- Suspected meningoencephalitis
- Suspected subarachnoid hemorrhage despite negative CT
Risk for cerebral herniation:
- Altered mentation
- Focal neurologic signs
- Seizure within the previous week
- Impaired cellular immunity
- Infected skin over the needle entry site
- Coagulopathy (e.g. anticoagulant or antiplatelet use, renal failure) is a relative contraindication
Prepare the Patient
- Inform the patient about the procedure
- Position the patient in the lateral recumbant or sitting position with the hips, knees and chin flexed towards the chest
- Identify the L3-L4 interspace which is at the level of the posterior superior iliac crests. Identify the L2-L3 interspace and the L4-L5 interspace. Mark the interspace which is widest.
Prepare the Equipment
- Mentally rehearse the procedure steps and assemble the necessary equipment
Sterilize and Drape
- Don sterile gloves
- Clean the skin over the L2-L4 area using antiseptic solution
- Place sterile drapes around the work area
- Administer local anesthetic under the surface of the skin at the target site +/- anesthetize the deeper tissue
- Insert the spinal needle, with the bevel parallel to the spine, at a slightly cephalad angle, aiming towards the umbilicus, and advance the needle approximately 3-4 cm.
- Remove the stylet and check for fluid return; if no fluid i obstained, replace the stylet, advance a few millimeters and repeat the process until CSF is obtained.
- Attach the manometer and note the height of the fluid column. The patient’s legs should be straightened during pressure measurement.
- Collect cerebrospinal fluid in each of 4-5 tubes (10 drops – 1 ml in each tube)
- Replace the stylet and remove the needle
- Apply a sterile dressing
- Cerebrospinal Fluid Analysis depending on the context:
- Cell count and differential (first and the last tube)
- Glucose and protein levels
- Direct microscopy, Gram stain, bacterial cultures, PCR for HSV etc.
- Spectrophotometry if the setting of suspected subarachnoid hemorrhage