7. Pre-disposing factors
• Age
• Virulent organisms
• Cholesteatoma or Bone erosion
• Presence of a congenital dehiscence
• Obstruction of drainage e.g polyp
• Low resistance of the patient
• Poor socio-economic status
9. Pathways of infections
• The commonest way for extension of
infection is by bone erosion due to a
cholesteatoma.
• Vascular extension (retrograde
thrombophlebitis).
• Extension along preformed pathways as
– Congenital dehiscences, fracture lines, round
window membrane, the labyrinth,
– Dehiscences due to previous surgery.
28. Lateral Sinus Thrombosis (sigmoid sinus)
Spread of infection by direct extension or
via mastoid emissary vein
↓
Pus and granulation adjacent to sigmoid
sinus
↓
Reactive thrombophlebitis
↓
intraluminal thrombus
↓
CSF obstruction
31. LST ……Treatment
• Empiric broad coverage until C&S
• antibiotic with good CSF penetration
• Surgery
– Mastoidectomy
– Decompression
– Thrombus evacuation
32. Intracranial Epidural Abscess
• Localized between dura
and bone
• dural adherence to bone
at suture lines
• Focal osteomyelitis
• Management and
etiology same as
subdural empyema
33. Subdural Abscess
• Between the dura and
the arachnoid.
• Potential space
• Lack of anatomical
boundaries
→ spread rapidly
• Ear 14%
• (paranasal sinusitis
75%)
