Perilymphatic fistulas.

The oft-quoted dictum that clinical suspicion rather than any specific test leads to the diagnosis is confirmed by our study. Further work is needed to define the vestibular findings more precisely and to work out relationships between CSF and perilymph pressures. Temporal bone study will be necessary to document the double membrane break theory. Future study may include analysis of suspected fistula fluid to determine if it represents a mixture of perilymph and endolymph. From our study, fistulae may occur from minimal or no trauma. The presentation is usually subtle. Because no diagnostic test is available to assure correct diagnosis, one must maintain a high index of suspension. Diagnosis usually cannot be made until the ear is surgically explored. The low morbidity of an exploratory tympanotomy, coupled with the high positive to negative ratio of exploration and the high degree of successful results, leads the authors to encourage exploration. Indeed, the overall concensus is that many active fistulae remain undiagnosed because of the lack of suspension and the reluctance to explore an ear without a concrete preoperative diagnosis. The duration of the fistulae and the recurrent nature of the problem poses another diagnostic dilemma. The first positive exploratory tympanotomy for perilymphatic fistula often leaves the surgeon with a dichotomy of emotion from pride of a correct diagnosis to fear that perhaps his observations of the minute clear fluid seepage was an error. Reversal of patient symptoms quickly erases such fears and presumptive diagnosis of perilymphatic fistula becomes easier to make. Eventually, one begins to worry, "How many have I missed."