Sudden sensorineural hearing loss (SSNHL) is a severe impairment for the affected person. Over the past decades, no specific treatment regimen could be established . One reason for that might be the fact that the majority of patients with an idiopathic sensorineural hearing loss show a high recovery rate even with no specific treatment . Exploratory tympanotomy was often indicated for the management of SSNHL occurring in the context of head trauma, barotrauma and chronic otitis media with cholesteatoma and in patients with congenital inner-ear abnormalities [17, 18]. Especially for patients after a diving accident, there is a clear indication for performing an exploratory tympanotomy . But it remains unclear whether patients with no typical history for a round window membrane rupture benefit from this procedure. There are a few retrospective studies that analyzed hearing after tympanotomy [14, 15, 20]. Selmani et al., who performed an endosopic inspection of the middle ear cavity, observed no perilymphatic fistula in 265 cases of patients with SSNHL and vertigo . With respect to the well-established microsurgery of the middle ear and the possible infection during a middle ear endoscopy, we prefer the better visualization of the round window membrane via the operation microscope. Reports of patients who underwent an exploratory tympanotomy in our institution due to sudden deafness over the last 6 years were retrospectively analyzed. There was only a minority of 10% of patients with a typical history of increased inner ear pressure with respect to the onset of symptoms. This is in contrast to Taylor et al., who reports 18 of 20 patients with a history of pressure elevation in context with the hearing loss . A similar retrospective study by Maier et al. reports 22% of patients had a typical history of perilymph fistula . We observed intraoperatively definite round window membrane ruptures in about 20% of the cases. This is in contrast to Arndt et al. , who documented a spontaneous perilymph fistula in 60% of their study population. Maier et al., who analyzed the same categories of intraoperative findings (fistula, no fistula and doubtful fistula), found a definite fistula in 35% and no fistula in 37% .
Assessment of perilymphatic fistulas remains a diagnostic problem. In our study we had a rate of 22% of doubtful fistulas. Visualizing the round window membrane often demands the removement of false membranes and bony ridges. Exact data on this technical detail were not possible to evaluate retrospectively in all cases. Indirect signs as the observation of persisting fluid in the round window niche were therefore considered as a criterion for the diagnosis of a doubtful perilymphatic fistula in the present study.
Whether other methods such as intrathecal fluorescein for perilymph staining are useful in this issue is still unclear . Poe et al. analyzed the value of intravenous fluorescein applications in an animal model and concluded that the administered fluorescein causes dramatic fluorescence of vessels and transudates that may be interpreted falsely as fluorescence of perilymph .
Only 4 of our patients with a definite or doubtful fistula reported a typical history. One conclusion concerning this observation might be that the patients’ history does not predict the finding of an intraoperative round window membrane rupture. Thus the anamnesis concerning a predisposing incident is not a reliable indication for the surgery.
18 patients (26%) had no hearing improvement in the control examination after 3 weeks in our study population. This result is similar to Gedlicka et al. , who performed a retrospective study with 60 patients after tympanotomy and found no improvement in 33% of their patients.
There was a correlation between the age and the pure-tone audiometry values, which demonstrated that older people had a more severe impairment of hearing pre- and postoperatively. There was no correlation between the history of the patient, the intraoperative finding and the diagnosis of tinnitus or vertigo preoperatively. That means that we could not predict the finding of a perilymphatic fistula. The analysis of our pre- and postoperative pure tone audiometry values revealed significantly improved hearing postoperatively. Almost half of the patients had an improvement of their mean average hearing loss by more than 20 dB. This result might be due to tympanotomy and the covering of the round window niche. But we have to consider other possible effects: All patients were simultaneously treated with intravenous steroids starting with 500 mg prednisone following a reduction scheme over 12 days. Also placebo effects and a spontaneous recovery have to be mentioned and could not be excluded. There is also a possible bias because only patients who consented to perform surgery were included to this study. A generally accepted definition of what constitutes improvement or recovery after a SSNHL is not existingamong studies and reports. One interpretation is an improvement of 20 dB in pure-tone audiometry  as chosen in the present study. Other authors use an improvement of 30 dB as definition for a relevant hearing recovery .
With respect to these limitations, exploratory tympanotomy seems to be a safe procedure, because none of the patients suffered from any major complications or a worsening of hearing afterwards. Concerning the technical issues, most of the surgeons at our institution used fat sealing to cover the round window niche. A variety of other techniques including fat-fibrin-glue  and postauricular collagen tissue  is described in the literature.
The occurence of a round window membrane rupture in SSNHL patients was under 20% in our study population. The patients’ history did not predict the finding of an intraoperative round window membrane rupture. Thus the anamnesis concerning a predisposing incident is not a reliable indication for the surgery.
We found no correlation between the hearing recovery of SSNHL patients with and without perilymphatic leak. Nevertheless, exploratory tympanotomy is a safe procedure that might be a useful addition to high-dose steroids in severe cases of SSNHL. With respect to our results an exploratory tympanotomy should be considered for patients with no improvement of hearing within 48 h after treatment with high-dose steroids and a SSNHL of more than 50 dB HL in three contiguous frequencies. Further prospective studies that compare different treatment regimens are necessary to identify the benefit of an exploratory tympanotomy in patients with sudden deafness.