Lumbar puncture

Description:

• A procedure that involves inserting a needle into the lumbar spinal canal.

Indications:

• To collect cerebrospinal fluid (CSF) samples in a suspected case of meningitis or other serious infection.
• To support or exclude diagnoses, such as subarachnoid hemorrhage or certain types of cancer involving the brain or spinal cord.
• To diagnose certain diseases of the central nervous system, such as multiple sclerosis or Guillain-Barré syndrome.
• To measure CSF pressure.
• To inject anesthetic medications, chemotherapy drugs, or antibacterial drugs.
• To inject contrast for a clear visualization of the spinal cord, spinal nerve roots, and the subarachnoid space during a myelogram.
• To remove CSF and reduce pressure in conditions such as benign intracranial hypertension (pseudotumor cerebri).

What to expect:

            Prior to the procedure

• If you have a bleeding disorder or are taking medications that thin your blood (such as warfarin, aspirin, or clopidogrel), notify your doctor.
• Empty your bladder immediately before the procedure for comfort.
• No dietary restrictions or pre-procedural medications are usually needed.
• Notify your doctor if you have had previous back surgery.
• If you are allergic to local anesthetics (such as lidocaine), report this prior to the procedure.

During the test

• The procedure is usually completed at the hospital bedside or in a doctor’s office.
• You will be positioned on your side along the edge of the bed with your knees drawn up to your chest.
• The small of your back (the lumbar area) will then be cleansed thoroughly with antiseptic skin swabs and draped with a sterile towel.
• The doctor will then inject a local anesthetic, such as lidocaine to numb the area.
• Once the area is numb, a long, thin needle will be inserted between the vertebrae (usually between the 3rd and 4th).
• At this point, you may be asked to straighten your legs so the doctor can accurately measure the CSF pressure.
• Once a sufficient amount of CSF is collected, the needle is removed and a Band-Aid is applied over the site.

After the test

• Once the procedure is completed, you may be asked to lie flat for 1 to 4 hours to avoid getting a headache.
• If you are able to go home afterwards, get plenty of rest and do not participate in strenuous activities the day of your procedure.
• It is important to drink plenty of fluids.
• The morning after the procedure, you may remove the Band Aid and take a bath or shower.
• If you develop a headache after resuming normal activity, return to resting and increase your fluid intake. 
• A pain-relieving medication, such as Tylenol or ibuprofen can help reduce headache or back pain.
• Call your doctor if you develop chills, fever, a stiff neck, a severe headache, or drainage from the puncture site.

How long will it take?

• The procedure usually lasts 20 to 30 minutes.

Will it hurt?

• When the doctor injects the numbing medication, you will probably feel a brief pinch or slight burning sensation.
• You may also feel some pressure and slight soreness when the spinal needle is inserted.
• The procedure is not usually painful because of the numbing medication, but it may be uncomfortable.  Generally, the overall discomfort is reported as minimal to moderate. 
• Following the procedure, 10-30% of individuals will develop a headache.  They usually last 24 to 48 hours and go away on their own.

Results:

• Your results will typically be given to you within a few days; however, the length of time varies significantly.  Your doctor should be able to give you an estimate as to when to expect the results.

Information from the National Institutes of Health, April 2010

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