Pus

Sources of Pus/Infection - four routes of microbial access to CNS

1. hematogenous spread (most common): arterial and retrograde venous

   1. adults: chest is #1 source (lung abscess, bronchiectasis, empyema)

   2. children: congenital cyanotic heart disease with R → L shunt

   3. immunosuppression (AIDS – toxoplasmosis)

2. direct implantation (dural disruption)

• 1. Trauma

  2. iatrogenic (e.g. following LP, post-op)

  3. congenital defect (e.g. dermal sinus)

3. contiguous spread (adjacent infection): from air sinus, naso/oropharynx, surgical site (e.g. otitis media, mastoiditis, sinusitis, osteomyelitis, dental abscess)

4. spread from PNS (e.g. viruses: rabies, herpes zoster)

common examples

• epidural abscess: in cranial and spinal epidural space, associated with osteomyelitis

  • treatment: immediate drainage and antibiotics, surgical emergency if cord compression

• subdural empyema: bacterial/fungal infection, due to contiguous spread from bone or air sinus, progresses rapidly

  • treatment: surgical drainage and antibiotics, 20% mortality

• meningitis, encephalitis

• cerebral abscess