A perilymph fistula (PLF) is an abnormal connection (a tear or defect) in one or both of the small, thin membranes (the oval window and the round window) that separate the air filled middle ear and the fluid filled perilymphatic space of the inner ear. This small opening allows perilymph (fluid) to leak into the middle ear.
Changes in air pressure that occur in the middle ear (for example, when your ears “pop” in an airplane) normally do not affect your inner ear. However, when a fistula is present, changes in middle ear pressure will directly affect the inner ear, stimulating the balance and/or hearing structures within and causing PLF symptoms.
The perilymphatic space of the inner ear is connected to the cerebrospinal fluid (CSF) that surrounds the brain. Perilymphatic fluid, which is high in sodium (Na+), is similar in composition to CSF. When an abnormal connection between the membranes between the middle and inner ear exists, perilymph in the inner ear escapes, driven by the hydrostatic pressure of the CSF, and is replaced by CSF. This can also result in lower than normal levels of CSF fluid around the brain and spinal cord, which may result in symptoms such as mild headache.
Patients with PLF often feel frustrated and depressed because, while they don’t feel well, they look fine to others. PLF patients specifically and vestibular patients in general often have a challenging time explaining to friends and family what they are going through. Sometimes it is enough to ask your support network for patience and understanding while you explore diagnosis and treatment options and learn to cope with the symptoms brought on by persistent dizziness.