Facial Canal Dehiscence and Prolapse of the Facial Nerve – Case Reports

Summary

Two cases are presented. The first of them involved a histological study of facial canal dehiscence with a retraction pocket of the tympanic membrane of the right ear. Prolapse of the facial nerve from its facial canal was revealed; the facial nerve was in contact with the stapes and retraction pocket. Computer-assisted three-dimensional reconstruction was performed with histological sections of the temporal bone. The second case involved malformation of the stapes suprastructure and fixation of footplate, with subsequent prolapse of the facial nerve, which covered the footplate. Our approach to the surgery consisted of gently retrac­ting the prolapsed facial nerve, then making a monitoring hole in the visible portion of the footplate, following down the fracture and removing the stapes superstructure. A piston prosthesis was inserted. After surgery, the patient suffered from slight facial paresis at H-B II level. The functions of facial nerve and hearing were normal after six months. The surgeon should bear in mind that procedures performed in the middle ear have a high potential to traumatize or damage the facial nerve at the site of dehiscence. We conclude that stapes surgery in patients with significant facial nerve prolapse can be performed safely, with good hearing results, in the hands of an experienced surgeon.

Key words:
facial nerve – canal dehiscence – prolapse of facial nerve – computer-assisted three-dimensional reconstruction – facial pares