Perilymphatic Fistula Treatment & Management

Some tears of the inner ear membranes probably heal without surgical intervention. Medical management includes bed rest, elevation of the head of the bed, use of stool softeners, avoidance of Valsalva maneuver, and sedation. Repeated audiometric evaluations should be performed, and medical management should be reconsidered if hearing deteriorates or balance disturbance fails to improve.

The definitive treatment for perilymphatic fistula (PLF) is surgical exploration, with grafting of the fistula. Early repair of PLF offers the potential for resolution of vestibular symptoms and preservation of residual auditory function. Many authors recommend immediate surgical exploration when the likelihood of perilymphatic fistula (PLF) is high. The timing of surgical exploration in the less-defined case is controversial. Depending on strict diagnostic criteria risks underdiagnosis of the disease, whereas overzealous exploration of all patients with auditory and vestibular complaints risks performing many procedures that, in retrospect, are unnecessary. Meyerhoff and Pollock have recommended that the patient become intimately involved in the decision-making process.

The procedure can be performed with the patient under local or general anesthesia . A standard tympanomeatal flap is designed, incised, and elevated. Generally, curetting away the posterior bony overhang (scutum) is necessary to permit adequate visualization of the round and oval window niche. These areas are then very carefully observed for the accumulation of clear fluid. However, even intraoperative observation can be inconclusive. Transudates from middle ear mucosa, irrigation, or injected anesthetic materials can collect within the dependent areas of the round window or oval window niche. The absence of detectable fluid in these areas does not exclude an intermittent or recurrent perilymphatic fistula (PLF). Use of intravenous fluorescein is not helpful because it can accumulate in the round window niches as a transudate from middle ear tissues.

Beta2-transferrin is specific for human aqueous humor, CSF, and perilymph. Western blot analysis for beta2-transferrin allows identification with very small amounts of dilute fluid. Unfortunately, the time required to perform the test prevents its use in surgical decision making. Preoperative irrigation of the middle ear via myringotomy has been suggested as a method of obtaining dilute perilymph that could be tested by Western blot analysis for the presence of beta2-transferrin, thus providing preoperative evidence of perilymphatic fistula (PLF). Intermittent or inactive perilymphatic fistula (PLF) is overlooked by this test, and its risk to the patient approaches the risk of exploratory tympanotomy. Additionally, sensitivity of Western blot analysis for beta2-transferrin has been demonstrated to be very low (29%) in one study testing specimens of known perilymph.

Provocative testing to confirm perilymphatic fistula (PLF) is advocated by some and includes intraoperative Valsalva maneuver, Trendelenburg positioning, increase in intrathoracic pressure, and compression of the internal jugular vein. Black et al observed postoperative hearing loss after intraoperative performance of provocative maneuvers in several patients; they since have discontinued this practice. ^[25]

Grafting is performed by removing mucosa of the round and oval window area. Autogenous tissue grafts are placed directly over the leak. If no actual leak is identified, the footplate and round window are grafted prophylactically. Adipose tissue originally was used, but its use resulted in an unacceptably high rate of recurrent fistula. Fascia or perichondrium now is used; this is reported to have decreased the incidence of recurrent fistula. Surgeons at the University of Texas Southwestern Medical Center make a small incision beneath the lobule from which parotid masseteric fascia is harvested for use as a graft. Some authors use fibrin glue; others do not.

Some surgeons do not graft unless an active leak is visualized. Other surgeons graft routinely, even if no leak can be detected by visual inspection. A poll of 167 members of the American Otologic and Neurotologic Society revealed that 78% placed grafts in all patients undergoing exploratory tympanotomy for PLF, regardless of whether a fistula could be demonstrated at operation.

Postoperative care is directed at maintaining the integrity of the graft. Patients are instructed to avoid heavy lifting, straining, and activities that place the head in a dependent position, all of which could lead to increasing intracranial pressure. Stool softeners are given for the first 10 postoperative days. Antinausea medications are used as necessary. Air flight is well tolerated in the immediate postoperative period because the middle ear space is filled with transudated blood, therefore providing no air-filled space upon which pressure can act.

The patient should be seen again 1-3 weeks postoperatively. A follow-up audiogram should be obtained at 6 weeks, and another follow-up audiogram should be obtained at 6 months. Beyond 6 months, follow-up care is determined by the patient's condition.

Few complications result from perilymphatic fistula (PLF) repair. Tympanic membrane perforations occur in 1-2% of patients. Postoperative conductive hearing loss may persist longer after round and oval window grafting than with simple exploratory tympanotomy. Approximately 5% of patients still have persistent mild (5-10 dB) postoperative hearing loss 2-3 months following surgery; however, in most patients, the loss resolves within 6 months. Some risk exists of severe-to-profound hearing loss. This is especially likely in individuals with Mondini dysplasia or other morphologic defects. These ears are unstable, and surgical manipulation can result in hearing deterioration. Conversely, additional hearing loss is almost certain in such cases, and surgical intervention with round and oval window grafting frequently is the least risky alternative. Alteration of taste as a result of chorda tympani injury occurs with some frequency. It generally resolves within a few weeks to a couple of months.

Rizer and House examined the outcome of 86 patients who underwent exploratory tympanotomy for suggested perilymphatic fistula (PLF). ^[26] Active perilymphatic fistula (PLF) was found in 35 of the patients, and all patients had placement of oval and round window grafts. Improvement was seen in 68% of patients with surgically confirmed perilymphatic fistulas (PLFs), as opposed to 29% who did not demonstrate active perilymphatic fistula (PLF).

Similarly, a retrospective study by Prenzler et al indicated that in patients with profound sudden sensorineural hearing loss (SSNHL), exploratory tympanotomy with sealing of the round and oval windows achieves better results when perilymphatic fistula (PLF) is present than when it is not. The study involved patients with unilateral profound SSNHL who did not show clinical evidence of perilymphatic fistula (PLF), with the investigators determining that in those who were found intraoperatively to have fistula, the postoperative reduction in the percentage of hearing loss was 2.4 times greater than in those not found to have perilymphatic fistula (PLF). ^[27]

Hearing improvement or restoration is less likely than elimination of balance disturbance after surgical repair of perilymphatic fistula (PLF). Seltzer and McCabe reported that 49% of treated ears improved in terms of auditory function, but only 23% improved to serviceable hearing levels, and 11% had continued hearing deterioration. ^[10] Rizer and House noted 13.3% of their patients had hearing improvement. ^[26] Black et al demonstrated hearing improvement in 17% of patients, stabilization of hearing in 67%, and continued progression in 17%. ^[25] The same authors report improvement of vestibular systems in 83-94% of patients.

A study by Ahn et al indicated that in patients with suspected barotraumatic perilymphatic fistula (PLF), surgically sealing both windows can improve hearing and subjective dizziness. In confirmed and probable cases of surgically treated barotraumatic perilymphatic fistula (PLF), postoperative hearing was improved in 65% and 61.9% of ears, respectively, while dizziness improved in 94.4% and 100% of patients, respectively. The investigators also found that hearing improvement was associated with the elapsed time between symptom onset and the performance of surgery. ^[28]

A retrospective study by Conway et al of patients who underwent transcanal reinforcement of the round or oval windows found a statistically significant postoperative hearing reduction at the 4000 Hz frequency, possibly due to stiffening of the windows. However, the investigators stated that this decrease was probably clinically insignificant and determined that the procedure caused no detrimental impact on the pure-tone average, word recognition score, and speech reception threshold. ^[29]

Surgical exploration is highly effective for vestibular symptomatology, but its effect on hearing loss is less predictable.

The entire area of perilymphatic fistula (PLF) is fraught with disagreement. Investigations in this area are severely constrained by the absence of any reliable tests to determine the presence of perilymphatic fistula (PLF). Because the presence or absence of the condition cannot be determined with certainty, its incidence remains unclear. Frequently, a physician cannot know whether an individual patient had a perilymphatic fistula (PLF); therefore, definitively constructing a typical clinical picture for the disorder is impossible.

A method of determining with certainty whether perilymph is within the middle ear space is needed. Perhaps a rapid assay for beta2-transferrin that could be performed intraoperatively can be developed. Until a technique is developed for unequivocal diagnosis, perilymphatic fistula (PLF) will remain mired in controversy.