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Tuesday, July 22, 2008

Diseases of external ear (cont..)

In this post we will discuss about few miscellaneous conditions affecting external ear.

  • cerumen
  • keratosis obturans
  • external auditory canal cholesteatoma
  • atresia of meatus


Cerumen or impacted wax:

composed of-

  • sebaceous gland secretions
  • apocrine sweat gland secretions
  • desquamated epithelium & keratin
  • dirt

function:

  • protective as it lubricates the canal & due to its acidic nature

Motion of the ear canal provided by ordinary chewing movements together with the process of epithelial proliferation and lateral migration propel the cerumen outward in a self-cleansing manner.

complaints:

  • hearing loss or blocked sensation
  • tinnitus & giddiness due to impaction on tympanic membrane
  • Reflex cough:Arnold's cough reflex-due to irritation of auricular branch of vagus nerve.also known as Ear cough.

Diagnosis

  • Cerumen impaction is diagnosed by direct visualization with an otoscope.
  • seen as brown to blackish mass

wax

Treatment

Cerumen removal may be attempted by

  1. irrigation of the external auditory canal, with or without the use of ceruminolytics;
  2. by ceruminolytics alone;
  3. or by manual removal using a curette, forceps, or suction.

Keratosis obturans:

  • Keratosis obturans is characterized by a dense plug of keratin debris located primarily within the deep meatus.
  • with no associated erosion or necrosis of the surrounding bone.{THIS IS PRESENT IN external auditory canal cholesteatoma}
  • commonly seen b/w 5 & 20 years

etiology:

  • due to defect in epithelial migration
  • increased production of keratin debris
  • both

keratosis

Clinical features:generally BILATERAL & is PEARLY WHITE MASS.

  • Severe ear pain
  • Mild / moderate conductive hearing loss
  • Associated bronchitis / sinusitis - common{due to shared etiology of defective ciliary function resulting in defective migration}
  • Rarely otorrhea
  • Thickened tympanic membrane due to pressure of the keratin
  • Presence of granulations
  • Ballooning of the ear canal (bony reabsorption circumferentially widens the external bony canal)
  • On histological examination, the keratin plug displays a lamellar pattern(onion skin pattern) to the circumferential shedding of keratin squames from the auditory canal, with older layers being pushed centrally.

{note:

Keratosis obturans external auditory canal cholesteatoma
  • generally bilateral
  • unilateral
  • younger patients
  • older patients
  • origin is diffuse(along circumference of canal)
  • focal
  • generally otorrhea absent
  • present
  • also associated with bronchiectasis & chronic sinusitis
  • not associated
  • no osteonecrosis
  • presence of osteonecrosis & focal overlying epithelial loss present
  • managed successfully by regular aural-toilet
  • surgical intervention required

Treatment

  • Debridement of keratin debris (may require anesthesia)
  • Treatment of any underlying inflammation and/or infection
  • Periodical follow-up to remove reaccumulations

external auditory canal cholesteatoma:

we will deal with cholesteatoma in detail, in diseases of middle ear since more common in middle ear.

commonly involves post-inferior part of external auditory canal

etiology:

  • may be due to trapping of epithelium below level of skin during previous episode of otitis externa.
  • margins of it secrete enzymes & also due to pressure effects results in bone erosion
  • so often Facial nerve is exposed & paralysed.

iatrogenic external auditory canal cholesteatoma:

  • generally at anterior angle of tympanic membrane
  • etiology:due to incorrect repositioning of skin flaps at end of procedure

Acquired atresia & stenosis of meatus:

causes-

  1. infections:chronic otitis externa - important cause
  2. burns
  3. trauma

treatment:

meatoplasty {In a meatoplasty, an incision is made immediately behind the meatus, and a portion of the conchal cartilage is excised.}


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