Sudden Sensorineural Hearing Loss

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SSNHL Basics - Deafening Debut

  • Definition: Rapid onset hearing loss.
    • 30dB sensorineural hearing loss.
    • Across ≥ 3 consecutive audiometric frequencies.
    • Developing within 72 hours.
  • Epidemiology: Affects ~5-27 per 100,000 annually; incidence may be ↑; peaks in 50s-60s.
  • Etiology: Often multifactorial.
    • Idiopathic: Most common.
    • Viral: Mumps, measles, VZV, CMV, HIV.
    • Vascular: Vertebrobasilar insufficiency, TIA, stroke, hypercoagulable states.
    • Autoimmune: e.g., Cogan's syndrome, SLE.
    • Neoplastic: Acoustic neuroma (Vestibular Schwannoma) - must rule out.
    • Traumatic: Head injury, barotrauma, perilymphatic fistula.
  • Pathophysiology: Commonly involves cochlear hair cell damage/inflammation or disruption of cochlear microcirculation.

⭐ The majority of SSNHL cases (up to 90%) are idiopathic.

Audiograms showing sudden sensorineural hearing loss

Clinical Picture & Diagnosis - Hear Today, Gone Tomorrow?

  • Symptoms:
    • Unilateral, sudden hearing loss (often < 72 hrs).
    • Tinnitus (ringing/buzzing).
    • Vertigo/Dizziness (in ~30-40% of cases).
    • Aural fullness (sensation of pressure in the ear).
  • History Taking:
    • Onset: Rapid, often discovered upon waking.
    • Risk factors: Viral prodrome, recent trauma, ototoxic medication use, vascular risk factors (e.g., diabetes, hypertension), autoimmune disease.
  • Otoscopy:
    • Typically normal external auditory canal and tympanic membrane.
  • Tuning Fork Tests:
    • Rinne: Air Conduction > Bone Conduction (AC>BC) in affected ear (or false negative if profound loss, where BC is perceived by contralateral ear).
    • Weber: Lateralizes to the better hearing ear, indicating SNHL in the poorer ear.
  • Audiometry:
    • Pure Tone Audiometry (PTA): Confirms SNHL (≥ 30 dB loss in ≥ 3 consecutive frequencies). Defines type & severity. ⭐> Pure Tone Audiometry (PTA) is the gold standard investigation to confirm SSNHL and quantify the hearing loss.

Audiograms showing sudden sensorineural hearing loss

Workup & Differentials - Rule Out the Rascals

  • Further Investigations:
    • MRI Brain with Gadolinium: Mandatory for unilateral SSNHL. Screens for retrocochlear pathology (e.g., vestibular schwannoma, CPA tumors).
    • Blood Tests (if clinically suspected):
      • CBC, ESR, Blood glucose, Lipid profile.
      • Autoimmune markers (e.g., ANA, RF).
      • Viral serology (e.g., HSV, VZV, CMV).
  • Differential Diagnosis (Consider these "Rascals"):
    • Meniere's disease (fluctuating HL, vertigo, tinnitus)
    • Ototoxicity (e.g., aminoglycosides, cisplatin)
    • Labyrinthitis (viral or bacterial infection)
    • Cerebrovascular Accident (CVA) affecting AICA/PICA
    • Multiple Sclerosis (demyelinating plaques)
    • Perilymphatic fistula (history of trauma/barotrauma)
    • Acoustic neuroma (vestibular schwannoma)

⭐ Gadolinium-enhanced MRI of the brain and internal auditory canals is mandatory in unilateral SSNHL to rule out retrocochlear pathology, especially vestibular schwannoma (acoustic neuroma).

Treatment & Prognosis - Sounding the Alarm for Recovery

SSNHL is an otologic emergency; prompt action is key!

  • Other Treatments:
    • Antivirals, Vasodilators: Generally not recommended due to limited/controversial evidence.
  • Prognostic Factors (Recovery Influencers):
    • Key: Time to treatment (↓ delay = ↑ recovery).
    • Severity of initial hearing loss.
    • Age (↑ age = ↓ prognosis).
    • Presence of vertigo (associated with poorer prognosis).
    • Audiogram pattern (e.g., upsloping favorable).

⭐ The most crucial prognostic factor for recovery in SSNHL is the time to initiation of steroid therapy, ideally within 72 hours to 2 weeks of onset.

High‑Yield Points - ⚡ Biggest Takeaways

  • SSNHL: ≥30 dB SNHL over ≤72 hours in ≥3 consecutive audiometric frequencies.
  • Mostly idiopathic; MRI Brain with Gadolinium essential to rule out acoustic neuroma (retrocochlear pathology).
  • Treat promptly with high-dose oral corticosteroids (e.g., Prednisolone 1mg/kg/day). Intratympanic steroids are an alternative.
  • Spontaneous recovery occurs in 30-65% of cases, often within the first two weeks.
  • Poorer prognostic factors: severe loss, associated vertigo, older age, and delayed treatment.
  • Pure Tone Audiometry (PTA) confirms diagnosis. Urgent ENT referral is critical.
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A 25-year-old woman presents with episodes of dizziness, tinnitus, and hearing loss in the right ear. What is the most likely diagnosis?

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