What is Alternobaric Facial Paresis?
Alternobaric facial paresis (AFP) is a less common, usually temporary condition in which the seventh cranial nerve—or facial nerve—gets affected due to pressure changes in the middle ear, a small cavity in your ear. This is also known by other names such as facial baroparesis and alternobaric facial nerve palsy. AFP happens when an imbalance of pressure in the middle ear pushes the facial nerve against a hard part of the ear called the cochlear promontory, resulting in symptoms similar to Bell palsy.
These symptoms can include inability to raise your eyebrows, to close one eye, to smile evenly, and occasionally a change in taste at the back of your tongue. The forehead not being affected may imply a central nervous system issue like a stroke, which doesn’t align with AFP.
The diagnosis relies on the patient’s history and symptoms that match with peripheral facial nerve palsy and exposure to situations that could cause pressure imbalance in the middle ear—this generally happens when you’re diving or flying. AFP most often happens while going up during a flight or while coming up to the surface when diving. Performing actions like yawning, swallowing, or doing specific maneuvers to equalize the pressure can make the symptoms disappear. An imbalance in pressure can also cause a symptom called alternobaric vertigo. Misdiagnosis could also lead to unnecessary treatments and restrictions on activities like diving.
AFP usually happens due to pressure build-up in the middle ear and often shows striking responses to pressure changes. The condition occurs quickly when the surrounding pressure decreases and disappears when the pressure increases or when the excess pressure in the middle ear is released.
Generally, AFP is a temporary condition and gets better once the pressure in the middle ear is balanced. However, if the pressure doesn’t balance out, the palsy can become permanent, similar to the range of symptoms seen in Bell palsy.
What Causes Alternobaric Facial Paresis?
Altered facial nerve function, also known as AFP, can be caused by a shift in pressure across the eardrum. This usually happens when there’s a problem with the Eustachian tube (a tube that links the middle ear with the back of the nose) and a weakened facial channel. This situation commonly arises during underwater diving, but it can also occur during high-altitude airplane travel.
Although your body can typically handle significant pressure changes, injuries can happen if an area filled with gas (like your ears) can’t adjust to these changes in the surrounding pressure. This issue, known as barotrauma, can happen under two conditions: a change in environmental pressure, and this pressure affecting a gas-filled space.
If your Eustachian tube is unable to balance the pressure between the middle and external ear due to swelling from irritation, infection or allergy, the pressure in your middle ear may increase on ascent. This can happen whether you’re underwater (as a diver, for example) or going up or down during a flight. A pressure increase equivalent to just a few feet of seawater can hinder the blood flow to the facial nerve in the area causing a compressive ischemic neuropathy, which is a nerve injury from not getting enough blood.
This type of pressure-related injury is most often seen in activities like scuba diving, free diving, and flying, but it has been reported from traveling to high altitudes, including hiking.
Risk Factors and Frequency for Alternobaric Facial Paresis
Peripheral facial paralysis, also known as alternobaric facial paresis (AFP), can be caused by a sudden change in pressure around a person, such as during a dive, flight ascent, or mountain climb. Occurrences of AFP are probably more common than reported, as many cases are brief and do not reoccur. Interestingly, this condition hasn’t been reported in scuba divers using helium gas mixtures but has been reported in breath-hold diving.
The Eustachian tube, a canal that connects the middle ear to the upper throat and back of the nasal cavity, can also play a role in AFP. In the United States, about 4.6% of people have some form of Eustachian tube dysfunction. This condition is more common in males, with a ratio of about 2:1, and typically affects one ear.
The facial nerve, which passes through the middle ear, is sometimes exposed due to defects in the bone known as dehiscences. These dehiscences along the facial canal are actually quite common. Studies have found them in more than half of a healthy population sample, and another study found them in as many as 29% of cases. In fact, about one-third of those were in both ears. However, most studies report dehiscence rates between 18% to 33%.
Signs and Symptoms of Alternobaric Facial Paresis
People suffering from AFP might experience a feeling of a “blocked ear” or ear fullness accompanied by sharp pain and hearing loss. Some may also experience facial and tongue numbness and tingling. On occasion, they may have a headache or may even notice blood inside their ear (with or without a tear in the eardrum). Additional symptoms like sudden ear pain and hearing loss can also occur. Some people may experience alternobaric vertigo, which is a spinning sensation caused by pressure imbalances in the ear chamber. Peripheral facial paralysis can also occur, particularly in water or shortly after emerging from it.
During a medical examination, the affected individual may exhibit signs of unilateral lower motor neuron facial paralysis (paralysis on one side of the face), which might sometimes be accompanied by alterations in taste sensation. An ear examination may reveal a bulging eardrum. One important thing to note is that in cases of peripheral facial nerve palsy, the whole side of the face is impacted, including the forehead. If the forehead is spared, it could suggest a central cause, like a stroke, which does not align with AFP symptoms.
- “Blocked ear” or ear fullness
- Sharp ear pain
- Hearing loss
- Facial and tongue numbness and tingling
- Headache (occasional)
- Blood inside the ear (occasional)
- Sudden ear pain and hearing loss
- Spinning sensation (vertigo) due to pressure imbalances in the ear
- Unilateral facial paralysis
- Altered taste sensation
- Bulging eardrum
Testing for Alternobaric Facial Paresis
The diagnosis of AFP, a condition where the facial nerve is affected, is based on a medical history and symptoms consistent with facial nerve problems. This condition is often linked to exposure to situations that can interfere with the pressure balance in the middle ear, such as diving or flying.
Magnetic Resonance Imaging (MRI), a technique that uses powerful magnets and radio waves to create pictures of the inside of the body, can be used to view the inner ear and rule out other possible causes such as stroke or tumors.
On the other hand, high-resolution CT scans, another type of imaging test, are not great at identifying the specific facial canal defect that can lead to AFP. However, these types of scans can still be useful for tracking the pathway of the nerve within the fallopian canal to the stylomastoid foramen (the pathway through which the facial nerve travels). This can help rule out other potential causes, such as tumors, especially in cases of repeated AFP incidents.
However, further testing is generally not needed and won’t usually provide additional useful information in diagnosing AFP.
Treatment Options for Alternobaric Facial Paresis
If you have a condition called Acute Facial Paralysis (AFP), you must act within 3 hours after its symptoms start to avoid lasting damage to the facial nerve. A few easy tricks, such as yawning, swallowing, or chewing gum, can help lessen pressure on the eardrum by opening the Eustachian tube, a small passage leading from your ear to your throat.
Other techniques like the Toynbee maneuver (swallowing while pinching your nose) and the Valsalva maneuver (blowing out while holding your breath and closing your mouth and nose) can also help. These exercises aim to open the Eustachian tube so that trapped air in your middle ear can escape. Local decongestants can also be used to accomplish the same goal: reduce swelling in the Eustachian tube to help trapped air escape from the middle ear. If all else fails, a practictioner may use a procedure called a myringotomy, where a tiny incision is made in the eardrum to release pressure.
Often, pressure changes in your eardrum when you’re on an airplane are resolved once the flight lands. It’s important to maintain good oxygen level in your body, as this helps counteract the effects of ischemia (limited blood flow) and allows the trapped air in your middle ear to be gradually removed or absorbed internally.
Hyperbaric oxygen therapy – inhaling pure oxygen in a pressurized environment – is another therapy to treat barotrauma (injury caused by changes in air pressure). With this therapy, you’ll likely recover within 2 minutes. A technique called normobaric oxygen therapy, where a high flow of oxygen at normal pressure is given to you, may also help in recovery within 15 minutes.
If you predict a recurrence, using inhaled decongestant sprays can be beneficial. Oral decongestants, such as pseudoephedrine, can also be effective in reducing symptoms. For the best prevention of AFP caused by this sudden change in ear pressure, oral decongestants may be your best option.
Note that for those who often experience AFP due to flying, doctors may recommend inserting small tubes in the eardrum, a procedure called myringotomy, to alleviate the pressure difference causing the issue. However, if you are a diver, this might not be a possibility due to the risk it could post for decompression sickness during diving.
What else can Alternobaric Facial Paresis be?
Cerebral air embolism, also known as decompression sickness, is a severe potential consequence of diving. It happens when gas forms bubbles as pressure decreases when a diver rises to the surface. This condition should always be considered when a diver surfaces and shows signs of a neurological deficit. However, in the case of facial paralysis (AFP), the circumstances and lack of symptoms (except maybe vertigo due to pressure-related vertigo) strongly point towards baroparesis (ear pressure-related facial paralysis).
There have also been other rare reports of temporary one-sided facial paralysis, which include:
- Bleeding in the subarachnoid space (between the brain and its covering)
- Transient ischemic attack (temporary stroke-like symptoms)
- High altitude cerebral edema (swelling of the brain caused by altitude sickness)
- Brain tumors
A history of diving, flying, or other changes in atmospheric pressure can help rule out these conditions.
What to expect with Alternobaric Facial Paresis
Generally, AFP, or acute facial paralysis, is a temporary condition that usually gets better once the pressure in the middle ear is balanced. However, if this ear pressure isn’t relieved, it can lead to a permanent facial nerve injury that could behave similar to Bell’s palsy, which causes sudden, temporary weakness or paralysis of the facial muscles.
This condition, AFP, could be a recurring problem for people involved in activities like diving and flying due to the pressure changes they experience. If it’s not treated quickly, it can cause lasting damage to the facial nerves.
For those who frequently fly and suffer from AFP, a surgical procedure called a grommet myringotomy could be used. This involves making a small hole in the ear drum to alleviate the pressure causing AFP. However, this approach wouldn’t be appropriate for divers, as the deliberate hole in the ear drum could expose the inner ear to open water and potential infection.
Possible Complications When Diagnosed with Alternobaric Facial Paresis
The current body of scientific literature provides limited understanding about AFP (Acute Facial Paralysis). This can result in both under-diagnosis and over-diagnosis. For instance, a misdiagnosis of central facial palsy (which is usually identified by forehead sparing) as AFP could delay the discovery and management of a stroke or other brain problems. Alternatively, if AFP is inaccurately identified as a stroke, it can trigger unnecessary emergency responses, such as forcing an airplane to land, an urgent hospital stroke evaluation, detailed scans of the brain, and an overnight hospital stay.
Additionally, failing to correctly understand AFP, especially in high altitude conditions, can lead to wrong diagnoses and improper treatment. Both recompression therapy and advanced imaging are costly and take a lot of time. If a diver is incorrectly diagnosed with an air embolism when they actually have AFP, it can lead to unnecessary recompression treatments, restrictions on diving activities, and the need for further tests and treatment.
The major risk associated with AFP until it is resolved is the damage it may cause to the outer layer of the eye, or cornea, from an inability to blink fully. This condition, known as keratitis, can be relieved with eye lubrication and patching.
Key Consequences of Misdiagnosing AFP:
- Delayed discovery and treatment of strokes and other brain conditions
- Unnecessary emergency activity (like airplane landings and emergency hospital evaluations)
- Unnecessary expensive and time-consuming treatments (like recompression therapy and advanced imaging)
- Restrictions on activities (like diving)
- Danger of eye damage from not being able to blink completely
Preventing Alternobaric Facial Paresis
If you’ve had just one bout of AFP (Acute Facial Paralysis) and don’t have any known issues with your Eustachian tube – the passage that connects the middle ear to the upper part of your throat – your treatment can usually be less aggressive. It’s important for you to know that AFP is a specific condition and isn’t the same as other causes of facial weakness.
Anyone who has had AFP should avoid flying if they have an upper respiratory tract infection, which is a fancy term for a cold or the flu. It’s also key to know how to perform specific techniques to balance the pressure in the middle ear. You should be aware that there is a risk of permanent facial nerve damage if your facial nerves lack blood flow for a long period during a future bout of AFP.