As acquired or congential cholesteatomas increase in size, they can also affect the nerve that moves the face, the facial nerve. This nerve extends from the brain to the face by going through the inner ear, the middle ear, exiting near the forward tip of the mastoid bone, rising up to the front of the ear, and finally branching into the upper and lower face. Infected cholesteatomas may erode the bone covering this nerve. Pressure or irritation by the cholesteatoma on the facial nerve may then result in facial weakness or actual paralysis of the face on the side of the involved ear. In this case, ear surgery may be necessary on an emergency basis to prevent permanent facial paralysis.