Barotrauma of the Ear
Tissue injury caused by failure to equalise pressure between a gas containing space and the ambient environment. Boyle law governs the process: gas volume varies inversely with pressure, and the greatest relative volume change occurs near the surface, which is why most diving injuries happen in the first 10 metres.
Three anatomical sites
- External ear barotrauma, or barotitis externa, occurring when a tight hood, earplug or wax plug traps gas in the canal, producing a relative vacuum with canal wall haemorrhage and blistering.
- Middle ear barotrauma, which is by far the commonest, occurring when the Eustachian tube fails to admit air during descent. The tube functions as a passive one way valve that vents easily on ascent but requires active opening on descent, which is why descent is the dangerous phase. At a differential of around 90 mmHg the tube locks shut and no amount of Valsalva will open it. Beyond 100 to 500 mmHg the drum ruptures.
- Inner ear barotrauma, caused by forceful Valsalva against a blocked tube generating a sudden cerebrospinal fluid pressure wave transmitted through the cochlear aqueduct, or by implosive pressure transmitted through the round window, causing round or oval window membrane rupture, perilymph fistula or intralabyrinthine haemorrhage.
Teed classification of middle ear barotrauma
- Grade 0: symptoms without otoscopic signs.
- Grade 1: erythema and retraction of the drum.
- Grade 2: erythema with mild haemorrhage within the drum.
- Grade 3: gross haemorrhage throughout the drum.
- Grade 4: dark blue haemotympanum with a middle ear effusion.
- Grade 5: perforation with free blood in the canal.
Risk factors: upper respiratory infection, allergic rhinitis, sinusitis, nasal polyps, deviated septum, adenoid hypertrophy, smoking, rapid descent, inability to perform equalisation manoeuvres, and prior middle ear surgery.

