Lumbar Puncture: Indications and Complications

The brain and the spinal cord are immersed in a fluid called the cerebrospinal fluid. This fluid is responsible for providing nutrients and oxygen to, and removing waste and carbon dioxide from, the brain and the spinal cord. Lumbar puncture is a diagnostic and therapeutic procedure. Your doctor introduces a needle into your lower back to reach the space around the spinal cord to measure the pressure of the cerebrospinal fluid, obtain a sample of cerebrospinal fluid or inject a drug into the cerebrospinal fluid.

Procedure of Lumbar Puncture

Lumbar puncture is done on an out patient basis. You will be asked to change into a hospital gown, after which you will be asked to lie on one side with your knees hugged to your chest. This procedure can also be done in the sitting position with you leaning onto a firm support. Flexing the back widens the space between the vertebral spines and makes it easier for the doctor to access the space around the spinal cord.

A local anaesthetic is injected at the site of the procedure. You might feel a slight stinging sensation which will slowly disappear. After the effect of the anaesthetic sets in, your doctor will insert a needle into your lower back, to reach the space around the spinal cord. On reaching the space your doctor will measure the pressure, followed by which a sample of the cerebrospinal fluid will be collected in a sterile container. If the lumbar puncture has been indicated for therapeutic purposes, the prescribed drug will slowly be injected into the space surrounding the spinal cord. After the procedure, the needle will slowly be removed from the back and sterile dressing will be applied to the area where the needle pierced the skin.

Indications for Lumbar Puncture

Lumbar puncture is indicated for diagnostic and therapeutic purposes. Your doctor would like to request a lumbar puncture to:

• Confirm diagnosis of meningitis and the causative organism
• Rule out sub arachnoid haemorrhage in patients with severe headache
• Investigate neurological disorders like sarcoidosis, multiple sclerosis and Gillian barre syndrome
• Demonstrate and manage disorders with increased pressure in the cranium
• Diagnose cancers of the nervous system
• Administer therapeutic agents like anaesthetic, chemotherapy drugs.

Preparation for Lumbar Puncture

Your doctor will want to know about the medications that you’ve been taking. On the appointment before the procedure you will be requested to stop taking blood thinning medications. Inform your doctor if you have a history of allergy to anaesthetic agents.

Complications of Lumbar Puncture

Lumbar puncture is considered to be a safe procedure. The complications following the procedure can be:

• Post lumbar puncture headache: experienced by nearly 25% of patients, the headache generally resolves within a few days
• Bleeding at the site of procedure, or bleeding into the space around the spinal cord
• Tenderness at the site of the procedure
• Herniation of the brainstem.

Recovery after Lumbar Puncture

After the procedure you will be advised to lie on the bed for some time. It is advisable to abstain from strenuous activity on the day of the procedure. You doctor will prescribe pain medications if necessary. The samples of cerebrospinal fluid taken during the procedure will be sent to a lab for analysis; your doctor will discuss the results with you during the upcoming appointment.

Resources

• Diagnostic Lumbar Puncture, Carolynne M Doherty, MRCP, Neurology Registrar and Raeburn B Forbes, MD(Hons) FRCP, Consultant Neurologist, Ulster Med J. 2014 May; 83(2): 93–102