Eustachian Tube Dysfunction

Etiology

Baro-challenge-induced ETD describes the failure of the Eustachian tube to open with the surrounding pressure changes, thereby inhibiting the regulation of middle-ear pressure. Patients have normal otoscopy and tympanometry findings, as the failure of tube opening is situation-specific and arises with increased atmospheric pressure, eg, deep-sea diving or descent from altitude. The stress imposed on the mucosal surfaces of the Eustachian tube by repetitive equalization maneuvers from the increased atmospheric pressure leads to localized inflammation and mucosal edema. This affects the ability to make subsequent attempts at opening and clearance. By applying oral or topical decongestants to treat baro-challenge-induced ETD, it is thought that mucosal edema and local tissue hyperemia are reduced, thereby shrinking the nasopharyngeal mucosa and improving Eustachian tube patency.

Patulous ETD is caused by an overtly patent Eustachian tube, whereby the failed tube closure at rest provides continuous communication between the nasopharynx and the middle ear. This creates the reported symptom of autophony, with habitual sniffing to help alleviate self-vocalization. Physiological causes of dilatory ETD involve the development of inflammation and mucosal edema caused by episodes of rhinitis, upper respiratory tract infection, or gastro-oesophageal reflux disease, which leads to blockage of the orifice and dysfunction. Malignancy such as nasopharyngeal carcinoma can present with unilateral obstruction and must be excluded, with benign causes of obstruction including adenoidal hypertrophy and sequelae following adenoidectomy. Aural fullness is a common symptom due to negative middle ear pressure build-up.[4][5][6]

Epidemiology

Prevalence is greater in children than adults, with recent studies demonstrating 0.77 adult visits to every 1 pediatric clinic visit for ETD. An estimated 90% of children develop otitis media with effusion, a recognized sequela of ETD, before starting school. Approximately 1% of the adult population is diagnosed with ETD. Males are more likely to be diagnosed before the age of 20, with females more likely affected at older ages. No statistically significant difference between seasons has been proven.[7]

History and Physical

History includes determining any precipitating factors that may lead to inflammation or edema of the mucosal surfaces, leading to reduced patency of the Eustachian tube, including gastro-oesophageal reflux disease, rhinosinusitis, Samter’s triad, allergies, and recent upper respiratory tract infections. A history of adenoidectomy is a risk factor, and it is important to establish a family history of ETD or diseases of reduced mucociliary clearance, eg, Kartagener syndrome and cystic fibrosis. Down syndrome and cleft palate disorders have an association with ETD. Irritants that lead to inflammation include exposure to cigarette smoking and environmental allergens. Has the patient participated in diving or hiking at high altitudes? Ensure that intranasal medication, including oxymetazoline and corticosteroids, is explored.

The examination involves a head and neck examination, with otoscopy required to visualize for tympanic membrane retractions and evidence of negative middle ear pressures. Occasionally, hemotympanum is present in baro-challenge-induced ETD. Visualize the oropharynx and perform anterior rhinoscopy. Flexible nasoendoscopy should be included to examine the nasal mucosa for signs of inflammation or edema and the larynx for evidence of gastro-oesophageal reflux disease. Flexible nasoendoscopy provides access to the postnasal space, including a view of the contralateral nasopharyngeal orifice of the Eustachian tube. The valve mucosa is S-shaped when closed at resting state and rounded when dilated. Dilation should occur with swallowing.

Evaluation

Tympanic insufflation is performed to demonstrate active negative pressure, and a type C Tympanogram suggests negative resting middle ear pressures. Audiological tests must be completed using pure tone audiometry and Rinne and Weber tuning fork tests. The Eustachian Tube Dysfunction Patient Questionnaire (ETDQ-7) aims to screen for patient-reported severity of ETD using a scoring system. It consists of 7 separate questions, scored between 1 (no problem) and 7 (severe problem). A mean overall score of more than 2.0 indicates the presence of ETD.[8]

Treatment / Management

Treatment of ETD is dependent on the likely cause of dysfunction:

• Gastroesophageal reflux disease is addressed with lifestyle changes, including losing weight and dietary modifications to reduce acid production. Anti-acid medication, such as proton pump inhibitors, may be considered.
• If possible, try lifestyle changes to avoid potential allergens. Medical interventions include antihistamines and nasal corticosteroid medication.
• If indicated, treatment of rhinosinusitis should commence. Immunosuppressive agents are required for granulomatous diseases, eg, sarcoidosis and granulomatosis with polyangiitis (Wegener disease).
• Surgical dilatation of the Eustachian tube is performed using a Eustachian tube balloon catheter, with studies demonstrating improvement of the ETDQ-7 score at 12 months follow-up. ETD from otitis media with effusion is commonly managed with tympanostomy tube insertion
• Patients should be considered for adenoidectomy if adenoid hypertrophy is thought to be the main contributing factor to ETD. This is more common in children, who may present with middle ear effusion. Using auto-inflation devices to reopen the Eustachian tube by raising the pressure in the nose has shown favorable results for correcting middle ear pressure and fluid clearance.[9][10]
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Differential Diagnosis

Autophony is not limited to patulous ETD. Symptoms may include superior canal dehiscence and a foreign body within the external ear canal. Temporomandibular joint dysfunction may present with ‘popping’ noises and associated reduced hearing; however, it is also associated with discomfort upon jaw movement.

Prognosis

The outcome is dependent on the underlying cause and compliance with treatment. However, pediatric ETD generally improves and resolves with the maturation of the Eustachian tube and its surrounding muscles, aiding air ventilation- this usually occurs at 7 years of age.[11]

Complications

Complications of untreated ETD include conductive hearing loss, chronic otitis media, otitis media with effusion (glue ear) and its sequelae, and eardrum retraction.[12]