Perilymphatic Fistula

What is Perilymphatic Fistula?

A labyrinthine fistula is a condition where there’s an unusual connection between the inner ear and the structures around it. This unusual connection, or fistula, most commonly occurs between the inner ear and the nearby structures, leading to leakage of a fluid called perilymph. The first cases of this happening naturally, without surgery, were reported in four patients in 1970 by medical researchers Stroud and Calcettera.

Before this, in 1962, there were some instances where, following a specific type of ear surgery, a plastic device used in the surgery would slip into the inner ear. This resulted in the build-up of perilymph in the inner ear, which would escape through the slipped device. This issue was dubbed the “slipped strut problem”. Patients with this problem reported symptoms such as changes in hearing, a feeling of fullness in the ear, dizziness, ringing in the ears (tinnitus), and balance problems.

It’s important to note that ‘labyrinthine fistula’ and ‘perilymphatic fistula’ are two terms that refer to the same problem. You might see these terms used interchangeably when you’re reading up on the subject.

What Causes Perilymphatic Fistula?

Labyrinthine fistulas, or tiny holes in the ear, can occur due to a birth defect, an injury, or as a result of medical procedures. Often, these fistulas are the result of head injuries which can happen due to accidents, strenuous activities like labor, coughing, sneezing, conditions that increase pressure inside the skull, injuries from explosions, or from sudden changes in air pressure like in diving or flying.

Oddly enough, things like lightning strikes, force from airbags, and loud noises such as fire engine sirens have been known to cause these fistulas too. Sneezing has been specifically observed to increase the fluid pressure in the brain, causing the round window membrane in the ear to rupture and result in fistulas.

Recurrent middle ear infections leading to cholesteatoma, a skin growth that occurs abnormally in the middle ear, can also cause labyrinthine fistulas. The occurence of cholesteatoma leading to these fistulas lies between 4% to 15% incidents. Cholesteatomas can erode bone and may lead to various complications, including these fistulas. The ear’s lateral semicircular canal, part of the inner ear responsible for balance, is most likely to get involved. However, the other semicircular canals can also be affected.

Although rare, there can be complications that involve the cochlea, the part of the ear responsible for hearing. Cochlear fistulas often occur with fistulas in other parts of the labyrinth, the complex system of canals within the inner ear.

Risk Factors and Frequency for Perilymphatic Fistula

Labyrinthine fistulas, a condition related to the inner ear, are quite rare and not frequently reported about. They often result from a complication of chronic ear infection called cholesteatoma. The occurrence of Fistulas due to cholesteatoma ranges between 4% and 15%.

Signs and Symptoms of Perilymphatic Fistula

A labyrinthine fistula is a medical condition that could potentially be overlooked or wrongly diagnosed. Therefore, a detailed medical examination and history are crucial. How do you suspect this condition? If a patient has had a fracture to the temporal bone or rupture of the delicate labyrinth (inner part of the ear) from head injury, labyrinthine fistula should be considered. Such injuries could result from blowing the nose too strongly (implosive injuries), or due to pressure caused by actions such as sneezing, coughing, weight lifting, or even a blast injury (explosive injuries).

The main symptoms of a labyrinthine fistula include sudden or worsening hearing loss and dizziness after the triggering event. People might experience dizziness as a feeling of imbalance, intense vertigo or dizziness related to changes in their position.

This condition should also be suspected if the patient complains of hearing loss or problems with balance (vestibular disturbances) after a specific surgical procedure called stapedectomy. This is when an artificial prosthesis can displace, leading to leakage of a fluid called the perilymph. The same should be considered for individuals suffering from ongoing otitis media (middle ear inflammation). In these individuals, a type of skin cyst known as cholesteatoma can develop, potentially leading to the erosion of the protective bony structure around the labyrinth, creating a fistula. An abrupt change in pressure, such as during diving or flying (barotrauma), can also induce this condition. Patients with a labyrinthine fistula complain of dizziness and sudden or worsening hearing loss following such pressure-related episodes.

There valuable pointers your doctor might find during examination, such as:

• The fistula test. If inflation of air in the ear leads to jerky eye movements (nystagmus), this is a positive sign.
• Cholesteatomas can sometimes be visible during an examination of the ear using an instrument called an otoscope.
• Dizziness induced by sound, known as Tullio’s phenomenon. The patient may also present with hearing loss that could be due to damage to the nerve (sensorineural), the ear’s structures (conductive), or a mix of both.
• The Fukuda/Unterberger test helps identify issues with balance due to dysfunction in the balance-related part of the ear (vestibular hypofunction). Here, the patient is asked to walk forward with their eyes closed, abruptly pivot on one foot and stop. If they have trouble keeping their balance after stopping, this could indicate a positive test.

According to some statistics, approximately 64% of individuals had dizziness in their medical history, while 15% were found to have severe sensorineural hearing loss and 97% exhibited indicative radiological findings suggestive of a fistula.

Testing for Perilymphatic Fistula

Diagnosing a condition called labyrinthine fistulas can be tricky because there’s no well-defined list of diagnostic criteria. Nevertheless, experts have suggested some factors to take into consideration:

1. Symptoms – Ringing in the ears (tinnitus), feeling of fullness in the ear, difficulty hearing, and balance-related issues that are related to previous or ongoing middle ear or inner ear problems or operations.
2. Lab results – Including various biochemical tests and microscopic or endoscopic inspection.
3. References – Using methods to detect cochlin-tomoprotein and beta2 transferrin.
4. Differential diagnosis – Ruling out other known causes of inner ear diseases.
5. Definite diagnosis – Detection of a certain protein specific to perilymph (a fluid in your inner ear), or conducting an exploratory surgery known as tympanotomy.

To evaluate hearing loss, a comprehensive hearing test should be carried out. This includes checking the auditory brainstem response (a test of the electrical signals of the nerve pathways), emission testing, and pure tone audiometry (a test to determine the quietest tones you can hear at different frequencies).

A computed tomography (CT) scan is usually the most reliable way to diagnose labyrinthine fistulas before surgery. If the scan shows an air pocket in your inner ear (pneumolabyrinth), then this confirms the diagnosis and indicates an immediate need for surgical treatment. Nonetheless, if the pneumolabyrinth is small, it might be hard to see on a CT scan. For better visualization, coronal views (front-facing views) of the bone around the ear leading up to the superior semicircular canals (part of your inner ear that helps with balance) would be helpful. However, a definitive diagnosis can only be made with exploratory tympanotomy, a surgical procedure to examine the middle ear.

Treatment Options for Perilymphatic Fistula

In terms of surgical treatment for labyrinthine fistulas (abnormal connections between the inner parts of the ear), there is no clear agreement among experts. Some researchers have found that immediate surgery does not necessarily improve hearing, while others have observed that patients can still experience hearing improvement after many years post-surgery, suggesting that early intervention may be crucial for hearing recovery.

It’s been noted that giving corticosteroids (medications that reduce inflammation) during surgery can improve hearing outcomes. Additionally, some patients have experienced less dizziness after having a part of their ear called the mastoid filled up (also known as “mastoid obliteration”).

Due to the lack of precise diagnostic criteria for this condition, doctors typically take a cautious approach to management. They will usually recommend that patients rest in bed with their head elevated and avoid activities that increase pressure in the skull or cause excessive effort. If the symptoms persist or return frequently, a surgical exploration of the middle ear (tympanotomy) may be the next step. Surgery can often reduce dizziness and vertigo symptoms, but it doesn’t usually improve hearing loss and in fact might increase the risk of additional, surgically-induced hearing loss.

When labyrinthine fistulas are caused by cholesteatomas (skin growths that occur in the middle ear), the treatment starts by fully removing the cholesteatoma and closing the fistula. When sealing the part of the ear called the horizontal semicircular canal, a resurfacing technique is preferred over “plugging” because the latter could impair canal function and increase the risk of hearing loss. As with other types of labyrinthine fistulas, surgery appears to have better results concerning symptoms related to balance, rather than those related to hearing.

What else can Perilymphatic Fistula be?

The possible conditions that could have similar symptoms and thus need to be ruled out when diagnosing the main disease are:

• Meniere syndrome (primary endolymphatic hydrops) – This is more common than a condition called perilymphatic fistula and may have the same symptoms.
• Secondary endolymphatic hydrops – This could be a result of a head injury, allergies, or existing health problems like an autoimmune disorder.
• Acoustic neuromas – These are benign (non-cancerous) tumors that develop on the nerve that connects the inner ear with the brain.
• Hemorrhagic stroke – This happens when a blood vessel within the brain bursts.
• Superior semicircular canal dehiscence – This is a rare medical condition that affects the balance and auditory functions of the inner ear.

What to expect with Perilymphatic Fistula

Surgery has been proven to be the most effective in reducing symptoms such as imbalance and dizziness. However, if there’s existing hearing loss, surgery might not always help to improve it. Some studies suggest that the chances of getting better and the level of symptom improvement depend on how severe the initial symptoms or triggers were.

The more serious the initial symptoms or triggers, the less likely it is for healing to occur naturally or for surgery to help. An example being with perilymphatic fistulas, a condition that involves leakage of inner ear fluid. Research conducted by Goto et al. and Black et al. found that only about 9% to 17% of patients observed an improvement in hearing post-surgery.

Possible Complications When Diagnosed with Perilymphatic Fistula

The main complications of a labyrinthine fistula include loss of hearing and feeling dizzy. Complications can also occur after the surgical repair of a fistula. These complications can be a tear in the eardrum, hearing loss after surgery, and damage to the chorda tympani, which is a nerve in the ear. In some instances, patients have seen improvements in their hearing loss and nerve damage a few months after surgery.

Another issue that can occur is Superior Canal Dehiscence Syndrome. This syndrome is thought to be related to the fistula, but it isn’t caused by a true fistula. Instead, it causes a kind of communication between the superior bone canal and the middle cranial fossa, which are parts of the ear and the skull. This can lead to strange experiences, including hearing your own voice, heartbeat, and eye movements. Sudden pressure changes such as doing the Valsalva maneuver (holding your nose and exhaling) can trigger nystagmus (involuntary eye movement) and/or oscillopsia (a sensation of visual disturbance), and feelings of dizziness.

Common Complications:

• Loss of hearing
• Feeling dizzy
• Tear in the eardrum
• Hearing loss after surgery
• Damage to the chorda tympani
• Superior Canal Dehiscence Syndrome, leading to auditory disturbances and feeling dizzy
• Nystagmus
• Oscillopsia

Preventing Perilymphatic Fistula

If you are diagnosed with a labyrinthine fistula, a condition that affects your balance and hearing, it’s crucial to avoid certain situations and exposures that could intensify your symptoms. These can include activities which require a lot of physical effort, such as straining or heavy lifting. You should also avoid environments with rapid pressure changes like during air travel, scuba diving, or even simple actions as popping your ears, and blowing your nose forcefully.

Of course, if you find yourself needing to be in one of these situations, it’s recommended you ask someone else for help, especially if you start to experience imbalance or feel dizzy. Additionally, you should steer clear of activities at night or in conditions with poor lighting, like driving. This is due to the fact that your condition might make it harder for you to navigate or control certain functions in these settings.