[Rupture of the membrane of the round window in stapes fixation]

A case of sudden deafness is described. Examination showed a mixed deafness on the left side, suspected to be due to fixation of the stapes and a simultaneous perilymph fistula. These lesions were proved by an exploratory tympanotomy. The interesting aspects of the case are emphasized: firstly recruitment caused by a perilymph fistula, present for 5 months without causing complete deafness; secondly improvement of hearing after surgical treatment of both pathological conditions; and finally the complete absence of vestibular signs.