Middle ear barotrauma (MEBT), also known to

underwater divers This is a list of underwater divers whose exploits have made them notable. Underwater divers are people who take part in underwater diving activities – Underwater diving Underwater diving, as a human activity, is the practice of d ...

as ear squeeze and reverse ear squeeze, is injury caused by a difference in

pressure Pressure (symbol: ''p'' or ''P'') is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure (also spelled ''gage'' pressure)The preferred spelling varies by country and eve ...

between the external ear canal and the

middle ear The middle ear is the portion of the ear medial to the eardrum, and distal to the oval window of the cochlea (of the inner ear). The mammalian middle ear contains three ossicles (malleus, incus, and stapes), which transfer the vibrations ...

. It is common in

and usually occurs when the diver does not equalise sufficiently during

descent Descent may refer to: As a noun Genealogy and inheritance * Common descent, concept in evolutionary biology * Kinship, one of the major concepts of cultural anthropology **Pedigree chart or family tree **Ancestry **Lineal descendant **Heritage ** ...

or, less commonly, on ascent. Failure to equalise may be due to inexperience or

eustachian tube The Eustachian tube (), also called the auditory tube or pharyngotympanic tube, is a tube that links the nasopharynx to the middle ear, of which it is also a part. In adult humans, the Eustachian tube is approximately long and in diameter. It ...

dysfunction, which can have many possible causes. Unequalised ambient pressure increase during descent causes a pressure imbalance between the middle ear air space and the

external auditory canal The ear canal (external acoustic meatus, external auditory meatus, EAM) is a pathway running from the outer ear to the middle ear. The adult human ear canal extends from the auricle to the eardrum and is about in length and in diameter. Stru ...

over the eardrum, causing inward stretching, serous effusion and haemorrhage, and eventual rupture. During ascent internal over-pressure is normally passively released through the eustachian tube, but if this does not happen the volume expansion of middle ear gas will cause outward bulging, stretching and eventual rupture of the eardrum known to divers as . This damage causes local pain and hearing loss. Tympanic rupture during a dive can allow water into the middle ear, which can cause severe vertigo from caloric stimulation. This may cause nausea and vomiting underwater, which has a high risk of aspiration of vomit or water, with possibly fatal consequences. Middle ear barotrauma can also be caused by shock waves and blows to the external ear, particularly in water, and large or fast changes in altitude or local environment pressurisation.

Classification

Deformation stress trauma caused by externally applied (environmental) pressure differences on the middle ear.

Signs and symptoms

Localised pain in one or both ears while the eardrums are stretched, which may be partly relieved if the eardrum ruptures, followed by longer term dull pain in the injured ears, and possible hearing loss.

Complications

*Unequal pressures in the middle ears can cause

alternobaric vertigo In aviation and underwater diving, alternobaric vertigo is dizziness resulting from unequal pressures being exerted between the inner ears, commonly due to one Eustachian tube being less patent than the other. Signs and symptoms Causes This m ...

, disorientation and nausea. *Cold water ingress through a perforated eardrum can cause caloric vertigo, usually a short term effect. *Ingress of contaminated water through a perforated eardrum can cause infections of the middle ear. *Over-vigorous attempts to equalise using the

Valsalva maneuver The Valsalva maneuver is performed by a forceful attempt of exhalation against a closed airway, usually done by closing one's mouth and pinching one's nose shut while expelling air, as if blowing up a balloon. Variations of the maneuver can be ...

can lead to

inner ear barotrauma Barotrauma is physical damage to body fluid compartments, tissues caused by a difference in pressure between a gas space inside, or in contact with, the body and the surrounding gas or liquid. The initial damage is usually due to over-stretchin ...

*Temporary or permanent hearing deficit, vertigo, or balance problems. *Infections of the external, middle or inner ear.

Causes

Any cause of sufficiently large and rapid environmental pressure change can potentially cause barotrauma. Several commonly recognised examples are listed below.

Depth changes while diving

When diving, the

differences which cause the barotrauma are changes in hydrostatic pressure: There are two components to the surrounding pressure acting on the diver: the

atmospheric pressure Atmospheric pressure, also known as air pressure or barometric pressure (after the barometer), is the pressure within the atmosphere of Earth. The standard atmosphere (symbol: atm) is a unit of pressure defined as , which is equivalent to 1,013. ...

and the water pressure. A descent of 10 metres (33 feet) in water increases the ambient pressure by an amount approximately equal to the pressure of the atmosphere at sea level. So, a descent from the surface to 10 metres (33 feet) underwater results in a doubling of the pressure on the diver. This pressure change will reduce the volume of a flexible gas-filled space by half.

Boyle's law Boyle's law, also referred to as the Boyle–Mariotte law or Mariotte's law (especially in France), is an empirical gas laws, gas law that describes the relationship between pressure and volume of a confined gas. Boyle's law has been stated as: ...

describes the relationship between the

volume Volume is a measure of regions in three-dimensional space. It is often quantified numerically using SI derived units (such as the cubic metre and litre) or by various imperial or US customary units (such as the gallon, quart, cubic inch) ...

of the gas space and the pressure in the gas. Barotraumas of descent are caused by preventing the free change of volume of the gas in a closed space in contact with the diver, resulting in a pressure difference between the tissues and the gas space, and the unbalanced force due to this pressure difference causes deformation of the tissues resulting in cell rupture. Barotraumas of ascent are also caused when the free change of volume of the gas in a closed space in contact with the diver is prevented. In this case the pressure difference causes a resultant tension in the surrounding tissues which exceeds their tensile strength.

Use of a hyperbaric chamber

Patients undergoing

hyperbaric oxygen therapy Hyperbaric medicine is medical treatment in which an increase in barometric pressure of typically air or oxygen is used. The immediate effects include reducing the size of gas emboli and raising the partial pressures of the gases present. Initial ...

must equalize their ears to avoid barotrauma. High risk of otic barotrauma is associated with unconscious patients.

Rapid decompression or pressurisation of an artificial environment

Explosive decompression An uncontrolled decompression is an undesired drop in the pressure of a sealed system, such as a pressurised aircraft cabin or hyperbaric chamber, that typically results from human error, structural failure, or impact, causing the pressurised v ...

of a hyperbaric environment can produce severe barotrauma, followed by severe decompression bubble formation and other related injury. Rapid uncontrolled decompression from caissons, airlocks, pressurised aircraft, spacecraft, and pressure suits can have similar effects of decompression barotrauma. Collapse of a pressure resistant structure such as a

submarine A submarine (often shortened to sub) is a watercraft capable of independent operation underwater. (It differs from a submersible, which has more limited underwater capability.) The term "submarine" is also sometimes used historically or infor ...

submersible A submersible is an underwater vehicle which needs to be transported and supported by a larger ship, watercraft or dock, platform. This distinguishes submersibles from submarines, which are self-supporting and capable of prolonged independent ope ...

, or

atmospheric diving suit An atmospheric diving suit (ADS), or single atmosphere diving suit is a small one-person articulated submersible which resembles a suit of armour, with elaborate pressure joints to allow articulation while maintaining an internal pressure of on ...

can cause rapid compression barotrauma.

Rapid change of altitude

A rapid change of altitude can cause barotrauma when internal air spaces cannot be equalised.

Self inflicted barotrauma

Excessively strenuous efforts to equalise the ears using the

Valsalva manoeuvre The Valsalva maneuver is performed by a forceful attempt of exhalation against a closed airway, usually done by closing one's mouth and pinching one's nose shut while expelling air, as if blowing up a balloon. Variations of the maneuver can be ...

can overpressurise the middle ear, and can cause middle ear barotrauma. This is more likely to happen when one tube opens and the other remains blocked. When a Valsalva maneuver is performed during descent with the intention of opening the Eustachian tubes, but they do not open, intrathoracic pressure, central venous pressure, spinal fluid pressure, and inner ear pressure are raised further above ambient pressure, which increases the pressure difference between perilymph of the inner ear and the gas space of the middle ear. This can cause the round or oval window to rupture outwards, allowing leakage of perilymph into the middle ear.

Blast-induced barotrauma

An explosive blast and

explosive decompression An uncontrolled decompression is an undesired drop in the pressure of a sealed system, such as a pressurised aircraft cabin or hyperbaric chamber, that typically results from human error, structural failure, or impact, causing the pressurised v ...

create a

pressure wave Longitudinal waves are waves which oscillate in the direction which is parallel to the direction in which the wave travels and displacement of the medium is in the same (or opposite) direction of the wave propagation. Mechanical longitudinal w ...

that can induce barotrauma. The difference in pressure between internal organs and the outer surface of the body causes injuries to internal organs that contain gas, such as the

lungs The lungs are the primary organs of the respiratory system in many animals, including humans. In mammals and most other tetrapods, two lungs are located near the backbone on either side of the heart. Their function in the respiratory syste ...

gastrointestinal tract The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the Digestion, digestive system that leads from the mouth to the anus. The tract is the largest of the body's systems, after the cardiovascula ...

, and

ear In vertebrates, an ear is the organ that enables hearing and (in mammals) body balance using the vestibular system. In humans, the ear is described as having three parts: the outer ear, the middle ear and the inner ear. The outer ear co ...

Impact over the external auditory canal

Blows to the outer ear which seal the canal and compress the trapped gas or water can burst an eardrum or cause lesser barotrauma to the middle ear. This is a recognised hazard in several contact sports.

Mechanism

The middle ear is an air-filled space between the external and inner ears. it is separated from the outer ear canal by the eardrum, and connected to the nose and throat cavity by the Eustachian tube. Pressure in the middle ear should match the ambient pressure for normal functioning of hearing. Under-pressure equalisation is normally through periodic opening of the Eustachian tubes during swallowing and yawning, and over-pressure usually vents passively through the collapsed soft part of the tube, as the inner end of the tube is normally closed. Middle ear barotrauma occurs when a pressure difference develops over the eardrum, causing bulging towards the low pressure side, stretching the tissues which in a severe case can rupture, which immediately equalises the pressure and removes the stretching forces, but leaves local trauma. Stretching of the eardrum to a lesser extent can also cause damage, including engorged blood vessels which exude serum into the surrounding tissues and cause inflammation. increased pressure difference will cause blood vessels to rupture, which may bleed into or inside of the membrane. In divers this usually occurs during descent, when the ambient pressure rises due to increasing hydrostatic pressure. Pressure on the outer side of the eardrum normally closely follows ambient pressure, and in the inner ear pressure equalises through the Eustachian tube, which must be open for gas to flow through. If the diver does not equalise sufficiently a pressure difference may develop that is large enough to damage the eardrum as described. During ascent, the convere occurs, with the internal pressure higher than external. This is usually passively released by the Eustachian tube, but in some cases it does not function correctly causing the eardrum to bulge and possibly rupture outward. The pressure difference required to rupture the eardrum is thought to be approximately 100 kPA (1 bar or 10 msw).

Diagnosis

Diagnosis is by symptoms, otoscope examination and history.

Differential diagnosis

Differential diagnosis In healthcare, a differential diagnosis (DDx) is a method of analysis that distinguishes a particular disease or condition from others that present with similar clinical features. Differential diagnostic procedures are used by clinicians to di ...

should consider alternative conditions which could produce the same symptoms. Depending on the actual symptoms presented, such conditions could include:

otitis media Otitis media is a group of Inflammation, inflammatory diseases of the middle ear. One of the two main types is acute otitis media (AOM), an infection of rapid onset that usually presents with ear pain. In young children this may result in pullin ...

otitis externa Otitis externa, also called swimmer's ear, is inflammation of the ear canal. It often presents with ear pain, swelling of the ear canal, and occasionally decreased hearing. Typically there is pain with movement of the outer ear. A high fever ...

, cerumen impaction,

inner ear decompression sickness Inner ear decompression sickness, (IEDCS) or audiovestibular decompression sickness is a medical condition of the inner ear caused by the formation of gas bubbles in the tissues or blood vessels of the inner ear. Generally referred to as a form o ...

, caloric stimulation,

benign paroxysmal positional vertigo Benign paroxysmal positional vertigo (BPPV) is a disorder arising from a problem in the inner ear. Symptoms are repeated, brief periods of vertigo with movement, characterized by a spinning sensation upon changes in the position of the head. * ...

(BPPV),

vestibular neuronitis Labyrinthitis is inflammation of the labyrinth, a maze of fluid-filled channels in the inner ear. Vestibular neuritis is inflammation of the vestibular nerve (the nerve in the ear that sends messages related to motion and position to the brain) ...

Ménière's disease Ménière's disease (MD) is a disease of the inner ear that is characterized by potentially severe and incapacitating episodes of vertigo, tinnitus, hearing loss, and a feeling of fullness in the ear. Typically, only one ear is affected in ...

acoustic neuroma A vestibular schwannoma (VS), also called acoustic neuroma, is a benign tumor that develops on the vestibulocochlear nerve that passes from the inner ear to the brain. The tumor originates when Schwann cells that form the insulating myelin sheath ...

, and possibly others. If there is sensorineural hearing loss or vertigo after exposure to a large change in ambient pressure or a change of

breathing gas A breathing gas is a mixture of gaseous chemical elements and compounds used for respiration. Air is the most common and only natural breathing gas, but other mixtures of gases, or pure oxygen, are also used in breathing equipment and enclosed ...

, the possibility of concurrent barotrauma and

(IEDCS) should be considered, because the symptoms can be very similar, and IEDCS is treated with

recompression Recompression is the process of returning to a state of higher ambient pressure. Often associated with underwater diving and compressed air work, but also relevant to aeronautics and space flight: * In therapeutic recompression, a form of hyperbaric ...

and

hyperbaric oxygen Hyperbaric medicine is medical treatment in which an increase in barometric pressure of typically air or oxygen is used. The immediate effects include reducing the size of gas emboli and raising the partial pressures of the gases present. Initial ...

Prevention

Among people playing underwater and swimming contact sports, such as water polo,

underwater hockey Underwater hockey (UWH), also known as Octopush in the United Kingdom, is a globally played limited-contact sport in which two teams compete to manoeuvre a puck across the bottom of a swimming pool into the opposing team's goal by propelling ...

underwater rugby Underwater Rugby (UWR) is an underwater team sport in which two teams compete to deliver a negatively buoyant ball into the opponents’ goal at the bottom of a swimming pool. It originated from physical fitness training programs in German d ...

, a cap with perforated ear cups is often used, such as a

water polo cap A water polo cap is a piece of headgear used in water polo and a number of underwater sports. The caps are used to identify both the player and their team, and to protect their ears from injury possibly caused by a water polo ball hitting the h ...

. The a risk of stretched or burst

eardrum In the anatomy of humans and various other tetrapods, the eardrum, also called the tympanic membrane or myringa, is a thin, cone-shaped membrane that separates the external ear from the middle ear. Its function is to transmit changes in pres ...

s, can be reduced by any of a variety of methods to let air into or out of the

s via the

Eustachian tube The Eustachian tube (), also called the auditory tube or pharyngotympanic tube, is a tube that links the nasopharynx to the middle ear, of which it is also a part. In adult humans, the Eustachian tube is approximately long and in diameter. It ...

s. Sometimes swallowing will open the Eustachian tubes and equalise the ears. Most of the methods are less likely than the Valsalva maneuver to cause collateral damage to the inner ear. The Eustachian tubes will close completely with a pressure difference of about 3msw (10fsw) above the middle ear pressure, at which point none of the equalising maneuvers will work, and the pressure difference must be decreased to make it possible again, This implies ascending during a dive, venting some of the pressure from a hyperbaric chamber, and ascending to a higher altitude in an aircraft, which is not always practicable.

Treatment and management

If inner ear barotrauma and decompression sickness can be excluded, treatment may include any combination of short term use of nasal decongestants, intranasal steroid sprays and antibiotics for secondary infections. Surgical repair of persistent perforation of the eardrum may be necessary. Treatment is in proportion to the injury, and may include education to reduce risk of repeat injury. It is often treated conservatively and usually resolves without medical intervention. Some cases are due to simple ambient pressure change and Eustachian tube dysfunction at the time, while others may be partly the consequence of a less obvious underlying condition. Antibiotics are not usually needed unless infection develops or the ear was exposed to contaminated water. MEBT may occur during pressurization for hyperbaric treatment for other conditions. If this happens, pressurization should be stopped and if necessary, reversed sufficiently to allow the Eustachian tubes to be opened more easily, and the middle ear to be cleared. Physician-prescribed oral decongestants may help. Compression should normally be aborted if equalization remains unsuccessful. In urgent clinical hyperbaric treatment, an emergency needle

myringotomy A myringotomy is a surgical procedure in which an incision is created in the eardrum (tympanic membrane) to relieve pressure caused by excessive buildup of fluid, or to drain pus from the middle ear. A tympanostomy tube may be inserted through th ...

or placement of tympanostomy ventilation tubes may be required. These will passively equalise the middle ear, and are effective with an unconscious person.

Outcomes

Mild symptoms may resolve within 1 to 2 weeks. All symptoms should be resolved before diving or flying recommences, including healing of any perforations of the eardrum, and equalisation must be possible, with no abnormal sounds, and hearing is normal.

Epidemiology

Middle ear barotrauma is the single most common diving disorder for which treatment is sought, at nearly 50% of all reported diving injuries. Many more milder cases may go unreported. A history of head and neck cancers, with associated radiation treatment, has been associated with a relatively higher incidence of MEBT, possibly due to radiation damage of the soft tissues of the Eustachian tubes or pharynx.

References

{{Use British English, date=August 2022 Diseases of middle ear and mastoid Underwater diving disorders Aviation medicine