Perilymph fistula is a very rare condition caused by leakage of perilymph (the fluid surrounding the membranous labyrinth of the inner ear) at the round or oval window.

Symptoms include vertigo, imbalance, tinnitus, fluctuating hearing, ear pressure, and aural fullness. These symptoms may fluctuate, with good and bad days. In some cases, pressure-maneuvers like straining, can aggravate these symptoms (which may also happen in Chiari I malformation). Some studies have described cognitive difficulties in some patients.

Head trauma is a common cause of perilymph fistula – the symptom similarity with vestibular migraine and concussion can lead to confusion and misdiagnosis. Other causes include acoustic trauma (exposure to very loud sounds), barotrauma (from flying, diving, or scuba diving), forceful sneezing or coughing, stapedectomy surgery (otosclerosis), and congenital abnormalities (e.g. Mondini malformation).

Perilymph fistula is a controversial disorder in otolaryngology. Tests that can help with the diagnosis include the fistula test, audiometry, and electrocochleography. It may be important for coordination between an otolaryngologist and neurologist to evaluate for other disorders that can cause similar symptoms.