The middle and lower 1.5cm of the vertical segment of the facial canal
was found dehiscent and covered with granulations (Fig ure 4).
Only in this group of CLA with otic capsule development, labyrinthine segment of the facial canal
is in its normal location.
When there are two canals the facial canal
is easier to locate and is generally straighter than the lingual canal which is often shielded by a lingual shelf.
Surgical trauma to a dehiscent facial canal
in the tympanic cavity may also lead to edema  and consequential paralysis of the facial nerve.
The bony facial canal
develops until birth, enclosing the facial nerve in bone throughout its course except at the facial hiatus (the site of the geniculate ganglion) in the floor of the middle cranial fossa [3,4].
erosion in 32.5% of patients and 6% of them was subject to posterior wall of the external ear erosion.
Preoperative CT establishes the type of surgical procedure as it determines the extent of the cholesteatoma, ocular chain involvement, facial canal
integrity, and tegmen tympani and dural plate involvement.
During middle ear surgeries, leakage of MESNA into the dehiscent facial canal
can increase the pressure on the nerve, and facial paralysis may occur following edema and inflammation.
In all cases, the facial canal
was identified intraoperatively.
The facial canal
was completely intact up to the stylomastoid foramen, and no injury to the facial nerve was detected along its course.
Politzer was the first person to describe facial canal
dehiscence (FCD) in 1894.