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Cholesteatoma is a destructive and expanding growth consisting of keratinizing squamous epithelium in the middle ear and/or
mastoid process The mastoid part of the temporal bone is the posterior (back) part of the temporal bone, one of the bones of the skull. Its rough surface gives attachment to various muscles (via tendons) and it has openings for blood vessels. From its borde ...
. 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 The ossicles (also called auditory ossicles) are three bones in either middle ear that are among the smallest bones in the human body. They serve to transmit sounds from the air to the fluid-filled labyrinth ( cochlea). The absence of the audit ...
), as well as growth through the
base of the skull The base of skull, also known as the cranial base or the cranial floor, is the most inferior area of the skull. It is composed of the endocranium and the lower parts of the calvaria. Structure Structures found at the base of the skull are for ...
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 Otitis externa, also called swimmer's ear, is inflammation of the ear canal. It often presents with ear pain, swelling of the ear canal, and occasionally decreased hearing. Typically there is pain with movement of the outer ear. A high fever is ...
) 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 Tinnitus is the perception of sound when no corresponding external sound is present. Nearly everyone experiences a faint "normal tinnitus" in a completely quiet room; but it is of concern only if it is bothersome, interferes with normal hearin ...
,
earache Ear pain, also known as earache or otalgia, is pain in the ear. Primary ear pain is pain that originates from the ear. Secondary ear pain is a type of referred pain, meaning that the source of the pain differs from the location where the pain is ...
, 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 The inner ear (internal ear, auris interna) is the innermost part of the vertebrate ear. In vertebrates, the inner ear is mainly responsible for sound detection and balance. In mammals, it consists of the bony labyrinth, a hollow cavity in the ...
. 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 there is less inflammation, the cholesteatoma may present the appearance of 'semolina' discharging from a defect in the tympanic membrane. The posterior and superior parts of the tympanic membrane are most commonly affected. If the cholesteatoma has been dry, the cholesteatoma may present the appearance of '
wax Waxes are a diverse class of organic compounds that are lipophilic, malleable solids near ambient temperatures. They include higher alkanes and lipids, typically with melting points above about 40 °C (104 °F), melting to give low ...
over the attic'. The attic is just above the eardrum. If untreated, a cholesteatoma can eat into the three small bones located in the middle ear (the ''
malleus The malleus, or hammer, is a hammer-shaped small bone or ossicle of the middle ear. It connects with the incus, and is attached to the inner surface of the eardrum. The word is Latin for 'hammer' or 'mallet'. It transmits the sound vibrations fr ...
'', '' incus'' and '' stapes'', collectively called
ossicles The ossicles (also called auditory ossicles) are three bones in either middle ear that are among the smallest bones in the human body. They serve to transmit sounds from the air to the fluid-filled labyrinth ( cochlea). The absence of the audit ...
), which can result in nerve deterioration,
deafness Deafness has varying definitions in cultural and medical contexts. In medical contexts, the meaning of deafness is hearing loss that precludes a person from understanding spoken language, an audiological condition. In this context it is written ...
, imbalance and
vertigo Vertigo is a condition where a person has the sensation of movement or of surrounding objects moving when they are not. Often it feels like a spinning or swaying movement. This may be associated with nausea, vomiting, sweating, or difficulties w ...
. It can also affect and erode, through the enzymes it produces, the thin bone structure that isolates the top of the ear from the brain, as well as lay the covering of the brain open to infection with serious complications (rarely even death due to
brain abscess Brain abscess (or cerebral abscess) is an abscess caused by inflammation and collection of infected material, coming from local (ear infection, dental abscess, infection of paranasal sinuses, infection of the mastoid air cells of the temporal bone ...
and
sepsis Sepsis, formerly known as septicemia (septicaemia in British English) or blood poisoning, is a life-threatening condition that arises when the body's response to infection causes injury to its own tissues and organs. This initial stage is follo ...
). Both the acquired as well as the congenital types of the disease can affect the facial nerve that extends from the brain to the face and passes through the inner and middle ear and leaves at the anterior tip of the mastoid bone, and then rises to the front of the ear and extends into the upper and lower face.


Cause

Cholesteatomas occur in two basic classifications: Acquired cholesteatomas, which are more common, are usually caused by pathological alteration of the ear drum leading to accumulation of keratin within the
middle ear The middle ear is the portion of the ear medial to the eardrum, and distal to the oval window of the cochlea (of the inner ear). The mammalian middle ear contains three ossicles, which transfer the vibrations of the eardrum into waves in the ...
. Congenital cholesteatomas are usually middle ear epidermal cysts that are identified deep within an intact ear drum.


Congenital cholesteatoma

Keratin-filled cysts that grow medial to the tympanic membrane are considered to be congenital if they fulfill the following criteria (Levenson's criteria): * mass medial to the tympanic membrane * normal tympanic membrane * no previous history of ear discharge, perforation or ear surgery Congenital cholesteatomas occur at three important sites: the middle ear, the petrous apex, and the cerebropontinio angle. They are most often found deep to the anterior aspect of the ear drum, and a vestigial structure, the epidermoid formation, from which congenital cholesteatoma may originate, has been identified in this area. Not all middle ear epidermal cysts are congenital, as they can be acquired either by metaplasia of the middle ear mucosa or by traumatic implantation of ear canal or tympanic membrane skin. In addition, cholesteatoma inadvertently left by a surgeon usually regrows as an epidermal cyst. Some authors have also suggested hereditary factors.


Acquired cholesteatoma

More commonly, keratin accumulates in a pouch of tympanic membrane which extends into the middle ear space. This abnormal folding or 'retraction' of the tympanic membrane arises in one of the following ways: * Jackler’s theory: Mucosal coupling with traction generated by interaction of migrating opposing surfaces leading to formation of cholesteatoma. * Wittmaack's theory: Invagination of tympanic membrane from the attic or part of pars tensa in the form of retraction pockets lead to the formation of cholesteatoma. * Ruedi's theory: The basal cells of germinal layer of skin proliferate under the influence of infection and lay down keratinising squamous epithelium. * Habermann's theory: The epithelium from the meatus or outer drum surface grows into the middle ear through a pre-existing perforation and form cholesteatoma. Cholesteatoma may also arise as a result of
metaplasia Metaplasia ( gr, "change in form") is the transformation of one differentiated cell type to another differentiated cell type. The change from one type of cell to another may be part of a normal maturation process, or caused by some sort of abno ...
of the middle ear mucosa or implantation following trauma.


Diagnosis

Cholesteatoma is diagnosed by a medical doctor by physical examination of the ear. A CT scan may help to rule out other, often more serious causes for the patient's clinical presentation. Non-ionizing radiation imaging techniques (
MRI Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to form pictures of the anatomy and the physiological processes of the body. MRI scanners use strong magnetic fields, magnetic field gradients, and radio waves ...
) may be suitable to replace a CT scan, if determined necessary by a physician.


Treatment

Cholesteatoma is a persistent disease. Once the diagnosis of cholesteatoma is made in a patient who can tolerate a general anesthetic, the standard treatment is to surgically remove the growth. The challenge of cholesteatoma surgery is to permanently remove the cholesteatoma whilst retaining or reconstructing the normal functions of the structures housed within the
temporal bone The temporal bones are situated at the sides and base of the skull, and lateral to the temporal lobes of the cerebral cortex. The temporal bones are overlaid by the sides of the head known as the temples, and house the structures of the ears. T ...
. The general objective of cholesteatoma surgery has two parts. It is both directed against the underlying pathology and directed towards maintaining the normal functions of the temporal bone. These aims are conflicting and this makes cholesteatoma surgery extremely challenging. Sometimes, the situation results in a clash of surgical aims. The need to fully remove a progressive disease like cholesteatoma is the surgeon's first priority. Preservation of hearing is secondary to this primary aim. If the disease can be removed easily so that there is no increased risk of residual disease, then the ossicles may be preserved. If the disease is difficult to remove, so that there is an increased risk of residual disease, then removal of involved ossicles in order to fully clear cholesteatoma has generally been regarded as necessary and reasonable. In other words, the aims of cholesteatoma treatment form a hierarchy. The paramount objective is the complete removal of cholesteatoma. The remaining objectives, such as hearing preservation, are subordinate to the need for complete removal of cholesteatoma. This hierarchy of aims has led to the development of a wide range of strategies for the treatment of cholesteatoma.


Surgery

The variation in technique in cholesteatoma surgery results from each surgeon's judgment whether to retain or remove certain structures housed within the temporal bone in order to facilitate the removal of cholesteatoma. This typically involves some form of
mastoidectomy A mastoidectomy is a procedure performed to remove the mastoid air cells, air bubbles in the skull, near the inner ears. This can be done as part of treatment for mastoiditis, chronic suppurative otitis media or cholesteatoma. In addition, it is ...
which may or may not involve removing the posterior ear canal wall and the ossicles. Removal of the canal wall facilitates the complete clearance of cholesteatoma from the temporal bone in three ways: # It removes a large surface onto which cholesteatoma may be adherent; # It removes a barrier behind which the cholesteatoma may be hidden; # It removes an impediment to the introduction of instruments used for the removal of cholesteatoma. Thus removal of the canal wall provides one of the most effective strategies for achieving the primary aim of cholesteatoma surgery, the complete removal of cholesteatoma. However, there is a trade-off, since the functional impact of canal wall removal is also important. The removal of the ear canal wall results in: * a space, the "mastoid cavity", which is less likely than the original ear canal to resist infection; * exposure of the ossicles, which may allow the subsequent formation of a new cholesteatoma deep to the ossicles. To prevent this, these ossicles must be removed, which may diminish the patient's hearing. The formation of a mastoid cavity by removal of the canal wall is the simplest and most effective procedure for facilitating the removal of cholesteatoma, but may bestow the most lasting infirmity due to loss of ear function upon the patient treated in this way. The following strategies are employed to mitigate the effects of canal wall removal: # Careful design and construction of the mastoid cavity. This is essential for the health and integrity of the protective sheet of migrating, keratising epithelium which lines the distorted ear canal. This requires the surgeon to saucerise the cavity. A high facial ridge and an inappropriately small cartilaginous meatus are obstructions to epithelial migration and are particularly high risk factors for failure of the self-cleaning mechanism of the external ear. # Partial obliteration of the mastoid cavity. This can be performed using a wide range of materials. Many of these resorb in time, which means that the long-term results of such surgery are poorer than the short-term results. # Reconstruction of the ear canal wall. Canal wall reconstruction has been performed using ear canal skin alone, fascia, cartilage, titanium as well as by replacing the original intact wall. 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 A middle ear implant is a hearing device that is surgically implanted into the middle ear. They help people with conductive, sensorineural or mixed hearing loss to hear.   Middle ear implants work by improving the conduction of sound vibrations fr ...
. 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 An endoscopy is a procedure used in medicine to look inside the body. The endoscopy procedure uses an endoscope to examine the interior of a hollow organ or cavity of the body. Unlike many other medical imaging techniques, endoscopes are inse ...

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 what's 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". # The endoscope allows minimally invasive access through the natural ear canal, rather than through the usual 5 cm incision behind the ear utilized in traditional microscopic surgery. # The 30 degrees endoscope allows access to the bony area of the Eustachian tube to address any obstructive pathologies.


Prognosis

It is important that the patient attend periodic follow-up checks, because even after careful microscopic surgical removal, cholesteatomas may recur. Such recurrence may arise many years, or even decades, after treatment. A 'residual cholesteatoma' may develop if the initial surgery failed to completely remove the original; residual cholesteatomas typically become evident within the first few years after the initial surgery. A 'recurrent cholesteatoma' is a new cholesteatoma that develops when the underlying causes of the initial cholesteatoma are still present. Such causes can include, for example, poor
Eustachian tube In anatomy, the Eustachian tube, also known as the auditory tube or pharyngotympanic tube, is a tube that links the nasopharynx to the middle ear, of which it is also a part. In adult humans, the Eustachian tube is approximately long and in d ...
function, which results in retraction of the ear drum, and failure of the normal outward migration of skin. In a retrospective study of 345 patients with middle ear cholesteatoma operated on by the same surgeon, the overall 5-year recurrence rate was 11.8%. In a different study with a mean follow-up period of 7.3 years, the recurrence rate was 12.3%, with the recurrence rate being higher in children than in adults. The use of the endoscope as an ancillary instrument has been shown to reduce the incidence of residual cholesteatoma. Although more studies are needed, so far, new techniques addressing underlying Eustachian tube dysfunction such as transtympanic dilatation of the Eustachian tube has not been shown to change outcomes of chronic ear surgery.


Infections

Recent findings indicate that the keratinizing squamous epithelium of the middle ear could be subjected to human papillomavirus infection. Indeed, DNA belonging to oncogenic HPV16 has been detected in cholesteatoma tissues, thereby underlining that keratinizing squamous epithelia could potentially be a target tissue for HPV infection.


Epidemiology

In one study, the number of new cases of cholesteatoma in Iowa was estimated in 1975–76 to be just under one new case per 10,000 citizens per year. Cholesteatoma affects all age groups, from infants through to the elderly. The peak incidence occurs in the second decade.


See also

* Chronic suppurative otitis media *
Otic polyp An otic polyp is a benign proliferation of chronic inflammatory cells associated with granulation tissue, in response to a longstanding inflammatory process of the middle ear. Signs and symptoms Patients usually present with otorrhea, conducti ...
* Endoscopic ear surgery


References


External links


Information on Cholesteatomas

Laser Cholesteatoma Surgery
{{Authority control Diseases of middle ear and mastoid Audiology