Technique

• Standard contraindications to lumbar puncture apply—alternatives will be needed in these situations. Cytotoxics should be made up freshly in smallest possible volume in a sterile pharmacy.

• Consider GA for children and IV sedation for adults.

• Use special LP 'blunt' needle or small gauge bevelled LP needle.

• Aim to remove the same volume of CSF as you are injecting intrathe-cally (may be several mL if giving triple chemotherapy).

• Take samples for CSF cytospin to determine blast cell concentration, microbiology for M/C/S, biochemistry for protein and glucose.

• Check syringe cytotoxic dose carefully with another person before connecting.

• Connect syringe and aspirate gently to confirm position in CSF. Inject slowly, drawing back at intervals to reconfirm position. Disconnect syringe and connect other syringes in turn if giving 'triple'.

• Follow standard post-LP precautions. Document procedure in notes.

• Repeated IT chemotherapy carries risk of CSF leakage and post-LP headache. Manometry pre-injection may help assess whether less CSF should be withdrawn pre-injection.

• A syndrome of methotrexate-induced neurotoxicity occurs in a few patients presenting with features of meningo-encephalitis. Aetiology is unknown. Treat with short pulse of high dose steroids.

^ Do not give further IT methotrexate to these patients.

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