The aim of the thesis is the analysis of the anatomical abnormalities and atypical conditions in the middle ear encountered during the surgery for otosclerosis and their influence for the course of the operation. These atypical conditions could result either from the congenital anomalies or from the disease itself.
Material and methods: The material comprises 572 stapedectomies performed in ENT Department of the Pomeranian Academy of Medicine in Szczecin (Poland) between 1969 and 2004. Partial stapedectomy was performed with removal of the stapes crura and usually posterior part of the footplate.
Results: Among 572 ears which underwent the operation different abnormalities in the tympanic cavity were found in 134 cases (23,4%). These included: narrowed oval window niche in 71 cases, stapes anomalies in 46 cases, obliterative otosclerosis in 20 cases, red otospongiosis of the stapes in 9 cases, increased perilymph pressure in 7 cases, malleus and incus bony fixation in 3 cases. The presented abnormalities were the reasons of many failures at the time of the operation. While in the 438 ears with normal anatomical status in the tympanic cavity failures during the operation occurred in only 6 cases (1,4%), in the 134 ears with such abnormalities failures happened in 33 cases (24,6%). The most frequent failure - 20 cases - was premature mobilization of the stapes followed by other consequences. In the other 9 cases the operation was discontinued for different reasons. Another failure was the floating footplate in 2 ears, facial nerve paresis in 1 ear and incus subluxation also in 1 ear. In a few cases in which the operation was stopped the successful stapedectomy was performed at the 2nd stage. Only in 3 ears the stapedectomy was totally given up what makes 0,5% out of the 572 ears operated on.