What Is a Perilymph Fistula?
A fistula is an abnormal connection between two spaces that allows flow of contents from one space to the other. In a perilymph fistula (PLF), the connection is between the inner ear and the middle ear. Because the inner ear is filled with perilymph and the middle ear is air filled, perilymph fluid leaks out from the inner ear into the middle ear.
What Are the Symptoms of PLF?
Hearing loss, vertigo, motion sickness, sensitivity to sound can be caused by a PLF. The symptoms are usually exacerbated by changes in either internal or external pressure.
What Causes a PLF?
A PLF may occur with trauma to the ear. A rapid increase pressure causes what is known as barotrauma to the ear. Conditions that result can barotrauma include flying, scuba diving, straining, exercising, coughing, sneezing, laboring in childbirth, etc. The weakest parts of the inner ear, the oval and round windows, are damaged. These areas consist of a thin layer of bone separating the middle and inner ear. A PLF forms when this thin layer of bone cracks, connecting the middle ear and inner ear.
PLF may also occur with head trauma. A blow to the head can result in temporal bone fracture (skull fracture involving the ear). Perforating injury to the ear drum can cause a perilymph fistula. A spontaneous PLF has been described by some physicians. It is difficult to diagnose a spontaneous PLF as symptoms are nonspecific without a history of trauma.
If severe, PLF can result in substantial loss of fluid in the inner ear. This can lead to permanent hearing loss and significant imbalance.
How Does My Doctor Diagnose a PLF?
Symptoms of hearing loss and vertigo after ear trauma raise clinical suspicion. Examination of the ear usually reveals no abnormality. A fistula test involves applying pressure to the ear drum. If positive, the eyes will involuntarily move in response to the pressure. The patient will feel off balance. This also raises suspicion for PLF, although other conditions also cause a positive fistula test. Your doctor can order a CT of your ear to check for these other conditions. Specialized hearing tests and balance tests may also be ordered to check for other conditions. If you have symptoms of PLF, a history of barotrauma, and no other explanation after CT scan and testing, surgery may be recommended to confirm PLF. Through the ear canal, the surgeon can lift your ear drum and look at the oval and round windows. Unfortunately, the amount of fluid can be quite small and the diagnosis may remain uncertain.
Is PLF Treatable?
PLF is treated by surgical repair. The oval and round windows can be accessed through the ear canal as previously described. This is called a tympanotomy. After looking for perilymph leaking, small grafts of soft tissue can be taken from beneath the skin behind your ear and placed at the possible sites of leak. The ear drum is then placed back in normal position completing the procedure. This takes approximately 1 hour. Pain is limited. It is considered day surgery.