Lumbar puncture Dr. Neil Stone Centre for Global Health, Institute of Infection and Immunity St. George’s, University of London

Intended learning outcomes To be aware of the indications and contra-indications for lumbar puncture To be aware of the equipment required for performing a lumbar puncture To understand how cerebrospinal fluid pressures are measured To be aware of the possible complications lumbar puncture

Lumbar puncture Diagnostic Therapeutic Indications CSF sample for CrAg, culture, protein, glucose, cell count Therapeutic To reduce intracranial hypertension in cryptococcal meningitis Contra-indications Infected skin over the needle entry site Suspected cerebral space occupying lesions Brain abscess Coagulopathy

Lumbar puncture Equipment Spinal/lumbar puncture tray Sterile dressing Sterile gloves Sterile drape Antiseptic solution with skin swabs Lidocaine 1% without epinephrine Syringe, 10 mL Needles, 20 and 25 gauge Spinal needles, 20 and 22 gauge Manometer with three-way stopcock Four plastic test tubes, numbered 1-4, with caps Spinal/lumbar puncture tray

Lumbar puncture Procedure Explain the procedure to the patient or attendant and get informed consent. Asepsis should be observed during the procedure. Use local anaesthetic agents to anaesthetise the skin. Access the subarachnoid space through L2-L3,L3- L4 or L4-L5 intervertebral spaces (L4 can be located between the iliac crests) Perform manometry. Collect at least 10 drops of CSF in each of the 4 test tubes. Apply sterile dressing at the site of the puncture Place patient in supine position. Draw serum glucose to compare CSF glucose

Lumbar puncture Estimating CSF opening pressure Normal CSF pressure ~10-20 cmH20 (recumbent) Patient must be in lateral recumbent position. After CSF is returned from the needle, attach the manometer through the stopcock. Note the height of the fluid when it stops rising. Keep the patients leg straight to avoid getting false elevated CSF pressure . Recheck the pressure at the end of the procedure (closing pressure) – aim for <20 cm H20

Lumbar puncture Samples collection Sterile conditions Specimens should be taken to the lab promptly 4 sterile tubes Tube 1 – CrAg, protein and glucose levels Tube 2 –India ink, Gram stain, C&S Tube 3 - Cell count and differential Tube 4 – “Special” or repeat tests CSF collection tubes. Image courtesy of Gil Z Shlamovitz, MD.

Lumbar puncture Possible complications Post–spinal puncture headache (20-70%) Bloody tap Dry tap Infection Haemorrhage Dysesthesia Post–dural puncture cerebral herniation Post-spinal headache Leakage of CSF from puncture site. Onset is usually 24-48 hours post- procedure Self-limiting (<7days). Improves in the supine position Treat with simple analgesics and caffeine.

Recommendations Improve access to lumbar puncture equipment including manometers Provide adequate training in the technique to health care workers Perform therapeutic lumbar punctures as often as needed during CM therapy aiming to keep pressure below 20 cm H20 Manometer should always be used - pressure cannot be assessed by simply observing the speed with which the CSF drips out of the needle

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