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Home › Information Diving › Injuries › Alternobaric Vertigo

Alternobaric Vertigo and Diving

Understanding the basic mechanism that causes a 'spinning' sensation underwater can help to prevent a panic due to the feeling of unexpected disorientation.

This help guide explains why some scuba divers get AV, how to recognise the symptoms, and simple steps you can take to reduce middle-ear injuries.

What Causes AV Vertigo with Scuba Diving?

Divers with incomplete (or insufficient) equalisation may encounter the effects of alternobaric vertigo during any of the following:

• Ascents (as the pressure decreases)
• Immediately after reaching the surface
• During a descent (increasing pressure)

The mechanisms of injury involve the middle ear chambers, eustachian tubes, and the nasopharynx.

As a diver ascends, air inside the middle-ear space expands resulting in an increase in relative pressure. As the eustachian tubes open (without resistance), excess gas usually escapes via the tubes into the nasopharynx, which is a box-shaped passageway behind the nose.

For one reason or another, any obstruction inside a eustachian tube is likely to disrupt normal air flow. In turn, this can increase the pressure inside the cavity of the middle ear.

This one-sided obstruction (with a pressure difference greater than 0.6 metres of water (2 feet)) can stimulate the vestibular apparatus and cause vertigo when scuba diving. Often, ascending to a shallower depth will increase the differential pressure and force the Eustachian tube to open.

In simple terms:

The main cause of alternobaric vertigo is disturbance to the inner ear balance mechanism (e.g. unequal middle ear pressures).

These kinds of ear barotraumas often result in the loss of spatial balance with symptoms including dizziness, light-headedness, and sometimes fainting.

Note: The common contributing factors of eustachian tube dysfunction (ETD) and alternobaric vertigo (AV) include allergies, middle-ear barotrauma (during a descent), smoking, and congestion (upper respiratory infections). They occur most often in aviation, flying, and in scuba diving vertigo.

Alternobaric Vertigo Symptoms

• Balance issues
• Disorientation (tilting to one side)
• Dizziness
• Giddiness
• Nausea and vomiting
• Nystagmus (involuntary rhythmic eye movement)
• Occasional pain
• Relief (e.g. upon middle ear equalisation)
• Spinning sensation

Often, the benign manifestations of AV result in an inability to discern up from down. Hence, being able to follow the safety procedures for ascending can be more challenging than normal.

Add to that, feeling nauseous - and the need to vomit underwater through a scuba regulator - poses extra hazards for a diver, and for others in the vicinity.

The key take away for new divers is that experiencing vertigo underwater will create a disorienting effect. It can be very dangerous and often makes the news headlines as scuba diving accidents stories.

In some cases, diver vertigo is a symptom of a contaminated air fill, decompression sickness (DCS), or insufficient oxygen (hypoxia).

Important: Medical attention should be sought by any scuba diver who experiences a loss of balance and giddiness underwater.

Diving Vertigo Prevention Techniques

Despite being in a static, vertical position, divers can experience disequilibrium of air spaces. This incongruence of middle ear pressure can lead to a strange, off-balance spinning sensation - especially during the ascent at the end of a dive.

Medical experts, such as the Divers Alert Network, recommend following these procedures to help prevent getting vertigo while you are scuba diving.

• Always provide full and honest answers when completing the RSTC Medical Statement.
• Avoid wearing a tight-fitting wetsuit hood or using earplugs while scuba diving because it may cause unequal pressurisation in the ears.
• Keep your ears healthy and maintain good ear hygiene (e.g. don't insert anything into your ears).
• Avoid using decongestants to help equalisation and do not go diving if you are congested, unable to equalise, or you feel unwell.
• Learn how to equalise the air spaces in your body and follow the recommended techniques (e.g. early and often).

Managing Alternobaric Vertigo During a Dive

There are several responses that scuba divers should try if they encounter vertigo or ear pain during an ascent to the surface.

For example, descending a few metres and performing the Toynbee maneuver can help to minimise the pressure imbalance. In many cases, doing so may open the eustachian tubes and relieve middle ear distension.

You might also try pressing the 'tragus' in front of the concha to close the external opening of the ear canal. This sudden 'inward' movement of any enclosed water may fix the problem.

Here's the good news:

The principle treatment for alternobaric vertigo (AV) is being able to re-establish the pressure equilibrium in the middle chambers of both ears. In most cases, you should be able to resolve uncomplicated issues within a few minutes of reaching the surface.

Nonetheless, you would need to seek medical attention (e.g. an ENT specialist) if the symptoms persist or if you suffer any associated injuries, such as middle-ear barotrauma (reverse squeeze) or inner-ear barotrauma.

Learning about vertigo, and understanding the mechanisms of alternobaric vertigo (AV), means scuba divers will be able to manage the symptoms better and minimise further mid-water risks.

The first step is to remain calm and focus on relaxed breathing. In some cases, you may be able to resolve the manifestations by following these recommendations:

• Stop the descent and end the dive if necessary.
• Stop the ascent (if possible).
• Maintain your position in the water and allow the symptoms to subside on their own. Try to hold a depth using a fixed visual reference or physical connection to an object that's not moving (e.g. an ascent line, large rocks, static marine life plants and animals, your dive buddy, depth gauge, or the seafloor).
• Equalise adequately (pinch the nostrils closed and gently attempt to exhale with a closed mouth).
• Do not attempt to force equalisation while you are experiencing alternobaric vertigo (AV).
• Ascend slowly and expect to experience a gradual resolution of the symptoms after exiting the water. There may be a serious injury (e.g. a ruptured eardrum) if the symptoms last for more than a few minutes.

Persistent Alternobaric Vertigo Treatment

So, what should a diver do if the symptoms of vertigo persist even after ending the dive and what should you take for vertigo dizziness?

In most cases, a medical doctor will prescribe a dose of antibiotics and decongestants as the common remedies for transient vertigo.

It may also be important to rule out certain conditions that may last longer, including caloric vertigo (temperature difference between the left and right ear) and inner-ear decompression sickness (IEDCS).

As a result, it should take only a few days for non perforating ear injuries to subside and completely heal. But, it can take several weeks for ruptured eardrums to repair and surgery may be a requirement (e.g. CPAP treatment) in some of the most severe cases.

Important: Divers who experience vertigo in the water will feel disoriented and may start to panic. Experts rank AV among most of the serious injuries associated with scuba because it can lead to an uncontrolled ascent. But, a return to diving may take place after the contributing factors of AV have cleared up.

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