Lumbar puncture, also known as a spinal tap, is a medical procedure whereby a needle is inserted into the spinal canal to collect cerebrospinal fluid for diagnostic (CSF) testing. CSF is the fluid that is found in the brain and the spinal cord. The main objective of this procedure is to help diagnose diseases and find infections in the central nervous system, which includes the brain and spine.

The Cerebrospinal fluid obtained from the Lumber puncture can be used to diagnose the following diseases:

• Hydrocephalus
• Meningitis
• Demyelinating diseases
• Bleeding around the brain
• Multiple sclerosis
• Myelitis
• Guillain-Barré syndrome
• Neurosyphilis
• Inflammation of the brain or spinal cord
• Cancers that affect the brain and the spinal cord
• Headaches that occur without any known cause

Although lumbar puncture is mostly used for diagnostic purposes, it is sometimes used to administer medication through the spinal canal, especially in some cases where chemotherapy medication is required.

The Need for a Lumbar Puncture

There are different reasons for conducting a lumbar puncture procedure, which include:

• To collect cerebrospinal fluid for laboratory analysis in order to diagnose different disorders
• To measure the pressure of the patient’s cerebrospinal fluid
• To inject anesthetics, chemotherapy drugs, or other medication
• Dye or radioactive substances are injected into the cerebrospinal fluid during diagnostic imaging
• To test certain cancers involving the brain or spinal cord
• Can be used to detect bleeding around the brain
• To detect certain inflammatory conditions of the nervous system

Possible Risks Associated with Lumbar Puncture

A lumbar puncture, just like any other procedure, has some possible risks including:

• Back pain: The patient may feel pain or tenderness in his/her lower back after the procedure
• Temporary numbness of the lower body
• Bleeding: Can occur near the puncture site or rarely into the epidural space
• Post-lumbar puncture headache: The headache experienced after a lumbar puncture procedure is normally caused by a leak of the fluid into nearby tissues. The pain can last from a few hours to a week or even more.
• Brainstem herniation: This is a condition that occurs when there is increased pressure within the skull. It can be a result of a brain tumor or other space-occupying lesions. It can lead to a compression of the brainstem after removing a cerebrospinal fluid sample.
• Infection: This can occur as a result of the needle piercing the skin and as a result bacteria entering the body.

Lumbar Puncture Procedure

During the procedure, which can be done on an out-patient or inpatient basis, the patient is injected with a local anesthetic into the lower back to numb the puncture site. A hollow needle is inserted between the two lower vertebrae through the spinal membrane into the spinal canal. At this stage the patient is requested to remain absolutely still once the needle is in place. The CSF pressure is measured, a small amount of the fluid is withdrawn and the pressure is measured again. If there is medication to be administered to the spinal canal, it is done through the same needle after collecting the cerebrospinal fluid. The needle is then removed, and the puncture site is covered with a bandage.

Possible Results After a Lumbar Puncture

• White blood cells: Increased number of white blood cells may indicate an infection
• Sugar (glucose): Low glucose level in the spinal fluid may indicate an infection
• Microorganisms: The presence of viruses, fungi, and bacteria may indicate an infection
• Cancer cells: The presence of abnormal cells in the spinal fluid may indicate a certain type of cancer
• Protein: Increased levels of total protein, normally above 45 milligrams per deciliter may indicate an infection
• General appearance: Based on the appearance of the CSF, the medical health providers can determine whether there is an infection or any other condition. The CSF is normally clear and colorless. Cloudy, yellow or pink, might indicate abnormal bleeding. Green might indicate an infection or the presence of bilirubin.

Post Op Care

After the lumbar puncture procedure, the patient may feel some degree of discomfort. For this, he/she is prescribed pain medication. The patient should take a nonprescription pain-relieving medication that contains acetaminophen which helps reduce headache or back pain. Additionally, he/she is advised to have sufficient rest and not to participate in any strenuous activities.

If the patient experiences tingling of the legs, numbness, bleeding from the injection site, severe headache or inability to pass urine, he/she is advised to call their doctor as soon as possible.