How is it Diagnosed?
Chronic otitis externa is diagnosed based on clinical evaluation of persistent
inflammation of the external auditory canal, typically lasting longer than three months. A
thorough patient history includes symptoms such as itching, otorrhea, pain, and hearing
loss, as well as recurrent water exposure, use of hearing aids, or dermatological
conditions like eczema or psoriasis.
On otoscopic examination, the ear canal often appears red, thickened, and may have
scaling or discharge. Narrowing of the canal (stenosis) and accumulation of debris are
common findings. In some cases, fungal elements (otomycosis) are seen as black or
white fluffy material.
Swab cultures may be taken from the discharge to identify bacterial or fungal
pathogens, especially in cases unresponsive to empirical treatment. Pseudomonas
aeruginosa and Staphylococcus aureus are the most common culprits in bacterial
infections, while Candida and Aspergillus species dominate fungal causes.
Audiometry may be performed to assess any conductive hearing loss caused by canal
obstruction. Imaging with CT scan of the temporal bone may be indicated if malignant
otitis externa (an aggressive, potentially life-threatening condition) is suspected,
especially in immunocompromised or diabetic patients.
Differential diagnosis includes chronic otitis media, seborrheic dermatitis, or contact
dermatitis, which must be ruled out. Accurate diagnosis is essential for targeted therapy
and to prevent complications like canal stenosis or persistent hearing loss.