What causes a black tympanic membrane?

Causes of a Black Tympanic Membrane

A black tympanic membrane is most commonly caused by fungal infection (otomycosis), particularly Aspergillus niger, which appears as a moist white plug dotted with black debris resembling "wet newspaper." 1

Primary Causes

1. Fungal Infections (Otomycosis)

• Aspergillus niger: The most common cause of black discoloration
  • Typically presents as white debris with black speckles ("wet newspaper" appearance) 1
  • Accounts for 60-90% of otomycosis cases
  • More common in:
    • Tropical/humid environments
    • Patients on long-term topical antibiotics
    • Diabetic patients
    • Immunocompromised individuals (HIV, etc.)

2. Blood Behind the Tympanic Membrane (Hemotympanum)

• Can appear dark or black when blood collects in the middle ear
• May occur following:
  • Head trauma
  • Barotrauma
  • Severe otitis media with hemorrhage

3. Necrotic Tissue

• In severe cases of necrotizing (malignant) otitis externa
• Particularly concerning in diabetic or immunocompromised patients 1
• Requires urgent treatment to prevent skull base osteomyelitis

Clinical Approach

Assessment

1. Examine the entire ear canal:

   • Distinguish between fungal elements, dried blood, or necrotic tissue
   • Look for accompanying symptoms (pain, discharge, hearing loss)
   • Assess for tympanic membrane integrity 2

2. Risk factor evaluation:

   • Diabetes status (increased risk of otomycosis and necrotizing otitis externa) 1
   • Immune status (HIV, chemotherapy patients)
   • Recent antibiotic use (predisposes to fungal overgrowth)
   • Swimming or water exposure history

Management

1. For otomycosis (most common cause):

   • Thorough debridement of fungal elements
   • Topical antifungal therapy
   • Avoid topical antibiotics as they may promote further fungal growth 1
   • Consider systemic antifungals in severe or resistant cases

2. For necrotizing otitis externa:

   • Urgent referral to otolaryngology
   • Systemic antibiotics covering Pseudomonas and Staphylococcus
   • Possible surgical debridement
   • Close monitoring for skull base involvement 1

Important Considerations

Diagnostic Pitfalls

• Black discoloration may be mistaken for cerumen impaction
• Fungal elements can obscure underlying pathology
• Pneumatic otoscopy should be avoided if tympanic membrane perforation is suspected 2

Red Flags Requiring Urgent Referral

• Black tympanic membrane with:
  • Severe pain
  • Cranial nerve deficits (especially facial nerve)
  • Immunocompromised status
  • Diabetes
  • Failure to respond to initial therapy 1

Prevention

• Keep ears dry in susceptible individuals
• Avoid prolonged topical antibiotic use
• Consider prophylactic acidifying drops in swimmers
• Proper glucose control in diabetic patients

Special Populations

• Diabetic patients: Higher risk of necrotizing otitis externa; require more aggressive management
• Immunocompromised: More susceptible to fungal infections and complications
• Children: Foreign bodies may occasionally appear black and should be ruled out

Remember that a black tympanic membrane is not normal and requires proper evaluation to determine the underlying cause and appropriate treatment strategy.