Section 10.2: Otic Disorders (Otitis Media/Externa, Vertigo, Labyrinthitis)
Key Takeaways
- Acute otitis media is defined by a bulging, erythematous, hypomobile tympanic membrane on pneumatic otoscopy, treated first-line with high-dose amoxicillin.
- Otitis media with effusion consists of fluid behind the tympanic membrane without signs of infection, requiring observation rather than antibiotics.
- Acute otitis externa presents with tragal or pinna traction tenderness and canal edema, most commonly caused by Pseudomonas aeruginosa and treated with topical fluoroquinolones (ciprofloxacin).
- Avoid ototoxic aminoglycosides (e.g., neomycin-polymyxin-hydrocortisone) if the tympanic membrane is perforated or cannot be fully visualized.
- Peripheral vertigo (BPPV, labyrinthitis) features horizontal/torsional fatigable nystagmus, whereas central vertigo (stroke, tumor) features vertical non-fatigable nystagmus and focal neurological deficits.
Section 10.2: Otic Disorders (Otitis Media/Externa, Vertigo, Labyrinthitis)
Why This Topic Matters for PANCE
Otologic and vestibular complaints are common on the PANCE. Focus on differentiating middle ear infections from external canal infections, and distinguishing peripheral from central vertigo. Recognizing classic findings (e.g., a bulging tympanic membrane in acute otitis media or tragal tenderness in otitis externa) and selecting the correct first-line therapy (e.g., oral amoxicillin vs. topical ciprofloxacin) are critical exam concepts.
Acute Otitis Media (AOM)
Pathophysiology & Risk Factors
Acute otitis media (AOM) is a bacterial or viral infection of the middle ear space, primarily driven by Eustachian tube dysfunction. Obstruction (often from viral infections or allergies) traps fluid in the middle ear, leading to secondary bacterial colonization. Children are predisposed due to their shorter, wider, and more horizontal Eustachian tubes. Primary pathogens:
- Streptococcus pneumoniae (most common).
- Haemophilus influenzae.
- Moraxella catarrhalis.
Clinical Presentation & Diagnosis
AOM presents with rapid onset of otalgia (ear pain), fever, and irritability. Infants may tug at the affected ear. The diagnostic gold standard is pneumatic otoscopy, showing:
- A bulging tympanic membrane (TM): The most specific sign of middle ear inflammation.
- Erythema and opacity of the TM.
- Absent or decreased TM mobility. Note: Middle ear fluid without inflammation is Otitis Media with Effusion (OME), which requires observation, not antibiotics.
Clinical Management
First-line therapy is high-dose Amoxicillin (80–90 mg/kg/day). Amoxicillin-clavulanate (Augmentin) is indicated if the patient had amoxicillin in the past 30 days, has concurrent purulent conjunctivitis, or fails to improve in 48-72 hours. Use oral cephalosporins (e.g., Cefdinir) for mild penicillin allergies. Use macrolides (e.g., Azithromycin) for severe Type I penicillin allergies.
Otitis Externa (AOE)
Pathophysiology & Risk Factors
Acute otitis externa (AOE), or "swimmer's ear," is an infection of the external auditory canal. Pathophysiology involves the loss of the canal's protective acidic environment due to excess moisture or trauma, facilitating bacterial growth. Pathogens:
- Pseudomonas aeruginosa (most common).
- Staphylococcus aureus.
Clinical Presentation & Diagnosis
Patients present with rapid-onset ear pain (otalgia), pruritus, and purulent discharge. The hallmark finding is exquisite pain on traction of the pinna or pressure on the tragus. Otoscopy reveals an erythematous, edematous external canal.
Clinical Management
- First-line Therapy: Topical fluoroquinolones, such as Ciprofloxacin/Dexamethasone or Ofloxacin drops.
- Contraindications: Avoid aminoglycoside preparations (e.g., Neomycin/Polymyxin B/Hydrocortisone) if the TM is perforated or cannot be visualized, as they are ototoxic.
- Malignant (Necrotizing) Otitis Externa: Severe osteomyelitis of the skull base, typically in elderly diabetics, caused by Pseudomonas. Presents with severe pain and granulation tissue. Requires urgent CT scan and IV antipseudomonal antibiotics (e.g., IV Ciprofloxacin).
Vertigo and Labyrinthitis
Vertigo is the illusion of spinning. It is classified as peripheral (inner ear) or central (CNS).
Peripheral vs. Central Vertigo
- Peripheral: Sudden, severe episodic vertigo. Features horizontal/torsional nystagmus (with latency, fatigable) and auditory symptoms (tinnitus/hearing loss).
- Central: Gradual onset, continuous mild vertigo. Features vertical or multidirectional nystagmus (no latency, non-fatigable) and focal neurological deficits (ataxia, dysarthria). Requires urgent brain MRI.
High-Yield Peripheral Vestibular Disorders
- Benign Paroxysmal Positional Vertigo (BPPV): Caused by free-floating calcium carbonate crystals (otoconia) in the semicircular canals. Presents with brief vertigo episodes (<60 seconds) triggered by head turning.
- Diagnosis: Dix-Hallpike maneuver (provokes fatigable nystagmus).
- Management: Epley maneuver (repositions crystals).
- Vestibular Neuritis vs. Labyrinthitis: Both involve post-viral cranial nerve VIII inflammation, presenting with continuous vertigo, nausea, and gait imbalance lasting days.
- Vestibular Neuritis: Auditory function is completely intact.
- Labyrinthitis: Accompanied by unilateral sensorineural hearing loss and tinnitus.
- Management: Treated with a corticosteroid taper (Prednisone) and short-term vestibular suppressants (e.g., Meclizine) for the first 48 hours.
Classic PANCE Traps & Clinical Pearls
- Ototoxicity Trap: Never use neomycin-polymyxin-hydrocortisone drops for otitis externa if the TM is ruptured; use ciprofloxacin or ofloxacin instead.
- Maneuver Check: Dix-Hallpike is diagnostic for BPPV; Epley is the corrective treatment.
- Hearing Loss Divider: Vestibular neuritis has normal hearing; labyrinthitis features sensorineural hearing loss.
- Central Red Flags: Vertical nystagmus or inability to walk indicates a central cause; obtain an urgent MRI to rule out cerebellar stroke.
Differentiating Vestibular Disorders
| Condition | Vertigo Duration | Hearing Loss / Tinnitus | Diagnostic Test / Finding | Management |
|---|---|---|---|---|
| BPPV | Seconds (< 60s) | Absent | Dix-Hallpike (fatigable nystagmus) | Epley maneuver |
| Vestibular Neuritis | Days (continuous) | Absent | Abnormal Head Impulse Test | Corticosteroids + Meclizine |
| Labyrinthitis | Days (continuous) | Present (unilateral SNHL) | Clinical examination | Corticosteroids + Meclizine |
| Meniere's Disease | Hours (20 min - 24 hrs) | Present (fluctuating low-frequency) | Audiometry showing SNHL | Low-sodium diet, Diuretics |
A 7-year-old girl is brought to the clinic due to severe left ear pain and itching that started yesterday. She recently returned from a summer camp where she swam daily. On physical examination, there is exquisite tenderness when pulling the left pinna and pressing on the tragus. Otoscopic examination shows an erythematous and edematous external auditory canal with purulent debris. The tympanic membrane is partially visualized and appears intact. Which of the following is the most common pathogen responsible for this patient's condition?
A 29-year-old male presents with a 2-day history of continuous, severe room-spinning vertigo accompanied by nausea and multiple episodes of vomiting. He reports that the symptoms are constant and do not resolve when lying still. He also complains of a constant ringing sound and significant hearing loss in his left ear. He reports having a mild upper respiratory infection two weeks ago. On exam, he has horizontal nystagmus beating to the right that is suppressed with visual fixation. There are no focal neurological deficits. Which of the following is the most likely diagnosis?
A 4-year-old boy presents with a 3-day history of fever, ear pain, and irritability. Pneumatic otoscopy reveals a severely bulging, erythematous right tympanic membrane with absent mobility. The patient's mother notes that he had a mild skin rash after taking penicillin two years ago, but no breathing difficulties or swelling occurred. Which of the following is the most appropriate first-line pharmacotherapy for this patient's condition?