CASE REPORT DIFFUSE OTITIS EXTERNA Presentator Koas THT periode 20 January-15 February 2014 : Geetha Balasubramaniyam Johannes Octan Daniel Rizky Ajrina Meidiyana Zahrifa Riandani Putri Putri Riadhini Resy Moderator : dr Akmal Otorinolaryngology and Head Neck Surgery Departments Medical Faculty of Gadjah Mada University
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CASE REPORT
DIFFUSE OTITIS EXTERNA
Presentator Koas THT periode 20 January-15 February 2014 :
Geetha Balasubramaniyam
Johannes Octan Daniel
Rizky Ajrina Meidiyana
Zahrifa Riandani Putri
Putri Riadhini
Resy
Moderator : dr Akmal
Otorinolaryngology and Head Neck Surgery Departments
Medical Faculty of Gadjah Mada University
DR Sardjito Hospital Yogyakarta
2014
CHAPTER II
INTRODUCTION
Otitis externa is an infection of the external auditory canal. Otitis externa
occurs in 4 of every 1000 people annually, and the chronic form affect 3-5% of
the population. Prompt diagnosis and treatment cures the majority of cases
without complication. Otitis externa is defined as chronic when the duration of the
infection exceeds more than 1 month or when more than 4 episode occur in 1
year.
If left untreated, the infection may invade the deeper adjacent structures
and progress into malignant otitis externa. This complication is almost exclusively
seen in immunocompromised patients such as those with diabetes, AIDS patients,
those undergoing chemotherapy, and patients taking immunosuppressant
medications (eg. Organ transplantation) such as glucocorticoids. Pseudomonas
Aueroginosa is the inciting organism in the vast majority of cases. When
untreated, malignant otitis externa has a mortality rate approaching 50%. This
complication should be suspected if tenderness, otalgia, rythema, or edema of the
external ear or adjacent tissues is present on physical examination.
People in some racial groups have small ear canals, which may predispose
them to obstruction and infection. Rates of occurrence of otitis externa are equal
in males and females. Although otitis externa is seen in all age groups, the peak
incidence is in children aged 7-12 years.
ANATOMY
The external ear is composed of the auricle and external auditory canal.
Both contain elastic cartilage derived from mesoderm and a small amount of
subcutaneous tisssue, covered by skin with its adnexal appendages. There is fat
but not cartilage in the lobule.
1. Auricle
The Auricula or Pinna is of an avoid form, with its langer end directed upward. Its
lateral surface is irregularly concave, directed slightly forward, and presents
numerous eminences and depressions to which names have been assigned.The
prominent rim of the auricula is called the helix; where the helix turns downward
behind, a small tubercle, the auricular tubercle of Darwin, is frequently seen; this
tubercle is very evident about sixth month of fetal life when the whole auricula
has a close resemblance to that of some of the adult monkeys. Another curved
prominence, parallel with and in front of the helix, is called the antihelix; this
divides above into two crura, between which is a triangular depression, fossa
triangularis. The narrow-curved depression between the helix and the antihelix is
called the scapha; the antihelix describes a curve around a deep,capacious cavity,
the concha, which is partially divided into two parts by the crus or commencement
of the helix; the upper part is termed the cymba concha, the lower part the cavum
concha. In front of the concha, and projecting backward over the meatus, is a
small pointed eminence, the tragus,so called from its being generally covered in
its under surface with a turf of hair, resembling a goat’s beard. Opposite the
tragus, and separated from it by intertragic notch, is small tubercle, the antitragus.
Below this is the lobule, composed of tough areolar and adipose tissues, and
wanting the firmness and elasticity of the rest of the auricula.
2. External Auditory Canal
The External Acoustic Meatus (muatus acusticus externus; external
auditory canal or meatus) exterds from the bottom of the concha to the tympanic
membrane. It is about 4 cm in length if measured from the tragus ; from the
bottom of the concha its length is about 2,5 cm. It forms an S-shaped curve, and is
directed at first inward and backward (pars media), and lastly is carried, inward,
forward and slightly downward (pars interna). It is oval cylindrical canal, the
greatest diameter being directed downward and backward at the external orifice,
but nearly horizontally at the inner end. It present two constrictions, one near
theinner end of the cartilaginous portion, and another the isthmus, in the osseous
portion, about 2 cm from the botton of the concha. The tympanic membran, which
closes the inner end of the meatus, is obliquely directed; in consequence of this
the floor and anterior wall of the meatus are longer than the roof and posterior
wall.
The external acoustic meatus is formed partly by cartilage and membrane,
and partly by bone and lined by skin.
The Cartilaginous portion ( meatus acustiocus externus cartilageus)
The length is about 8mm in the length. It is continous with the cartilage of
the auricula, and firmly attached to the circuference of the auditory process of the
temporal bone. The cartilage is deficient at the upper and back part of the meatus,
its place being supplied by fibrous membran; two or three deep fissures are
present in the anterior part of the cartilage.
The skin of the cartilaginous canal contains many hair cells and sebaceous and
apocrine glands such as cerumen glands. Together, these three adnexal structures
provide a protective function and are termed the apopilosebaceous unit. Glandular
secretion combine with sloughed squamous epithelium to form an acidic coat of
cerumen, one of the primary barriers to infection of the canal.
The osseous portion (meatus acusticus externus osseus)
The length is about 16 mm and narrower than the cartilaginous portion. It
is directed in ward and a little forward, forming in its course a slight curve the
convexity of which is upward and backward. Its inner and smaller than the outer
and sloped the anterior wall projecting beyond the posterior for about 4 mm. It is
mark, except at its upper part, by a narrow groove, the tympanic sulcus in which
the circumference of the tympanic membrane is attached. Its outer end is dilated
and rough in the greater part of its circumference, for the attachment of the
cartilage of the auricula. The front and lower parts of the osseous portion are
formed by a curved plate of bone, the tympanic part of the temporal, which in the
fetus, exists as a separate ring (annulus tympanicus), incomplete at its upper part.
4. Vascularitation
The arteries of the auricula are the posterior auricular from the external
carotid, the anterior auricular from the superficial temporl, and a branch from the
occipital artery. The arteries supplying the meatus are branches from the posterior
auricular, internal maxillary, and temporal. The veins accompany the
corresponding arteries.
5. Innervation
The sensory nerve of the auricle are the great auricular, from the cervical
plexus the auricular branch of the vagus ; the auriculotemporal branch of the
mandibular nerve ; and the lesser occipital from the cervical plexus. The nerves of
meatus are chiefly derived from auriculotemporal branch of the mandibular nerve
and the auricular branch of the vagus.
6. Lympatic
Lympatic drainage of external ear consist of
Lnn Parotis superfisial
Receive drainage from tragus and anterior auricula
Lnn Retroauricular
Receive lymph drainage from posterior and cranial auricula
Lnn Cervical Superfisialis
Receive lymph drainge from lobulus
DIFFUSE OTITIS EXTERNA
1. Definition
Diffuse otitis externa is inflammation of the external ear canal, with or
without involment of the pinna or tympanic membrane. Diffuse otitis externa is
the most common form of otitis externa.
2. Etiology
The most common offending organisms that cause otitis externa are
Pseudomonas aeruginosa (50%), Stapylococcus aureus (23%), anaerobes and
gram-negative organisms (12,5%)
3. Risk Factor
The risk factor of diffuse otitis externa are swimming, swimming in water
where bacterial level are high, people with allergic condition, people who has
small ear canal because water can be trapped more easily, over cleaning the ear
canal, too much ear wax, making it more likely that water gets trapped.
Predisotition factors :
Moisture (swimming, perspiration, high warmth CAE
High ambient temperature
Contamination by water contaminated with bacteria
Habits take cerumen, cerumen impaction
The entry of foreign materials (cotton swab, fingernail, toys, insect, ear plugs)