High-Yield Otitis Externa
Otitis externa represents inflammation of the external auditory canal. Board examinations heavily emphasize distinguishing between the common **Acute Diffuse Otitis Externa** (Swimmer’s Ear) and the life-threatening invasive **Malignant Otitis Externa**.
Clinical Manifestations & Profiling
| Feature | Acute Localized / Diffuse | Malignant (Necrotizing) Otitis Externa |
|---|---|---|
| Primary Pathogen | Pseudomonas aeruginosa (most common) or Staphylococcus aureus. | Pseudomonas aeruginosa (in >95% of cases). |
| Patient Population | Swimmers, tropical climates, or secondary to mechanical trauma (e.g., cotton swabs). | Elderly patients with Diabetes Mellitus or severely immunocompromised individuals. |
| Key Physical Findings | Severe **tragal tenderness** or pain on manipulation of the pinna. Erythema and edema of the canal walls. | Exquisite, unyielding nocturnal otalgia; pathognomonic granulation tissue at the bony-cartilaginous junction. |
| Complications | Temporary conductive hearing loss due to canal occlusion. | Skull base osteomyelitis; lower cranial nerve palsies (**CN VII** is typically hit first, followed by IX, X, XI). |
| First-Line Management | Topical antibiotic drops (e.g., fluoroquinolones) ± topical glucocorticoids. Keep your ear completely dry. | Prolonged systemic antipseudomonal therapy (e.g., **IV Ciprofloxacin** or Piperacillin-Tazobactam). |
NEET PG “Must-Know” Variants & Pearls
- Otomycosis: Fungal infection of the external canal driven by *Aspergillus niger* or *Candida albicans*. Often occurs after prolonged topical antibiotic usage.
- *Aspergillus niger* displays a characteristic **”wet blotting paper”** appearance covered in black filamentous spores.
- *Candida albicans* yields a thick, white/creamy exudate. Treatment relies on thorough microscopic debridement and topical antifungals (e.g., clotrimazole).
- Ramsay Hunt Syndrome (Herpes Zoster Oticus): Reactivation of varicella-zoster virus within the geniculate ganglion. Presents with severe otalgia, painful vesicular eruptions along the external ear canal/concha, and an ipsilateral lower motor neuron facial nerve palsy (CN VII).
- Malignant Otitis Externa Imaging: Diagnosis and structural bony erosion are assessed via **High-Resolution CT (HRCT)**. However, because bone remineralization delays structural resolution, **Technetium-99m** bone scans are ideal for assessing early bony involvement, while **Gallium-67** or Indium-111 labeled leukocyte scans are utilized to monitor clinical response and declare cure.
- Furunculosis: Acute localized otitis externa restricted to the outer cartilaginous third of the canal, caused by staphylococcal infection of a hair follicle. Pain is highly localized and intensified by jaw movement.