What is Middle Ear Barotrauma (Middle Ear Injury)?
Otic Barotrauma, or ear barotrauma, is an ear injury caused by a lack of pressure balance between the ear’s gas-filled spaces and the outside environment. This situation commonly occurs during diving or with hyperbaric oxygen treatment, which is a high-pressure oxygen therapy. In such circumstances, the inability to balance pressure, known as Eustachian tube dysfunction, and middle ear barotrauma are common complications.
The outer ear, or the pinna, is mainly composed of ridged cartilage covered by skin. It includes the external ear’s entry point, leading to the eardrum. Behind the eardrum is an air-filled space in the middle ear containing three small bones: the malleus, incus, and stapes. The stapes connect with the oval window that leads into the inner ear. The inner ear is vital for hearing and balance and is divided into separate parts with different roles: the cochlea for hearing and the vestibular system for balance and spatial orientation.
The middle ear communicates with the throat via the eustachian tube. This tube opens near the back part of the nasal openings, letting the fluid from the middle ear to drain. It also balances the air pressure between the middle ear and the external ear canal. It’s worth noting that while this balance is naturally maintained when we ascend (go upwards), it requires conscious effort when descending. Another less significant exchange of air occurs through the middle ear lining and mixed veins, but this is less crucial during rapid pressure changes while diving, flying, or in a hyperbaric chamber.
Sound travels in the form of waves through the external ear canal, causing the eardrum to vibrate. This vibration is then transmitted to the three small bones in our middle ear, eventually moving the stapes bone in and out against the oval window. This triggers a fluid motion within the cochlea, which is then interpreted as sound in our central nervous system via the eighth cranial nerve.
While small-scale injuries due to middle ear barotrauma can quickly heal, more serious injuries may take weeks or months to recover. In some cases, severe barotrauma may cause permanent issues, including hearing loss and balance imbalances. Thus, it’s essential for divers, air travel passengers, and hyperbaric oxygen therapy patients to understand how to frequently and early equalize middle ear pressure during pressurization. Identifying and preventing Eustachian tube dysfunction and middle ear barotrauma are crucial when assessing and treating a pressure-related injury.
What Causes Middle Ear Barotrauma (Middle Ear Injury)?
MEBT, or middle ear barotrauma, is caused by unequal pressure between the space in the middle ear and the surrounding environment. According to a principle known as Boyle’s law, if the outside air pressure increases, this causes the volume of gas in body cavities, like the ear, to reduce. This can occur when you move downwards in an aircraft or a hyperbaric chamber, go diving, or following a physical force or blast to the external ear canal.
When the external pressure rises due to changes in either the atmospheric or water pressure, this increases the pressure in the ear canal and reduces the gas volume in the middle ear, effectively creating a vacuum. To offset this, there needs to be an equal pressure in the middle ear which usually comes from air from the back of the nose and mouth. If the middle ear doesn’t fill up enough with air, MEBT happens.
A person might fail to balance their middle ear pressure for various reasons such as during trauma, improper technique, or inability to open their Eustachian tube (the tube that links the throat to the middle ear) during activities with higher external pressure. MEBT can occur even at very shallow water depths of around 4 feet, and it takes pressure equivalent to about 10 feet of seawater to completely close the Eustachian tube. This is why it’s common among individuals who participate in these activities. Once the Eustachian tube closes completely, it rarely reopens with basic balancing techniques. To reopen the Eustachian tube, the ambient pressure needs to reduce, but this is not always immediately possible or effective, depending on the activity.
For divers, they can decrease their depth and swim upwards; for chamber operators, they can increase the exhaust until the person can balance their middle ear pressure. However, for pilots, it’s not always possible to stop landing the pressurized aircraft and increase altitude when a passenger complains of MEBT.
Risk Factors and Frequency for Middle Ear Barotrauma (Middle Ear Injury)
If you’ve ever dived deep into a pool, traveled on an airplane, or driven up a mountain, you’ve experienced changes in ambient pressure. These changes can cause certain complications like ETD and MEBT, which are most common when SCUBA diving, commercial diving, or during a clinical treatment called hyperbaric oxygen treatment (HBOT). The occurrence of these complications can vary greatly, ranging from 4.1% to 82% according to different studies.
Different reports suggest that factors such as gender, age, allergies, type of diving, water temperature, climate, smoking history, certain nasal conditions, and a previous history of ear infections might cause significant differences in the occurrence of these complications. People who have previously had head and neck cancers or radiation treatment are prone to higher rates of ETD and MEBT, which might be due to the soft tissue damage caused by radiation in certain parts of the throat and ear. Also, people having certain anatomical peculiarities in their ears may be at higher risk.
- ETD and MEBT are common complications related to changes in ambient pressure.
- These complications mostly occur during SCUBA diving, commercial diving, or hyperbaric oxygen treatment (HBOT).
- The probability of experiencing these complications can fluctuate between 4.1% to 82%.
- The occurrence of these complications can be influenced by factors like gender, age, allergies, smoking history, and type of diving.
- People with a history of head and neck cancers or radiation treatment are more likely to develop these complications.
- Certain anatomical peculiarities in the ear structure can increase the risk of these complications.
Signs and Symptoms of Middle Ear Barotrauma (Middle Ear Injury)
MEBT, which is pressure-related ear trauma, can happen due to exposure to changes in atmospheric pressure or physical harm to the ear. Initially, people may feel a sensation of fullness or dullness in the ear due to changes in pressure across the eardrum. If the atmospheric pressure keeps increasing, or the pressure inside the middle ear space does not equalize, discomfort can escalate to severe pain. Some patients may report hearing loss resulting from fluid build-up or bleeding within the middle ear space. If the eardrum ruptures, patients may experience a sudden relief from increasing pain, along with varying degrees of hearing loss. Should the patient develop IEBT or PLF, there might also be cases of hearing loss, ringing in the ears, increased sensitiveness to sounds, feeling dizzy, nausea and vomiting.
It’s worth mentioning that not all patients with ETD and MEBT experience noticeable symptoms. Some studies found that a significant percentage of divers with ear barotrauma didn’t show any symptoms, and in people with diabetic neuropathy, ear barotrauma was often painless. Thus, this stresses the importance of routinely checking the ears of hyperbaric patients, especially those with known peripheral neuropathy, before and after exposure to high pressure.
An otoscopic examination, which allows for a direct look at the ear canal and eardrum, can help detect any abnormalities. However, visualizing the eardrum may be obstructed due to impacted earwax or bone growths. As such, earwax needs to be cleared to get a clear view of the eardrum. Bear in mind, each ear canal could vary slightly in its anatomical structure, skin color, blood vessel formations, etc. Also, superficial changes may occur due to previous trauma to the ear canal and eardrum. Potential signs of MEBT that can be seen during an otoscopic exam include redness, bleeding, fluid build-up in the middle ear space, or eardrum perforation. In the case of IEBT, patients may present with unstable walking patterns, involuntary eye movements, and hearing loss.
Testing for Middle Ear Barotrauma (Middle Ear Injury)
If someone shows symptoms of Ear Barotrauma or Eustachian Tube Dysfunction (ETD), a medical examination of the ear using an instrument called an otoscope becomes necessary. This would help the doctor identify and categorize the severity of the injury, leading to a more accurate diagnosis and treatment plan. Right now, there are three commonly used grading systems for ETD and Middle Ear Barotrauma (MEBT) assessment – the Teed, Modified Teed, and O’Neill systems. However, it’s important to note that these grading systems are mainly used by undersea and hyperbaric medical experts, and are less commonly used by ear, nose, and throat specialists (otolaryngologists).
The Teed Classification was developed by Dr. Teed in 1944, he studied diver trainees for the U.S. Navy. This grading system allows the examiner to assess possible trauma to the eardrum with classifications ranging from 0 (normal eardrum) to 4 (perforation or hole in the eardrum). The Modified Teed Classification is an expanded version of the original, introducing an additional grade which assesses symptoms without any visible indications of trauma.
The O’Neill Grading System is unique in that it uses a video otoscope to take a baseline image of the eardrum before any exposure to pressure changes. These images can then be compared with the appearance of the ear following exposure to aid in diagnoses, reducing variance between doctors. They also offer treatment guidance based on the grades.
While Ear Barotrauma can often be easily diagnosed with this method, sometimes further investigations from an ear, nose and throat specialist are required to rule out other conditions, especially if symptoms like new-onset vertigo or loss of hearing are present. Patients might be referred for pneumatic otoscopy – a test involving gentle air pressure changes to the ear – or even exploratory surgery in certain cases.
If Inner Ear Barotrauma is ruled out, yet the patient has experienced significant pressure changes, like those involved in deep-sea diving, another potential diagnosis could be Inner Ear Decompression Sickness. This condition requires treatment with a therapy involving the inhalation of pure oxygen while in a pressure-controlled chamber (hyperbaric oxygen therapy). Tools like the HOOYAH criteria can assist medical experts in differentiating between the two conditions based on factors like symptom onset, ear examination results, diving history, and additional symptoms.
Treatment Options for Middle Ear Barotrauma (Middle Ear Injury)
Treatment for MEBT, or pressure-related ear troubles, ranges from educating the patient on pressure management to using medical or surgical treatments. Management is usually by healthcare professionals familiar with pressure situations, like emergencies or hyperbaric medicine. In many cases, MEBT can be solved without any medical treatment. If such ear troubles are because of pressure changes surrounding a person, it’s important to determine whether it’s because of the pressure change itself (primary ETD) or due to an underlying health condition (secondary ETD). Figuring this out can help in finding the best treatment plan to prevent further ear troubles due to barotrauma (BT).
If MEBT occurs during the process of increasing pressure or pressurization, it’s important not to increase the pressure further. Instead, allow time for the Eustachian Tube (ET) and the middle ear to clear. Reducing pressure slightly and using specific pressure balancing techniques can benefit the patient. If there’s an existing Eustachian Tube Dysfunction (ETD), doctors may suggest treatments like oral decongestants. If equalization still fails, then the hyperbaric treatment should be stopped and the patient referred to an ear specialist.
In urgent situations, emergency action may be needed. This could mean a procedure to puncture the eardrum (emergency needle myringotomy) or insertion of ventilation tubes into the eardrum. These procedures help equalize the pressure within the middle ear. But, they also carry risks for complications like infection, bleeding, tubes moving into the middle ear, hearing loss, and long-term damage that may need surgical repair.
Antibiotics aren’t usually needed unless there are signs of an infection or exposure to contaminated water. It’s important to avoid certain antibiotics that can harm the ear in cases of eardrum perforation.
If a patient is suspected of having IEBT (a type of barotrauma related to internal pressure), an ear specialist should do the assessment and manage the condition. Some instances may require a surgical procedure to correct issues like a large eardrum perforation, a perforation not healing, or a perforation related to IEBT symptoms.
There’s no guaranteed way to predict or prevent ETD or Otic BT unless there’s a physical connection between the external ear canal and middle ear. The causes for differences between individuals in pressure equalization are not clear. Some tests may provide some indications of which individuals are at risk. However, these tests alone can’t predict who will struggle to equalize middle ear pressure during pressure changes.
Preventing more MEBT might be achieved by educating patients more on pressure balancing techniques as well as managing the rate of pressure changes more closely. There are many techniques to help with equalizing ear pressure, like Valsalva, BTV, Toynbee, Frenzel, Edmonds, and Lowry. One device, the Ear Popper, provides a continuous air flow into the nasal cavity, which can help equalize ear pressure.
Medical prevention is a controversial topic. Some believe that pre- treatment with pseudoephedrine could decrease the risk of barotrauma during air travel in adults, but its effectiveness in children is not clear. The use of topical decongestants to reduce barotrauma is also not clear.
Patients who experience persistent ETD or MEBT might need an elective surgical procedure called myringotomy with tympanostomy ventilation tubes inserted. This procedure isn’t suitable for those involved in diving activities due to the risk of water getting into the middle ear. But, it may be an option for those involved in dry hyperbaric activities, like Hyperbaric Oxygen Therapy (HBOT), or those traveling in pressurized aircraft.
Overall, people who have experienced ear barotrauma should avoid being exposed to high pressure environments until their symptoms are resolved and ear examinations come back normal.
What else can Middle Ear Barotrauma (Middle Ear Injury) be?
When a patient experiences symptoms like feeling fullness in the ear, hearing loss, ringing in the ears (tinnitus), and/or dizziness, doctors need to consider several potential causes. These could include:
- Build-up of earwax (cerumen impaction)
- Ear infections (otitis media or otitis externa)
- Nerve-related hearing loss (IEDCS)
- Fluid imbalance in the inner ear (Meniere’s disease)
- Caloric stimulation, a test that determines the healthiness of parts of your ear responsible for balance
- An episode of brief, intense vertigo (Benign Paroxysmal Positional Vertigo, or BPPV)
- Inflammation of the inner ear (vestibular neuronitis)
- A noncancerous growth in the inner ear (acoustic neuroma)
In conclusion, it’s crucial that doctors thoroughly evaluate these potential causes and carry out the necessary tests to make an accurate diagnosis.
Possible Complications When Diagnosed with Middle Ear Barotrauma (Middle Ear Injury)
Complications linked to otic barotrauma, or injury to the ear due to changes in pressure, can include a variety of symptoms and conditions. These may involve fluids such as a serous or serosanguinous effusion, or clear and blood-tinged liquid, forming in the ear, bleeding into the middle ear, or a rupture of the eardrum. This condition is also known as Inner Ear Barotrauma (IEBT). As a result, patients may experience temporary or permanent hearing loss, dizziness, and unsteadiness while walking.
Additionally, conditions like infections in the ear canal or middle ear, chronic pain, and temporary facial nerve palsy, which causes facial weakness, have been noted. These complications are important to acknowledge for their potential impact on a patient’s quality of life.
Here’s a summary:
- Clear liquid forming in the ear (Serous effusion)
- Blood-tinged liquid in the ear (Serosanguinous effusion)
- Bleeding into the middle ear
- Eardrum rupture (Perforation of the TM)
- Inner Ear Barotrauma (IEBT)
- Temporary or chronic hearing loss
- Dizziness (Vertigo)
- Unsteadiness while walking (Gait instability)
- Infections in the ear canal or middle ear
- Chronic pain
- Temporary facial weakness (Facial nerve palsy)
Preventing Middle Ear Barotrauma (Middle Ear Injury)
Steering clear of any recognized risky situations, using balancing methods frequently and promptly, and addressing any hidden causes of ear tube dysfunction are very important when it comes to preventing ear damage due to pressure changes. Those at risk, including divers, must be informed about the potential complications of such ear injuries and how to prevent them.
