Special Sense Infections Quiz

Special Sense Infections

• The presentation is about special sense infections, specifically focusing on otitis, keratitis, conjunctivitis, blepharitis, chalazion, and stye.
• Learning objectives (LOS) include understanding different types of otitis, identifying types of otitis media, clarifying pathological aspects of keratitis and conjunctivitis, and differentiating between blepharitis, chalazion, and stye.

Otitis

• Types of otitis:

  • Otitis media
  • Otitis externa
  • Otitis interna

• Detailed anatomical structure of the human ear, including the malleus, incus, stapes, external auditory meatus (ear canal), tympanic membrane (eardrum), Eustachian tube, and cochlea, is shown in diagram.

Otitis Media

• Definition: Inflammation of the middle ear (earache).
• Commonest type of otitis.
• Causes:
  • Streptococcus pneumoniae (30-35%)
  • Haemophilus influenzae
  • Moraxella catarrhalis
  • Other bacteria (e.g., group A strep) and viruses.

Routes of Infection of Otitis Media

• Eustachian tube: The most common route of transmission, with infection spreading from the nose and throat through the tube to the middle ear.
• External ear: Infection can reach the middle ear through traumatic perforations of the tympanic membrane (eardrum), creating an opening for outside pathogens to enter.
• Direct spread from mastoiditis
• Blood-borne: Less common infection route.

Risk Factors of Otitis Media

• Age:
  • First peak between 6-24 months of age
  • Second peak between 4-5 years old
  • Eustachian tube in infants and young children is shorter, wider and more horizontal.
• Sex: More common in males.
• Anatomical abnormalities: Cleft palate, cleft lip, narrow Eustachian tubes.
• Breastfeeding: Breastfeeding for at least six months may protect against otitis media. Breast and bottle feeding in supine position may increase the risk of otitis media.
• Seasons: Upper respiratory tract infections (URTIs) are more common in autumn and winter, potentially leading to acute otitis media.
• Overcrowded homes/large number of siblings: Close contact with others increases the risk of infection.
• Passive exposure to smoking
• Air pollutants

Types of Otitis Media

• Acute otitis media (AOM): Acute inflammation and effusion (fluid accumulation) of the middle ear, commonly seen in younger children
• Otitis media with effusion (OME): Middle ear effusion (fluid) without acute infection symptoms.
• Chronic suppurative otitis media (CSOM): Chronic inflammation of the middle ear and mastoid cavity, often with recurrent otorrhea (ear discharge) through a perforated tympanic membrane.

Acute Otitis Media

• Mostly caused by bacteria, rarely viruses.
• Severe earache with fever.
• Erythema (redness), bulging tympanic membrane, loss of light reflex.

Otitis Media with Effusion (OME)

• Definition: Fluid in the middle ear with no signs of acute infection.
• Pathogenesis: Fluid buildup in the middle ear and Eustachian tubes puts pressure on the tympanic membrane, impairing proper vibration for sound conduction resulting in decreased hearing.
• Over weeks or months, the fluid thickens, becoming like glue.

Chronic Suppurative Otitis Media (CSOM)

• Definition: Chronic inflammation of the middle ear and mastoid cavity, usually associated with recurrent ear discharge (otorrhoea) through a perforated eardrum.
• Causes: Spontaneous perforation caused by acute otitis media (AOM) or other less severe forms of otitis media.
• Clinical features: Continuous discharge of mucus for 6 weeks to 3 months despite medical treatment. Increased incidence of hearing impairment.

Otitis Externa

• Definition: Infection of the cutaneous and subcutaneous tissues of the external ear canal (EAC), sometimes involving the pinna.
• Four types:
  • Acute diffuse otitis externa
  • Acute localized otitis externa (furunculosis)
  • Chronic otitis externa
  • Malignant (necrotizing) otitis externa

Otitis Interna

• Definition: Inflammation of the inner ear (more commonly known as labyrinthitis). Affects hearing balance.
• Stages:
  • Serous
  • Purulent
  • Fibrous
  • Osseous

Keratitis and Conjunctivitis

• The anatomy of the eye, including the cornea, anterior chamber, pupil, posterior chamber, ciliary body, ciliary muscle, conjunctiva, lens, sclera, retina, choroid, blood vessels, and optic nerve are detailed in a diagram.

Keratitis

• Definition: Inflammation of the cornea.

• Types:

  • Infectious keratitis (bacterial, viral, parasitic, fungal)
  • Non-infectious keratitis (injury, exposure to UV light, dry eye syndrome, eyelid disorders).

• Symptoms: Eye pain, redness, excessive tear production/discharge, difficulty opening eyelids, decreased vision, sensitivity to light (photophobia).

Conjunctivitis (Pink Eye)

• Definition: Inflammation or infection of the transparent membrane lining the eyelids and eyeballs
• Causes:
  • Viral (e.g., adenovirus, herpes simplex, herpes zoster)
  • Bacterial
  • Allergic
• Symptoms: Redness, discharge (crusting at night, gritty feeling, itching, tearing, photophobia)

Blepharitis

• Definition: Eyelid inflammation.
• Causes: Acne rosacea, allergies, dandruff, dry eyes, lice, mites, meibomian gland dysfunction (oil gland).

Stye & Chalazion

• Stye (hordeolum): Painful infected lesion on the eyelid edge (eyelash follicle); usually drains independently.
• Chalazion: Less painful, small swelling on the inside of the eyelid (conjunctival side) caused by oil gland blockage.

Recommended References

• Robbins & Cotran Pathologic Basis of Disease, 10th edition (2018)
• Pathmax website
• Webpath website, University of Utah

Test your knowledge on special sense infections including otitis, keratitis, conjunctivitis, blepharitis, chalazion, and stye. This quiz will cover definitions, anatomical structures, and different types of infections, as well as their causes and pathological aspects.