![]() ![]() (B) If the Eustachian tube is blocked, lower pressure in the middle ear occurs. (A) In the case of a patent Eustachian tube, if a vigorous Valsalva maneuver is performed, an uncontrolled increase in pressure in the middle ear occurs with a consequently violent outward displacement of the stapes footplate and inward movement of the slight round window membrane. Schematic diagram of inner ear barotrauma: pressure increases during descent and a Valsalva maneuver can help equalize the middle ear pressure. 8, 9 There are many pathogenetic mechanisms that explain inner ear injury due to IEB: hemorrhage following rupture of blood vessels in the cochlea, a tear in the Reissner's membrane or in the basilar membrane, perilymph fistula, and pneumolabyrinth. A forceful Valsalva at this stage can increase the cerebrospinal fluid pressure (CFP), and consequently the pressure in the inner ear, causing rupture of the round or oval window. In the second case, the blocked Eustachian tube does not allow middle ear pressure equalization and consequently generates a pressure difference between the middle ear, the external ear canal, and the inner ear fluids. 7 In the first case, vigorous Valsalva maneuver may cause an uncontrolled increase in middle ear pressure with a violent outward displacement of the stapes footplate and inward movement of the slight round window membrane. 7 Two pathological conditions may favor inner ear damage during descent: one with normal Eustachian tube function, the other when the tube is obstructed ( Figure 3). 6 The round window is most commonly affected because it is covered by a thin membrane, whereas the oval window maintains greater stability thanks to the stapes footplate, stapedial muscle, and associated ligaments. IEB results from inappropriate equalization of middle ear pressure and consequent injury produced by pressure changes within the middle ear transmitted to the cochlea through the round and/or oval window. Dalton’s law states that the total pressure exerted is equal to the sum of the partial pressures of the individual gases. Charles’s law states that a volume of gas equals a constant value multiplied by its temperature as measured on the Kevin scale. Henry's law states that the amount of dissolved gas in a liquid is proportional to its partial pressure above the liquid at a constant temperature. 1 Boyle’s law states that at a constant temperature, there is an inverse relationship between the volume of a gas and its pressure. Inner ear disorders in SCUBA divers depend on 4 gas laws: Boyle’s law ( Figure 1), Henry’s law ( Figure 2), Charles’s law, and Dalton’s law. 5 Inner ear involvement is less common but usually more serious, often resulting in permanent hearing loss, tinnitus, vertigo, and unsteadiness. 3, 4 Among ear injuries, middle ear barotrauma is the most common condition, 5 fortunately, in most cases, it resolves spontaneously in a short time without serious complications. Nearly 80% of diving-related problems concern otolaryngology, and the ear is the most frequently involved organ. There are millions of Self-Contained Underwater Breathing Apparatus (SCUBA) divers in the world, a popular activity appreciated at any age but not free from risks. This review aims to provide an overview of the pathological conditions characterized by inner ear injury in SCUBA divers, discussing their pathogenetic mechanisms, diagnostic work-up, and prevention. It is of utmost importance to identify individual risk factors and predisposing pathological conditions that favor inner ear injury before diving, to prevent acute events and preserve auditory and vestibular functions in SCUBA divers. It should include an otolaryngologic examination with audiological assessment to evaluate nasal, middle ear, and tubal patency and to minimize the risk of IEB, IEDS, and AV. Before starting SCUBA diving, a fit-to-dive assessment is recommended. The clinical pictures of these pathological conditions are partly superimposable, even if they have specific peculiarities. IEB results from inappropriate equalization of middle ear pressure and consequent inner ear injury produced by pressure changes within the middle ear IEDS is characterized by the formation of gas bubbles within the vessels of the inner ear during rapid ascent AV typically develops while ascending or performing the Valsalva maneuver and can follow asymmetrical equalization of middle ear pressure transmitted via the oval and round window membranes. ![]() Three main inner ear pathological conditions can occur underwater: inner ear barotrauma (IEB), inner ear decompression sickness (IEDS), and alternobaric vertigo (AV). The majority of dive-related disorders concern otolaryngology, and may include hearing loss, tinnitus, aural fullness, disequilibrium, and vertigo. However, improper diving may injure different organs. Self-Contained Underwater Breathing Apparatus (SCUBA) diving is a popular sport. ![]()
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