Cholesteatoma is a destructive and expanding growth consisting of keratinizing squamous epithelium in the middle ear and/or mastoid process. Cholesteatomas are not cancerous as the name may suggest, but can cause significant problems because of their erosive and expansile properties. This can result in the destruction of the bones of the middle ear (ossicles), as well as growth through the base of the skull into the brain. They often become infected and can result in chronically draining ears. Treatment almost always consists of surgical removal. Signs and symptoms
Other more common conditions (e.g. otitis externa) may also present with these symptoms, but cholesteatoma is much more serious and should not be overlooked. If a patient presents to a doctor with ear discharge and hearing loss, the doctor should consider cholesteatoma until the disease is definitely excluded. Other less common symptoms (all less than 15%) of cholesteatoma may include pain, balance disruption, tinnitus, earache, headaches and bleeding from the ear. There can also be facial nerve weakness. Balance symptoms in the presence of a cholesteatoma raise the possibility that the cholesteatoma is eroding the balance organs in the inner ear. Doctors initial inspections may only reveal an ear canal full of discharge. Until the doctor has cleaned the ear and inspected the entire tympanic membrane, cholesteatoma cannot be diagnosed. Once the debris is cleared, cholesteatoma can give rise to a number of appearances. If there is significant inflammation, the tympanic membrane may be partially obscured by an aural polyp.
If the reconstruction is poorly performed, it may result in a high rate of recurrent cholesteatoma. Preservation of the ear canal wall. If poorly performed, it may result in a high rate of both residual and recurrent cholesteatoma. Reconstruction of the chain of hearing bones using a passive middle ear implant.Clearly, preservation and restoration of ear function at the same time as total removal of cholesteatoma requires a high level of surgical expertise. Endoscopic surgery
Traditionally, ear surgery has been performed using the surgical microscope. The direct line of view dictated by that approach necessitates using the  mastoid as the access port to the middle ear. It has long been recognized that failure in cholesteatoma surgery occurs in some of the out of view spaces of the tympanic cavity like the sinus tympani and facial recess that are out of view using the traditional microscopic technique. More recently, the endoscope has been increasingly utilized in the surgical management of cholesteatoma in one of two ways:

Using the endoscope as an ancillary instrument to the microscope when trying to visualize areas that are hidden from the microscope such as the sinus tympani. This work was pioneered by Professor Thomassin. Using the endoscope as the main surgical instrument through the ear canal, or whats called:  Endoscopic Ear Surgery, pioneered by Professor Tarabichi.There are multiple advantages for the use of the endoscope in cholesteatoma surgery:

The endoscope wide angle of view and the ability to "see around the corner".