ENT Week 1 - Introduction/Basics/Otitis Externa

Anatomy of the outer ear (picture)

Anatomy of the middle/inner ear (picture)

Cochlea

Fluid-filled structure within the inner ear that contains hair cells that convert sound waves into electrical impulses that are carried along the auditory nerve to the brain.

Vestibular Apparatus

• vestibule + semicircular canals

• important in maintaining the sense of equilibrium

  • detects movement and the position of the head

Middle ear ossicular chain

• malleus —> incus —> stapes —> oval window displacement —> pressure wave in the fluid within the inner ear

Three regions of the ear overview

• External ear

  • Auricle and external acoustic meatus

• Middle ear

  • Tympanic cavity (with middle ear bones)

  • Epitympanic recess

  • Eustachian tube*

• Inner ear

  • vestibulocochlear organs

  • innervation by vestibulocochlear nerve (VIII)

Germ layer

One of the primary layers of cells formed during embryonic development

• Ectoderm

• Endoderm

• Mesenchyme

Inner ear embryology

• return

Uncomplicated Otitis Externa (UOE)

• Inflammation of the outer ear / external auditory canal caused by bacteria or fungus. Also known as “swimmer’s ear.”

• Symptoms include ear canal swelling, ear pain with tragus palpation or pulling on the ear superiorly / inferiorly, itching (more common with fungal etiology), otorrhea

• Acute Bacterial Otitis Externa is the most common OE seen by PCPs

• vinegar can prevent

Pathogens causing UOE

1. Pseudomonas aeruginosa (38%)

2. Staph species (9%)

3. Fungus infrequently, although infections are more common after bacterial treatment

Greatest risk factors for otitis externa

Water in the ear canal, and trauma

Treatment of UOE

• Aural toilet*** — irrigation to remove any wax, purulent material, dead skin

  • drying the canal after irrigation is beneficial

  • mainstay of treatment for both bacterial and fungal presentations

• Initiate treatment with topical therapy (antibiotic route)

  • Ciprodex (4 drops BID x 7 days)

  • Floxin (5 drops BID x 7 days)

  • Cortisporin Otic (4 drops QID x 7 days)

  • Sulfonamides do not treat Pseudomonas**

• (Fungal route)

  • Clotrimazole or miconazole swabs / powder

Malignant Otitis Media - Key Facts

• Caused by Pseudomonas aeruginosa

• Often seen in those immunocompromised (90% diabetics; includes cancer, HIV, etc.)

• Progressive condition = fatigue, nausea, changes in vision and mental status may occur. Ear pain and discharge unresponsive to normal interventions = warning sign

• Can progress to skull base osteomyelitis

Malignant Otitis Externa - Imaging

• begin with CT of temporal bone

• MRI for dura to assess nerve involvement

Malignant Otitis Externa - Treatment and Outcomes

• 4-6 weeks of IV fluoroquinolones

• MRI with contrast to evaluate progress

• Cure rate is greater than 80%