Neurosurgery notes/Procedures/Cranial procedures/CSF procedures/Fontanelle taps

Fontanelle taps

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CSF procedures

Theory

  • Small baby with thin scalp → EVD often problematic due to skin breakdown/leak/infection
  • Fontanelle tap is a useful temporising measure to control ICP until more definitive treatment (e.g. shunt insertion or endoscopic surgery)
  • Basic equipment, no anaesthetic required
  • Aseptic/sterile procedure
  • No local anaesthetic
  • Swaddle and sucrose instead

Numbers

  • Neonate/infant with open anterior fontanelle
    • Median age of closure 14-16 months
    • 96% closed by 2 years

Setting

  • Temporising emergency procedure in child with acute hydrocephalus (right frontal horn via anterior fontanelle)
  • Done bedside
  • Can also tap a subdural collection via the anterior fontanelle
notion image

Clinical procedure

  • Experienced nurse/colleague to assist
  • Baby on bed/trolley, swaddled, held
  • Head neutral. Chair for you.
  • Sucrose
  • Prep skin, sterile dressing pack
  • Butterfly needle
    • Check on scan that butterfly long enough to get from entry point to ventricle
    • Go at 90° so it is long enough
  • Right side
  • Lateral aspect of fontanelle (avoid sagittal sinus)
  • "Z-plasty" skin to avoid a straight line track
  • Check
    • To see if there is vessel at fontanelle
    • To see if there is cortex: you want some cortex
  • Ask parents to leave
  • Go to edge of bone

Instructions and cautions

  • Max 10 mL/kg CSF
  • Take it slowly
  • Replace mL for mL with normal saline (risk of hyponatraemia) → status epilepticus
  • Send CSF to microbiology etc
  • Can be repeated but risk of infection, leak, skin breakdown
    • → Consider insertion of reservoir and/or more definitive treatment

Risks

  • Infection
  • Intra-parenchymal/intraventricular haemorrhage
  • Skin breakdown
  • Seizures if sodium dropped
  • Subdural etc if CSF taken very quickly/in excessively large amounts
  • Sinus injury if in midline
  • Child with massive ventricles and thin cortical mantle → try to choose somewhere with cortex to reduce risk of leaking post procedure

Contraindications 

  • Check for large vessels/lesion in vicinity

Other options to manage HCP in a child

  1. Fontanelle tap
    1. Closes at 9-18 months
    2. Cannot do repeatedly
      1. Iatrogenic encephalocele
      2. Bleeding
      3. CSF leak
    3. Method
      1. Right frontal
      2. Edge of fontanelle (away from midline)