Eustachian Tube Dysfunction
The eustachian tube (ET), also known as the auditory or pharyngotympanic tube, connects the posterior nasopharynx to the middle ear. The proximal two-thirds of the ET is composed of cartilage, whereas the distal third closest to the middle ear is made of bone. Its primary function is to equilibrate pressure within the middle ear to atmospheric pressure. It also ventilates and drains the middle ear space which prevents and clears infection and debris. When the ET malfunctions by either becoming too dilated (patulous dysfunction) or occluded (obstructive dysfunction), it results in ET dysfunction (ETD).
- A spectrum of disorders involving impairment of the functional valve of the ET
- ETD can be classified as patulous dysfunction, in which the ET is excessively open, or dilatory dysfunction, in which there is failure of the tubes to dilate (i.e., open) appropriately.
- Pathophysiology related to pressure dysregulation, impaired protection secondary to reflux of irritating material into the middle ear, or impaired clearance by the mucociliary system
- May occur in the setting of pressure changes (e.g., scuba diving or air travel) or acute upper airway inflammation (e.g., allergic or infectious rhinosinusitis, acute otitis media [OM])
- Chronic ETD may lead to a retracted tympanic membrane, recurrent serous effusion, recurrent OM, adhesive OM, chronic mastoiditis, or cholesteatoma.
- Synonym(s): auditory tube dysfunction; ET disorder; blocked ET; patulous ET
Sudden sensorineural hearing loss (SSNHL) can be misdiagnosed as ETD.
- A simple 512-Hz tuning fork test lateralizes to the opposite ear in SSNHL and to the affected ear in ETD with conductive hearing loss.
- Any SSNHL is a medical emergency and should be referred to an otolaryngologist immediately.
Adults: >2 million health care visits annually
- Median age: 48
- Females > males
- Most common comorbidity is acute rhinitis.
Etiology and Pathophysiology
- Under normal circumstances, the ET is closed, opening to release a small amount of air to equilibrate middle ear pressure with surrounding atmospheric pressure.
- ETD is failure of the ET, palate, nasal cavities, and nasopharynx to regulate middle ear and mastoid pressure.
- ET functions:
- Ventilation/regulation of middle ear pressure
- Protection from nasopharyngeal secretions
- Drainage of middle ear fluid
- ET is closed at rest and opens with yawning, swallowing, and chewing.
- Cycle of dysfunction: structural or functional obstruction of the ET:
- Negative pressure develops in middle ear.
- Serous exudate is drawn to the middle ear by negative pressure or refluxed into the middle ear if the ET opens momentarily.
- Infection of static fluid causes edema and release of inflammatory mediators, exacerbating the cycle of inflammation and obstruction.
- In children, a horizontal and shorter ET predisposes to difficulties with ventilation and drainage.
- Adenoid hypertrophy can block the torus tubarius (proximal opening of the ET).
- In adults, paradoxical closing of the ET with swallowing occurs in a majority of affected patients.
- Tumors that impair/occlude the ET or that invade the tensor veli palatini to impair normal swallow regulation can also lead to dysfunction.
Twin studies show a genetic component. Specific genetic cause is undefined.
Adult and pediatric:
- Allergic rhinitis, tobacco exposure, GERD, chronic sinusitis, adenoid hypertrophy or nasopharyngeal mass, neuromuscular disease, altered immunity
- Prematurity and low birth weight, young age, daycare, crowded living conditions, low socioeconomic status, prone sleeping position, prolonged bottle use, craniofacial abnormalities (e.g., cleft palate, Down syndrome)
ETD may be exacerbated by rhinitis of pregnancy; symptoms resolve postpartum.
- Control of upper airway inflammation: allergies, infectious rhinosinusitis, GERD
- Autoinsufflation of middle ear (i.e., blow gently against pinched nostril and closed mouth)
- Avoid atmospheric pressure changes (e.g., plane flight, scuba diving) in the setting of acute allergy exacerbation or URI.
- Avoid exposure to environmental irritants: tobacco smoke and pollutants.
Commonly Associated Conditions
- Hearing loss
- OM: acute, chronic, and serous
- Chronic mastoiditis
- Allergic rhinitis
- Chronic sinusitis/URI
- Adenoid hypertrophy
- Cleft palate
- Down syndrome
- Nasopharyngeal carcinoma or other tumor
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