Tests of Eustachian Tube Dysfunction - 10 Marks (MS ENT Exam Answer)

Introduction

Classification of Tests

A. CLINICAL/BEDSIDE TESTS

1. Valsalva Manoeuvre

• The patient forcibly exhales against a closed airway (pinching the nose shut with the mouth closed)
• Generates approximately 20-40 mmHg of positive nasopharyngeal pressure
• A positive test (air entering the middle ear) is felt as a crackling or popping sensation, and a change in the TM can be seen on otoscopy
• Limitation: The sensation of equalization when performing the Valsalva manoeuvre has a poor (0%) predictive value for potential barotrauma (Scott-Brown's, Vol 2)
• Useful to assess opening of the ET when pressure is applied from the nasopharyngeal side
• It is easier to expel air from the middle ear than to bring it in, so Valsalva (which inflates the ET from the nasopharynx) tends to be more successful than Toynbee in normal subjects

2. Toynbee Manoeuvre

• The patient pinches the nose and swallows
• Swallowing opens the ET while simultaneously creating negative nasopharyngeal pressure, which draws air out of the middle ear
• A positive test: a sensation of ear "clicking" or pressure change, with TM moving inward
• Predictive value: Toynbee test has a positive predictive value of 25% for barotrauma susceptibility (Scott-Brown's, Vol 2)
• More physiological than Valsalva as it mimics normal ET function

3. Politzer Test (Politzerization)

• A Politzer bag is placed in one nostril, the other is compressed, and air is forced in while the patient swallows or says "K-K-K"
• This creates positive pressure in the nasopharynx that may open the ET
• Used both as a diagnostic test and as a treatment for ETD
• Observed via otoscopy or felt by the patient as relief of pressure

4. Catheterization of the Eustachian Tube

• A Eustachian tube catheter is passed transnasally to the ET orifice and air (or fluid) is insufflated
• Historically used since the 18th century; a positive result is confirmed by auscultation through a Toynbee listening tube
• Fell into disfavor due to technical difficulty and risk of fatal complications without direct visualization
• Still performed where other tests are unavailable

5. Otoscopy / Pneumatic Otoscopy (Siegel's Speculum)

• Direct inspection of the TM: retracted TM, fluid level or air-fluid bubbles (effusion), reduced TM mobility
• Pneumatic otoscopy: air is gently insufflated into the sealed ear canal; reduced TM mobility suggests middle ear negative pressure or effusion
• Inspection alone (even with otomicroscopy) is not adequate by itself to diagnose ETD - static TM findings do not reliably correlate with the presence or severity of dysfunction (Cummings)

B. AUDIOLOGICAL TESTS

6. Tympanometry (Impedance Audiometry)

• A probe with an airtight seal is placed in the external auditory meatus, measuring compliance of the middle ear system across varying air pressures
• The most commonly used indirect test of ET function
• Type B tympanogram: flat trace - suggests middle ear effusion (non-compliant system)
• Type C tympanogram: peak compliance at negative pressure (e.g., -200 daPa or more negative) - indicates chronic negative middle ear pressure from ET obstruction
• The hallmark of obstructive ETD is negative pressure persisting within the middle ear (Cummings)
• Limitation: cannot directly assess ET opening or closing; tympanometry is unhelpful in patulous ETD

7. Pure Tone Audiometry (PTA)

• Conductive hearing loss (air-bone gap) is a consequence of ETD and middle ear effusion
• Audiometry quantifies the degree of hearing impairment and monitors the response to treatment
• Used in conjunction with tympanometry as part of the standard assessment battery

C. OBJECTIVE / SPECIALIZED TESTS

8. Nine-Step Inflation-Deflation Test (Bluestone's Test)

• A tympanometric technique that evaluates ET function in patients with intact tympanic membranes
• A standardized sequence of positive and negative pressure is applied to the ear canal while the patient performs swallowing manoeuvres
• The ability of the ET to equalize pressure (seen as a shift of tympanometric peak toward zero) reflects ET function
• Nine-step sequence: baseline tympanogram → apply +200 daPa → 5 swallows → repeat tympanogram; then apply -200 daPa → 5 swallows → final tympanogram
• Predictive value: 25% positive predictive value, 75% negative predictive value for barotrauma
• Combining the nine-step test with the Toynbee test yields 100% reliable predictive results (Scott-Brown's, Vol 2)

9. Forced Response Test

• Requires a patent ventilation tube in the TM or a TM perforation (i.e., tests across an open TM)
• A specialized tympanometry probe combined with an air pump is placed in the ear canal
• Increasing pressure is applied at the ear canal until the ET is forced open
• The pressure at which opening occurs (opening pressure) and system resistance during swallowing can be measured
• Used to evaluate ET function pre-tympanoplasty in children (Cummings)

10. Tubomanometry (TMM)

• Described by Estève in 2001
• A stimulus of a controlled gas bolus is applied to the nasopharynx during swallowing, while a pressure sensor in the occluded external ear canal records pressure changes
• Measures the opening pressure and timing of ET opening
• The opening latency index (R): R < 1 = early/optimal opening; R > 1 = delayed opening; no opening = 0
• TMM results combined with clinical symptoms form the ET Score (range 0-10):
  • 0 = complete obstruction
  • 10 = normal tubal function
  • Incorporates TMM at 30, 40, and 50 mbar, plus symptom scoring (clicking with swallowing, positive Valsalva: 0 = never, 1 = sometimes, 2 = always)
• Currently the most semi-objective, validated method for quantifying ET function (Scott-Brown's, Vol 2; Cummings)

11. Sonotubometry

• A sound probe (usually 8 kHz tone) is placed in the nasal cavity; a microphone in the external auditory canal detects changes in sound amplitude when the ET opens during swallowing
• A rise in sound level at the ear microphone during swallowing indicates ET opening
• Useful in patulous ETD (consistently open ET - continuous sound transmission)
• Limitation: poor sensitivity in the setting of secretions or mucosal edema in the ET

12. Inflation-Deflation Test (Ascending/Descending)

• Uses a tympanometry probe placed in the ear canal to record pressure changes while the patient swallows
• Positive and negative pressures are applied alternately to evaluate ET function
• Used with both intact and non-intact TMs; primarily applicable in patients with perforations or grommets

D. IMAGING AND ENDOSCOPIC TESTS

13. Eustachian Tube Endoscopy (Tuboscopy)

• Direct endoscopic visualization of the ET lumen (transnasally via the pharyngeal orifice or via the middle ear through the tympanic orifice)
• Allows assessment of mucosal pathology, luminal narrowing, secretions, and structural causes of ETD
• Nasopharyngoscopy is recommended as part of assessment to visualize the ET orifice (Scott-Brown's)
• Improves diagnostic accuracy beyond clinical examination alone (Cummings)

14. Pressure Chamber Testing

• ET function is assessed under varying barometric pressure conditions, simulating flight or diving
• Useful regardless of whether the eardrum is intact or perforated
• Limitation: complex, expensive, and not widely available (Scott-Brown's, Vol 2)

E. OTHER DESCRIBED METHODS (Research Use)

Best Clinical Practice Summary

"There is no single test to diagnose Eustachian tube dysfunction. Therefore assessment should include otomicroscopy, tympanometry, Rinne's and Weber's tuning fork tests, pure tone audiometry, nasopharyngoscopy (to visualize the ET orifice), and where available, tubomanometry." - Scott-Brown's Otorhinolaryngology Head & Neck Surgery, Vol 2