Lumbar puncture

Last revised by Henry Knipe on 14 Mar 2023

Lumbar puncture is a commonly-performed hospital procedure in which a needle is inserted through the back to the subarachnoid space in the spinal canal often to collect some cerebrospinal fluid or inject a therapeutic agent. The procedure can be performed under imaging guidance, e.g. fluoroscopy, CT or ultrasound-guided. In many locations, imaging-guided lumbar punctures are increasingly the norm 3.

  • CSF sampling (for suspected meningitis or encephalitis, or in suspected subarachnoid hemorrhage with a normal CT)

  • opening pressure measurements

    • large volume taps (30-40 mL) can be performed as a diagnostic procedure to assess short-term relief of symptoms of normal pressure hydrocephalus prior to VP shunting

  • administration of intrathecal chemotherapy

  • administration of contrast (e.g. CT myelography, nuclear medicine CSF leak studies) 1,4

  • severe bleeding disorders, extreme thrombocytopenia

  • suspected epidural abscess or infections in the line of entry

  • deformation of / trauma to the lumbar vertebrae

  • brain tumor, abscess, or other lesions that cause elevated intracranial pressure

Due to the possibility of brain herniation in patients with elevated intracranial pressure, many clinicians will order a head CT before the procedure. Different medical societies have varying recommendations about this issue, however, focal neurological findings or altered level of consciousness should prompt consideration of this complication.

The basic equipment for the procedure should be gathered beforehand and may include needles, specimen bottles and tubes, and manometers.

Blind lumbar punctures are usually performed with patients in a decubitus position with their knees bent towards their chest. Aseptic technique is mandatory. Local anesthesia can be given. With manual palpation, the performer identifies L3, L4, and L5, then guides a needle through the opening between the vertebrae.

  • patient to rest supine on the bed (varies by institution but typically up to 4 hours)

  • pain score assessed immediately and 15-20 minutes post procedure

  • observe for 20-30 minutes for any immediate complications

Complications associated with LP occur rarely. However, minor and major complications can occur even when good technique and standard infection control measures are used. These complications include:

  • post-LP headache (in up to 33% 4)

  • failure to obtain a specimen / need to repeat LP / traumatic tap (common)

  • infection (or spinal abscess)

  • bleeding (e.g. from vertebral artery puncture)

  • minor neurologic symptoms, e.g. transient pain/numbness/paralysis

  • back pain

  • seizure

  • cerebral herniation (rare)

  • late onset of epidermoid cysts of the thecal sac

ADVERTISEMENT: Supporters see fewer/no ads

Updating… Please wait.

 Unable to process the form. Check for errors and try again.

 Thank you for updating your details.