Perilymphatic Fistula

Perilymphatic Fistula - Leaky Labyrinth Intro

• Definition: An abnormal communication between the perilymph-filled space of the inner ear and the air-filled middle ear cavity or mastoid.
• "Leaky Labyrinth": Refers to the leakage of perilymph, typically through the oval or round windows.
• Common Sites of Leakage:
  • Oval window (especially fissula ante fenestram).
  • Round window membrane.
• Etiology:
  • Traumatic: Head injury, barotrauma (e.g., diving, flying), iatrogenic (post-stapedectomy, cochlear implantation).
  • Congenital: Inner ear malformations (e.g., Mondini dysplasia, enlarged vestibular aqueduct).
  • Spontaneous: Often after sudden increases in intracranial or intralabyrinthine pressure (e.g., straining, coughing, sneezing, Valsalva maneuver).
  • Erosive (rare): Cholesteatoma, tumors.

⭐ The oval window is the most common site for perilymphatic fistulas, particularly following trauma or stapes surgery.

Perilymphatic Fistula - Inner Ear Mayhem

• Abnormal communication between perilymph-filled inner ear & air-filled middle ear/mastoid.
• Etiology:
  • Trauma: Head injury, barotrauma (diving, flying), iatrogenic (stapedectomy).
  • Congenital: Inner ear malformations (e.g., Mondini dysplasia).
  • Spontaneous: Often after straining, coughing, sneezing.
  • Erosive: Cholesteatoma, tumors.
• Pathophysiology: Leakage of perilymph → pressure changes in cochlea & vestibule → auditory & vestibular symptoms.
• Clinical Features:
  • Episodic vertigo, often triggered by Valsalva, loud noises (Tullio phenomenon), or pressure changes.
  • Fluctuating sensorineural hearing loss (SNHL), often low-frequency initially.
  • Tinnitus, aural fullness.
  • Hennebert's sign: Nystagmus/vertigo on tragal pressure (positive fistula test).
  • Tullio phenomenon: Sound-induced vertigo/nystagmus.

⭐ Fistula Test (Hennebert's Sign): Induction of nystagmus and vertigo by applying positive or negative pressure to the external auditory canal using a Politzer bag or pneumatic otoscope. A positive test strongly suggests PLF, but can also be seen in Meniere's disease (due to saccular fibrosis) or semicircular canal dehiscence.

• Diagnosis: Often clinical; CT temporal bone may show defect. Exploratory tympanotomy is gold standard for confirmation & repair.
• Management: Bed rest, head elevation, avoidance of straining. Surgical repair (grafting oval/round window) if conservative measures fail or symptoms are severe/persistent.

Perilymphatic Fistula - Spotting the Seep

• Objective: Confirm perilymph leakage from inner ear (oval/round window) to middle ear.
• Clinical Provocative Tests:
  • Fistula Test (Hennebert's sign): Nystagmus/vertigo with pneumatic otoscopy/tragal pressure.
  • Tullio Phenomenon: Loud sounds induce vertigo/nystagmus.
• Investigations:
  • Audiometry: Sensorineural hearing loss (SNHL), often fluctuating/progressive.
  • VEMP/ECoG: May be abnormal; non-specific.
  • Imaging (HRCT/MRI): Rarely diagnostic for leak; may show fluid, helps rule out other issues.
• Gold Standard: Exploratory tympanotomy for direct visualization and repair.

  ⭐ Beta-2 transferrin assay of aspirated middle ear fluid is highly specific for perilymph/CSF, confirming leak.

Perilymphatic Fistula - Plugging the Problem

• Conservative Management (Initial):

  • Strict bed rest, head elevation.
  • Avoidance of straining (stool softeners, cough suppressants).
  • Observation for 1-2 weeks; spontaneous healing possible.

• Surgical Management (If conservative fails or severe symptoms):

  • Tympanotomy and exploration of oval and round windows.
  • Grafting material: temporalis fascia, perichondrium, fat, fibrin glue.
  • Aim: Seal the fistula.

• Flowchart: Management Approach

• Post-operative Care:

  • Continued bed rest initially.
  • Avoidance of pressure changes (flying, diving).

• Prognosis & Complications:

  • Variable; depends on duration and severity.
  • Potential for persistent hearing loss or vestibular symptoms.
  • Rare: meningitis.

⭐ High-Yield Fact: Surgical repair of a perilymphatic fistula primarily aims to stabilize or improve vestibular symptoms; hearing improvement is less predictable and often not the primary outcome achieved.

• 📌 Mnemonic: PLUG it - Positioning (bed rest), Limit straining, Undergo surgery (if needed), Grafting windows.

High‑Yield Points - ⚡ Biggest Takeaways

• Abnormal connection between perilymphatic space of inner ear and middle ear/mastoid.
• Often post-traumatic (e.g., head injury, barotrauma, stapes surgery) or congenital.
• Key symptoms: Episodic vertigo, fluctuating/progressive sensorineural hearing loss (SNHL).
• Tullio phenomenon (sound-induced vertigo) and Hennebert's sign (pressure-induced nystagmus/vertigo) are suggestive.
• Diagnosis is often clinical; exploratory tympanotomy is gold standard for confirmation & repair.
• Management: Initial conservative measures (bed rest, head elevation); surgical repair (grafting) if symptoms persist.
• Associated with sudden SNHL or vertigo after straining, coughing, or nose-blowing (Valsalva).