By Marcello Cherchi, MD PhD
For patients
Otic barotrauma refers to pressure changes in the external environment that are sufficiently abrupt and/or large, and result in damage to the ear, manifesting with ear symptoms (ear fullness, hearing loss, tinnitus) and disequilibrium. A clinician often will examine a patient’s ears (to assess the integrity of the eardrum) and may check a hearing test. Depending on those results, referral to otolaryngology may be appropriate.
For practitioners
Overview
One of the main functions of the ear is to detect vibrations (minute changes in air pressure) in the external environment. The mechanism for accomplishing this detection is exquisitely sensitive, and therefore also susceptible to damage when the pressure changes in the external environment are very large, or very rapid. Large and/or rapid changes in pressure can traumatize the ear, and such damage is called otic barotrauma. The offending pressure changes are often abrupt (such as blast injuries), though more gradual changes can also cause damage when prolonged (such as SCUBA diving). Otic barotrauma can present with auditory symptoms (aural fullness, hearing loss, tinnitus), vestibular symptoms or both; most literature states that auditory symptoms are more common than vestibular ones.
Introduction
One of the main functions of the ear is to detect vibrations (minute changes in air pressure) in the external environment. The mechanism for accomplishing this detection is exquisitely sensitive, and therefore also susceptible to damage when the pressure changes in the external environment are very large, or very rapid. Large and/or rapid changes in pressure can traumatize the ear, and such damage is called otic barotrauma (King 1976, Lacey and Amedee 2000).
Consequences of abrupt change in pressure
Common causes of abrupt barotrauma include blast injuries (Darley and Kellman 2010), or a physical blow to the ear, which result in an extremely abrupt and large increase in external pressure. We have also seen patients with avulsion of the stapes footplate after yanking an insert earphone out of their ear – presumably there was an extremely abrupt and large decrease in external pressure in this circumstance.
Abrupt pressure changes that are sufficiently large deliver kinetic energy to the ear that can cause physical disruption of its structures, including rupturing the tympanic membrane, dislocating the ossicular chain or fracturing its individual components (malleus, incus, stapes) (Harris and Butler 1985), avulsing the stapes footplate from the oval window, or rupturing the round window (Choo 1984). Kinetic energy that traverses the oval and/or round windows can also be transmitted to inner ear structures and cause further damage.
Consequences of more prolonged change in pressure
A pressure change that is more gradual yet is sufficiently large can cause symptoms as well, such as remaining in a situation of persistently increased pressure (as in SCUBA diving (Livingstone, Smith et al. 2017)), or one of persistently decreased pressure (as in air travel (Mirza and Richardson 2005)).
When the Eustachian tube opens (such as during yawning) it makes the middle ear space continuous with the back of the throat, and therefore with the outside world, and therefore with the outer ear, and thus equilibrates pressure on both sides of the tympanic membrane. If Eustachian tube dysfunction impairs the Eustachian tube’s ability to open, then a pressure differential can develop between the sides of the eardrum. As Mirza and Richardson comment, during airplane travel (when cabin pressure is generally lower than at sea level) the following can occur:
“When there is a sustained negative pressure in the middle ear, serous fluid is produced by the mucous glands in the middle ear in an effort to equalize the pressure. Sufficient negative pressure may exist to cause the rupture of blood vessels from the surrounding vasculature, resulting in a haemotympanum, or in severe cases, bulging and perforation of the tympanic membrane.”
The opposite circumstance occurs when there is unequilibrated elevated external pressure, such as during SCUBA diving (Farmer 1977, Money, Buckingham et al. 1985, Molvaer and Albrektsen 1988). Even if an individual dive does not provoke symptoms, there is evidence that repeated SCUBA diving may result in cumulative damage from recurrent otic barotrauma (Molvaer and Albrektsen 1990, Ramos, Rapoport et al. 2005).
Presentation
Otic barotrauma can present with auditory symptoms (aural fullness, hearing loss, tinnitus), vestibular symptoms or both. Most literature states that auditory symptoms are more common than vestibular ones.
Diagnosis and treatment
A patient with a clinical history compatible with otic barotrauma should be examined, including if with binocular otomicroscopy (or at least with a standard handheld monocular otoscope). It is also medically reasonable to check a standard audiogram (with tympanometry) and (for age <60 years) otoacoustic emissions. If examination shows a ruptured tympanic membrane, or if there is evidence of conductive hearing loss on audiometry, or if results from tympanometry suggest possible ossicular chain dislocation, then referral to otolaryngology is appropriate.
References
Choo YB (1984) Microscopic characteristics of round window problems in otology. Laryngoscope 94: 1-9. doi: 10.1002/lary.5540940101
Darley DS, Kellman RM (2010) Otologic considerations of blast injury. Disaster Med Public Health Prep 4: 145-52. doi: 10.1001/dmphp.d-08-00057r2
Farmer JC, Jr. (1977) Diving injuries to the inner ear. Ann Otol Rhinol Laryngol Suppl 86: 1-20. doi: 10.1177/00034894770861s201
Harris JP, Butler D (1985) Recognition of malleus handle fracture in the differential diagnosis of otologic trauma. Laryngoscope 95: 665-70. doi: 10.1288/00005537-198506000-00006
King PF (1976) Otic barotrauma. Audiology 15: 279-86. doi: 10.3109/00206097609071788
Lacey JP, Amedee RG (2000) The otologic manifestations of barotrauma. J La State Med Soc 152: 107-11.
Livingstone DM, Smith KA, Lange B (2017) Scuba diving and otology: a systematic review with recommendations on diagnosis, treatment and post-operative care. Diving Hyperb Med 47: 97-109. doi: 10.28920/dhm47.2.97-109
Mirza S, Richardson H (2005) Otic barotrauma from air travel. J Laryngol Otol 119: 366-70. doi: 10.1258/0022215053945723
Molvaer OI, Albrektsen G (1988) Alternobaric vertigo in professional divers. Undersea Biomed Res 15: 271-82.
Molvaer OI, Albrektsen G (1990) Hearing deterioration in professional divers: an epidemiologic study. Undersea Biomed Res 17: 231-46.
Money KE, Buckingham IP, Calder IM, Johnson WH, King JD, Landolt JP, Laufer J, Ludman H (1985) Damage to the middle ear and the inner ear in underwater divers. Undersea Biomed Res 12: 77-84.
Ramos CC, Rapoport PB, Brito Neto RV (2005) Clinical and tympanometric findings in repeated recreational scuba diving. Travel Med Infect Dis 3: 19-25. doi: 10.1016/j.tmaid.2004.06.002
