otitis extena

LectureNo 3 26/10/2016
Otitis externa
Is a generalized condition of the skin of EUC is characterized by general oedema and erythema associated with ichy discomfort and usually an ear discharge Acute otitis externa affects approximately 4 of every 1000 children and
adults per year Approximately 80% of cases occur in the summer
Predisposing factors
? Anatomical
like Narrow EUM (heridatory,iatrogenic,exostosis,etc.)
Obstruction of the normal meatus(keratosis obturance, FB,hearing aid,hirsute canal,etc.)
? Dermatological like eczema,sebhorrhic dermatitis
? Allergic like exposure to topical medication
? Physiological like humid environment or immunocompromization
? Traumatic skin maceration (bathing), ear probing,laceration,radiotherapy
? Microbiological like in active CSOM,exposure
Pathology
The clinical course of OE has been divided to following stages
1 preinfalmmatory
The protective lipid/acid balance (normal pH 4-5) is lost and stratum corneum become oedematus ,blocking off the sebaceous and apocrine glands producing aural fullness ,itching.With increase oedema and scratching there is disruption of epithelial layer and invation of resident or introduced organisms
and will result in stage 2
2 Acute inflammatory stage (Mild,Moderate or Severe)
More oedema,obliteration of the lumen Mild,Moderate or Severe with thickening exudates. In severe cases increasing pain ,auricular changes and cervical lymphadeopathy,after six months or some consider chronicity after inflammation lasting longer than three weeks as entering the chronic phase,there is some evidence that individuals whose skin has a tendency to remain at low pH are more prone to develop a chronic problem
3 Chronic stage
Is characterized by thickening of external canal skin and fibrous canal stenosis .
Microbiology
Pseudomonas aeruginosa was the most common bacteria responsible for infections.
Staphylococcus sp were the next most common pathogens.
Fungi were responsible for only 2% of cases, but may be more prominent in casesof persistent or chronic infection
Investigations
Investigations are rarely required for cases of otitis externa. Cultures for
bacteria and fungus are indicated in cases of persistent or refractory
infection, particularly to identify fungal infection
Clinical Manifestations
Pain is a common symptom associated with bacterial infection. The
pain may be severe and is exacerbated by manipulation of the
auricle or the tragus. Itching may be experienced in early bacterial
infections, and in fungal infections and in all forms of chronic otitis
externa. Aural fullness and decreased hearing may be experienced
in any case of otitis externa resulting in accumulation of debris in
the ear canal. Otorrhea is more common in bacterial infections.
Examination of the canal may reveal the following findings:
1. An erythematous canal with scant discharge in cases of early
bacterial otitis externa
2. An edematous canal filled with purulent-squamous debris in
cases of well-established bacterial otitis externa
3. An accumulation of white debris sprouting hyphae best seen with
the otologic microscope, typical of candidal otitis externa
4. An accumulation of a moist white plug dotted with black debris
(“wet newspaper”) typical of Aspergillus niger
5. A maculopapular eruption on the conchal bowl and in the ear
canal consistent with an allergic reaction to a topical agent (e.g.,
neomycin)
6. A thickened, erythematous canal associated with an allergic or
contact dermatitis
7. Granulation tissue in the canal and on the tympanic membrane
caused by chronic infection
Treatment
Careful débridement of the ear canal in any case of otitis externa is
crucial to facilitate clearance of the infectious organism and to
allow topical medications to reach the target tissue.
If the ear canal is so edematous that topical medication would not
reach its medial extent, an ear wick may be inserted.




Classically, the physician made these fromstrands of cotton.
Currently available Merocel wicks (Medtronic, Inc.), offer better absorption of the drug, however, and
expand when wet to decrease canal edema substantially
Antibiotic drops remain the mainstay of treatment for otitisexterna.

For many years mainstay of treatment was a combination solution of polymyxin, neomycin, and hydrocortisone (PNH)
Quinolone antibiotics are available in otic and ophthalmic solutions.
Ciprofloxacin is available as an otic preparation combined with hydrocortisone and as a newer
Fungal otitis externa can be treated with meticulous débridement
of the ear Clotrimazole
1% solution (Lotrimin) is available over the counter and provides
broad-spectrum antifungal activity
ketoconazole ointment are effective as well.
Complications
If untreated,mild attachs of otitis externa can spontaneously resolve as the epithelial barrier becomes re-established ,the piloapocrine unit produce normal secreations and the pH of the canal returns to normal.
If the inflammation progress faster than repair pain will increase ,otorrhea,and oedema of the canal occur,lymphadenopathy due to rich lymphatic drainage.
This can lead to perichondritis,chondritis,cellulits,parotitis and\or erysipelas,in immunocompromised patient malignant otitis externa can develop
Malignant otitis externa
Is an aggressive and potentially life threatening infection of the soft tissue of the external ear and surrounding structures. quickly spreading to involve the periostium and bone of the skull base.it is not a neoplastic process so it is a misnomer.
Sometime called necrotizing OE, or skull base osteomyelitis.
Staging
Stage 1 malignant OE with infection of soft tissue beyond the EUM,but negative bone scan
Stage 2 soft tissue infection with positive bone scan
Stage 3 as above with cranial nerve paralysis
Stage 4 meningitis,empyema,sinus thrombosis or brain abscess
Lecture 4 Acute Otitis Media