Dehiscences of the bony horizontal segment of the facial canal are rat
her common in human adults. These facial canal dehiscences occur most
offen in the region of the oval window, This study presents the observ
ations of the facial canal in the oval window region in 427 operations
for otosclerosis. The incidence of dehiscences in the facial canal to
the middle ear space in otosclerosis was studied, Dehiscences were ob
served in 14 of the 427 patients (3.27%) who had a stapedotomy, This i
ncidence is very low compared to the anatomical studies of the facial
nerve in human cadaver temporal bones. Dehiscences of the facial canal
are a variation of the normal anatomy of the facial nerve and these d
ehiscences occur sposadically in otosclerosis.