Otic Barotrauma (Aerotitis Media)
High-Yield Revision Notes for NEET PG / NEXT
Otic barotrauma is tissue injury occurring within the middle ear cleft caused by a steep ambient atmospheric pressure mismatch across an intact tympanic membrane (TM). It typically occurs during rapid descent in aviation (flights) or underwater diving.
Teed Classification Scale: Graded severity of tympanic membrane structural barotrauma induced by rapid descent pressure changes.
Pathophysiology & Mechanism
- The Descent Crisis: During rapid descent, the surrounding atmospheric pressure rises rapidly. The Eustachian tube must actively open to equalize middle ear pressure. If opening fails (due to mucosal edema from URTI, allergies, or structural dysfunction), a profound relative negative pressure develops within the middle ear.
- Structural Retraction: The negative vacuum aggressively retracts the TM inward toward the promontory.
- Vascular Transudation: If the pressure differential crosses 60 to 90 mmHg, mucosal blood vessels dilate, leading to transudation of sterile fluid (serous effusion) or vascular rupture, causing frank hemotympanum.
- Eustachian Tube Locking: When the pressure differential exceeds 90 mmHg, the cartilaginous Eustachian tube undergoes architectural collapse and “locks” completely shut, rendering standard voluntary equalization maneuvers impossible.
Teed Otoscopic Classification
The structural damage is classically categorized using the Teed Scale, a popular examiner target:
| Grade | Otoscopic Assessment Findings |
|---|---|
| Grade 0 | Normal examination; symptoms present without visible clinical pathology. |
| Grade 1 | Vascular congestion (injection) is isolated along the handle of the malleus and pars flaccida. |
| Grade 2 | Diffuse vascular injection across the entire tympanic membrane surface. |
| Grade 3 | Evidence of serous fluid effusion or early patchy submucosal hemorrhage within the TM. |
| Grade 4 | Frank Hemotympanum (grossly blue/dark-red blood collection filling the middle ear). |
| Grade 5 | Perforation of the tympanic membrane. |
Clinical Presentation
- Suddenly, severe, sharp otalgia developed during descent.
- Subjective ear blockage, pressure sensation, and Conductive Hearing Loss (CHL).
- Autophony (hearing one’s own voice altered) or tinnitus.
- INNER EAR INVOLVEMENT (DANGER SIGN): Concomitant explosive rupture of the round window or oval window membrane causes perilymphatic fistula, causing immediate severe sensorineural hearing loss (SNHL), incapacitating vertigo, and nystagmus.
Prevention & Equalization Maneuvers
- Valsalva Maneuver: Forced expiration against a closed airway (pinched nose and mouth). Increases nasopharyngeal pressure to mechanically push the Eustachian tube open.
- Toynbee Maneuver: Swallowing while the nose is pinched shut. Activates the Tensor Veli Palatini muscle to open the tube under negative nasopharyngeal pressure conditions.
- Prophylaxis: Use of topical nasal decongestants (e.g., Oxymetazoline spray) or systemic pseudoephedrine 30 minutes before descent to reduce mucosal edema around the Eustachian tube pharyngeal cushion. Prohibit flying or diving with an active URTI.
Management
- Conservative (Majority): Analgesics, oral or topical decongestants, and avoidance of pressure changes until resolution. Most low-grade effusions and small TM perforations heal spontaneously.
- Myringotomy: Reserved for extreme, unremitting otalgia or persistent severe fluid/hemotympanum to immediately normalize pressure across the cleft.