Lumbar puncture is a potentially uncomfortable procedure that must not be rushed. It is essential to position the patient correctly and take your time.
Lumbar Puncture Reference Links
Indications
- Diagnostic
- Evaluate CSF in suspected meningitis, SAH, carcinomatosis, multiple sclerosis and syndromes such as Guillain-Barré.
- Measure CSF pressure.
- Therapeutic
- Intrathecal administration of medications.
- Removal of CSF in benign intracranial hypertension.
- Indications for CT head scan prior to LP
- Age >60 years
- Immunocompromised state
- Neurological findings, such as ALOC or focal neurological deficits
- Objective evidence of raised ICP such as papilloedema, bradycardia and headache
- History of CNS lesion (e.g. stroke, mass lesion, focal CNS infection)
- Seizure activity in the preceding week
Complications
- Failure to obtain adequate CSF
- Post-LP headache
- Increased risk with large bore needle, multiple attempts, excessive CSF removal, dehydration, women
- Reduce risk by using an atraumatic needle (e.g. Sprotte or Whitacre) rather than a cutting needle (e.g. Quincke) – (separation rather than cutting of dural fibers) and by orienting the bevel of the needle parellal to the long axis of the spine (back flexion is more likely to close a longitudinal rather than a horizontal slit.
- Brain-stem compression secondary to brain herniation
- Local haemorrhage and epidural haematoma
- Back pain (very common)
- Infection (very rare): epidural abscess, meningitis
- Acquired intraspinal epidermoid tumors (due to use of an LP needle without a stylet)
Handy Hints
- Positioning:
- Prone positioning may reduce risk of post-LP headache [Reference: Medscape]
- Failure of postural manoeuvres to prevent lumbar puncture headache Hilton Jones – 1982 PDF
- Flexion of the neck may be uncomfortable and is not necessary
- Sitting position for LP
- When performing LP sitting the legs should not be hanging – they should be on a stool to facilitate hip flexion which increases the interspinous width
- In the sitting postion the midline is easier to determine and CSF flows are higher, especially in the dehydrated patient. Manometer readings are unreliable however
- Locating the inter-vertebral space:
- In adults the spinal cord may terminate as low as the L2 body, therefore LP should performed at the L23, L34, or L5S1 intervertebral spaces.
- Ask the patient if the needle feels like it is dead centre. People can usually tell if it feels like the needle is off to one side
About Mike Cadogan
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