What is lumbar puncture (LP) ?

Lumbar puncture is a procedure where we introduce a needle in coverings of spinal cord to collect fluid (CSF). The place at which we perform lumbar puncture is in lower back and spinal cord ends well before site of needle introduction. What continue there are the coverings of spinal cord which contain fluid. This is the same fluid which is produced in brain and circulates around the brain and then it drains down to spinal cord.

What is CSF (Cerebro-pinal Fluid) ?

This literally means brain and spinal cord fluid. This Fluid is produced in brain. This, then circulates within brain before entering brain coverings where it gets absorbed. This process of absorption happens through out the coverings of brain and spinal cord. CSF has various functions. Important functions are providing nutrition and act as shock absorbent for brain. CSF is produced and absorbed 3 times in 24 hours.

How it is performed ?

Patient is asked to bring his knees and head closer to chest if he is lying down or simply asked to bend forward if in sitting position. This maneuver increases space between 2 vertebral bodies creating space for introducing needle. In infants toddlers and neonates a second person bends them forward for achieving the same position. A needle is introduced in the space between 2 vertebrae (Called ‘Manka’ in Marathi) in lower back. Nowhere during this procedure a bone is touched. What is pierced is the muscle layer between 2 bones. Then needle travels to the CSF covering through which we collect approx 5-7 ml of fluid following which the needle is taken out. The space created by needle gets sealed automatically. Usually the chance of bleeding are exceptionally low during procedure. In younger children we use sedatives to keep child calm and achieve pain relief. Older children are given local anesthesia only. 

What are the indications (when do we perform) of lumbar puncture ?

Usually the fluid collected will give us information about various conditions. As blood test gives information about various conditions in body, this fluid will tell us about many diseases of brain and spine.

Common indications to perform a lumbar puncture are:

To understand about brain infections like meningitis or encephalitis

To understand about demyelinating brain disorders

To understand inflammatory brain disorders

To assess response to treatment in case of brain infection

Rare indications to perform a lumbar puncture are:

To understand about metabolic conditions of brain

To understand about neurotransmitter disorders of brain

Lumbar puncture for drug delivery:

Lumbar puncture is often done to give medications directly in spinal fluid which reach brain and spinal cord directly like, cancer medications, anesthetic medications and certain other rarely used medicines.

What are side effects of lumbar puncture ?

Lumbar puncture is one of the safest procedure if it is done in carefully selected patient.

Common side effects:

  1. Lower back pain (most common side effect)
  2. Local bleeding at the site of lumbar puncture
  3. Local infection in the area of lumbar puncture
  4. Post lumbar puncture headache
  5. Shock like sensation because of irritation of nerves while doing a lumbar puncture

Less common side effects:

  1. Meningitis
  2. Brain herniation: Extremely uncommon but a reported complication. This is life threatening complication needing urgent neurosurgery.
  3. Cranial neuropathy: happens because of stretch on cranial nerves (nerves which supply face) secondary to negative pressure. It is self resolving with treatment.

What is post lumbar puncture headache ?

It is a fairly common complication of lumbar puncture. It tends to happen often in older children and adults. The reason is the CSF leak through the puncture area. This causes negative pressure in the brain and stretches the meninges (Brain coverings) leading to pain. Treatment to this remains conservative. This usually subsides within 2-3 days but can last up to 2 weeks.

Steps to prevent:

  1. Increased liquid intake which helps creating more CSF
  2. Lying down flat or head low increases positive pressure within brain

(We suggest patients not to sit for longer time, not to ambulate frequently and not to

use pillow, for 24-48 hours post lumbar puncture)

  1. Use of smaller size needles for procedure

Treatment of post lumbar puncture headache:

  1. Caffeine increases CSF production (We suggest to drink coffee & caffeinated drinks)
  2. IV fluids, if oral intake is poor
  3. Pain relief (Medications like paracetamol, Ibuprofen etc)
  4. Epidural Blood Patch (EBP):If conservative measures fail A small amount of the patient’s blood is injected into the epidural space near the puncture site to create a clot that seals the leak

Facts and Conclusion:

  1. Unfortunately people think twice before doing lumbar puncture because of unnecessary reservations.
  1. Overall lumbar puncture is safe procedure.
  2. Younger the child, tolerance to the procedure is better.
  3. Children by far have very low rate of complications.
  4. They have lower back pain much less often than adults.
  5. It can be done in awake state with local anesthesia in older children.
  6. Younger children, we use sedatives to calm the child and achieve good pain relief.
  7. Sedation helps to keep child calm reducing number of attempt to perform procedure.

Lesser number of attempts are equivalent to lesser complications. 

  1. Information received by lumbar puncture can not be replaced by any other test.
  2. In most of the situations Lumbar puncture and MRI brain are complimentary.
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