Diagnosis of acute diffuse otitis externa

Acute diffuse otitis externa (swimmer’s ear) is inflammation of the external ear canal that often follows water exposure and maceration of the skin. It can usually be diagnosed with clinical history and examination.

Presenting signs and symptoms of acute diffuse otitis externa may include:

  • ear pain
  • pruritus
  • conductive hearing loss
  • swelling of the ear canal
  • tenderness of the ear canal on manipulation of the tragus or pinna
  • discharge or debris.

In more severe cases, there may be regional lymphadenitis, or cellulitis of the pinna and adjacent skinRosenfeld, 2014.

Fungal infection (otomycosis) and necrotising otitis externa are more likely to occur in patients with diabetes or immune compromise. These conditions may present similarly to bacterial acute diffuse otitis externa but require different therapy – see Antimicrobial ear drops for acute diffuse otitis externa when fungal infection is suspected or Necrotising otitis externa. In otomycosis, patients are more likely to present with itch and a blocked ear (from fungal debris) than pain; in necrotising otitis externa, pain is typically unrelenting despite improvement in the canal appearance.

Otoscopy is important to distinguish between acute diffuse otitis externa, otitis media, and other ear problems. In acute diffuse otitis externa, the external ear canal (if visible) appears inflamed, with erythema and oedema. In otomycosis, fungal debris is typically visualised in the canal on otoscopy (having the appearance of wet newspaper).

In addition to infective causes, noninfective causes of ear pain include trauma, foreign bodies, impacted cerumen and otologic neoplasms. Secondary causes include referred dental pain, temporomandibular joint dysfunction, trigeminal neuralgia, head and neck cancer, temporal arteritis and Eagle’s syndrome (elongation of the styloid process or calcification of the stylohyoid ligamentMayrink, 2012)Harrison, 2016.

Perichondritis may be secondary to otitis externa; refer patients with suspected perichondritis to the emergency department and an otolaryngologist because without prompt treatment, perichondritis may progress to cartilage necrosis and permanent deformity.