Ear barotrauma

INTRODUCTION — Ear barotrauma occurs when the tympanic membrane (TM) is distorted due to pressure differences between the middle ear and the outside environment, leading to discomfort, hearing loss, and injury.

This topic will focus on the clinical manifestations, diagnosis, and treatment of ear barotrauma. Other issues related to Eustachian tube dysfunction are discussed in detail elsewhere. (See "Eustachian tube dysfunction".)

PATHOGENESIS — The middle ear is an air-filled space, separated from the external environment by the tympanic membrane (TM) laterally and the Eustachian tube anteromedially (figure 1). Pressure within the middle ear has to match that of the environment for the TM to vibrate normally. During normal physiologic function, air in the middle ear is absorbed slowly by the lining mucous membranes and is continually replaced by the opening of the Eustachian tube [1]. This happens normally when one swallows or yawns, during which time airflow can occur. When the Eustachian tube does not function adequately, pressure differences develop between the middle ear and the outside environment, resulting in ear barotrauma.

The Eustachian tube extends from the middle ear to the nasopharynx and is made up of two parts (figure 1):

●The posterior half leading from the ear is a bony tube lined with mucosa that does not change shape.

●The anterior half is made of soft tissue that is mucosa-lined; it is normally collapsed.

The Eustachian tube opens momentarily during swallowing or yawning due to actions of the levator veli palati and the tensor veli palati muscles. These muscles elevate and tense the palate and simultaneously open the Eustachian tube. This ensures that the Eustachian tube is only open when it is protected against reflux from the oral cavity by elevation of the soft palate to close off the nasopharynx. The Eustachian tube also needs to be closed most of the time to prevent TM motion with respiration.

ETIOLOGIES

Eustachian tube dysfunction — Dysfunction of the Eustachian tube can occur for a variety of reasons. Swelling of the mucosa in the nasopharynx or within the Eustachian tube may occur with infection (eg, upper respiratory infection or acute otitis media) or edema (eg, due to allergies or acid reflux). This swelling can impede normal Eustachian tube function and lead to difficulties in equalizing middle ear pressure, thereby predisposing to ear barotrauma. Increased tissue mass in the nasopharynx, enlarged adenoids, and nasopharyngeal tumors also may obstruct adequate middle ear ventilation. (See "Eustachian tube dysfunction", section on 'Pathophysiology of Eustachian tube dysfunction'.)

In some situations, positive pressure can be generated in the nose and nasopharynx (Valsalva maneuver) to try to overcome the Eustachian tube barrier. When the pressure difference is great, air can be forced through the Eustachian tube into the middle ear to equalize pressure. Concomitant infection in the nose or nasopharynx may spread to the middle ear with this maneuver.

Generally, buildup of pressure inside the middle ear will resolve, as air can usually force its way out of the middle ear via the Eustachian tube. In addition, slower equilibration may occur with absorption of the gases by the middle ear mucosa.

Flying — The most frequently encountered cause of ear barotrauma is flying [2,3]. Commercial aircraft have pressurized cabins, with the pressure generally equal to that at 7000 to 10,000 feet, not sea level. Outside barometric pressure decreases as the plane ascends. Normally this change is gradual and is equilibrated by swallowing or absorption of air by the middle ear mucosa. The opposite occurs on descent; air pressure has to increase in the middle ear to balance the increase in atmospheric pressure. When this does not occur (usually due to a non-functioning Eustachian tube), the tympanic membrane (TM) is forced medially and stretched. This can lead to bruising of or bleeding into the tympanic membrane, formation of fluid exudates in the middle ear, and occasionally TM rupture.

Diving — While pressure changes due to flying are less than one atmosphere, pressure changes with diving can be several atmospheres, resulting in more severe injuries [4-10]. Large pressure differences between the middle ear and the surrounding water can lead to the same injuries as with flying. In addition, inner ear barotrauma may occur due to rupture of the round and oval membranes separating the middle and inner ear (figure 2) [11]. This can result in formation of a perilymphatic fistula, leading to loss of inner ear fluid with consequent hearing loss and vertigo. Although length, depth, and number of dives may be correlated with temporary changes in ear function, they are not associated with long-term problems [11,12]. (See "Complications of SCUBA diving", section on 'Ear barotrauma'.)

Dizziness from decompression sickness is thought to be due to the difference in circulation in the vestibular and auditory parts of the inner ear. The vestibular side has 30 percent more volume and gets four times less circulation than the cochlea. This slows any compensation to changes in gas partial pressures and makes it more susceptible to injury [13].

Blast injuries — Blast injuries can occur with greater frequency in settings of war and terrorist attacks. Ear barotrauma results from the air pressure wave generated by an explosion [14]. This rapid pressure change is too rapid to allow for the normal equalization of pressures. Injuries include bruising of the eardrum, bleeding into the drum and middle ear, eardrum rupture, ossicular disruption, and inner ear injury resulting in dizziness and tinnitus [15-19]. Surgery is necessary for repair of the eardrum perforation in up to half of these barotrauma-induced perforations [15,16].

Other — While ear barotrauma theoretically may be induced by skydiving because of the rapid descent, little in the literature supports this as a cause [20]. A 2018 study reviewing symptoms of 31 diving school participants suggests that otologic symptoms do occur from skydiving but are seldom reported or studied [21]. Other causes of barotrauma include use of decompression chambers and hyperbaric oxygen chambers [22-24]. There are even some reports of rapid pressure changes during continuous positive airway pressure (CPAP) causing inner ear injuries [25].

CLINICAL MANIFESTATIONS — Barotrauma can manifest as ear pressure, pain, hearing loss, and tinnitus. The hallmark is a pressure differential between the middle ear and the outside environment [26,27]. As the pressure differential increases, the pressure sensation turns to pain due to the stretching of the tympanic membrane (TM). Hearing loss occurs due to deformation of the TM and the pressure differential hindering membrane mobility. With mild pressure differences, the sensation is that of having a blocked ear. As the pressure difference increases, changes occur in the TM and middle ear that lead to greater hearing loss. Bleeding into the TM can occur (picture 1), and a serous or occasionally hemorrhagic effusion may form in the middle ear. With pressure differences greater than one atmosphere, ossicular disruption can cause a persistent conductive hearing loss and, as mentioned above, rupture of the round or oval window membranes can lead to severe vertigo and sensorineural hearing loss secondary to loss of perilymph from the inner ear.

Any of the above injuries also may cause tinnitus. This can be pulsating or constant. The pulsating tinnitus usually resolves with resolution of the edema and serous effusion. The tinnitus often resolves as the ear heals but occasionally may become permanent. When severe injuries occur with rupture of the round or oval windows, vertigo (with or without nystagmus) may be present.

DIAGNOSIS — The diagnosis of ear barotrauma is based upon a consistent clinical history and a compatible findings on physical examination. Symptoms occurring in the setting of a change in surrounding air pressure increases the likelihood of barotrauma: if the physical examination confirms the injury, then the diagnosis is certain.

Ear barotrauma injuries occur from the stretching of the tympanic membrane (TM), which can cause swelling, TM perforation, or middle ear effusion. It can also result in tears in blood vessels leading to bleeding along the malleus, into the TM (picture 1), and into the middle ear, causing a hemotympanum.

Physical findings reflect the severity of the injury. A small amount of bleeding in the TM, usually along the malleus, is commonly seen. Bleeding in the middle ear will lead to visible hemotympanum with dark blood filling the middle ear. Mild injuries can cause swelling of the eardrum, while more severe injuries can lead to TM perforation. Severe injuries with rupture of the round or oval windows can result in vertigo (with or without nystagmus). Rupture of the oval or round window in the middle ear can lead a perilymphatic fistula with symptoms of dizziness, hearing loss, and tinnitus. Hearing loss from a fistula is sensorineural and can be progressive. Dizziness is often accompanied with nystagmus and can worsen with positive pressure applied to the ear or when the patient strains.

Rinne and Weber testing can help classify any hearing loss, if present, as conductive or sensorineural (figure 3 and table 1). A conductive hearing loss occurs from disruption of the eardrum or ossicles, swelling of the eardrum or accumulation of fluid or blood in the middle ear. A sensorineural loss occurs from injury to the inner ear.

MANAGEMENT

Conservative treatment for most patients — Most injuries due to ear barotrauma, including edema and/or hemorrhage of the tympanic membrane (TM) and serous or hemorrhagic otitis, will heal with time. Most mild injuries clear within hours as the middle ear pressure equalizes with the outside world. Swelling of the eardrum, fluid or blood accumulation in the middle ear, or bleeding into the eardrum can take days to weeks to resolve. TM ruptures also typically heal within weeks if normal Eustachian tube function is restored and the perforation is not secondary to a blast injury [11,15,16]. Mild imbalance often clears as the underlying ear blockage resolves. Transient vestibular symptoms from repeated diving barotrauma clear over time without long-term disequilibrium [28].

Medications are of variable utility in the management of ear barotrauma. Decongestants and antihistamines probably produce little if any change in the speed of recovery from barotrauma. Antibiotics are often mistakenly given to treat this noninfectious injury. They are indicated only when the eardrum has been ruptured and the middle ear has been contaminated or there is evidence of infection. Analgesics are effective for pain relief as necessary. There is no evidence to support the use of glucocorticoids to expedite recovery.

Urgent referral for some patients — Emergency situations occur when trauma creates a perilymphatic fistula between the middle and inner ear. Loss of fluid from the inner ear can lead to dizziness (vertigo) and sensorineural hearing loss. In these patients, there may also be ossicular disruption from skull fractures or contamination of the middle ear with debris from penetrating objects such as metal, wood, water, or dirt.

Immediate referral should be made to an otolaryngologist for any patient presenting with vertigo, sensorineural hearing loss, nystagmus, or an eardrum perforation greater than 25 percent of the drum in order to limit the risk for permanent hearing loss and dizziness.

Surgical treatment of severe injuries — When injuries from ear barotrauma are severe, referral to an otolaryngologist is indicated. Surgery, including tympanoplasty or patching of the round or oval window, may be necessary for serious injuries due to inner ear barotrauma such as ossicular disruption and perilymphatic fistula. Complete bed rest with head elevation to avoid increases in cerebrospinal fluid pressure is usually indicated to decrease the leakage of perilymph [6]. Sensorineural hearing loss from a perilymphatic fistula may be permanent despite early intervention. Dizziness usually resolves, but resolution may take weeks to months in severe cases.

Myringotomy (incision in the TM) has been used as both prevention and treatment for ear barotrauma. The pressure differences that lead to barotrauma cannot occur with a hole in the TM. If barotrauma has occurred, fluid can be drained to restore hearing. The difficulty with this approach has been that the myringotomy usually heals within a few days, which is inadequate time for most injuries to heal. A tube may be placed in the eardrum (tympanostomy or ventilation tube) to keep the hole patent for a longer time.

PREVENTION OF EAR BAROTRAUMA — The best prevention of barotrauma is avoidance of precipitants when injury is more likely to occur.

Treatment of underlying Eustachian tube dysfunction — Patients with Eustachian tube dysfunction are prone to ear barotrauma. Treatment of various forms of dysfunction are discussed elsewhere. (See "Eustachian tube dysfunction".)

Decrease swelling around the Eustachian tube — We routinely counsel patients with a history of ear difficulties when flying to consider trying some preventive options. The use of oral decongestants, oral antihistamines, and nasal decongestant sprays prior to flying or diving may reduce obstruction around the Eustachian tube and allow for improved pressure equalization [29-32]. Pseudoephedrine taken 30 minutes prior to flight may reduce the incidence of ear barotrauma [30]. Topical (intranasal) oxymetazoline taken at the same time may also help avoid barotrauma. However, in a study using fluticasone and oxymetazoline prior to hyperbaric oxygen treatment, no benefit was found in preventing barotrauma symptoms [33]. In addition, avoidance of airplane flight or self-contained underwater breathing apparatus (SCUBA) diving while congested may avoid injury [2,11,15].

Maneuvers to equalize pressure — Swallowing to open the Eustachian tube or using the Valsalva maneuver (positive pressure against a closed nasal airway) usually equilibrates pressure in the middle ear with the external environment. Doing this frequently during change in pressure can prevent large pressure differences from forming and prevent tissue injury. To encourage frequent swallowing, chewing gum or sucking on hard candies helps for adults; nursing or sucking on a bottle helps for infants.

Other methods — Earplugs designed to slow down the pressure changes with flying are widely available. These plugs allow more time to equalize the pressure change, but they do not eliminate the need to equilibrate the pressure changes. Their benefit, however, has not been clearly demonstrated [34]. Such earplugs cannot be used with diving, since equilibration of air pressure in the external ear canal blocked by earplugs cannot easily occur underwater.

It is common practice in aviation to apply moist heat to the ear when passengers are complaining of ear pain, although there is no evidence of efficacy in preventing barotrauma. This is usually done with a hot, wet cloth or napkin placed in the bottom of a cup and then placed over the ear. While often soothing, it has not been shown to prevent barotrauma [35] and has led to occasional burn injuries.

Surgery — For patients undergoing hyperbaric oxygen therapy for wound healing, and those who have poor Eustachian tube function and who must fly frequently, surgery may be an option [36]. In such patients, surgical placement of ventilation tubes can eliminate the pressure differential between the middle ear and the outside world. (See "Eustachian tube dysfunction", section on 'Surgical management if symptoms persist despite medical therapy'.)

Another option for severe Eustachian tube dysfunction is balloon dilatation of the Eustachian tube [37-41]. In a limited case series, it was used successfully to prevent diving-related ear barotrauma [42]. New studies are showing success in maintaining adequate Eustachian tube function after balloon dilation [43-45]. (See "Eustachian tube dysfunction", section on 'Surgical management if symptoms persist despite medical therapy'.)

Myringotomy (incision in the tympanic membrane [TM]) has been used for prevention in some patients. However, myringotomies with or without tubes are not appropriate for prevention of SCUBA diving injuries. They open the middle ear up to fluid and infection from water that can pass into the middle ear.

INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, “The Basics” and “Beyond the Basics.” The Basics patient education pieces are written in plain language, at the 5^th to 6^th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10^th to 12^th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on “patient info” and the keyword(s) of interest.)

●Basics topics (see "Patient education: Eustachian tube problems (The Basics)")

SUMMARY AND RECOMMENDATIONS

●Etiologies – The most common cause of ear barotrauma is flying. Diving, use of decompression or hyperbaric oxygen chambers, and blast injuries are other etiologies. (See 'Etiologies' above.)

●Clinical manifestations – Barotrauma can manifest as ear pressure, pain, hearing loss, and tinnitus. Bleeding into the tympanic membrane (TM) may occur, and, rarely, rupture of the round or oval window membranes can cause vertigo and sensorineural hearing loss. (See 'Clinical manifestations' above.)

●Management

•Conservative treatment for most patients – Most barotrauma injuries heal spontaneously, and analgesics can be used as needed. Antibiotics are not indicated, and decongestants, antihistamines, and glucocorticoids have not been shown to be effective. (See 'Conservative treatment for most patients' above.)

•Referral for some patients – Patients with vertigo, sensorineural hearing loss, nystagmus, or an eardrum perforation greater than 25 percent of the drum require immediately referral to an otolaryngologist. Tympanoplasty or patching may be needed for serious injuries such as ossicular disruption or perilymphatic fistula, which usually occur in the setting of trauma. (See 'Urgent referral for some patients' above and 'Surgical treatment of severe injuries' above.)

●Prevention – We routinely counsel patients with a history of ear difficulties when flying to consider preventive options. Oral decongestants, antihistamines, and nasal decongestant sprays used prior to flying or diving may reduce obstruction around the Eustachian tube and facilitate pressure equalization. Swallowing and the Valsalva maneuver can equalize pressures and prevent barotrauma. Chewing gum or sucking on hard candies can help adults, and nursing or sucking on a bottle may help infants. (See 'Prevention of ear barotrauma' above.)