What is a cholesteatoma?
Fret not! A cholesteatoma has nothing to do with your cholesterol levels. It is a condition associated with the ear. As you may already know that the human ear is divided into three parts, 1. The outer ear, 2. The middle ear, 3. The inner ear. The outer ear is the pinna and the ear canal. Separating the ear canal from the middle ear is the tympanic membrane or the ear drum. The ear canal and the side of the ear drum facing the ear canal is lined by the skin. As anywhere else on our body, the ear canal skin also sheds squames. This shed skin is cleared out of the ear canal by a self-cleaning mechanism whereby the shed skin slowly migrates out of the ear canal and drops off outside. This mechanism also prevents excessive accumulation of wax with in the ear canal. The middle ear and the side of the ear drum facing the middle ear on the other hand is lined by mucus membrane similar to the back part of the nose. The middle ear connects to the back part of the nose also (nasopharynx) through a tube called the Eustachian tube. The main function of this tube is to keep the pressure of the middle ear the same as the external atmosphere. To be able to efficiently conduct sound from the ear canal to the inner ear it is required that these pressures be the same. The Eustachian tube also provides drainage to the middle ear. In patients with poor Eustachian tube function there is a persistent negative pressure in the middle ear causing the ear drum to gets sucked into the middle ear which now behaves like a vacum. This “sucking in” effect or retration is more likely to occur at a weak area of the ear drum. That weak area is called the “pars flaccida”. The pars flaccida is a very small area on the upper part of the ear drum. This retracted part of the ear drum form a small pouch. The shed skin within this pouch is not able to be cleared and keeps on collecting within forming a sac or a cyst which has now formed a “cholesteatoma”. Over time this cholesteatoma continues to grow. Initially it grows along the paths of least resistance invading the nicks and corners of the middle ear. The condition does not happen overnight. It may take years to develop. The patient initially has no or minimal symptoms. Attention is drawn to the ear, when the cholesteatoma gets infected and the the ear starts to hurt and discharge. Though not a tumour, the cholesteatoma behaves like one. It grows slowly destroying the structures around it.The cholesteatoma secretes several enzymes that destroy the bone around it. Destruction of the ossicles, the small bones in the middle ear results in hearing loss. It may erode into the inner ear destroying cochlea and the vestibular system and may extend as deep as the petrous apex. Destruction of the thin plate of bone that separates the middle ear from the brain predisposes the brain to serious complications such as meningitis and brain abscess. It may also break through the bone behind the ear and present as a skin abscess.Facial nerve, which supplies the muscles of the face may be destroyed resulting in paralysis of that side of the face.
What are the symptoms of a cholesteatoma?
In the early stages symptoms are minimal and often ignored. Patients usually present when the cholesteatoma gets infected. Typically the symptoms are, ear pain and ear discharge which is often scanty and foul smelling. The discharge may be blood stained. Patients may present with a complication such as mastoiditis, abscess, facial palsy and meningitis.
How is a cholesteatoma treated?
The treatment will depend on the presentation and the extent of the cholesteatoma. The ENT surgeon will take a detailed history and do a microscopic or endoscopic examination of the ear. Other investigations may include a hearing test and imaging studies such as CT scan of the temporal bone. Very small cholesteatomas that are still contained within a small sac which can easily be cleaned in the clinic may require nothing more than that. Larger cholesteatomas that have eroded the bone and the ossicles will need surgery to contain its spread. The objective is to remove all the cholesteatoma including the ossicles that have been involved and convert the ear into a wide cavity that can be cleaned in the clinic. Sometimes hearing may have to be sacrificed to achieve this goal. Though there are several modifications of the surgery, the common surgical procedures done for a cholesteatoma include atticomy, modified mastoidectomy, radical mastoidectomy and tympanomastoidectomy.