What Causes a Perilymph Fistula?

A perilymph fistula occurs inside the ear when there is a tear in the thin membrane called the oval or round window. This window separates the inner ear from the middle ear. The inner ear is filled with a fluid called perilymph, so when the tear occurs it causes fluid to leak into the middle-ear space. The middle ear normally is filled with air and doesn't contain any fluid.

Causes

The most common cause of a perilymph fistula is head trauma. It can also be caused by barotrauma, a condition that usually occurs on an airplane or while scuba diving (when there are rapid changes in atmospheric pressure). Barotrauma can also cause severe pain in the ear and sometimes a ruptured eardrum.

More rarely, perilymph fistulas can happen during childbirth, can be congenital (have happened before birth), or from other unknown causes.

Symptoms

You may experience some or all of the following symptoms with a perilymph fistula:

• Hearing loss, which may fluctuate or be sudden
• Tinnitus
• Vertigo (dizziness, nausea, vomiting), which may occur in response to loud noises
• Pressure in the ear

Symptoms of perilymph fistula may become worse when you change altitude.

Diagnosis

Diagnosis of a perilymph fistula can be difficult because symptoms overlap with other inner ear disorders such as Meniere's disease. There also is not a "gold standard" test for diagnosing a perilymph fistula. However, you can sometimes make the diagnosis from an MRI or CT scan.

Since the diagnosis can be so challenging and treatment can often involve surgical intervention, they recommend receiving a second opinion as well as the following tests to increase the likelihood of an accurate diagnosis:

• Fistula test
• Fraser test
• Valsalva test
• Audiometry
• Electrocochleography (ECOG) (a test that records the activity of the inner ear)
• Electronystagmography (ENG)
• Temporal bone CT scan, high resolution
• MRI

A thorough history can be very important in helping your healthcare provider determine whether or not perilymph fistula is a possible problem that is causing your symptoms. It is common to have your symptoms get worse when you are sneezing, straining, or coughing, and you should share this with your healthcare provider. Another common symptom is the Tullio phenomenon, which causes you to experience vertigo when exposed to loud sounds.

Of the tests listed above, there is some research that suggests that the best way to make a diagnosis of perilymph fistula is a thorough medical history and a positive fistula or Fraser test.

Treatment

The two main treatment options are surgical repair or strict bed rest to allow your body to repair the fistula on its own. Many factors can affect the decision of whether to use a non-surgical or surgical approach. As long as symptoms are improving your healthcare provider may continue bed rest or strict activity restriction for up to six months before considering surgical repair of a perilymph fistula.

Certain medications may help treat symptoms but will not have any effect on the fistula itself. For example, medications like ondansetron and promethazine may be used to control nausea. Diazepam is another medication that is sometimes used.

Surgical repair of a perilymph fistula involves a tissue graft to repair the tear in the round window. Unfortunately, this approach is not always successful in treating a perilymph fistula.