Spinal Tap (Lumbar Puncture)

A spinal tap, also called lumbar puncture, refers to the procedure of inserting a thin, hollow needle into the lower back area of the spine between two lumbar bones (vertebrae).

Uses of a spinal tap

A spinal tap can be used to remove a sample of cerebrospinal fluid (CSF), the clear, colorless fluid that surrounds the brain and spinal cord.  The extracted fluid can then be analyzed for the presence of an infection or other problems such as abnormal cells or cancers.

A spinal tap can also be used to measure the pressure of the fluid in the spinal canal and brain. In cases that require relieving pressure in the spinal canal, a small amount of CSF may be withdrawn using the needle.

Sometimes a spinal tap is used to inject chemotherapy drugs, spinal anesthetic agents, or other medications such as painkillers or antibiotics into the CSF.

Spinal tap as a diagnostic tool

The procedure can help physicians diagnose serious bacterial, viral, or fungal infections such as meningitis, syphilis or encephalitis.

A spinal tap can also help diagnose inflammatory conditions of the nervous system such as Guillain-Barré syndrome and multiple sclerosis. It can also be used to diagnose cancers involving the brain and spinal cord, as well as bleeding around the brain.

Spinal tap and ALS

A spinal tap is performed to exclude inflammatory nerve conditions and usually done only when the patient has unusual symptoms of ALS, such as spinal nerve abnormalities or no sign of abnormal reflexes or spasticity.

Many studies have indicated elevated levels of neurofilaments, a type of cellular proteins, in the CSF of ALS patients.

Other information

The procedure is safe and takes around 30 to 45 minutes. Common side effects include a headache and lower back pain.


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