Imaging Studies
See the list below:
-
No diagnostic test can be considered a criterion standard for perilymph fistula, and none are immediately useful in the emergency department.
-
Clinical history and symptoms are more sensitive than radiographic studies for the assessment of perilymph fistula.
-
A 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.
High-resolution CT scans are inadequate for evaluation of the round and oval window regions.
MRI with intrathecal gadolinium enhancement can detect inner and middle ear communication, but a more cost-effective modality is preferred.
Other Tests
See the list below:
-
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. Positive results include the elicitation of nystagmus or onset of dysequilibrium with the sensation of motion or nausea. Some otologists administer the test with electronystagmography or by using platform posturography.
-
Perilymph labeling methods
Initial studies used intrathecal or intravenous fluorescein, but these have been abandoned for perilymph-specific protein testing, such as beta-2 transferrin, apo D, and apo J.
Beta-2 transferrin, a protein found in perilymph and CSF but not in serum, has been the most actively studied. Initial enthusiasm for a Western blot assay for this protein has wavered due to low sensitivity. The presence of beta-2 transferrin in perilymph has been unreliable, possibly due to current collection methods or small sample volumes, and false-positive results may be secondary to CSF contamination during collection.
Focus has recently switched to the efficacy of apolipoprotein D (apo D) as a marker for perilymph with encouraging results.
Results of a study by Ikezono et al strongly suggest that cochlin-tomoprotein may be a specific marker of perilymph leakage. Additionally, cochlin-tomoprotein could be a potential marker, allowing definitive diagnosis of perilymph fistula related hearing loss and vestibular disorders. [9, 10]
Procedures
See the list below:
-
The current criterion standard for confirmation of perilymph fistula is direct visualization either by operative middle ear exploration or by in-office endoscopy.
-
The subjectivity of this diagnostic maneuver has been questioned because no universally accepted criteria exist for diagnosis during surgery. More objective tests are being developed, particularly those that identify compounds specific to perilymph upon the examination of the fluid contents.
