The fluids of the inner ear are normally separated from the air-filled middle ear cavity by two membranes: the oval window (where the stapes sits), and the round window. It is hypothesized that a tear in either membrane can cause a leakage of perilymph (one of the inner ear fluids) into the middle ear cavity (the space behind the ear drum). This leakage is called a “perilymphatic fistula”, or PLF. It is thought to cause fluctuating sensorineural hearing loss (SNHL), and dizziness with pressure changes (such as sneezing, coughing, or straining). While it seems clear that this can occur after surgical opening of these membranes (such as during a stapes surgery), whether or not a PLF can occur spontaneously is controversial. It is generally agreed upon that the incidence of PLF was overestimated in the past. Treatment is aimed at closing the fistula, with surgical reinforcement of the round and oval windows with autologous materials (such as fat, fascia, or 
perichondrium harvested during the surgery).