Perilymph Fistula in Emergency Medicine

A perilymph fistula (perilymphatic fistula [PLF], labyrinthine fistula) is a pathologic communication between the fluid-filled space of the inner ear and the air-filled space of the middle ear, most commonly occurring at either the round or oval window. ^{[1, 2, 3, 4]}  The primary manifestations of perilymph fistulization are sudden or progressive fluctuating sensorineural hearing loss and vertigo. ^[5]  Other symptoms that may be present include tinnitus, disequilibrium, and aural fullness.

This clinical entity was proposed more than a century ago, yet it remains a topic of controversy, especially regarding the occurrence of spontaneous perilymph fistula (PLF). Trauma and poststapedectomy are etiologies proven to cause PLFs and must be considered in the appropriate settings. A PLF should be considered in pediatric patients with recurrent meningitis, and the option of middle ear exploration should be pursued. It is likely that most pediatric patients with PLFs will have an anatomic abnormality of their middle ear or labyrinth. It is also known that although several potential pathways exist between the perilymphatic space and the middle ear, actual leaking of fluid can be difficult or impossible to prove.

There is no agreed upon diagnostic test with enough sensitivity and specificity to identify the presence or absence of perilymph fistula. This has made it difficult to establish criteria to determine when surgical exploration might be indicated. Additionally, there are no universally accepted criteria to confirm diagnosis at surgery; the determination of the presence or absence of PLF is the subjective decision of the surgeon. Additionally, the presence of clear fluid in the middle ear at the time of surgery may represent perilymph or may be CSF, serum, or local anesthetic. No reliable and accurate test is currently available to reliably distinguish these fluids from one another. No studies have been reported to account for the substantial placebo effect of a surgical procedure for vertiginous symptoms in patients with suspected PLF, and no appropriate long-term follow-up of patients after surgery has been reported.

The presenting complaint and symptoms of perilymph fistula are often consistent with Meniere syndrome. Therefore, in the absence of prior surgery or definite traumatic event, distinguishing a perilymph fistula from Meniere syndrome may be difficult.

Signs and symptoms of perilymph fistula

History for perilymph fistula may include the following:

• Fluctuating  sensorineural hearing loss that may be sudden or progressive
• Vestibular symptoms - Vertigo, with or without head position changes; disequilibrium; motion intolerance; nausea and vomiting; disorganization of memory and concentration; and perceptual disorganization in complex surroundings such as crowds or traffic
• Tinnitus - May be roaring in nature
• Aural fullness

Workup in perilymph fistula

Clinical history and symptoms are more sensitive than radiographic studies for the assessment of perilymph fistula.

A computed tomography (CT) or MRI scan may be indicated with a history of head trauma if temporal bone fracture is considered, but its use as a diagnostic study for nontraumatic perilymph fistulas is questionable.

Otologists may use the following tests to diagnose perilymph fistulas:

• Audiograms - To detect hearing loss
• Electrocochleography
• Fistula tests (Hennebert sign) - The subjective fistula test is performed by applying positive and negative pressure to the intact eardrum using a pneumatic otoscope

The current criterion standard for confirmation of perilymph fistula is direct visualization either by operative middle ear exploration or by in-office endoscopy.

Management of perilymph fistula

The primary purpose of emergency evaluation is to seek other, more emergent causes of symptoms. However, consider the diagnosis with hearing loss and vertigo following head trauma. Vertigo suppressants, such as diazepam and meclizine, may be used, although their benefit remains unproven in this setting. Medical therapy is rarely reported. Some reports exist of spontaneous healing with bedrest, head elevation to 30°, and avoidance of lifting or middle-ear pressure–increasing activities.