Lumbar puncture

Removal of cerebrospinal fluid (CSF) for diagnostic purposes.

Indications

Suspicion of meningitis (fever, vomiting, nuchal rigidity.)

Contraindications

Intracranial hypertension, Pott's disease.

Material

Lumbar puncture needle with a stylette (for adults, 20G; for children, 23G).

Position of the patient

If possible, the patient should be sitting, back rounded, vertebral column rectilinear, head bent, chin on the sternum, and arms across the knees. If this is not possible, put the patient in the fetal position with back rounded and head flexed.

Technique

· Cleanse the lumbar region with polyvidone iodine(see table page 7) and if possible use sterile gloves.

Mark the spinous process of the 4th lumbar vertebra by a horizontal line between the superior iliac crests (in adults, the spinal cord descends to the second lumbar vertebra; in children, it descends to the 4th).

· Place the tip of the left index finger on this spine.

· Inject exactly between the two spines (L3 and L4 or L4 and L5) rapidly traversing the skin, then horizontally or obliquely towards the head.

· In adults, at a depth of 3 to 4 cm, there is resistance due to the transverse ligaments: if a needle is advanced a little further, the epidural space is reached.

· Remove the stylette and if the puncture is successful, liquid will appear. Do not aspirate the syringe, but collect the liquid in a bottle.

· Replace the stylette in the needle and withdraw together, then compress the puncture wound with a dressing of polyvidone iodine (see table page 7).

· After the lumbar puncture, confine to bed for 24 hours.

Incidents

· Failed puncture
Start again (the axis of the needle is incorrect, there has been contact with bone, the position of the patient is incorrect, the needle has not been advanced sufficiently).

· Bloody puncture
Start again (puncture of a peridural vein, or subarachnoid hemorrhage).

· Sudden pain in the inferior limb
Occasionally a caudal nerve is hit; do nothing but ensure that the CSF is examined.