Definition: C.S.O.M is a chronic inflammation of mucosal lining of middle ear cleft, characterized by irreversible pathological changes, intermittent or persistent discharge, with permanent abnormality of the pars tensa or flaccida.
Types of C.S.O.M:
1. Tubo – tympanic disease:
- It is also called "mucosal”, because it starts in the middle ear & Eustachian tube mucous membrane.
- It is called “safe CSOM”, because it is much less liable to cause complications, as the infection is mucosal.
2. Attico-antral disease:
- It is called “attico – antral disease”, because it starts in the attic (epitympanum) & mastoid antrum.
- It is called “unsafe CSOM”, because it is much more liable to cause complications, as it causes bone erosion.
- Cholesteatoma is usually present.
Tubotympanic (mucosal) CSOM
Causes:
It occurs usually secondary to A.S.O.M due to:
- Inadequate treatment: inadequate antibiotic therapy, or inadequate drainage of discharge (small or high perforation).
- Repeated middle ear infection through the Eustachian tube or through a persistent T.M. perforation.
- High virulence of the organism.
- Low resistance of the patient.
- Persistent predisposing factor e.g. E.T. dysfunction.
Symptoms of Tubotympanic (mucosal) CSOM:
- Persistent or intermittent aural discharge, profuse, mucoid or mucopurulent.
- Deafness (usually mild).
- Tinnitus.
Signs:
- Aural discharge: it is mucopurulent or mucoid, usually odourless, and profuse in amount.
- T.M. perforation: the perforation is usually central in the pars tensa. It may attain any size or shape.
- Middle ear mucosa: if visible through the perforation may look:
a. Oedematous, congested and velvety pink during active infection.
b. Thin pale during the inactive phase.
Investigations:
- Audiogram (PTA): conductive hearing loss.
- Plain X-ray of mastoid: usually well pneumatised.
- Culture and sensitivity of the discharge.
Treatment of Tubotympanic (mucosal) CSOM
A. Conservative treatment:
The aim of conservative treatment is to obtain a safe dry ear, to allow spontaneous healing of the perforation, or before surgery.
1. systemic antibiotics:
- Best according to culture and sensitivity, avoid ototoxic drugs.
- They may not be effective as fibrosis doesn’t allow antibiotics to reach tissues in a proper concentration.
2- Topical application of antibiotic ear drops, but avoid ototoxic ones.
3- Aural toilet: repeated local cleaning and removal of discharge by suction or mopping.
4- Avoidance of reinfection:
- Avoid forcible blowing of the nose during rhinitis.
- Avoid wetting the ear.
- Control upper respiratory tract infection e.g :sinusitis.
- Adenotonsillectomy, in children to avoid reinfection.
B. Surgical treatment:
Tympanoplasty , with or without cortical mastoidectomy, with the aim of:
- Eradication of irreversible changes in the middle ear mucosa and to clear it from infection.
- Reconstruction of the conductive hearing mechanism (ossicular reconstruction).
- Cortical mastoidectomy is combined with tympanic membrane grafting, if there is persistent aural discharge (mastoid reservoir) to eradicate the mastoid pathology.
- The grafting material commonly used to repair the defect in the T.M. is temporalis fascia, or tragal perichondrium.
Squamous (atticoantral) C.S.O.M
The presence of a squamous epithelium within the middle ear (i.e. skin in an abnormal site). Cholesteatoma is a misnomer because it is neither a tumor, nor it necessarily contains cholesterol crystals.
Aetiology:
A- Congenital cholesteatoma.
-Develops from persistent embryonic squamous epithelial cells,may be at different sites related to petrous bone.
-It is sterile so long as it is not connected with the external canal (i.e. an intact T.M.)
Presents usually in adult life, with deafness or facial palsy.
B- Acquired cholesteatoma
1-Primary acquired cholesteatoma (no previous history of O.M)
Retraction pocket theory (Attic retraction): most accepted. Prolonged intratympanic negative pressure causes invagination of part of T.M. into the middle ear with formation of retraction pocket which becomes filled with keratin.
2-Secondary acquired cholesteatoma (previous history of O.M.)
a- Migration therapy: direct migration of stratified squamous epithelium from surface of T.M. into the middle ear through a marginal perforation.
b- Metaplasia theory: due to chronic irritation of the middle ear mucosa by chronic infection.
Pathology:
A cholesteatoma is a sac lined by keratinizing stratified squamous epithelium (matrix) and is filled with concentric sheets of white-yellow keratin flakes, in which the cholesterol crystals may be embedded. It has an onion like appearance on cut section.
Bone erosion is due to:
1- Osteolytic enzymes and collagenases
2- Secondary bacterial infection, so, the cholesteatoma becomes activated to secrete deminiralizing and osteolytic enzymes.
3- Increase osteoclastic activity.
4- Pressure necrosis by the cholesteatoma sac (doubtful).
Signs of Squamous (atticoantral) C.S.O.M
1- Aural discharge: occurs due to secondary infection of the cholesteatoma. It is purulent (never mucoid or mucopurulent), and may be bloody due to formed granulations and polypi.
It is scanty and has a foul odour (characteristic) which is due to bone necrosis (osteitis) and anaerobic infection.
It may contain cheesy white epithelial flakes (debris).
2- Tympanic membrane perforation: it is a marginal perforation (destruction of the bony annulus), in the posterosuperior quadrant of pars tensa or attic perforation.
3- A retraction pocket may be seen posterosuperiorly without perforation in the T.M (inactive).
4- Cholesteatoma itself may be seen as pearly white sheets or cheesy white masses of keratin (active).
5- Granulations are frequent and appear as sessile, fleshy red projections that bleed easily on touch, or polyp
6- Signs of complications when they arise.
7- Tuning fork tests:
- Variable degrees of conductive hearing loss, but may be mixed.
- Sometimes, there is normal or mild conductive hearing loss, and this occurs with early retraction pocket or when the cholesteatoma itself “bridges” the gap in the ossicular chain.
Investigation:
- Audiogram (PTA): Variable degrees of conductive or mixed hearing loss.
- Plain X-ray mastoid: The cholesteatoma appears as an irregular area surrounded by sclerosed bone, bone erosion.
- CT scan of petrous bone: to detect the cholesteatoma mass, bone erosion and condition of the ossicular chain. It should always be done if complication is suspected, in children, and in revision cases.
- Culture and sensitivity of discharge.
Treatment of Squamous (atticoantral) C.S.O.M (surgical)
- The main line of treatment is surgery, aiming at safe & dry ear.
- Two techniques are used to eradicate the cholesteatoma:
A. Open (canal wall down) technique
This entails removal of all or a part of the posterosuperior bony meatal wall and includes:
1-Radical mastoidectomy; this is the most common procedure performed, where all mastoid cell are exenterated, ossicles are removed except footplate of stapes, with the posterior and superior meatal wall; aiming at dry and safe ear regardless of hearing.
2-Modified radical mastoidectomy: in limited cholesteatoma with good hearing.
NB: Atticotomy; in limited attic cholesteatoma.
B. Closed (Canal wall up) technique
- An opening is done in the posterior meatal wall (posterior tympanotomy), in a site called facial recess, via which small cholesteatoma could be removed.
- A second look operation is mandatory after 6 months for detection of residual or recurrent cholesteatoma.
Reconstruction of the radial cavity:
may be needed including reconstruction of hearing after being sure of complete eradication of the cholesteatoma for a year or later on.
Uses of endoscopy in cholesteatoma (recently introduced)
- It is used to detect residual or recurrence after performing the closed technique.
- It may also be used to clean difficult sites as the sinus tympani