateral SNHL with notch at 4 kHz on audiogram; occupational/recreational noise exposure
Sudden sensorineural hearing loss (SSNHL) — ≥30 dB loss over ≥3 contiguous frequencies within 72 h; idiopathic in 90%; urgent oral corticosteroids + MRI to exclude vestibular schwannoma
Meniere disease — Episodic vertigo + low-frequency SNHL + tinnitus + aural fullness; low-salt diet, diuretics, intratympanic steroids/gentamicin
Vestibular schwannoma (acoustic neuroma) — Unilateral progressive SNHL, tinnitus, imbalance; MRI internal auditory canal with gadolinium
Cholesteatoma — Conductive loss, foul otorrhea, retraction pocket or attic perforation; CT and surgical excision
Ototoxic drug exposure — Bilateral SNHL temporally related to aminoglycoside, cisplatin, or loop diuretic; high-frequency loss earliest

Diagnostic workup

Diagnostic criteria

Type determined by audiogram: CHL = air-bone gap ≥10 dB with normal bone conduction. SNHL = both AC and BC thresholds elevated with no air-bone gap. Mixed = elevated BC plus an air-bone gap. SSNHL = ≥30 dB SNHL across ≥3 contiguous frequencies developing within 72 h.

Labs

Not routine; consider TSH, ANA, RPR/FTA-ABS, Lyme, autoimmune panel in atypical or rapidly progressive SNHL
Genetic testing (GJB2/connexin 26) for congenital nonsyndromic SNHL

Imaging

Pure-tone audiometry — defines type, severity (mild 26-40 dB, moderate 41-55, moderately severe 56-70, severe 71-90, profound >90 dB), and configuration
Tympanometry — middle ear pressure/effusion
Speech audiometry — word recognition score
MRI internal auditory canals with gadolinium — asymmetric SNHL, sudden SNHL, retrocochlear symptoms
CT temporal bone — conductive loss with normal otoscopy (otosclerosis, ossicular abnormality, cholesteatoma extent)
Newborn hearing screen — otoacoustic emissions (OAE) and/or automated auditory brainstem response (AABR) before discharge

Diagnostic algorithm

Test	Normal	Conductive Loss	Sensorineural Loss
Weber (midline forehead)	Midline	Lateralizes to AFFECTED ear	Lateralizes to UNAFFECTED ear
Rinne (mastoid then EAC)	AC > BC (positive)	BC > AC (negative) on affected side	AC > BC (positive) bilaterally
Audiogram	All thresholds <25 dB	Air-bone gap ≥10 dB; BC normal	Both AC and BC elevated; no air-bone gap
Tympanometry	Type A	Type B (effusion) or As (otosclerosis)	Type A
Typical etiologies	—	Cerumen, OME, perforation, otosclerosis	Presbycusis, noise, ototoxicity, Meniere, vestibular schwannoma

Bedside and audiometric distinction of conductive vs sensorineural hearing loss.

Treatment

First-line

Cerumen impaction: ceruminolytic (carbamide peroxide), warm-water irrigation, or curettage under direct visualization
Conductive loss from OME persisting >3 months with hearing loss: tympanostomy tubes
Otosclerosis: hearing aids OR surgical stapedectomy/stapedotomy
Presbycusis and chronic SNHL: hearing aids; cochlear implant if severe-to-profound bilateral SNHL with poor aided speech recognition
Sudden SNHL: oral corticosteroids (prednisone 1 mg/kg/day × 7-14 days, then taper) within 2 weeks of onset; intratympanic dexamethasone salvage if oral course incomplete response
Counsel on hearing protection (earplugs/muffs) for ongoing noise exposure

Second-line / adjunct

Intratympanic dexamethasone for SSNHL — primary or salvage therapy, especially if systemic steroids contraindicated (diabetes, immunosuppression)
Cochlear implantation for severe-to-profound bilateral SNHL with limited benefit from hearing aids
Bone-anchored hearing aid (BAHA) for unilateral SNHL or chronic conductive loss
Auditory rehabilitation, lip-reading instruction, assistive listening devices
Treat underlying cause: discontinue ototoxic medication, manage Meniere with diet/diuretic, surgical removal of vestibular schwannoma when appropriate

Complications

Speech and language delay in untreated congenital/early-childhood hearing loss
Social isolation, depression
Cognitive decline and increased dementia risk in untreated adult hearing loss
Falls (linked to age-related hearing loss)
Reduced occupational performance and earning capacity

PANCE pearls

Weber lateralizes to BAD ear in conductive loss; to GOOD ear in sensorineural loss.
Sudden SNHL is an ENT emergency — give oral steroids within 2 weeks AND order MRI internal auditory canals (5-10% have vestibular schwannoma).
Universal newborn hearing screening: failed screen → confirmatory audiologic evaluation by 3 months; intervention by 6 months ('1-3-6 rule').
4 kHz notch on audiogram = noise-induced hearing loss.
Bilateral conductive loss in a young adult with family history and normal otoscopy → otosclerosis.

References

AAO-HNS 2019 — Chandrasekhar SS et al. Clinical Practice Guideline: Sudden Hearing Loss (Update). Otolaryngol Head Neck Surg 2019;161(1S):S1-S45
USPSTF 2021 — Screening for Hearing Loss in Older Adults. JAMA 2021;325(12):1196-1201 (I statement)
AAP/JCIH 2019 — Joint Committee on Infant Hearing. Year 2019 Position Statement. J Early Hear Detect Interv 2019

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