ZusammenfassungFormerly explorative tympanotomies including sealing of the round/oval window/s have only been used in treating perilymphatic fistulas. During the last years this operation especially in the middle European countries has also been performed more and more in patients suffering from an ISSNHL. In this chapter the effect of this operation including a simultaneous systematic steroid therapy on hearing levels has been collected from data presented in literature and the results will be presented by means of a systematic review. The survey also includes the results of this operative procedure in 41 patients who have been treated by us.Based on 19 publications dealing with the above mentioned topic only 6 studies (4 of them with information about the hearing loss at the time of admission at the hospital and additionally at a follow-up examination (n = 309)) could be integrated in this study and another 2 in which the hearing gains –regardless of the initial hearing loss- according to the modified „Kanzaki“-criteria (n = 288)) have been evaluated- could be used for estimating the therapeutic effects of tympanoscopy with sealing of the round/oval windosw/s in patients with sudden deafness.The follow-up examination had to exceed a 3 weeks interval up from the time of the operation. It is shown that several methods of evaluation the median hearing loss (PTA4 and PTA5) in pure tone audiograms are suitable to be accepted for the analysis of hearing losses in order to compare the results of the treatment.In each study-group collected from literature and two study-groups of our own patients the hearing loss before therapy was significantly higher than that which had been measured at the follow-up examination.Patients in which tympanoscopy was combined with a systematic application of steroids in a „first-line-mode“ (n = 79) had a hearing loss of 94,1 dB. Their hearing improved up to a hearing level of 70,7 dB at the follow-up examination (hearing gain: 23,4 dB; n = 79). Those who first had got systematic steroids followed by the tympanoscopy („second-line-mode“) had an intitial hearing loss of 105,1 dB and a hearing gain of 38,6 dB. So the final hearing level reached 66,5 dB (n = 197).Median hearing thresholds still rose after detamponation of the external ear canal which was usually done 10 days after the operation up to the follow-up examination.Based on the modified „Kanzaki“-criteria 58,7 % of the patients had a restoration in their hearing exceeding 30 dB. In 18,7 % of the cases the hearing improvement was between 10 and 30 dB. 23,1 % of the patients didn`t profit from tympanoscopy.Indications for deciding to perform an explorative tymapnosocopy which are mentioned in literature are collected and discussed.Explorative tympanotomy including sealing of the round/oval window/s seems to be a very valuable method in treating sudden deafness especially when the hearing loss was severe, profound or even when the patients were totally deaf and the therapeutic procedure had been done sequentially after having performed a systematic steroid application before operation. Further studies have to find out if tympanoscopy used in a „first-line-mode“ can also be a method in which the hearing gain is successful enough that this form of therapy can also be recommended.