ENT (Otorhinolaryngology) · MU Sofia

16. Intracranial complications of otogenic origin – labyrinthitis, otogenic meningitis, epidural, subdural and intracerebral abscess. Thrombosis of the sigmoid sinus.

Covers intracranial complications of ear infections, tracing how infection spreads from the middle ear and mastoid through bone erosion, venous channels or nerve sheaths. It then takes labyrinthitis, otogenic meningitis, epidural, subdural and intracerebral abscesses, and sigmoid sinus thrombosis in turn, with definitions, clinical features, imaging, treatment and differential diagnoses. A summary table of sources, routes and general symptoms opens the note, and a closing section compares non-otogenic conditions.

Inside: 1 section · 7 labelled pictures · 1 table · 15 flashcards · 7 min

Topic 16 of 52 in the MU Sofia syllabus for ENT (Otorhinolaryngology) (Medicine, Year 4). The free AceMed note covers it in 1 section, about 947 words (7 min of reading), with 15 flashcards.

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  1. Intracranial complications of otogenic origin – labyrinthitis, otogenic meningitis, epidural, subdural and intracerebral abscess. Thrombosis of the sigmoid sinus.

Intracranial complications of otogenic origin – labyrinthitis, otogenic meningitis, epidural, subdural and intracerebral abscess. Thrombosis of the sigmoid sinus.

Intracranial complications arising from ear infections (otogenic origin) are rare but life-threatening emergencies. They occur due to the spread of infection from the middle ear and/or mastoid through bony erosion or venous channels.

1. Labyrinthitis: an intratemporal complication but is a crucial route for intracranial spread.

  • Definition: Inflammation of the membranous labyrinth (cochlea and vestibular organs) caused by toxins or bacteria from the middle ear.
  • Etiopathogenesis:
  • Serous/Toxic Labyrinthitis: (AOM) Toxins from the middle ear pass into the inner ear through the round or oval window membrane (most common, reversible).
  • Suppurative/Purulent Labyrinthitis: (COM) Direct bacterial invasion (most dangerous, irreversible).
  • Classification
  • Serous (toxic) labyrinthitis – inflammation without bacterial invasion
  • Suppurative (purulent) labyrinthitis – bacterial penetration into inner ear; severe SNHL
  • Circumscribed (fistula) labyrinthitis – localized due to cholesteatoma-induced lateral semicircular canal fistula
  • Clinical Picture: Sudden, severe vertigo (spinning sensation), nausea/vomiting, hearing loss (SNHL), and nystagmus (beating away from the affected ear).
  • Treatment: IV Antibiotics (for suppurative type), steroids (for serous type), bed rest, and vestibular suppressants. Suppurative labyrinthitis is a direct indication for mastoidectomy and potential cochlear drainage to prevent meningitis.
  • Complications: Permanent severe SNHL and vertigo and is the most common route of spread leading to otogenic meningitis.
  • Differential Diagnosis: Vestibular neuritis, Ménière’s disease, BPPV, Stroke (PICA/AICA), Acoustic neuroma

2. Otogenic Meningitis

  • Definition: Inflammation of the meninges caused by spread of infection from the middle ear or mastoid.
  • Etiopathogenesis: Bacteria (often S. pneumoniae, H. influenzae) spread via direct erosion or through the inner ear (labyrinthitis) or venous channels.
  • Classification: Acute purulent meningitis.
  • Clinical Picture: High fever, severe headache, neck stiffness (nuchal rigidity), photophobia, altered mental status, Signs of otitis or mastoiditis and positive meningeal signs (Kernig's and Brudzinski's).
  • Paraclinical & Radiological:
  • CT/MRI: May show enhancement of the meninges.
  • Lumbar Puncture (LP): Mandatory. CSF analysis shows high pressure, high protein, low glucose, and neutrophilic pleocytosis. Gram stain/culture identifies the pathogen.
  • Treatment: Urgent IV antibiotics (broad-spectrum, ceftriaxone+vancomycin), Myringotomy or mastoidectomy.
  • Complications: Hearing loss (SNHL), hydrocephalus, permanent neurological deficits, death.
  • Differential Diagnosis: Viral meningitis, Subarachnoid hemorrhage, Brain abscess, Encephalitis, Drug-induced meningitis

3. Extradural (Epidural) Abscess

  • Definition: Localized collection of pus between the dura mater and skull, in the temporal region, secondary to otitis media or mastoiditis.
  • Etiopathogenesis: Direct contact and erosion of the bone (Tegmen tympani/mastoideum) due to cholesteatoma or acute mastoiditis. The dura acts as a barrier, localizing the pus.

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