Lumbar Puncture (Upright)
Possible indications:
- Assessment of CNS infection.
- Diagnosis of subarachnoid hemorrhage in setting of normal CT scan.
- Diagnosis of normal pressure hydrocephalus.
- Diagnosis of other neurological disorders (i.e. lymphoma, GBS).
- Intracranial hypertension diagnosis and management.
- Lumbar drainage in aortic surgery.
- Drug administration (i.e. intrathecal chemotherapy).
- Myelography (intrathecal injection of contrast in imaging).
Contraindications:
- Increased intracranial pressure (risk of herniation).
- Platelets < 50,000.
- INR > 1.7, therapeutic anticoagulation.
- Suspected spinal epidural abscess or infection at LP site.
When to obtain CT Head Before LP:
- Focal neuro deficits.
- Altered mental status.
- New onset seizures.
- Immune compromised.
- Papilledema.
- Suspected metastatic cancer.
Equipment to obtain:
- Note: All equipment here can be found in the Davies 4 ICU.
- Lumbar puncture kit
- Sterile gloves + chlorhexidine swab x2
- 5mL syringe + lidocaine 1% without epi + blunt tip needle + 25+ gauge needle
- Extra LP needle can be kept in room
- Tegaderm bandage
Initial setup:
1. Initial patient assessment
- Assess patient for contraindications or need for possible CT.
- Obtain patient consent for procedure from patient or family. Complications to discuss: local discomfort, Infection< 1%, bleeding < 1%, nerve injury < 0.01%, post LP headache 10-20%.
- Have patient sit upright in bed, then bend over side table, with knees elevated. Upright position may be preferred when no opening/closing pressures needed. Lateral decubitus position is better for opening/closing pressure measurement.
- Landmark the highest points of the superior iliac crests (approx. 4th lumbar vertebrae) and feel spinous processes and interspaces, identify L3-L4, or L4-L5 interspace.
- Ultrasound with abdominal probe can be used in transverse + longitudinal plane to ensure that palpated area truly is midline + spinous process visualized.
- Mark area of target needle insertion with blunt tip or surgical marker.
Procedural Steps:
1. Needle insertion
- Patient sitting at edge of bed leaning on bedside table.
- Apply chlorhexidine wipe to lower spine at area of needle insertion.
- Open LP tray + empty supplies onto sterile field (empty in blunt tip, lidocaine 1% without epi, and 25-gauge needle). Place LP tubes upright (and in order-the numbers are written on the tubes) + note how many mL will be needed in each tube (i.e. 2-4mL).
- Note for diagnosis ie in lymphoma = may need higher volumes ie 20-30cc.
- Drape patient over site of insertion.
- Inject skin and deeper subcutaneous tissue with lidocaine.
- Use the longer needle to then anesthetize down to periosteum. Wait 1-2 minutes.
- Insert LP needle into L3-L4 or L4-L5 space (as previously landmarked).
- Needle bevel pointed to the left or right of patient. Since patient is upright, this will be parallel to long axis of spine.
- Angle needle at 30 degrees to skin + aim needle towards umbilicus. Needle will pass through skin, superficial fascia, supraspinous ligament, interspinous ligament, ligamentum flavum, (can feel this pop here) epidural space, dura, (can feel this pop here) arachnoid membrane.
- As advancing needle can remove stylet when approach dura to see if have CSF flow back out. Once in the subarachnoid space + CSF flowing easily: Opening pressure can be measured.
- CSF samples collected in each tube labelled 1-4 (usually 2mL in each).
- Closing pressure can be measured prior to needle withdrawal.
- Place bandage or Tegaderm over puncture site.
2. Post-procedure:
- Have patient lie flat for 30 minutes. Monitor for post dural headache.
- Possible LP diagnostic tests:
- Tube 1 = cell count + differential.
- Tube 2 = glucose, protein, Ace level.
- Tube 3:
- bacterial testing:, gram stain + culture,
- viral testing: PCR for HSV, varicella, ebv, cmv, west nile virus, HHV6, JC virus, adenovirus, enterovirus. Igm for west nile virus.
- mycobacterial/other: mycobacterial culture, VDRL, lyme, AFB. fungal: culture, cryptococcus.
- Tube 4 = cytology + flow cytometry
Prcoedural steps written by: Muraile Vignarajah MD
Staff Reviewed by; Dr. Gordon Boyd (Neurology, Critical Care)