Clinical guide
- Can you obtain CSF?
- Small volume of CSF → are ventricles slit like?
- Free flowing or only on aspiration?
- Opening pressure?
- Clear CSF? Turbid? Debris?
Procedure
- Bedside, quick, minimal equipment, no anaesthetic
- Diagnostic – proximal shunt malfunction/infection
- Therapeutic – temporise patient by removing a volume of CSF prior to shunt revision/EVD insertion (can be lifesaving if patient in local hospital)
Preparation
- Check on imaging/operation notes:
- Type of valve – in built reservoir vs separate reservoir vs no reservoir (cannot tap if no reservoir)
- (vs reservoir without valve)
- Location of valve
- Shunt series – distal fracture/disconnection? May obviate need for tap
- Difficult to palpate valve/reservoir?
- Can patient/parent help you find it?
- If recent surgery, can you count staples on 3D CT to work out where to tap reservoir?
- Paediatric patient (or confused adult)?
- Take an assistant to hold patient for you
- Small baby → swaddle, sucrose, assistant holding baby
- Child → try not to cover face with drape, judge whether parents will be helpful
- Prep, sterile pack, butterfly needle, manometer
- Risks of introducing infection, introducing an airlock, or damaging valve
- Dry tap – ventricular catheter likely blocked
- High opening pressure suggests distal malfunction
Risk
- Speigelman 2014: Risk of shunt tap causing infection 0.2%
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