Neurosurgery notes/Infection/Cranial infection/Shunt infections

Shunt infections

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Cranial infection

Infection rate

  • 7% but can be high to 20%
  • Basics trial: 2-6% (ave 5%)

Risk factors

  • Very young patients.
    • Ammirati 1987: Waiting to insert shunt when patient is 2 weeks old significantly reduce risk of infection
  • Length of procedure
  • Open neural tube defect

Morbidity of shunt infection in children

  • Has worse
    • Mortality rate (10%)
    • Seizure rate
    • Lower IQ

Pathogens

  • From patient’s own skin
  • 50% occurs within 2 weeks, 70% within 2 months
  • Early: (<6months)
    • S epidermidis: aka coag neg staph, (70% of infection)
    • S aureus
    • Gram neg bacilli (10%)
  • Late: (>6months)
    • 6% for patients
    • S.epidermidis: Mostly
    • Due to
      • Indolent infection
      • Seeding of a vascular shunt during episode of septicaemia
      • Colonisation from episode of meningitis

Candida spp.

  • Majority of fungal infection in shunts
  • <1yrs old
  • 7%
  • Due to
    • Use of prophylactic abx
  • CSF: elevated WCC, protein, normal glucose
  • Treatment
    • Remove shunt → EVD
    • Replace shunt 1 week days of therapy
    • Antifungal therapy for 6-8 weeks

Presentation

  • Fever, N/V, lethargy, anorexia, irritability
  • Shunt nephritis:
    • Occur when there is chronic low infection → immune complex deposition in renal glomeruli → proteinuria and haematouria

Test

  • CSF: WCC usually not >100cell/cm3, gram stain positive in 50% cases
    • CSF culture is negative in 40% cases
    • Definition for shunt infections
        • Culture
        Clinical signs
        CSF pleocytosis
        Gram stain
        Definite
        + @ primary/repeated subculture (enrichement)
        +/-
        Probable
        + @ one subculture only
        +/-
        +
        +
        Probable
        -
        +/-
        +
        +
        Possible
        Uncertain, growth after enrichment in one CSF sample only
        •
        •
        -
        Shunt deep incision infection
        Infection of the deep surgical wound and subcutaneous shunt but no CSF infection
        n/a
        •
        -
  • Do shunt tap do not do LP: dangerous in obstructive hydrocephalus with a non functioning shunt

Treatment

  • Antibiotics alone
    • Poor rate
    • Indicated for ill patients, poor anaesthetic risk
  • Shunt removal
    • Externalise or removed
  • Empirical: Vancomycin
    • Add rifampin to inc coverage
    • Change Vancomycin to nafcilliun if patient is pen allergic or no MRSA
    • Add IT antibiotics if required
      • Too high [antibiotics] can cause neurological side effects
      • Aim for peak blood levels

If patient has peritonitis

  • Due to
    • Penetrating injury
    • Seeding from infected VP shunt: gram + organism
    • Spontaneous bacterial peritonitis: mainly from cirrhosis
  • Treatment: other than treatment main pathology
    • Externalisation
      • To not infect sterile portions of the shunt
          1. Reopening the skin incision used for inserting the peritoneal catheter
          1. Making a second incision over the shunt tubing, well above this entry point.
          1. The catheter is then divided at the upper incision.
          1. The catheter is grasped at the lower incision and is pulled, extracting both ends (the peritoneal end and the end just cut).
          1. The remaining catheter coming from above is connected to an external drainage system
    • CSF cultures are monitored daily
      • If 3 consecutive cultures are negative → a new distal catheter may be implanted
    • If cultures continuously grow organisms, then the shunt may be contaminated and should then be replaced with an entirely new shunt system
    • When it is time to replace the shunt, some authors recommend using an alternative site other than the peritoneum, but this is not mandatory