Lumbar puncture

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A lumbar puncture (CSF puncture) refers to the removal of a nerve water sample from the spinal canal. It is used to diagnose various diseases and is also used for therapeutic purposes or to introduce local anesthetics. Read everything about the lumbar puncture, the areas of application and the risks here.

What is a lumbar puncture?

With a lumbar puncture, nerve fluid (liquor) is taken. To do this, the doctor uses a thin puncture needle, which he pierces into the spinal canal at the level of the lumbar spine. The nerve water drips from this into a sample vessel. During the CSF examination, the doctor examines the nerve water (which is why the term brain water examination is also used) for the presence of different cells, for example blood or inflammatory cells.

When to do a lumbar puncture

The lumbar puncture is used for both diagnostic (liquor diagnostics) and therapeutic purposes.

Lumbar puncture as a diagnostic tool

The CSF puncture serves to detect or exclude various diseases:

• Brain and spinal cord tumors
• Cancer of the meninges, for example lymphoma
• inflammatory diseases of the brain (encephalitis) or meninges (meningitis)
• Infectious diseases (Lyme disease, neurosyphilis, and others)
• Subarachnoid hemorrhage
• multiple sclerosis

In addition, the doctor can measure the pressure inside the skull as part of the CSF diagnostics in order to determine an expansion of the so-called liquor spaces (hydrocephalus).

Lumbar puncture for therapy

Medicines can be introduced into the spinal canal through the puncture needle. These include, for example, local anesthetics or chemotherapy drugs. If a patient has normal pressure hydrocephalus, i.e. an enlargement of the liquor spaces without increasing pressure, the fluid spaces can be relieved by means of a lumbar puncture by draining nerve water.

When is it not allowed to perform a lumbar puncture?

The bleeding tendency of the patient is excluded prior to the removal of the CSF. Blood-thinning medication may have to be discontinued.

Blood platelets (thrombocytes) can be given to patients who suffer from thrombocytopenia, which is associated with a blood platelet deficiency and thus an increased tendency to bleed, if the lumbar puncture is urgently needed.

A lumbar puncture is not possible with increased intracranial pressure or inflammation of the skin, subcutaneous tissue or muscles at the puncture site.

What do you do with a lumbar puncture?

Whether the lumbar puncture is to be performed on an outpatient or inpatient basis is always decided on an individual basis, depending on the general health of the patient.

The brain and spinal cord are surrounded by three membranes. The hard meninges are on the outside, soft meninges are on the inside. In between there is a narrow gap, the so-called subarachnoid space, in which the nerve water is located.

Lumbar puncture: implementation

For a lumbar puncture, the patient either sits relaxed on a patient couch with his back bent or lies on his side, pulls legs and arms and puts his chin on his chest.

As a result of these positions, the vertebral body processes diverge widely and allow good access to the intervertebral spaces through which the lumbar puncture takes place. As a rule, the doctor punctures the space between the third and fourth or fourth and fifth lumbar vertebrae after marking and disinfecting the puncture site. Upon request, the patient can be given a syringe with a topical anesthetic.

If cerebrospinal fluid cannot be withdrawn from the lumbar region, the puncture can be made below the occiput (suboccipital puncture).

The doctor carefully pierces the skin and muscles with a hollow needle and pushes them into the spinal canal between the vertebral bodies. The liquor now drips through the hollow needle into a sample vessel.

Once sufficient nerve fluid has been obtained, the doctor withdraws the needle and bandages the wound.The CSF diagnostics are then carried out in a laboratory.

What are the risks of a lumbar puncture?

Risks that exist and that the patient must be informed about include:

• Bleeding and bruising
• Infection and inflammation
• Circulatory and consciousness disorders (syncope)
• temporary nerve failure with numbness or paralysis

The lumbar puncture can trigger a seizure in patients with seizure disorders such as epilepsy or migraines.

Another risk is the so-called CSF negative pressure syndrome, in which the patient suffers from headaches, neck stiffness, ringing in the ears (tinnitus), nausea and sensitivity to light. It can occur after a CSF puncture when the patient sits up or stands up from a lying position. The symptoms can be alleviated by the administration of certain medications such as theophylline or an injection of autologous blood into the epidural gap (blood patch). The use of a puncture needle that is as thin as possible and a correct insertion angle reduces the risk of developing CSF negative pressure syndrome.

Is a lumbar puncture painful?

The lumbar puncture can be performed under local anesthesia if desired. Nevertheless, patients sometimes find the procedure uncomfortable because the meninges are irritated when the puncture needle is inserted.

What should I watch out for after a lumbar puncture?

After the lumbar puncture, you should lie on your stomach for about half an hour to a full hour to prevent nerve water from flowing in. Even in the first few hours after the puncture, you should largely keep bed rest. However, you can go to the toilet on your own or sit up to eat.

Lumbar puncture: side effects

Before the lumbar puncture, your doctor will tell you about possible side effects that may occur in the days after the procedure:

• Headache, backache
• Nausea, vomiting
• Localized pain at the injection site

The most common side effects are nausea and headache after a lumbar puncture. However, the symptoms are rarely severe and usually resolve on their own within a few days - sometimes only after a few weeks. Drink enough water after the lumbar puncture; You can often relieve pain in the head and back. If the symptoms do not go away or get worse, you should consult a doctor. If the side effects are particularly severe, you may have to be admitted to the hospital or your stay in hospital may be extended.

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