Bulging Eardrum Without Infection: Differential Diagnosis

A bulging tympanic membrane (TM) without acute infection suggests Eustachian tube dysfunction (ETD) or non-infectious middle ear effusion.

Differential Diagnosis

1. Eustachian Tube Dysfunction (ETD): Impaired ventilation → negative middle ear pressure → TM retraction → if persistent, transudate effusion → bulging. Causes: URI, allergies, sinusitis, smoking, barotrauma, tumors (nasopharynx).
2. Otitis Media with Effusion (OME): Sterile serous/mucoid fluid behind intact TM. Common in children (adenoid hypertrophy); adults: post-viral, ETD, nasopharyngeal mass. Hearing loss (conductive), fullness, tinnitus.
3. TM Perforation: Chronic perforation with granulation/edges may appear bulging; usually history of trauma/infection.
4. Ménière's Disease: Endolymphatic hydrops → episodic vertigo, fluctuating hearing loss, tinnitus, aural fullness. TM normal or slightly bulging during attacks.
5. Vestibular Schwannoma (Acoustic Neuroma): CN VIII tumor → asymmetric SNHL, tinnitus, imbalance; TM normal. Rarely causes bulging via secondary ETD.
6. Cholesteatoma: Keratinizing squamous epithelium in middle ear → erosion, chronic drainage, conductive loss. TM may show retraction pocket/bulge.
7. Barotrauma: Rapid pressure change (diving, flying) → hemorrhage/fluid in middle ear.

Evaluation

• Pneumatic otoscopy (mobility), tympanometry (Type B/C), audiometry.
• Nasal endoscopy (adenoid, mass).
• CT temporal bone (cholesteatoma, bony erosion).
• MRI IAC (vestibular schwannoma).

Management

• ETD/OME: Autoinflation (Valsalva, Otovent), nasal steroids, antihistamines, treat allergy/sinusitis. Myringotomy ± tubes if >3 months with hearing loss.
• Ménière's: Low-salt diet, diuretics, vestibular rehab, intratympanic steroids/gentamicin.
• Cholesteatoma: Surgical (tympanomastoidectomy).
• Vestibular schwannoma: Observation vs. radiosurgery vs. resection.

Persistent unilateral OME in adult → rule out nasopharyngeal carcinoma.