Cholesteatoma

Skin Cyst in the Middle Ear

Cholesteatoma (Skin Cyst in the Middle Ear) and Endoscopic (Keyhole) Ear Surgery

Author of Article:

Associate Professor Nirmal Patel specialises in keyhole (Endoscopic Ear Surgery) management of cholesteatoma since 2012 when the first surgeries were performed in Australia.  He was the first Australian member of the International Working Group on Endoscopic Ear Surgery, the premier international group in demonstrating and promoting the method.  Nirmal is also a founding member of Australia’s first Research Collaboration (Sydney Endoscopic Ear Surgery Research Group) and teaches international fellows, local and international trainees.  In 2015 he performed over 150 endoscopic ear surgery operations.

In order to understand chronic ear infection, one must have some knowledge of the hearing mechanism.

Anatomy of the Outer Ear

The auricle and the external ear canal make up the outer ear. Here, the sound waves are collected and amplified, to be transmitted to the eardrum.

Anatomy of the Middle Ear

The section behind the eardrum and before the inner ear is the middle ear, home to the three hearing bones (the hammer, anvil and stirrup). Vibrations from the sound waves collected by the outer ear are collected, and transmitted to the fluid-filled space of the inner ear by the three bones. Lining the middle ear chamber is a membrane similar to your nasal lining. The membrane contains blood vessels and mucous glands, and is punctuated by the Eustachian tube, which connects the middle ear to the back of the nose.

The Eustachian tube is needed to equalise pressure in the middle ear when differentials occur. Opening your Eustachian tube during a plane flight or other altitude change results in a ‘popping’ sensation and reduction of pressure inside your ear.

Anatomy of the Inner Ear

The chamber behind a dense layer of bone is the inner ear. It is lined with a delicate membrane and filled with fluid, which transfers the vibration of the stirrup bone into fluid waves, which are transformed into electrical impulses by hair cells in the cochlea.

What is Cholesteatoma?

Cholesteatoma is a term used to describe a skin cyst (or growth) in the middle ear.  A patient can be born with skin in the middle ear, or they can get the condition usually after recurring ear infections.  The skin cyst, if left untreated, can grow and destroy local important structures such as the bones of hearing, inner ear, facial nerve (that makes you smile) and sometimes it can inflame the brain lining or the brain itself and cause serious illness.  The condition occurs in approximately 1 in 10,000 in adults and 1 in 30,000 in children.

Cholesteatoma occurs when the middle ear forms a negative pressure (often due to the shape of the eustachian tube and/or sinus problems).  The negative pressure collapses the ear drum into the middle ear.  The ear drum normally generates the skin that travels through the ear canal and contributes to wax formation.

How does Cholesteatoma present and how is it diagnosed?

Often a patient has a history of childhood ear infections. The chief complaint is usually recurring ear infections, a blocked ear or hearing loss.

A hole in the ear drum in the roof of the ear (the attic) or the margin of the ear (marginal perforation) is characteristic of the disease.

A CT Scan (computed tomography or Xray of the ear) confirm the disease by showing a destruction of middle ear structures. A hearing test sometimes shows a hearing loss, which is usually conductive in nature.

How is Cholesteatoma treated?

Cholesteatoma is usually treated surgically – the skin cyst growth should be removed to prevent serious complications such as recurrent ear infections, deafness, facial weakness, permanent dizziness and brain infection.

Surgery has been the recommended option for chronic ear disease for decades, since the use of the operating microscope became commonplace. It is necessary to eliminate the infected bone and skin cyst and therefore prevent serious complications.  Endoscopic (Keyhole) techniques are becoming more commonplace and can be used to treat even larger cholesteatoma.  Modern day cholesteatoma surgery is either performed as a day surgery or overnight stay in hospital.

Three broad techniques are used – Endoscopic (Key Hole), Canal Wall Up and Canal Wall Down Surgery.  One of these three techniques is used depending on the aggressiveness of the cholesteatoma.  Endoscopic is the least invasive (with no external cuts), Canal Wall Up preserves the bony ear canal (but involves a cut behind the ear) and Canal Wall Down removes the bony ear canal and most of the mastoid bone (in this technique there is a large cut behind  and in the ear canal; leaving the patient with a very large ear hole and a flattened ear).

Endoscopic (Keyhole) Ear Surgery

This is the newest technique and depends upon specialised equipment, high definition cameras and low heat light sources.  This is the technique of choice by Dr Nirmal Patel if the cholesteatoma is localised to the middle ear (including the roof of the middle ear ).  It has the advantage of requiring no cuts outside the ear canal and no hair shaving.  This newer option is usually a day surgery procedure.  The recovery is in general less painful and quicker than canal wall up or down techniques.  The patient usually returns to normal activities a lot quicker.

Canal Wall Up Techniques

The is often more technically difficult but may have the benefit of preserving near normal bony anatomy.  If the cholesteatoma extends into the mastoid bone then this technique can be used.  Canal Wall Up surgery allows the patent to ultimately (in a few months) treat the affected ear relatively normally (i.e. allow water exposure and swim normally).

The disadvantage is sometimes this technique requires two operations; the first to remove the disease and the second to reconstruct the hearing.  To prevent the formation of scar tissue and help normalise middle ear function, a thin plastic sheet is often inserted behind the eardrum. If the chronic ear disease has progressed to fill the ear with scar tissue, or if the ear bones have been completely destroyed, surgeons will perform the operation in two stages.

At first, the plastic sheet will be inserted to allow normal healing without scar tissue formation. In the next operation, the plastic sheet is removed and prosthetic ear bones will be placed to attempt to restore hearing. It won’t be known until the time of your first surgery whether it will be necessary to separate the two stages of the operation.

Canal Wall Down Techniques

These are used when the disease is severe and has already damaged the ear canal wall, inner ear, brain lining or facial nerve.  They are not the technique of choice in our clinic as the technique is more deforming causing a wider opening of the ear canal and more bone removal (which ultimately means the ear sits more recessed and flatter on the skull; the healing is also prolonged compared to canal wall up techniques.  Also in our hands, the Wall Down technique means a worse hearing outcome (compared to transcanal or canal wall up) with hearing bone reconstruction, as the middle ear space is usually shallower.  After canal wall down mastoidectomy it is necessary to have the cavity cleaned every 6 to 12 months, and some patients will need to permanently avoid getting water in their ear.

Prosthetic ear bones made of plastic can replace any diseased ear bones in the middle ear; alternatively cartilage may be used or the bone may be relocated. Tissue grafts made of a layer of muscle and a layer of cartilage are used to repair the perforation in the eardrum.

Click to read more information about this topic on the Sydney Endoscopic Ear Surgery Research Group website.

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Videos

How hearing works

Video by Associate Professor Nirmal Patel.