Mastoiditis: Pathogenesis and clinical findings



Acute or Chronic Otitis Media -> 

Stage 1: Hyperemeia of the mastoid air cells (inflammation of middle ear mucosa leads to inflammation of the mastoid cavity as middle ear and mastoid air cells are connected)

Stage 2: Transudation or exudation of fluid &/or pus within mastoid air cells (inflammation blocks antrum causing accumulation of pus in mastoid air cells)

Stage 3: Necrosis of bone (air pressure increases causing decreased vascularity and destroying thin bony septae between air cells)

Stage 4: Cell wall loss with coalescence into larger & irregular cavities

Stage 5: Extension of inflammatory process into contiguous areas



 • Through aditus ad antrum -> Patent ET = resolution of infection; Obstructed ET= rupture of the tympanic membrane

 • Through lateral cortex of mastoid -> Subperiosteal abscess: Erythema, fluctuant, tender mass over mastoid bone, loss of postauricular crease

 • Inferior through medial aspect of mastoid tip -> Bezold abscess (Neck abscess between SCM & digastric muscles): Swelling & tenderness below mastoid process & under SCM 

 • Medially to petrous air cells -> Petrositis (infection or inflammation in the petrous portion of the temporal bone): facial nerve palsy

 • Posteriorly to occipital bone -> Osteomyelitis

 • Through oval or round window -> Labyrinthitis (inflammation or infection of bony labyrinth): Tinnitus, hearing loss, nausea, vomiting, dizziness, vertigo, nystagmus

 • Toward inner cortical bone -> Meningitis, Venous sinus thrombosis, Temporal lobe, cerebellar, epidural, or subdural abscesses



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